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- Publisher
- Hindawi Publishing Corporation
- ISSN
- 2356-654X
- eISSN
- 2314-7539
- DOI
- 10.1155/2023/8224053
- Publisher site
- See Article on Publisher Site
Abstract
Hindawi Advances in Agriculture Volume 2023, Article ID 8224053, 16 pages https://doi.org/10.1155/2023/8224053 Research Article Adaptability of Genetically Engineered Bt Cotton Varieties in Different Growing Regions of Ethiopia 1 2 3 4 Bedane Gudeta , Endale Gebre Kedisso, Donis Gurmessa, Dawit Tesfaye, 3 4 3 3 Samuel Damtew, Workishet Taye, Arkebe Gebre-Egziabher, Merdasa Balcha, 5 6 2 Tadessa Daba, Alehegn Workie, and Karim Maredia Ethiopian Institute of Agricultural Research (EIAR), Ambo Agricultural Research Center, P.O. Box 37, Ambo, Ethiopia College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA Ethiopian Institute of Agricultural Research (EIAR), Werer Agricultural Research Center, P.O. Box 2003, Addis Ababa, Ethiopia Ethiopian Institute of Agricultural Research (EIAR), Melkasa Agricultural Research Center, P.O. Box 436, Adama, Ethiopia Ethiopian Institute of Agricultural Research (EIAR), National Agricultural Biotechnology Research Center, P.O. Box 2003, Addis Ababa, Ethiopia Ethiopian Institute of Agricultural Research (EIAR), Debre Markos Agricultural Research Center, P.O. Box 2003, Addis Ababa, Ethiopia Correspondence should be addressed to Bedane Gudeta; bedaneg@gmail.com Received 3 March 2022; Revised 24 February 2023; Accepted 12 April 2023; Published 8 May 2023 Academic Editor: Othmane Merah Copyright © 2023 Bedane Gudeta et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Cotton varieties that are high yielding and resistant to pests are required to improve production and productivity and to capitalize on the crop’s enormous potential and its critical role in Ethiopia’s expanding textile industry. Lack of improved cotton technology has forced farmers to recycle local varieties for ages which have become very susceptible to pests which are the major causes of very low productivity and quality of cotton in the country. Among major pests, bollworms (Helicoverpa armigera and Pectinophora gossypiella) account for 36–60% of yield losses. In the absence of genetically resistant or tolerant varieties, genetically engineered bollworm-resistant Bacillus thuringiensis (Bt) cotton has ofered a great opportunity to reduce crop losses from bollworms. Te objective of the study was to evaluate the efcacy of bollworm resistance and adaptability of Bt cotton varieties across cotton growing environments in Ethiopia and provide recommendations. Two Bt cotton hybrids (JKCH 1947 and JKCH 1050), one Bt OPV (Sudan), and three OPV conventional varieties (Weyito 07, Stam-59A, and Deltapine-90) were evaluated at seven diferent agro-ecologies using a randomized complete block design (RCBD) with three replications. Results showed signifcant diferences among genotypes for yield and other traits. Hybrids JKCH 1947 and JKCH 1050 were the top high yielders under high and mild −1 −1 bollworm infestations, with mean seed cotton yield of 3.10 t·ha each and lint yield of 1.20 and 1.19 t·ha , respectively, whereas −1 −1 the standard check Deltapine-90 (popular variety) recorded a mean seed cotton and lint yield of 2.3 t·ha and 0.8 t·ha , re- spectively. Combined analysis showed that genotypes, environment, and the genotypes × environment interactions had a highly signifcant efect (P < 0.05) on fber quality. Weyito 07 and the two hybrids (JKCH 1947 and JKCH 1050) had upper half mean fber lengths in the range of 27.78 to 32.11 mm. For fber strength, genotypes Weyito 07, JKCH 1050, Stam-59A, and JKCH 1947 had 33.50 g/tex, 28.59 g/tex, 28.00 g/tex, and 27.75 g/tex, respectively. Te fber quality values of the hybrids were within acceptable limits, with staple lengths ranging from 27.78 to 28.44 mm and fber strengths ranging from 27.75 to 28.59 g/tex. Results show potential adaptation of the hybrids under diferent cotton growing environments and their superior yield performance due also to added protection of yield losses from damage by bollworms. Te contrast is bigger under high insect pressure conditions due to the genetically engineered Bt trait compared to the conventional varieties. Te efective feld resistance against bollworms in most locations shows that wider use of these hybrids can enhance cotton productivity and quality in Ethiopia. 2 Advances in Agriculture Cry genes identifed in the subsequent years such as Cry1, 1. Introduction Cry2, Cry9, and Cry13 were found efective against lepi- Cotton (Gossypium hirsutum L.) is the most important dopterous pests. Whereas, Cry3, Cry7, and Cry8 proteins industrial fber crop in Ethiopia. Te culture of cotton were efective against coleopterans, and Cry4, Cry10, and production and use in Ethiopia has been deeply rooted since Cry11 were efective against dipterous pests (Pathania et al., ancient times [1]. Cotton is a major cash and industrial crop 2019). Rapid global adoption occurred to this and other Cry extensively grown in the lowlands under large-scale irri- gene containing varieties developed periodically including gation schemes as well as under rain-fed conditions on those containing double Cry genes due to the efective small-scale farms [2]. Medium-staple cotton (G. hirsutum protection provided to the plant from pest attack and the L.) accounts for more than 95% of the total production in the proven safety and beneft brought to farmers and the en- country [3]. Being one of the major cash crops, cotton ofers vironment. Te benefts to farmers are refected in a higher considerable employment opportunity on farms, in textile yield and lower cost without the need for the expensive and factories, and in the ginneries [4]. Ethiopia has estimated 3.0 hazardous chemicals used to control bollworms. [23]. million hectares of potentially suitable cotton growing en- Ethiopia’s Biosafety Bill was passed in 2015, and global vironments for cotton production [5]. Of this, less than 3% is progress has been one of the driving factors for the Ethiopian currently cultivated with cotton [6]. Government to acquire Bt cotton varieties that have been Te industrial development policy of the Ethiopian approved for cultivation by national authorities in India and government has