Genetic effects on morphological and yield traits in cotton (Gossypium hirsutum L.)

Abstract

The nature and magnitude of genetic effects on morpho-yield traits were studied in a 6 × 6 F 1 and F 2 diallel cross in upland cotton. An additive-dominance model was adequate for most of the traits except plant height and seed cotton yield, where the model was partially adequate. Genetic parameters were estimated following Hayman's and Mather's model. Additive effects controlled lint percentage and monopodia in both generations, and plant height and sympodia in F 2 . Non-additive inheritance with over-dominance controlled yield in both generations, and plant height and sympodia in F 1 . Most traits presented an unequal proportion of positive (U) and negative (V) alleles in the loci (H 2 < H 1 ) and an asymmetrical distribution of genes in the parents (H 2 /4H 1 < 0.25 and F different to zero). The value of H 2 /4H 1 was lower than maximum value (0.25) for all of traits, which arises when U = V = 0.5 over all loci. The proportion ͌ʳʲ 4DH1 ʲʲ + F ʲ/͌ʳʲ 4DH1 ʲʲ -F ʲ) confirmed by half of the traits that dominant alleles were in excess as compared to recessive alleles. Dominance effects (h 2 ) for most of the traits suggested that substantial contribution of dominance was not due to heterogeneity of loci in these parameters. Broad and narrow sense heritabilities were high for most of the traits. Correlation coefficient between the Wr + Vr and mid parental (y) indicated that dominant genes were responsible for increased sympodia, lint % and yield, and recessive genes increased monopodia and plant height. Genetic gain was encouraging for most traits. Cultivar CIM-1100 was identified by genetic advancement as a promising parental cultivar to cross combinations.Additional key words: additive-dominance model; additive and dominance effects; D, H 1 & H 2 genetic components of variance; seed cotton yield; upland cotton. ResumenEfectos genéticos en caracteres morfológicos y de rendimiento en algodón (Gossypium hirsutum L.)Se estudió la naturaleza y la magnitud de los efectos genéticos sobre los caracteres morfo-productivos en un cruce dialélico F 1 y F 2 de 6 × 6 en algodón tipo upland. Para la mayoría de los caracteres, excepto altura de planta y rendimiento de semilla, fue adecuado un modelo aditivo-dominante. Se estimaron los parámetros genéticos según Hayman y Mather. Los efectos aditivos controlaron el porcentaje de pelusa y los monopodios en ambas generaciones, y la altura de la planta y los simpodios en la F 2 . La herencia no aditiva con superdominancia controló el rendimiento en ambas generaciones y la altura de planta y los simpodios en la F 1 . La mayoría de los caracteres presentaron una proporción desigual de alelos positivos (U) y negativos (V) en los loci (H 2 < H 1 ) y una distribución asimétrica de los genes en los parentales (H 2 /4H 1 < 0,25 y F 0). El valor de H 2 /4H 1 estuvo por debajo del valor máximo (0,25) para todos los caracteres, lo que surge cuando U = V = 0,5 en todos los loci. La proporción ͌ʳʲ 4DH1 ʲʲ + F ʲ/͌ʳʲ 4DH1 ʲʲ -F ʲ) confirmó, para la mitad de los caracteres, que había un exc...

Assessing gene action for hypoxia tolerance in cotton (Gossypium hirsutum L.)

“…The value of H 2 /4H 1 was less than 0.25, which depicted unequal distribution of genes for the trait among the parents for all the traits under normal and hypoxic conditions. Negative F value was observed for staple length under normal and for seed cotton yield under hypoxia signified the unimportant role of dominant genes which are in conformity to the findings of Khan and Hassan (2011), which reported negative F value for lint percentage and seed cotton yield in the F 1 generation, same researchers reported positive values for these traits while studying F 2 generation. The dominance additive ratio represents the degree of dominance.…”

“…The estimation of genetic components of variation revealed that value of additive component (D) was positive and significant found more than the values of dominance components (H 1 ) and (H 2 ) indicating the important role of additive and non-additive effects in controlling all the characters studied. Khan and Hassan (2011) reported additive effects for ginning out-turn percentage and non-additive effects for seed cotton yield. Moreover, Shakeel et al (2011) also reported about the contribution of additive effects in F 1 generation and non-additive effects in F 2 generation for seed cotton yield.…”

Diallel analysis in cotton (Gossypium hirsutum L.) for water stress tolerance

“…Raza et al (2013) evaluated five cultivars and detected additive effects to plant height, lint yield, lint percentage and boll weight. Khan and Hassan (2011) estimated the GCA and SCA in a diallel scheme involving 12 cotton cultivars and found differences in all hybrid combinations to lint yield, boll weight and boll numbers, with more genetic variances to SCA than to GCA indicating predominance of non-additive gene.…”

Genetic Diversity and Correlation Studies for Cotton Leaf Curl Disease (CLCuD), Fiber &amp; Yield Related Attributes in Exotic Lines of &lt;i&gt;Gossypium arboreum&lt;/i&gt; L.

“…It contributes to the oil and seed sector as well as fiber industries [1]. Pakistan's economy totally relies upon cotton production directly or indirectly [1] [2]. Among the four cultivated species of cotton, Gossypium arboreum also called "true cotton", is a specie native to the Indian subcontinent and presently used in introgressive breeding as a donor species for improving resistance to insect pests and disease especially CLCuD in upland cotton [3] [4].…”