Estimates of general and specific combining ability for yield components in a partial sugarcane diallel cross

M.A Silva,J.A Bressiani,P.S Gonçalves,M.G.A Landell,M.P Campana

doi:10.12702/1984-7033.v02n01a14

Abstract

The performance of 21 sugarcane progenies (Saccharum spp.) obtained in a diallel cross between three and seven varieties was evaluated from progeny tests conducted in Jau Agronomy Experimental Station, Instituto Agronomico de Campinas, Sao Paulo State, Brazil. Measurements for average Brix, stool weight, stalk height, stalk diameter and stalk number were analyzed to obtain estimates of the relative magnitude of general (GCA) and specific combining ability (SCA) effects. Significant differences among GCA of the varieties were obtained for all characters, except stalk height, while significant differences among SCA effects were not expressed only for stalk height. An evaluation of variance components revealed that the variances of GCA for average Brix was almost the same of the component for SCA effects. A similar ratio for the two effects was obtained for stalk diameter. For average Brix, the ratio of GCA/SCA effects was bigger than the ratio observed for the other characters. This indicated that with the relatively bigger proportion of the genetic variance resulting from general effects, parental breeding value can be estimated from progeny of open-pollinated or polycross seed. The proportion of the genetic variance resulting from GCA effects of the other studied characters, the parental breeding value could be estimated from control-pollinated progeny tests.

Highlights

Most progeny testing programs for sugarcane (Saccharum spp.) are designed to obtain information about the breeding value of selected parents
Selection for high general combining ability (GCA) assumes that each variety will cross-pollinate with a number of other varieties and that the majority of the seed production from the seed field will be from such crosses
Interest in specific combining ability (SCA) is usually based on three considerations: 1) high specific combining ability is an indication of a relatively large amount of non additive variance affecting the trait under consideration; 2) the relative magnitude of SCA over GCA can be important to determine the method of progeny testing used for assessing breeding value; and 3) in some instances, high SCA can be used to establish seed fields which would use the dominant gene effects for the production of seeds having potential for great improvement in one trait

Summary

Introduction

Most progeny testing programs for sugarcane (Saccharum spp.) are designed to obtain information about the breeding value of selected parents. Hogarth (1973) reported that the value of GCA was more significant consistent compared with SCA values for average Brix, stalk number, stool weight and stalk yield. Like stool weight, stalk height, stalk number, stalk diameter, and average Brix were evaluated.

Results

Conclusion