【摘要】 <正> 前言 在过去几年中我们曾对陆地棉的纤维长度、早熟性和丰产性状做过一些遗传力的估测。目的是要通过对遗传力的研究,提高棉花育种工作的计划性和预见性,多快好省地选育新品种。更多还原

【Abstract】 The genetic advance of 16 economic characters of upland cotton were predicated from the data of experiments carried out on two locations for three years. The "relative genetic advance" (△G’), i.e. the relative value of genetic advance in percentageof mean, was calculated from the formulae, where σ8, is thestandard deviation of genotypic value, x is the estimated mean from the sample, h2 is heritability, and K is selection differential (I) expressed in percentage of standarddeviation of phenotypic value (i.e. K =I/ σph%). Under normal distribution, K is estima-ted from K = -z/q , where q is selection intensity, and Z is the ordinate of normal curveseparated q from the rests of the area under the curve. For a given value of q, there is a corresponding value of Z that can be found in the table of area and table of ordinate under normal curve. For q = 0.40, 0.30, 0.25, 0.20, 0.10, 0.05 and 0.01, the corresponding value of △G’ can be calculated and compared. The results obtained show that:1. The magnitude of relative genetic advance (△G’) is not only related to heritability (h2), but also in proportion to σ8/x. Furthermore, the increase of σ8/x had a greater effect to the increase of △G’ than an increase of heritability (h2).2. The magnitude of △G’ predicated from population of cotton varieties can be classified into four classes: (1) those with higher △G’, characters like % of first picking, yields per plant, boll weight, lint percentage and number of bolls per plant had 15 - 20% of △G’ under 30% selection intensity; (2) those with median △G’, character like lint index had 12% of △G’ under 10% selection intensity; (3) those with lower △G’, characters like fiber length, time of ’’ square’’ appearing, time of blossoming, time of the first boll opening and time of 50% boll opening, had 2-9% of △G’ tinder 10% selection intensity; (4) those with lowest △G’, characters like time of seedling emergence, height of first fruiting branch, mean length of internodes of main stem, had 3-5% of△G’ under 10% selection intensity.3. The magnitude of △G’ predicated from P1, P2, F2 populations varied with the genetic purity of parents (P1; P2). When the purity of parents is higher, heritability (h2) and △G’ predicated will be higher, when the purity of parents is lower, h2 and △G’ predicated will also be lower.4. The magnitude of △G’ predicated from F5 population is usually lower than that of the same character predicated from varieties population or from P1, P2, F2 populations.更多还原