given priority to the development of the Sudan and have proven safety and efcacy in insect pest textile and garment sector, which demands a well- control for more than ten years. Te Bt cotton hybrids functioning and competitive cotton sector [7]. In Ethio- obtained from India and Sudan contain truncated Cry1Ac pia, the total cotton consumption of the factories is showing gene which has registered very high mortality of bollworms. an increasing trend every year [8]. However, the availability India ranks frst in cotton acreage (12.4 m·ha), occupying and quality of raw material are not satisfying the growing about 38% of the global area (32.6 m·ha) [9, 24]. Bt cotton is demand of rapidly expanding cotton-based textile industries planted by 7.7 million smallholder farmers with an adoption in the country. Despite increasing demand for raw cotton, rate of more than 96% [25]. Sudan ranks frst in the sub- production has been declining from time to time, particu- Saharan Africa in Bt cotton production, covering about 0.24 larly since 2010/11 (Figure 1) due to various problems af- million ha [26]. Tis paper is the frst report on the per- fecting cotton production and productivity in the country. formance of two commercial genetically engineered Bt Even though cotton is the main fber crop that plays a key hybrids, JKCH 1947 and JKCH 1050, developed by JK Agri role in the economic development of many countries in the Genetics Ltd. (JKAL) in India, as well as one open pollinated world [10], the growth, yield, and fber quality of cotton are Bt cotton variety, Sudan, tested and evaluated across constrained by several abiotic and biotic factors [11–14]. Ethiopia’s cotton growing regions. Te two Bt cotton hybrids Among the biotic factors are insect pests which are the and one open pollinated Bt variety were selected by the primary causes of yield and quality losses. Based on a feld Ethiopian Institute of Agricultural Research (EIAR) because survey conducted from 1986/87 to 1995/96, more than 60 of familiarity with the cultivars’ performance, efcacy of the insect and 2 mite species were reported from cotton felds in trait, and relative similarity of growing conditions where the Ethiopia [15, 16]. Among these insect pests, African boll- cultivars were developed and grown. Tus, decision was worm (ABW) (Helicoverpa armigera) and pink bollworm made to access seed from India and Sudan for a confned (Pectinophora gossypiella) were shown to be key pests of feld testing in Ethiopia. cotton, severely limiting production [15, 16]. Bollworms cause about 36–60% yield loss [17–19]. 2. Materials and Methods Signifcant eforts have been made to control the key pests through the use of chemical pesticide applications, which 2.1. Genotypes and Locations. Two Bt cotton hybrids: JKCH have proven inefective. Producers spray a minimum of fve 1947 and JKCH 1050 engineered with a truncated Cry1Ac to nine insecticidal applications without promising results, gene developed by JK Agri Genetics Ltd. (JKAL), India, and and no germplasm has proven resistant against the major one open pollinated variety (Sudan) containing Cry1A gene pests, which are bollworms. In large farms, pest control costs obtained from Sudan were introduced by Ethiopian Institute amount to 30–40% of the total production costs. Te re- of Agricultural Research (EIAR) for evaluation and release peated chemical spray not only triggers resistance devel- for commercial production in Ethiopia. Te three Bt vari- opment in the target pest, but it has also been noted that eties and three OPV conventional cotton varieties (Weyito cotton growers usually use the most hazardous (toxic) 07, Stam-59A, and Deltapine-90 or DP-90) that were re- pesticides without applying appropriate personal protection leased earlier from the National Cotton Research Program of measures that have signifcant health and environmental EIAR in Ethiopia and are under current production were efects. used in the experiment. Te conventionally improved va- Global adoption of bollworm resistance Bt trait- rieties were thus used as standard checks in the evaluation of containing cotton varieties began in 1996, when the frst the two Bt hybrids and an OPV. cotton transgenic with the Cry1Ac transgene conferring Tis study was conducted during the 2017 cropping bollworm resistance was approved for cultivation in the season at seven diferent cotton growing agro-climatic lo- United States after several years of research [20, 21]. Other cations (Figure 2), with altitude (m.a.s.l.) and rainfall (mm Advances in Agriculture 3 Area ‘000 ha 2000/01 2002/03 2004/05 2006/07 2008/09 2010/11 2012/13 2014/15 2016/17 2018/19 2020/21 Year of production Area (000 ha) Production (000 metric tonnes) Figure 1: Cotton acreage (‘000 ha) and production (‘000 MT) in Ethiopia since 2000/01 (source: [9]). per annum) shown in parenthesis: Werer Agricultural Re- larvae per plant in 10 randomly selected plants per plot. search center (WARC) station (740; 500–1000); Blen (722; Yield and quality data included seed cotton and lint yield, 500–1000); Gewane (587; 300–500); and Asayita (351; 0–300) ginning percentage, yield components (boll numbers and in the Afar Region; Omorate (372; 500–1000) at Southern boll weight), and fber characteristics such as fber length, Nations, Nationalities, and People’s Region (SNNPR); Kamashi strength, and fneness, and other agronomic and morpho- (1216; 1600) at Benishangul–Gumuz Region; and Humera logical characteristics such as fowing date, boll setting and (699; 500–1000) in Tigray Region. Te respective maximum boll opening date, and plant height were collected. Ginning percentage was calculated as weight of lint/weight of seed and minimum average annual temperatures ( C) of Werer, Blen, Gewane, Asayita, Omorate, Kamashi, and Humera were cotton × 100. (35.2, 16.8), (34.9, 16.6), (31.5, 14.7), (39.6, 20.0), (37.9, 21.9), (28.2, 13.1), and (34.9, 20.6), respectively. Te trials were 2.4. Statistical Analysis. Data were analyzed using SAS conducted under rain-fed conditions at Kamashi and Humera software to evaluate the adaptability, yield, and quality re- and under irrigation system in all the remaining locations. sponse of cotton cultivars carrying the Cry1Ac traits versus the conventional varieties in diferent locations. For