Combining ability analysis over the environments for harvest index and its components in sorghum [Sorghum bicolor (L.) Moench]

Abstract

Harvest index measures the physiological efficiency of the plants [1]. Breeders have recognized the importance of a favourable harvest index in terms of partitioning of photosynthates to economically important plant parts. Improvement in sorghum have been concentrated primarily on those traits, which have direct bearing on grain yield, eventhough harvest index in local and hybrids of sorghum has been reported up-to 29 and 50 per cent, respectively [2, 3]. Thus, there is a greater need for genetic manipulations to increasing the harvest index in sorghum. The present investigation was an attempt to obtain information on combining ability of harvest index, grain yield and related characters over the environments in sorghum by taking seven grain sorghum genotypes representing fairly wide range of genetic diversity were crossed in diallel fashion (without reciprocals). Twenty-eight genotypes including parents and their crosses were evaluated in a randomized block design with three replications in four environments, which were created by growing these genotypes in two successive seasons viz., kharif 2001 and kharif 2002 along with two fertilizers doses viz., recommended dose of fertilizers i.e. 80 kg N: 40 kg P20S/ha and half of the recommended dose of fertilizers i.e. 40 kg N: 20 kg P20s/ha. Each genotype was planted in single row of 3-meter length with 45 cm x 15 cm plant geometry. The data were recorded on nine quantitative characters (Table 1) on a sample of 10 randomly selected plants/replication/environment in each genotype. The pooled combining ability analysis was done following [4-6].