Ethiopian cotton productivity is 860 to 1800 kg/ha in rain fed and 2200 kg/ha in irrigated farms. These low yields may be attributed to several factors like poor management practices, diseases and pests and lack of knowhow by growers about the advanced package of technology concerning cotton production. However, most common cause of low productivity in Ethiopia is lack of improved varieties in form of seed cotton yield and yield components. The new variety CIM-608 has been developed through interspecific hybridization, that is, (Gossypium hirsutum × Gossypium anomalum) × G. hirsutum and produced significantly higher yield in varietal trials compared with the standard variety, that is, MNH-786 (Zahid et al ., 2014). Significant differences were observed in yield and yield contributing traits with the development of new varieties of Upland cotton (Singh et al., 1973). Arshad et al. (2003) found significant variation for various characters like ginning out percentage, staple length, number of bolls and boll weight due to the use different genotypes.

 

Therefore, various parents have been involved in crosses of intraspecific crosses at Werer Agricultural Research Center to improve seed cotton yield and yield components and many of the crosses have passed through a series of evaluations and the best ones are now at the National yield trial and have almost reached homozygosity and the present study was conducted to evaluate these genotypes in form of seed cotton yield and yield components at different cotton growing agro-ecologies of Ethiopia to release as new varieties if found to be superior to the varieties under cultivation.

The experiment was carried out from 2011 to 2013 main growing season at three locations (Werer,  Sille  and  Weyto) of cotton growing regions. Werer is located at 9° 34’12” N latitude and 40° 17’22”E longitude and 740 m above sea level (masl), Sille is located at 5° 51’42” N latitude and 37° 28’32” E longitude at an elevation of 1120 masl, and Weyto is located at 5° 23’31” N latitude and 36° 58’41” E longitude at an elevation of 550 masl. Eleven cotton genotypes (Table 1) with three check varieties (Deltapine-90, Stam 59 A and Ionia) were obtained from Werer Agricultural Research Center. The experiment was carried out in randomized complete block design with three replications. Sowing was carried out in five rows each 5-m long with plant to plant distance of 20 cm and row to row distance of 90 cm (plot size of 5 m × 5 rows × 0.9 = 22 m²). Three seeds per hole were hand sown on the top of the ridges. Thinning was done fifteen days after emergence to have the required population of 125 plants per plot. Appropriate agronomic practice and field evaluations were also implemented as per the schedule. The central three rows with net plot size of 5 m × 3 rows × 0.9 = 13.5 m² were used for harvesting seed cotton yield to avoid border effect, and other data were taken from fifteen selected plants from central rows of a plot. Agronomic traits, namely: plant height, number of bolls per plant, mature boll weight (g), seed cotton yield, ginning outturn and lint yield, were collected.  The data collected were statistically analyzed according to Steel and Torrie (1984) by using SAS software for analysis of variance (ANOVA).

 

According to analysis of variance (Table 2), the overall mean values of fourteen cotton genotypes manifested highly significant differences (p≤0.01) for plant height, bolls per plant, boll weight, seed cotton yield, ginning outturn and lint yield. The differences among locations were found significant for all characters while the location × genotype interactions were non-significant for all characters except seed cotton yield and lint yield. Therefore, the results revealed significant variations among the genotypes and locations for all of the traits studied.

 

 

Plant height

 

Data regarding the plant height is shown in Table 3. On average, the plant heights were varied from 107.72 to 132.05 cm among fourteen cotton genotypes. The tallest plant height was observed in Sanju F5#9-2-1 (132.05 cm) followed by Arba × GL-7 F5#1-2/3 (129 cm) and Indam 206 F5#6-1-1 (126.05 cm) genotypes. The shortest plant height was observed in Deltapine-90 (107.72 cm) and it was statistically at par with seven genotypes with plant height from 111.39 to 118.07 cm. The differences among genotypes for plant height might have been due to the difference in genetic makeup of genotypes considered in the experiment. These results are in confirmation with those of Premalatha et al. (2020) and Nikhil et al. (2018) who reported that plant height is affected due to genetic makeup of genotypes.

 

 

Bolls per plant 

 

The highest  bolls per plant were picked from Indam 2194 F5#2-1-2, Guru F5#1-2 and Delcero × GL-7 F5#1-4-1 cotton genotypes at all locations (Weyto (24.79 bolls plant-1), (23.24 bolls plant-1)  and (23.43 bolls plant-1), Sille (18.78 bolls plant-1), (21.29 bolls plant-1) and (18.56 bolls plant-1) and Werer (19.28 bolls plant-1), (20.33 bolls plant-1) and (20.6 bolls plant-1)), respectively. The lowest bolls per plant were picked from Ionia cotton genotype at Werer (13.37 bolls plant-1) and Sille (15.45 bolls plant-1). Overall locations, bolls per plant gave that the maximum value from Guru F5#1-2 (21.62 bolls plant-1) followed by Indam 2194 F5#2-1-2 (20.95 bolls plant-1) and Delcero × GL-7 F5#1-4-1 (20.87 bolls plant-1). Seven genotypes had bolls plant-1 higher than that of the best check variety Deltapine-90 (18.1395 bolls plant-1). The minimum bolls per plant were picked from check variety Stam 59 A (15.72 bolls plant-1) and were found statistically at par with five genotypes (15.93 to 17.31 bolls plant-1) (Table 3). The differences among genotypes for number of bolls per plant might have been due to the difference in genetic potential of the genotypes and environment. The significant differences among varieties for number of bolls per plant had also been reported by Shakeel et al. (2015). The results were also in accordance with the findings of Chaudhari et al. (2017) who also reported variable number of bolls per plant for different genotypes. 