statis- tical analysis, the locations were treated as random and the 2.2. Experimental Design and Management. Te trial with the genotypes were treated as fxed efects, and a mixed-efects six genotypes was arranged in a randomized complete block model ANOVA was used. Te following ANOVA model has design with three replications at all seven locations. Te spacing been used to test the performance of genotype (G) at each was 90 cm × 60 cm between rows and plants for the two Bt location or environment (E): Yij � μ + Gi + Bj + eij, where cotton hybrid varieties (JKCH 1050 and JKCH 1947) and Yij � observed value of genotype i in block j; μ � grand mean 90 cm × 20 cm between rows and plants for the remaining four of the experiment; Gi � the efect of genotype i; Bj � the efect OPV cotton genotypes, with a plot size of 5 of block j; and eij � error efect of genotype i in block j. After rows × 5 meters × 0.9 meters = 22.5 m . A total of 175 kg of testing the homogeneity of error variance for each location, nitrogen (N) and 80 kg of phosphorus (P) per hectare of a combined analysis of variance was performed over seven fertilizer rate were applied to the plots. Nitrogen was applied in locations. Te variance for variety was broken down into three splits at the sowing, squaring, and peak fowering stages. three components: G, E, and GXE interaction (GEI) efects Phosphorus was applied as a basal dose at planting. No using the equation: Yijk � μ + Gi + Ej + GEij + Bk (j) + eijk, chemical pesticides were applied for bollworm control. Special where Yijk � observed value of genotype i in block k of measures similar to a confned feld trial were taken for the feld environment j, μ � grand mean of the experiment, Gi � the trials to meet any additional requirements of safety procedures. efect of genotype i, Ej � environment or location efect, GEij � the interaction efect of genotype i with environment 2.3. Variables and Data Recorded. All important agronomic j, Bk (j) � the efect of block k in location j, and eijk � error and insect pest data were collected at feld level from each (residual) efect of genotype i in block k of environment j. plot of all the diferent genotypes, including standard checks and locations. Data collected include African bollworm 3. Results (ABW) (Helicoverpa armigera) and pink bollworm (Pecti- nophora gossypiella) infestation larvae count, number, and 3.1. Yield-Related Parameters (Plant Height, Boll Number per damage to fruiting bodies (squares, fowers, and bolls) at Plant, and Boll Weight). Te results of the analysis of var- intervals, number of damaged bolls per plant, and number of iances showed that boll number per plant (BOLPP) varied 4 Advances in Agriculture W E Km 0 95 190 380 570 760 33°20′0′′E 34°30′0′′E 35°40′0′′E 36°50′0′′E 38°0′0′′E 39°10′0′′E 40°20′0′′E 41°30′0′′E 42°40′0′′E 43°50′0′′E 45°0′0′′E 46°10′0′′E 47°20′0′′E 48°30′0′′E Experimental sites werer Asayita Humera Blen Omorate Kamashi Gewane Figure 2: Experimental sites for the Bt cotton and non-Bt conventional variety evaluation in the cotton growing regions of Ethiopia. highly signifcantly (P < 0.05) among tested cotton geno- both yields were recorded at the same location, Gewane. types in all the locations except Kamashi. Te mean per- Such contrasting records occurred at Gewane because of formance of BOLPP of tested cotton genotypes across the a severe pink bollworm infestation at this site during the trial environment ranged from 6.5 to 57.8. Te highest mean season, which afected the performance of all the conven- BOLPP (57.8) was recorded at Gewane, while the lowest tional varieties (Figures 3(a)–3(c) and 4(a)–4(c)). Tere was mean BOLPP (6.5) was recorded at Kamashi. Te Bt cotton a change in performance rank of genotypes from one lo- hybrids JKCH 1050 and JKCH 1947 scored the highest cation to the other suggesting the presence of crossover BOLPP throughout all the locations (Table 1). interaction (Table 2). For example, genotype JKCH 1947 had −1 Te analysis of variance for boll weight (BOLWT) in- high SCY at Gewane (4.77 t·ha ) followed by Blen −1 −1 dicated signifcant diferences (P < 0.05) among genotypes at (3.54 t·ha ), Omorate (3.3 t·ha ), and Kamashi −1 all locations except at Humera, where no statistical difer- (1.81 t·ha ), while genotype JKCH 1050 had high SCY at −1 ence was observed among genotypes (Table 1). Te results Humera (1.17 t·ha ). Te genotype from Sudan was supe- −1 ranged from 4.02 to 6.03 grams. Te two GM hybrid Bt rior at Asayita (4.45 t·ha ) and genotype Weyito 07 was −1 cotton varieties had higher mean performance for BOLWT superior at Werer (3.8 t·ha ) (Table 2). SCY was also very than the standard checks in all locations except Humera. low under rain-fed conditions for all the varieties, but the two Bt hybrid varieties performed better under rain-fed conditions. 3.2. Seed Cotton Yield and Ginning Percentage. Results show Genotype variation for ginning percentage (GINPCT) that seed cotton yield (SCY) was signifcantly diferent has shown signifcant variation among genotypes (Table 2). JKCH 1947 had the highest GINPCT (42.8%) at Omorate, (P< 0.05) among genotypes in four out of seven locations (Blen, Gewane, Kamashi, and Werer) (Table 2). Te mean and 36.0% at Asayita, whereas JKCH 1050 was superior at −1 Werer (39.86%). Both Bt cotton hybrid varieties had the SCY among genotypes ranged from 0.30 t·ha for Weyito 07 −1 (locally released variety) to 4.8 t·ha in JKCH 1947, and highest GINPCT consistently across the test environments. 4°0′0′′N 5°0′0′′N 6°0′0′′N 7°0′0′′N 8°0′0′′N9°0′0′′N10°0′0′′N 11°10′0′′N 12°20′0′′N 13°30′0′′N 14°40′0′′N Advances in Agriculture 5 Table 1: Performance of Bt cotton and local improved genotypes for boll number per plant (BOLPP) and boll weight (BOLWT) at seven irrigated and rain-fed locations in Ethiopia. Irrigated Rain-fed Irrigated Variety Asayita Blen Gewane Humera Kamashi Omorate Werer BOLPP BOLWT (gm) BOLPP BOLWT (gm) BOLPP BOLWT (gm) BOLPP BOLWT (gm) BOLPP BOLWT (gm) BOLPP BOLWT (gm) BOLPP BOLWT (gm) Sudan 22.5b 4.5ba 15.1bc 4.7bac 50.8a 4.6b 6.8c 4.1a 12.2ba 5.2b 14.3b 3.6ba 17.1b 4.3bc JKCH 1947 48.4a 5.0a 27.8a 5.0a 56.2a 5.5a 17.7b 3.7a 15.2a 5.7ba 24.5a 4.0a 32.6a 5.0a JKCH 1050 46.0a 4.9a 25.4a 5.2a 57.8a 5.0ba 21.1a 4.1a 15.0a 5.5ba 26.1a 3.9a 36.1a 5.2a Weyito 07 27.2b 3.9b 21.0ba 3.6c 22.0b 3.2c 9.0c 3.9a 13.2ba 4.7c 13.4b 3.1b 20.7b 4.0c Stam-59A 22.8b 4.7a 11.9c 3.8bc 22.3b 3.2c 6.5c 3.6a 11.4ba 5.2b 13.1b 3.7ba 19.7b 4.7ba DP-90 22.8b 4.5ba 9.3c 4.9ba 31.3b 3.1c 7.1c 4.2a 10.5b 6.0a 17.6ba 3.4b 16.6b 4.8ba Mean 31.6 4.6 18.4 4.5 40.0 4.1 11.3 3.9 12.9 5.4 18.2 3.6 23.8 4.7 CV 13.5 7.7 26.7 14.0 23.5 8.4 13.3 9.4 17.1 5.6 27.1 8.8 10.1 8.4 ∗∗∗ ∗ ∗∗ ∗ ∗∗ ∗∗∗ ∗∗∗ ∗∗ ∗ ∗ ∗∗∗ ∗ Signifcance NS NS LSD 7.62 0.65 8.94 1.16 17.11 0.63 2.75 0.55 8.97 0.58 4.37 0.71 ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly signifcant at P< 0.001. NS � non-signifcant. Means that do not share the same letter are signifcantly diferent at 5% level. 