Heterosis and Combining Ability in Upland Cotton—Effect on Yield¹

Abstract

I festation of heterosis k n o w n as h y b r i d vigor, has received increased attention from cotton breeders. Heterosis was first utilized in obtaining increased production in asexually propagated plants. Through the use of malesterility, gametocides, and imperfect-flowered plants, heterosis is now used to advantage in many species. Considerable evidence exists (4) t h a t heterosis is expressed in crosses between Gossypz'um hiisutum (Upland cotton) and G. barb~rdeizse (e x t r a-l o n g staple cotton). There are indications that heterosis may exist also in crosses among different varieties of Upland cotton and that varieties may vary considerably in combining ability. Data from crosses among three varieties of Upland cotton, in a study begun in 1754 at the Georgia Experiment Station, indicated that appreciable heterosis existed in i n t e r va r i e t a1 crosses. Becauses of these favorable results, a larger study designed to obtain further information on heterosis and combining ability of other varieties was begun in 1756. The purpose of this paper is to report the magnitude of the heterotic effect in crosses a m o n g four varieties of Upland cotton. REVIEW OF LITERATURE Loden and Richmond (4) presented a thorough review of work on heterosis in cotton. One of their conclusions was that the maximum heterotic effect was obtained in the F1 generation and few significant increases in yield occurred in subsequent generations. Ware (8) , working with crosses between G. hirszLtum and G. b~zrbade~re, found that heterosis occurred in the F, generation of species crosses in cotton but was not expressed for all plant charackers. In discussing heterosis in intraspecific crosses, Kime and Tilley (3) reported that the general assumption had been made that heterosis did not occur in crosses within cotton species. However, Brown (1) reported that F, hybrids were frequently larger, more vigorous, and more productive than their parents. Loden and Richmond (4) were of the opin

Evaluation of twenty four new Gossypium hirsutum strains for growth, yield, fibre quality and ClCuV resistance under environment of Punjab, Pakistan

“…Results are in agreement with those of Marani (1963); Hawkins et al (1965), Young and Murray (1966) and Rafique (1972).…”

Impact of Heterozygosity and Heterogeneity on Cotton Lint Yield Stability

“…Degree of heterosis and relatedness were not correlated (Tables 2 and 5). Hawkins et al (1965) also found increasing heterosis associated with decreasing environmental mean. They attributed this to similar hybrid response over all environments where the relative percent heterosis declined as inbred means increased.…”

“…They attributed this to similar hybrid response over all environments where the relative percent heterosis declined as inbred means increased. Hawkins et al (1965) also found increasing heterosis associated with decreasing environmental mean. Heterotic response, however, was not consistent across environments, resulting in 35.0, 16.6, and 9.2% high-parent heterosis for environments that had means of 642, 712, and 1005 kg lint ha -1 , respectively.…”

Ação gênica, heterose e depressão endogâmica de caracteres de produção em linhagens mutantes de algodoeiro herbáceo

“…Valores heteróticos variando de 18% a 35% foram obtidos por Miller & Lee (1964). Hawkins et al (1965) encontraram valor heterótico de 24% e vários de seus híbridos foram significativamente mais produtivos do que o melhor progenitor. Os valores heteróticos registrados nesses trabalhos foram de alta magnitude, principalmente quanto às características produção, número de capulhos e tamanho do capulho.…”