 

Boll weight

 

Two cotton genotypes (namely, Arba × Cucurova 1518 F5#1-4/3 and Ionia) produced biggest boll weight at all locations (Sille (5.82 g) (5.54 g), Weyto (5.46 g) (5.53 g) and Werer (5.14 g) (5.22 g)). Indam 206 F5#6-1-1 cotton genotype produced biggest boll weight at Sille (5.64 g) and Werer (5.08 g). Delcero × GL-7 F5#1-4-1 (3.87 g) and Guru F5#1-2 (3.89 g) cotton genotypes produced the smallest boll weight at Weyto and Werer, respectively. Average boll weight of the cotton genotypes revealed that the biggest boll weight was noticed in genotypes Arba × Cucurova 1518 F5#1-4/3 (5.47 g) and Ionia (5.43 g), followed by Arba × GL-7 F5#1-2/3 (5.17 g), Indam 206 F5#6-1-1 (5.14 g)  and Stam 59 A (5.11 g). The smallest boll weight was noticed in genotypes Delcero × GL-7 F5#1-4-1 (4.29 g) and Stam 59A × ICA 01 bulk (4.31 g). The variation was due to the use of different genotypes. These results are also in line with those of Ahsan et al. (2015) and Farooq et al. (2017) who reported that average boll weight varies significantly among the varieties studied. 

 

Seed cotton yield 

 

In Table 4, it can be seen that the maximum seed cotton yield was recorded in Stam 59A × ICA 01 bulk and Sanju F5#9-2-1 cotton genotypes at Werer (5099  and 5021  kg ha-1)  and  recorded  in Guru F5#1-2, Arba × Cucurova 1518 F5#1-3/3 and Arba × GL-7 F5#1-2/3 genotypes at Weyto (5112, 5052, and 5019 kg ha-1); but there, the results were exceeded by check variety Ionia (5188 kg ha-1). The minimum seed cotton yield was observed at Sille in all varieties, rather than other locations. The overall mean values of seed cotton yield ranged from 3485 to 4618 kg ha-1 among cotton genotypes. The highest seed cotton yield was obtained from Guru F5#1-2 (4618 kg ha-1) and Sanju F5#9-2-1 (4541 kg ha-1) cotton genotypes, followed by Arba × Cucurova 1518 F5#1-3/3 (4304 kg ha-1) and Deltapine-90 (4297 kg ha-1) cotton genotypes. The lowest seed cotton yield was obtained from Indam 206 F5#6-1-1 (3485 kg ha-1) genotype; but was found statistically at par with two other genotypes, whose seed cotton yields were 3883 and 3896 kg ha-1. These results are in line with those of Premalatha et al. (2020) who reported seed cotton yield traits in cotton vary depending on the genotypic structure of cultivar and environmental conditions.

 

Lint yield

 

The data pertaining to lint yield is presented in Table 4. The highest lint yield was produced in  Arba × Cucurova 1518 F5#1-3/3, Arba × GL-7 F5#1-2/3 and Arba × Cucurova 1518 F5#1-4/3 genotypes at Weyto (namely, 2086, 2022, and 2021 kg ha-1, respectively); and produced in  Stam 59A × ICA 01 bulk, Indam 2194 F5#2-1-2, Delcero × Cucurova  1518 F5#1-3 and Guru F5#1-2 at Werer (namely, 1902, 1849, 1835, and 1829 kg ha-1, respectively). Cotton genotypes Indam 206 F5#6-1-1 and Polaris F5#3-2-2 revealed the lowest lint yield at all locations; namely, Sille (1016 and 1145 kg ha-1), Weyto (1220  and  1458 kg ha-1) and Werer (1268 and 1345 kg ha-1), respectively. 

 

On average, the lint yields of the genotypes varied between 1168 and 1743 kg ha-1. The maximum lint yield was observed in Arba × Cucurova 1518 F5#1-4/3 (1743 kg ha-1)  and Guru F5#1-2 (1740 kg ha-1)  genotypes, followed by genotypes Arba × Cucurova 1518 F5#1-3/3 (1686 kg ha-1), Stam 59 A (1667 kg ha-1), Stam 59A × ICA 01 bulk (1650 kg ha-1) and Sanju F5#9-2-1 (1649 kg ha-1); and the minimum lint yield was observed in Indam 206 F5#6-1-1 (1168 kg ha-1) genotype.   

 

 

The authors have not declared any conflict of interests.