6 Advances in Agriculture −1 Table 2: Mean seed cotton yield (t·ha ) and ginning percentage of Bt cotton and local improved genotypes at diferent cotton growing areas in Ethiopia. Locations Irrigated Rain-fed Irrigated Variety Asayita Blen Gewane Humera Kamashi Omorate Werer −1 −1 −1 −1 −1 −1 −1 A (t·ha ) B (%) A (t·ha ) B (%) A (t·ha ) B (%) A (t·ha ) B (%) A (t·ha ) B (%) A (t·ha ) B (%) A (t·ha ) B (%) Sudan 4.5a 35.4ba 2.1b 41.8a 3.4b 40.1a 0.8b 36.7a 1.2c 40.4ba 2.7ba 40.2b 2.5c 37.9ba JKCH 1947 4.2a 36.0a 3.5a 42.4a 4.8a 38.0ba 0.9b 36.9a 1.8a 41.4ba 3.3a 42.8a 2.9bc 38.1ba JKCH 1050 4.0a 35.2ba 3.4a 41.1ba 4.7a 38.6ba 1.2a 36.0a 1.8a 41.6a 3.0ba 42.3a 3.3ba 39.9a Weyito 07 4.4a 31.1d 2.1b 35.6d 0.3c 36.7ba 1.0ba 33.5b 1.7ba 37.6c 3.0ba 35.2d 3.8a 33.8d Stam-59A 4.4a 33.2c 1.8b 38.9bc 0.4c 36.2b 0.9ba 33.8b 1.4bc 40.8ba 2.5ba 36.7c 3.5ba 36.0bc DP-90 4.7a 34.2bc 2.5b 38.4c 1.0c 35.2b 1.1ba 36.7a 1.4bc 39.6b 2.3b 37.9c 3.2bac 35.5dc Mean 4.4 34.2 2.6 39.7 2.4 37.5 1.0 35.6 1.5 40.2 2.8 39.2 3.2 36.9 CV 17 2 17.5 3.26 22.3 5.2 15.9 3.11 12.5 2.6 17.3 1.9 13.4 3.3 ∗∗∗ ∗∗ ∗∗∗ ∗∗∗ ∗ ∗ ∗∗ ∗∗∗ ∗ ∗∗ Signifcance NS NS NS NS LSD 1.24 0.82 2.35 0.98 2.02 0.35 1.88 1.4 0.78 2.18 ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly signifcant at P< 0.001. NS � non-signifcant; A � seed cotton yield; B � ginning percentage (%). Means that do not share the same letter are signifcantly diferent at 5% level. Advances in Agriculture 7 (a) (b) (c) Figure 3: Cotton showing full bloom and contrasting performance between Bt cotton hybrids ((a) JKCH 1050 and (b) JKCH 1947) and a widely grown cultivar DP-90 (c) at experimental plots at Gewane, Ethiopia. (a) (b) (c) Figure 4: Pink bollworm infestations on standard checks: (a, b) before boll opening and (c) at boll opening stage at Gewane in rift valley in Ethiopia. Te Bt cotton OPV from Sudan had comparable results with Blen was high and led to very low yields and poor fber the hybrid varieties across test environments. Te conven- qualities (Tables 2 and 3; Figures 5(a) and 5(b)). tional varieties recorded low GINPCT almost consistently across the test environments, except at Gewane, Humera, 3.4. Lint Yield. In terms of lint yield (LNTY), there were and Kamashi (Table 2). signifcant diferences (P < 0.05) among the mean perfor- mances of the tested genotypes at Blen, Gewane, Kamashi, 3.3. Infestation of Bollworms. Natural infestation records and Omorate but non-signifcant at Asayita, Humera, and showed that damage due to bollworms was very high at Werer (Table 3). Nevertheless, the highest mean lint yield Gewane, followed by Blen, where infestations occurred lately was recorded at Asayita followed by Werer, Omorate, and in the growing season. A high number of damaged bolls per Blen. Te mean LNTY across environments ranged from −1 −1 plant occurred in all the conventional varieties at the two 0.3 t·ha at Humera to 1.8 t·ha at Gewane. Te minimum locations, but more so at Gewane, which is also a high LNTY was recorded at Humera because of shortage of potential area for cotton production. Damaged bolls per rainfall during the season, and the maximum LNTY was plant were low on the Bt cotton varieties due to an efective recorded at Gewane for favorable environment during the feld resistance level against the bollworm (Figures 5(a) and cropping season. JKCH 1947 had high mean performance of −1 −1 −1 5(b)). Although records showed some infestation on the Bt 1.8 t·ha at Gewane, 1.5 t·ha at Blen, 1.4 t·ha at Omorate, −1 varieties, this did not result in damaged bolls or yield loss. At and 0.8 t·ha at Kamashi. JKCH 1050 had high mean −1 −1 both locations, the number of bolls per plant was higher for performances of 1.3 t·ha and 0.4 t·ha at Werer and all varieties due to favorable growing conditions, but most of Humera, respectively. the matured bolls in the conventional varieties were afected Genotype DP-90, a widely grown variety used as by bollworms and were not open or only partially open. a standard check, recorded a numerically high lint yield −1 Natural bollworm infestations were very low in the (1.6 t·ha ) at Asayita, but this was not statistically diferent remaining fve locations. Overall, the damage due to pink from the other tested genotypes. Te mean lint yield across bollworm larvae on conventional varieties at Gewane and locations showed both JKCH 1947 and JKCH 1050 to be 8 Advances in Agriculture 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 Location Weyto- 07 Stam-59A JKCH 1947 DP-90 Sudan JKCH 1050 (a) 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 WERER ASAYITA GEWANE BLEN KAMASHI OMORATE HUMERA Location Weyto 07 Stam-59A JKCH 1947 Deltapine-90 Sudan JKCH 1050 (b) Figure 5: Bollworm infestation level on each variety across all testing locations in Ethiopia: (a) number of bollworm larvae infesting cotton fruiting parts; (b) percentage of cotton fruiting parts damaged by bollworms. −1 superior (1.2 and 1.9 t·ha , respectively), followed by Bt higher SCYLD than the standard checks Weyito 07 −1 −1 −1 OPV from Sudan (0.94 t·ha ). (2.33 t·ha ), DP-90 (2.30 t·ha ), and Stam-59A −1 −1 (2.12 t·ha ), while the Bt OPV from Sudan (2.44 t·ha ) gave comparable seed cotton yield with the standard checks 3.5. Combined ANOVA. Results of the combined ANOVA across locations. indicated highly signifcant variation among genotypes, Overall ANOVA showed signifcant diferences environments, and GEI for BOLPP, BOLWT, SCYLD, among genotypes, environments, and GEI for GINPCT GINPCT, and LNTY. Genotypes JKCH 1050 and JKCH and LNTY, such that JKCH 1947 and JKCH 1050 had 1847 recorded higher BOLPP (32.5 and 31.7, respectively) as higher mean GINPCT of 39.37 and 39.23, respectively, well as higher BOLWT (4.84 and 4.83 g, respectively) than than the standard checks (Table 4). JKCH 1947 and JKCH −1 conventional standard checks. 