Line x tester analysis for yield components and fiber properties in some cotton crosses of (Gossypium Barbadense L.) [electronic resource].

Includes references.

The present study was carried out at Sakha Agricultural Research
Station, Cotton Research Institute, Agricultural Research Center, Egypt, during 2017 and
2018 seasons. This investigation was carried out to estimate heterosis, combining ability,
proportional contributions, genetic components and heritability estimates of some
characters for six Egyptian cotton varieties as lines i.e, Giza 90, Giza 95, Giza 86, Giza 94,
Giza 92 and Giza 96, while, the other five genotypes used as testers were Karshenky,
Suvin, Australy 13, Pima S1 and Pima S6, using line x tester analysis. In 2018 season a
randomized complete blocks design with three replications was carried to evaluate all
genotype (eleven parents and their 30 Fts crosses) for some genetic parameters. The
results indicated that mean squares due to the genotypes, parents, crosses and parents
vs. crosses were significant and highly significant for all traits studied, except No. o~
bolls/plant in the parents, lint percentage in the crosses and fiber strength in the crosses
and parents vs. crosses. The mean squares due to lines were significant for all studied
traits. Mean square for testers and Line x Tester were significant for most traits studied.
The following crosses demonstrated the best heterosis relative to mid- and better-parent,
i.e, Giza 95 x Karshenky, Giza 95 x Australy 13 and Giza 95 x Pima S1 for most traits
studied, while the following crosses demonstrated the best heterosis relative to mid- and
better-parent for most studied yield traits, i.e. Giza 90 x Australy 13 and Giza 86 x
Karshenky. The crosses Giza 92 x Karshenky, Giza 92 x Australy 13, Giza 92 x Pima S1,
Giza 96 x Suvin and Giza 96 x Pima S1 were the best heterosis relative to mid-parent for
most studied fiber traits. The results revealed that the line Giza 95 was significant and
positive desirable GCA effects fOr all yield traits. Giza 92 had significant and positive
desirable GCA effects for seed index and fiber strength and negative desirable for
micronaire reading Giza 96 had significant and positive desirable GCA effects for fiber
strength and negative desirable for micronaire reading. In this respect, the results of
testers showed that Australy13 had significant and positive desirable for No. of
bolls/plant, seed cotton yield/plant and lint cotton yield/plant. However, estimates of
specific combining ability (SCA) effects for the crosses Giza 90 x Karshenky, Giza 95 x
Pima S1, Giza 92 x Karshenky and Giza 96 x Suvin were significant desirable SCA effects
for some yield traits. Proportion contribution of testers contribution was higher than
lines contribution for all traits studied except No. of bolls/plant. However proportion
contribution of lines x testers interaction was higher than of lines and testers for most
traits studied. The non-additive of genetic parameters were larger than additive genetic
variance with respect to all studied traits. Broad sense heritability (h2b%) estimates were
larger than the corresponding values of narrow sense heritability (h2n%) for all traits
studied. The highest broad sense heritability estimates was observed in case of lint
percentage with values of 71.70% and the lowest was for uniformity index with value of
27.55%, while for narrow sense heritability, it ranged from zero to 4.37% for boll weight
and lint index, respectively. Generally, Giza 95 and Australy13 could be used in breeding
programs for improving high yielding varieties, while Giza 92 and Giza 96 could be
considered as excellent parents for breeding programs to produce new varieties
characterized with best fiber properties.

Summary in Arabic.