Heritability and correlation analysis of morphological and yield traits in genetically modified cotton

Cotton is for its and it is grown in tropical and sub-tropical areas of the world. It has a significant role in GDP of Pakistan. Therefore, present two years research was conducted to estimate heritability and association among various yield contributing parameters of cotton. The selected genotypes of cotton were hybridized in green house of the department. The F 0 cotton seed along with parents were planted in the field conditions during May, 2018. The sowing of this experiment was completed in three replications followed by RCBD. The data was recorded at maturity for various agronomic traits including plant height, number of bolls per plant, number of sympodial branches per plant, seed cotton yield, boll weight, seed index, ginning out turn, fiber length, fiber strength, and fiber fineness. Level of significance of data was computed by ANOVA to assess the difference among cotton genotypes which was used for estimation of heritability and correlation analysis among the related traits. Whereas, cross NIAB-414 × CIM-632 was good for plant height. The CIM-632 was best for number of sympodial branches per plant, boll weight, fiber length and strength. VH-367 × CIM-632 proved best for ginning out turn. The correlation results from this study would be helpful to breed cotton cultivars with good yield and quality characters. Broad sense heritability was high for all of parameters which provides the strong evidence that selection in early generations can improve the performance of these traits.


Introduction
Cotton is also known as white gold due to its white and soft fiber. The cotton plant grown like shrub in nature and its fiber is pure cellulose. Cotton is cultivated all over the world which is mainly considered for fiber production. Its fiber is usually used to spin into yarn which is further used for making socks, curtains and towels etc. Its fiber also consumed in textile industry for cloth making (Stewart and Rossi 2010). Significant amount of oil (16-27%) is extracted from cotton seed and seed cake is used in livestock industry, and oil extracted from cotton seed is used as vegetable oil for making fries, excite etc. because taste of cottonseed oil is similar to coconut oil. In addition, it is an important source of vitamins, fat and antioxidants (Dowd et al., 2010). During 2018-2019 survey, cotton was cultivated on an area of 2,373 thousand hectares with 9.861 million bales production. It shares 0.8% in GDP and 4.5% in value addition (Govt. of Pakistan, 2018-19).
The world population is increasing day by day therefore it is necessary to increase the productivity of crop to meet the requirement of cotton. Utilization of breeding tools is the only method to meet the demand of textile industry (Farooq et al., 2014).  Komala et al., 2018). Positive correlation and high heritability were observed for plant height, sympodial branches, boll weight, number of bolls, seed cotton yield, fiber fineness and shoot length. Hence, concluded that these traits may be considered as selection criteria for improvement in seed cotton yield (Jarwar et al., 2018;Rathinavel et al., 2017). The present research was planned to determine correlation among various yield contributing traits due to increased demand of cotton in the country. In addition, heritability of these parameters was also computed which could be used for the selection of suitable traits from certain parents for the development of new germplasm of upland cotton.

Materials And Methods
The experiment was performed at two places, first in glasshouse and then at cotton Ginning Out Turn (%) First seed cotton yield was weighed then ginned with a single roller electrical gin machine.
The lint obtained from each sample was weighed separately. Ginning percentage was calculated by using following formula: Fiber length (mm), Fiber strength (g/tex) and Fiber fineness (µg/inch) Fiber traits were measured by high using high volume instrument (HVI-900) system and means for each parent/cross were calculated.

Statistical Approaches
The data collected were subjected to analysis of variance following the method of Steel and Dickey (1997) in order to determine the significant differences in plant characters of upland cotton. Genotypic and phenotypic correlation among traits were analyzed by a statistical technique that is known as correlation analysis (Kwon and Torrie, 1964). Furthermore, significance was assessed according to Steel and Dickey (1997). Whereas, Heritability in broad sense was estimated according to Burton and Devane (1953).

Results
The analysis of variance (ANOVA) exhibited significant differences and confirm the presence of variations among genotypes for traits namely plant height, number of bolls per plant, number of sympodial branches per plant, boll weight, yield of seed cotton, seed index, fiber length, fiber strength and fiber fineness (Table 1). Actually, these genotypes are significantly different from each other and significant differences allow the breeder to proceed for further analysis useful for selection of suitable candidate parental lines. In later stage this data was used for correlation and heritability analysis.

Discussion
Plant height was positively linked with sympodial branches per plant, number of bolls per plant, ginning out turn, seed cotton yield, staple length and fiber fineness ( Table 2) Heritability value for seed cotton yield was 54.56% (  (Table 3)