1050 also had the highest LNTY, 1.20 t·ha and −1 A combined ANOVA indicated highly signifcant var- 1.19 t·ha , respectively. Te non-Bt local OPVs had LNTY −1 −1 iation among genotypes, environments, and GEI, such that of 0.84 t·ha (DP-90), 0.79 (Weyito 07), and 0.76 t·ha −1 −1 JKCH 1947 (3.06 t·ha ) and JKCH (3.05 t·ha ) expressed (Stam-59A) (Table 4). Percentage of cotton fruiting parts Number of boll worms larvae observed damaged by boll worms at on each variety at each location each location ABW larvae Damaged flower WERER Damaged square ABW larvae ASAYITA Damaged boll Damaged flower PBW larvae Damaged square ABW larvae GEWANE Damaged boll Damaged flower PBW larvae Damaged square ABW larvae Damaged boll BLEN Damaged flower PBW larvae Damaged square ABW larvae Damaged boll KAMASHI Damaged flower PBW larvae Damaged square Damaged boll ABW larvae OMORATE Damaged flower Damaged square PBW larvae Damaged boll ABW larvae HUMERA Damaged flower Damaged square PBW larvae Damaged boll Advances in Agriculture 9 Table 3: Mean performance of lint yield of tested Bt cotton and local improved genotypes at diferent cotton growing areas in Ethiopia. −1 Lint yield (t ha ) Variety Locations Asayita Blen Gewane Humera Kamashi Omorate Werer Mean Sudan 1.6a 0.9b 1.4b 0.3c 0.5b 1.1bc 0.9b 0.9 JKCH 1947 1.5a 1.5a 1.8a 0.3bc 0.8a 1.4a 1.1ba 1.2 JKCH 1050 1.4a 1.4a 1.8a 0.4a 0.7a 1.3ba 1.3a 1.2 Weyito 07 1.4a 0.8b 0.1c 0.4bac 0.6ba 1.0bc 1.3a 0.8 Stam-59A 1.5a 0.7b 0.1c 0.3bc 0.6b 0.9c 1.3a 0.8 DP-90 1.6a 1.0b 0.4c 0.4ba 0.6b 0.9c 1.1ba 0.8 Mean 1.5 1.0 0.9 0.3 0.6 1.1 1.2 1.0 CV 17.8 19.6 23.6 14.4 14.3 16.1 13.4 ∗∗ ∗∗∗ ∗ ∗ Signifcance NS NS NS LSD 0.367 0.399 0.160 0.321 ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly signifcant at P< 0.001. NS � non-signifcant. Means that do not share the same letter are signifcantly diferent at 5% level. Variety Weyito 07 recorded long fber length and very strong 3.6. Quality Performance at Individual Location. Length, strength, and micronaire are the three most important prop- fber strength that exceeded all the other varieties, including the two Bt cotton hybrid varieties, at all locations except erties of fber qualities. For the fber properties analyzed, that is, fber micronaire, strength, and length (upper half mean length Omorate. However, the fber length of JKCH 1947 was in the (UHML)), the acceptable ranges are shown in Table 5. Ac- acceptable range at all locations except Blen, Humera, and cepted values for length >27.4 mm, strength >28 g/tex, and Omorate. Te fber length of JKCH 1050 was in the ac- micronaire 3.5–4.9 are described by Pretorius et al. [28] (see ceptable range at all locations except Kamashi. Te fber also Table 5). Cotton lint with a micronaire below 3.5 is usually strength of JKCH 1947 was in the acceptable range at considered immature and weak [29]. Micronaire values greater Asayita, Blen, Gewane, Kamashi, and Werer but below the than 4.9 are less desirable as the fber becomes too coarse for acceptable range at Humera and was very marginal at spinning. Te various fber quality results are discussed below. Omorate. Fiber strength of genotype JKCH 1050 was within the acceptable range in all locations except at Humera. 3.7. Micronaire. Genotypes signifcantly varied (P < 0.05) for micronaire values at all locations except Humera and 3.10. Combined Analysis of Fiber Quality Traits. Results Omorate (Table 6). All micronaire values were in the ac- showed highly signifcant diferences (P < 0.05) among ge- ceptable range according to Chaudhry and Guitchounts [29] notypes, environment, and GEI for fber quality parameters. and the Ethiopian cotton quality specifcation (Table 5), According to Pretorius et al. [28], environments afected except for Bt OPV from Sudan (5.36) and DP-90 (5.01) at micronaire more signifcantly (P < 0.05). However, all Asayita, which are in the discount range as the fber became micronaire values of genotypes in this study were in the too coarse for spinning. At Gewane, the standard checks acceptable range according to the Ethiopian cotton quality Weyito 07 (2.79), Stam-59A (2.73), and DP-90 (2.76) had grading system specifcation (Table 5) and standards referred micronaire values below the acceptable range, which are to by Chaudhry and Guitchounts [29]. Combined analysis considered as immature and weak fbers [29] and less de- indicated that genotypes, environment, and GEI had a very sirable for spinning. In this study, micronaire values were highly signifcant efect (P < 0.05) on UHML (Table 9). Te signifcantly afected by the environment, which is in fber lengths of genotypes Weyito 07 (32.11 mm), JKCH agreement with previous studies by Pretorius et al. [28]. 1050 (28.44 mm), and JKCH 1947 (27.78 mm) were in the acceptable range, while the fber lengths of the other remaining genotypes, including the widely cultivated variety 3.8. Length Uniformity. Length uniformity is the ratio be- DP-90, were in unacceptable range or marginally acceptable tween the mean length of fber and the upper half mean (Table 5). In terms of fber strength, only the genotypes length expressed in percentage. Low uniformity values are Weyito 07 (33.50 g/tex), JKCH 1050 (28.59 g/tex), and Stam- a function of fbers that are more easily broken. Signifcant 59A (28.00 g/tex) were in the acceptable range according to diferences (P < 0.05) were found among genotypes for the Pretorius et al. [28], but they were considered marginally uniformity index only at locations Blen and Gewane, where optimum by the Ethiopian cotton quality specifcation. low percentages were recorded for standard checks DP-90, Generally, most fber quality values of the Bt cotton hybrids Stam-59A, and the Bt OPV from Sudan at Blen (Table 7). in this study were within acceptable ranges. Since they are competitive with or better in fber quality than the standard 3.9. Fiber Length and Strength. In terms of cotton fber checks, their added merits in yield and quality, in addition to their efective protection against bollworms, make them the length and strength, genotypes showed signifcant difer- ences (P< 0.05) at all