This current study was performed to determine the influences of plant spacing, Nitrogen (N) fertilization rate and their effect, on growth traits, yield, and yield components of cotton (Gossypium barbadense L.) cv. Giza 97 during the 2019 and 2020 seasons. A split plot experiment in three replicates was utilized whereas the cotton seeds were planted at 20, 30, and 40 cm, as main plots and nitrogen at 75, 100, and 125%, was in subplots. The results revealed that the planting spacing at 40 cm significantly (p ≤ 0.01) increased plant height, number of fruiting branches per plant, number of bolls per plant, boll weight (BW), lint percentage (L%), seed cotton yield (SCY), lint cotton yield (LCY), seed index and lint index by 165.68 cm, 20.92, 23.93, 3.75 g, 42.01%, 4.24 ton/ha, 5.16 ton/ha, 12.05, 7.86, respectively, as average in both seasons. The application of N fertilizer rate at 125% caused a maximum increase in growth and yield parameters i.e., plant height (169.08 cm), number of vegetative branches (2.67), number of fruiting branches per plant (20.82), number bolls per fruiting branch (1.39), number of bolls per plant (23.73), boll weight (4.1 g), lint percent (41.9%), seed index (11.8 g), and lint index (8.2), while the plants treated with 100% N rates exhibited highest seed cotton yield (4.3 ton/ha) and lint cotton yield (5.6 ton/ha), as average in both seasons. Combining plant spacing at 40 cm between plants with a 100% N fertilizer rate recorded the highest lint cotton yield (5.67 ton/ha), while the highest seed cotton yield (4.43 and 4.50 ton/ha) was obtained from 125% N fertilizer rate under planting spacing 20 and 40 cm, respectively. Conclusively, a wide density (40 cm) with 125% N is a promising option for improved biomass, cotton growth, yield, physiological traits, and fiber quality.

No abstract

Two experiments were carried out at Sakha Agriculture Research Station,

The present research uses Pearson's correlation coefficient and multivariate analysis to assess the interrelationships, similarities, and dissimilarities among non-segregation (P1, P2 and F1) and segregation (F2, BC1 and BC2) generations for seed cotton yield and yield components in the two crosses, Giza 92 x Pima S6 and Giza 93 x C.B. 58. For all variables evaluated in the two crossings, the analysis of variance revealed significantly substantial genetic variability across six generations. For all of the tested features in the two crossings, the F1 performed better than the other generations. Across all six generations of the two crossings, there were positive and highly significant correlations between seed cotton yield/plant, lint cotton yield/plant, and no. of bolls/plant characteristics. Seed cotton yield and yield components in the two crosses showed some favourable connections over the six generations. The UPGMA hierarchical clustering revealed a greater degree of similarity coefficients between the six generations and the attributes investigated. The similarity coefficients for the six generations and the examined features, respectively, ranged from 0.96 to 0.99 and 0.65 to 0.96. In the principal component analysis (PCA), the PCA1 extracted had an Eigenvalue of greater than 1 across six generations for all studied traits in the two crosses. The PCA displayed a total variation of 91.84% among the six generations contributed by PCA1 (79.47%) and PCA2 (12.38%) and mainly distinguished the generations into different groups. The PCA1 and PCA2 were dominated by F1 and segregation generations in the two crosses, respectively, showing high correlations with the first two PCAs. All studied traits, as well as boll weight and lint percentage traits, contributed to positive significant component loadings for the PCA1 and PCA2, respectively. The biplot analysis of the relationship between the six generations revealed that the most appropriate generations for selecting yield traits were F1 in the two crosses and BC1 and BC2 in the cross Giza 93 x C.B. 58. As a result, we recommend considering backcrossing for 2-5 cycles (BC2-BC5) at the C.B. 58 parent in the future to improve Egyptian cotton yield.

It is crucial to understand how targeted traits in a hybrid breeding program are influenced by gene activity and combining ability. During the three growing seasons of 2015, 2016, and 2017, a field study was conducted with twelve cotton genotypes, comprised of four testers and eight lines. Thirty-two F1 crosses were produced in the 2015 breeding season using the line x tester mating design. The twelve genotypes and their thirty-two F1 crosses were then evaluated in 2016 and 2017. The results demonstrated highly significant differences among cotton genotypes for all the studied traits, showing a wide range of genetic diversity in the parent genotypes. Additionally, the line-x-tester interaction was highly significant for all traits, suggesting the impact of both additive and non-additive variations in gene expression. Furthermore, the thirty-two cotton crosses showed high seed cotton output, lint cotton yield, and fiber quality, such as fiber length values exceeding 31 mm and a fiber strength above 10 g/tex. Accordingly, selecting lines and testers with high GCA effects and crosses with high SCA effects would be an effective approach to improve the desired traits in cotton and develop new varieties with excellent yield and fiber quality.