Inheritance of Seedling Root Length and Relative Root Weight in Cotton¹

Abstract

A perennial problem in cotton, Gossypium hirsutum L., involves obtaining a vigorous, uniform stand when planted early. Strains that grow roots longer and higher in relative root weight (mg/mm length) than currently used cultivars when temperatures are cool may help alleviate this. Using the standard cotton, cool temperature (18°C) germination test we determined root lengths and relative root weights for 124 day‐neutral composite F3 strains. Variability among lines was significant for each seed and seedling parameter. Fixed model diallel analyses of five strains indicated that among the five strains one would have difficulty in selecting for long roots with high relative root weight. Generation mean analysis indicated from one of two crosses that large amounts of additive, dominance, and additive by additive epistatic effects were present for the two primary root traits. One should thus be more successful if selection is delayed to the F3 to allow genetic recombination of additive and additive by additive epistatic genes to occur. Recurrent selection should be a useful method of breeding. The cross of strains 3822 ✕ 3851, involving accessions T‐214 and T‐225, respectively, should be useful for developing lines with root length equal or longer than ST 213 and relative root weight greater than ST 213. We speculate that plants with long roots and a high relative root weight should possess increased levels of resistance to seedling disease through a mechanical type of resistance; i.e., the plants should have more root tissue to slough off as diseased tissue and yet maintain a viable root system and a healthy plant than would plants with short roots with a low relative root weight.

Estimation of gene effects of the drought avoidance root characteristics in chickpea (C. arietinum L.)

“…These results have close resemblances to gene components that control the expression of root dry weight and root surface area in common bean (Araujo et al, 2005). Also in cotton, the gene effects of root characteristics showed that additive and additive  additive gene effects account for about 50% of the variation in root length in one of the two crosses tested at seedling stage (Eissa et al, 1983).…”

Relationships between shoot and root characteristics of white clover cultivars differing in response to phosphorus

“…In other species, genetic variation for root/shoot ratio has also been commonly observed (Eissa et al, 1983; Downloaded by [Monash University Library] at 11:33 04 February 2015 Gabelman et al, 1986;Singh et al, 1988;McMichael and Quisenberry, 1991). For many species, narrow sense heritabilities for root/shoot ratio were high (hN > 0.5), e.g.…”

“…Significant correlations between shoot and root dry weight of cultivars or genotypes within species have been commonly observed (Ali-Khan and Snoad, 1977;Monyo and Whittington, 1970;Salleh and Gritton, 1988;Singh et al 1988;Veronesi, 1990) but are not universal (Eissa et al, 1983;McMichael and Quisenberry, 1991). Highest correlations between root dry weight and either shoot dry weight, leaf number, or stolon length were recorded at low and intermediate P levels (40,120, and 200 mg P/kg soil) (Table 6a), levels at which responses to P were occurring (Figure 1).…”

Genetic analysis and quantitative trait locus mapping of PEG‐induced osmotic stress tolerance in cotton

“…, Eissa et al. , Taylor , Cook , Ludlow and Muchow ). Physiological traits include leaf water content, carbon isotope discrimination (Leidi et al.…”