locations except Omorate (Table 8). best candidates for further expansion by farmers. Te GEI, 10 Advances in Agriculture Table 4: Overall mean of cotton genotypes for yield and yield-related traits tested across seven locations in Ethiopia. Seed −1 Variety Plant height (cm) Boll no./plant Boll weight (gm) Ginning percent Lint yield (t·ha ) Stand count −1 cotton yield (t·ha ) Sudan 93.8cb 19.8b 4.4ba 2.4ba 38.9a 0.9ba 43.2b JKCH 1947 111.7a 31.7a 4.8a 3.1a 39.4a 1.2a 29.8c JKCH 1050 114.7a 32.5a 4.8a 3.1a 39.2a 1.2a 28.7c Weyito 07 110.0a 18.1b 3.8c 2.3ba 34.8c 0.8b 56.5a Stam-59A 98.9b 15.4b 4.1bc 2.1b 36.5b 0.8b 59.9a DP-90 86.6c 16.5b 4.4ba 2.3ba 36.8b 0.8b 56.1a Mean 102.6 22.3 4.4 2.6 37.6 1.0 45.7 CV 10.2 21.9 9.1 18.3 3.2 18.8 23.6 R 0.89 0.928 0.86 0.93 0.91 0.93 0.79 ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ Genotype ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ Environment ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ Geno∗ ENV Ns LSD 10.549 6.5524 0.4761 0.923 1.23 0.343 8.3326 ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly signifcant at P< 0.001. NS � non-signifcant. Means that do not share the same letter are signifcantly diferent at 5% level. Advances in Agriculture 11 Table 5: Ethiopian cotton quality grading system specifcations. Grade Specifcation A B C Staple length (mm) ≥28.5 27 − 28.5 25 Micronaire/fneness 3.5–4.2 4.3–4.9 3.2–3.4 and >5 Strength (g/tex) ≥29 26–28.9 25–25.9 Average sticky points 0–10 11–20 21–32 Short fber content (%) ≤10 11-12 13-14 Trash content (%) <3.5 3.5–4.5 4.6–5 Moisture content (%) <8 <8 ≤8 Maturity ratio (%) ≥85% 81–84 75–80 Length uniformity ratio (%) ≥83 81-82 76–80 Color grade 11 − 1 up to 21 − 1 21 − 1 up to 31 41 − 1 up to 51 − 4 Contamination (g/bale) ≤5 11 10–15 Source: adapted from Tiliksew et al. [27]. Table 6: Mean performance of cotton genotypes for micronaire at diferent cotton growing locations in Ethiopia. Variety Asayita Blen Gewane Humera Kamashi Omorate Werer Sudan 5.36a 4.33a 3.78a 3.30bc 4.51a 4.15a 4.66ba JKCH 1947 4.23dc 4.18a 3.99a 3.74ba 3.83b 4.20a 4.25bc JKCH 1050 4.47dc 4.02a 3.77a 3.45bac 4.04b 3.79a 4.11c Weyito 07 4.08d 3.13b 2.79b 3.05c 3.04c 3.81a 3.56d Stam-59A 4.59bc 4.19a 2.73b 3.42bac 4.50a 3.91a 4.25c DP-90 5.01ba 4.13a 2.76b 3.92a 4.65a 3.77a 4.78a Mean 4.62 4.00 3.30 3.48 4.09 3.94 4.27 CV 5.98 5.10 4.29 9.21 5.12 6.86 5.28 ∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗ Signifcance NS NS LSD 0.50 0.37 0.26 0.38 0.41 ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly signifcant at P< 0.001. NS � non-signifcant. Means that do not share the same letter are signifcantly diferent at 5% level. Table 7: Mean performance of cotton genotypes for uniformity index at seven cotton growing locations in Ethiopia. Locations and uniformity index values expressed as a percentage Variety Asayita Blen Gewane Humera Kamashi Omorate Werer Sudan 83.4a 79.5b 81.9ba 79.6c 81.8ba 80.6b 81.7ba JKCH 1947 83.6a 81.0b 83.0a 80.3bac 83.8a 82.1ba 81.6b JKCH 1050 83.7a 81.8ba 82.4ba 81.5ba 79.5b 82.2a 82.9ba Weyito 07 84.6a 83.8a 81.0bc 81.9a 84.1a 81.7ba 83.3a Stam-59A 83.0a 80.2b 79.2dc 79.8bc 80.8ba 81.9ba 82.6ba DP-90 83.6a 81.6ba 77.7d 79.5c 82.6ba 81.6ba 81.4b Mean 83.7 81.3 80.9 80.4 82.1 81.7 82.3 CV 1.33 1.63 1.32 1.16 2.50 1.04 1.12 ∗ ∗∗ Signifcance NS NS NS NS NS LSD 2.41 1.94 ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly signifcant at P< 0.001. NS � non-signifcant. Means that do not share the same letter are signifcantly diferent at 5% level. on the other hand, suggests that genotypes, including the Bt 3.11. AMMI Biplot Analysis for Lint Yield. Te results of hybrids, responded diferently to environment. However, AMMI analysis for mean LNTY are presented as genotype across most locations, JKCH 1947 and JKCH 1050 had by environment interaction biplot in Figure 6. Te plot shown good adaptation and statistically similar performance captures GEI efects and distributes all the seven environ- for most parameters. ments into four diferent sectors. Te small angle between 12 Advances in Agriculture Table 8: Mean performance of cotton genotypes for upper half mean length and strength at seven locations in Ethiopia. Locations Variety Asayita Blen Gewane Humera Kamashi Omorate Werer UHML Str UHML Str UHML Str UHML Str UHML Str UHML Str UHML Str Sudan 28.0cb 29.7b 26.3c 26.8b 28.5cb 28.4a 26.0c 22.5b 27.2cb 28.9cb 26.9a 25.6a 26.6d 26.4c JKCH 1947 28.2cb 31.1b 26.7c 26.6b 28.4cb 27.8ba 27.3cb 24.5b 28.5b 30.2b 27.3a 25.2a 28.0cb 28.9b JKCH 1050 28.3cb 31.5b 28.2b 27.2b 29.3b 28.8a 28.7b 25.8b 27.1c 29.3cb 29.1a 29.2a 28.3b 28.2cb Weyito 07 34.0a 40.3a 33.8a 35.1a 31.6a 30.7a 31.5a 31.9a 32.4a 34.5a 29.0a 27.4a 32.6a 34.6a Stam-59A 27.2c 32.3b 26.4c 26.2b 27.1c 25.2bc 26.1c 25.4b 27.4cb 29.3cb 26.8a 28.3a 28.4b 29.4b DP-90 28.9b 29.6b 26.5c 26.1b 27.2c 22.6c 27.0cb 23.0b 27.5cb 27.5c 26.5a 25.0a 27.5c 27.6cb Mean 29.1 32.4 28.0 28.0 28.7 27.2 27.8 25.5 28.4 30.0 27.6 26.8 28.6 29.2 CV 2.4 6.4 2.7 2.5 3.4 6.0 3.6 9.1 2.7 4.3 5.8 9.5 1.5 4.4 ∗∗∗ ∗∗ ∗∗∗ ∗∗∗ ∗∗ ∗∗ ∗∗ ∗ ∗∗∗ ∗∗ ∗∗∗ ∗∗∗ Signifcance NS NS LSD 1.3 3.8 1.4 1.3 1.8 3.0 1.8 4.2 1.4 2.3 2.9 4.6 0.8 2.4 ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly signifcant at P< 0.001. NS � non-signifcant; UHML � upper half mean length (mm); Str � strength. Means that do not share the same letter are signifcantly diferent at 5% level. Table 9: Overall mean performance of cotton genotypes on quality Generally, JKCH 1050 and JKCH 1947 performed well at parameters. all environments except at Asayita and Werer (Figure 7). Genotypes e, d, and f were the low yielding at all envi- Variety Mic UHML UI Str ronments as they are far from all environments. Sudan 4.30a 27.06c 81.21b 26.90cb JKCH 1947 4.06a 27.78cb 82.20ba 27.75b JKCH 1050 3.95a 28.44b 82.00ba 28.59b 4. Discussion Weyito 07 3.35b 32.11a 82.92a 33.50a Stam-59A 3.94a 27.05c 81.09b 28.00b Adaptability of cotton varieties carrying the Bt trait, that is, DP-90 4.15a 27.30c 81.13b 25.92c their ftness to the diferent growing locations, is a pre- Mean 3.96 28.29 81.76 28.44 requisite for its efectiveness in protecting the plant from CV 6.10 3.36 1.52 6.32 damage by the bollworms [30]. Terefore, after the efcacy ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ Genotype tests for the bollworm-resistantBt trait, the national ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ENV adaptability trial for the Bt cotton hybrids (JKCH 1947 and ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ENV × genotype JKCH 1050) and Bt containing open pollinated variety was LSD 0.38 0.98 1.26 1.78 compared with improved and widely grown conventional ∗ ∗∗ ∗∗∗ Signifcant at P< 0.05; highly signifcant at P< 0.01; very highly local varieties across diferent cotton growing agro-ecologies signifcant at P< 0.001. NS � non-signifcant; Mic � micronaire; in Ethiopia. Te study across diferent agro-ecologies also UHML � upper half mean length; UI � uniformity index; Str � strength. allowed for the confrmation of previous efcacy fndings Means that do not share the same letter are signifcantly diferent at 5% level. that the Bt gene Cry1Ac protein in the two Indian hybrids and the Cry1A Bt trait in the Sudanese OPV variety are adequately expressed in Ethiopia’s various cotton growing environments Kamashi (K) and Werer (W) indicated the environments. similarity of the two environments for lint yield. Te large For bollworm infestations, at Gewane and Blen, which angle between environments Humera (H) and Gewane (G) are among the most favorable for cotton production as well indicated the two environments’ dissimilarity. Among the as for pest growth, infestation of both African bollworm locations, Gewane (G) provided the most favorable season, (ABW) and pink bollworm (PBW) during the study period and JKCH 1947 and JKCH 1050 interacted with Gewane, but was higher than any of the other locations (Figures 4(a)– JKCH 1050 somehow favored at Blen. Weyito 07 (d) and 4(c), 5(a), and 5(b)). Nevertheless, Bt hybrids, JKCH 1947 Stam-59A (e) were favored at Werer and Kamashi, whereas and JKCH 1050, including the open pollinated Bt variety, Deltapine-90 (f) performed its best at Humera and Asayita. have shown 4–10 folds increase having seed cotton yield Among the seven environments, Omorate and Kamashi range of 3.4–4.8 t ha-1 which is more than the conventional were the least favorable for all varieties. varieties, which had seed cotton yield range between 0.3–1.0 t ha-1 at Gewane. Te performance at Gewane was a genuine 3.12. GGE Biplot for Cotton Lint Yield. To know which ge- refection of the whole evaluation, which showed a phe- notype performed well where, the GGE biplot was generated nomenally superior performance of the Bt varieties. Te Bt based on the cotton LNTY, with the seven environments gene was adequately expressed in the two hybrids and the falling into four sectors with diferent cultivars, which in- OPV in the cotton growing environments and had suf- dicated the presence of crossover GEI. Blen, Omorate, ciently protected against boll damage by both the African Kamashi, and Humera were grouped under one mega- and pink bollworms. Te level of protection in the two environment while Gewane, Werer, and Asayita were hybrids was better than that in the OPV from Sudan. Cotton each under a separate mega-environment. yield was higher in Bt cotton hybrids due to the high number Advances in Agriculture 13 AMMI BIPLOT OF Bt COTTON LINT YIELD -4 -8 -12 -16 -20 -24 -28 -32 -36 -40 -40 -34 -28 -22 -16 -10 -4 2 8 14 20 26 32 38 IPC 1 Figure 6: AMMI biplot for mean lint yield of cotton genotypes (lower case) and environments (upper case). GGE BIPLOT FOR Bt COTTON LINT YIELD -10 -20 -30 -40 -50 -50 -40 -30 -20 -10 0 10 20 30 40 50 GGE 1 Figure 7: GGE biplot of lint yield of cotton genotypes based on the G × E analysis (lower and upper case letters showing means for genotypes and environments, respectively). of bolls per plant and signifcantly less damaged bolls where also realize a signifcant reduction in chemical insecticide infestation occurred. At Gewane and Blen, where infestation spray over their non-Bt cotton varieties [31, 32]. Te efcacy was high, the larvae population for both ABW and PBW in performance was similar both under rain-fed and irrigated the Bt containing varieties was checked at a minimum, conditions, giving sufcient protection against bollworms. which efectively reduced damage due to the pests. As Te results of the mean comparison tests for the agro- a result, without the use of insecticides, the Bt cotton hybrids nomic performance of Bt cotton hybrids, Bt OPV, and non- enabled higher boll retention through efective pest control Bt open pollinated varieties showed that hybrids had better and protected potential yield losses due to bollworm plant height, number of bolls, boll weight, seed cotton yield, damage. Several previous works have also shown that Bt ginning percentage, and lint yield almost in all locations when compared to the non-Bt conventional varieties. Te cotton hybrids not only give signifcantly higher yields but GGE 2 IPC 2 14 Advances in Agriculture [28]. But, all micronaire values of the tested cotton varieties results are in agreement with the fndings of other re- searchers who concluded that F1 hybrids performed better in this study were in the acceptable range according to Chaudhry and Guitchounts [29]. For fber length, unifor- for the majority of the traits [33, 34]. In all the seven ex- perimental sites and under both irrigated and rain-fed mity, and strength, genotypes, environment, and the gen- conditions, JKCH 1947 and JKCH 1050 had up to 33% otypes × environment interaction had a very highly yield advantage over the most widely cultivated variety, signifcant efect. Te two hybrids and the standard checks Deltapine-90. However, comparison in the absence of pest under all environments show that the Bt hybrids had closely incidence as it happened in most locations is bound to similar fber quality with UHML and fber strength values underestimate the potential advantage of the Bt hybrid being exceeded only by Weyito 07, which had 32.11 mm and 33.5 g/tex, respectively, compared to 27.78 mm and cotton varieties against bollworms. Te ginning percentage of the two Bt hybrids (39.2–39.4%) was very comparable 28.44 mm of fber length and 27.75 g/tex and 28.59 g/tex of fber strength, respectively, for JKCH 1947 and JKCH 1050. among each other but higher than the local conventional varieties (34.8–37.6%). Similar superior results have been But all fber characteristic values of the two Bt cotton hybrid varieties were not within the acceptable range of the quality reported for hybrid derived Bt cotton varieties in earlier studies [35, 36]. Seed cotton yield was heavily afected by the standards issued by the Ethiopian Textile Industry Devel- type of production, i.e., rain-fed or irrigated. All varieties opment Institute (ETIDI) in Ethiopia (Table 5). signifcantly underperformed in rain-fed conditions, while Te AMMI and GGE models were used to analyze lint the hybrids had relatively higher seed cotton yields. yield data for the tested cotton varieties in seven environ- Te analysis of variance for most variables showed that ments. Environment as a main efect contributed to most of boll number per plant, boll weight, seed cotton yields, the variability for this trait. Both JKCH 1947 and JKCH 1050 recorded the highest mean lint yield and interacted and ginning percentage, and lint yield were signifcantly afected by genotype, environment, and genotype by environment performed best at most environments. Another study of lint yield trait in cotton by Shahzad et al. [43] also reported that interaction (GEI). Te Bt cotton hybrids JKCH 1050 and JKCH 1947 had a higher average boll number per plant, boll hybrids outperformed in a wide range of environments than inbred lines. Among the seven environments, Gewane was weight, seed cotton yield, and ginning percentage than the conventional controls. Results further demonstrated that the most favorable. Te two Bt hybrids, JKCH 1947 and 80.30%, 56.80%, and 27.10% of the variation in cotton seed JKCH 1050, performed well at all environments except at yield were mainly due to the variation in bolls per plant, Asayita and Werer, and other non-Bt cotton varieties were plant height, and boll weight, respectively [37]. Te fnal low yielding at all environments as they are far from all yield of a cotton cultivar is determined by the number of environments on GGE biplot. bolls per plant, plant height, and the morphological Tese results showed that the Bt containing hybrid va- rieties are well adapted to the cotton growing agro-ecologies framework of the plant, which is infuenced directly or indirectly by the growing conditions and its genetic ability to in Ethiopia. Tis could be due to the broad adaptability of the two Bt cotton hybrid varieties. Studies with the same Bt cotton perform in the given environmental conditions [38, 39]. Te hybrids outperformed the diferent non-hybrid cotton ge- hybrids from JK Agri Genetics Ltd., India, have shown good notypes in yields and other physiological traits under normal adaptability of both Bt hybrids (JKCH 1050 and JKCH 1947) and heat stress, supporting the concept of hybrid adapt- and successful commercialization in the cotton growing ability across stress environments [40, 41]. Other fndings environments in Sudan [44] and Eswatini [31, 32]. Te su- reported that hybrids were found to be more stable and perior performance of the Bt cotton varieties in terms of performed better than conventional genotypes under opti- number of bolls per plant and seed cotton yield across lo- mal and defcit water (irrigation) conditions and concluded cations compared to the standard local varieties in Ethiopia is that the genotypic and phenotypic variances for various attributable to the successful control of bollworms without any chemical pesticide spray and the adaptability of the va- traits were greater under water defcit conditions than under the optimal irrigation regime [42]. Tis is true because the rieties to the diferent cotton agro-ecologies in the country. Te adapted hybrids and similar Bt products appear to be two Bt cotton hybrids have performed better at all locations and have also expressed their higher yield potential even a great promise for the potential opportunity of cotton im- under water stressed, rain-fed, and other stress conditions. provement in Ethiopia. Tere is a need however to strategize Tis has proven the competitive and promising nature of the the seed access issue by smallholder farmers through forming hybrids containing Bt trait for high yield and strong strong public private partnerships to strengthen the current adaptability to stressed growing conditions. On the other poor cotton seed system [45, 46]. Tis is very critical in view of hand, the signifcant infuence of rain-fed growing condition the growing role of the textile industry in the country’s economy. More work is needed to test more varieties, in- on the yield of all genotypes shows the importance of drought tolerant varieties for such agro-ecologies and cluding second-generationBt cotton products, as well as the introgression of such traits into the most adapted local va- farming conditions. Fiber characteristic values for fneness (micronaire) rieties, for better results. Moreover, the possibility of re- sistance development of targeted species and potential showed that genotypes, environment, and the genoty- pes × environment interaction had a very highly signifcant emergence of challenges from currently less important pests efect. Tis result is in agreement with previous works which need to be seriously considered through integrating appro- reported that micronaire was afected more by environments priate resistance management strategies [47, 48]. Te health Advances in Agriculture 15 [8] International Cotton Advisory Committee (Icac), Cotton: benefts of Bt cotton due to signifcantly reduced chemical Review of the World Situation, ICAC, vol. 75, no. 3, Wash- insecticide use are an added beneft to the growers over the ington, DC, USA, 2022. non-Bt cotton varieties that require extensive chemical in- [9] Faostat, Crops and Livestock products/Cotton Unginned (2001- secticide application [31, 32, 49]. 2021), Food and Agriculture Organization of the United Nations, Rome, Italy, 2022. 5. Conclusion [10] T. S. G. Salem, H. A. Rabie, S. A. E. Mowafy, A. E. M. Eissa, and E. Mansour, “Combining ability and genetic components Te transgenic Bt cotton hybrids provided superior pro- of Egyptian cotton for earliness, yield, and fber quality traits,” tection against bollworm infestation, resulting in a higher SABRAO J Breed Genet, vol. 52, no. 4, pp. 369–389, 2020. number of bolls per plant, which helped to increase cotton [11] S. J. N. 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Published: May 8, 2023