Studies on heterosis in rice (Oryza sativa L.)

摘要

In plant breeding programme, exploitation of heterosis is vital and considered to be one of the greatest achievements. The F_1 hybrids can be exploited commercially or can be used for selecting promising recombinants in the subsequent generations torelease the best variety when it attained homozygosity. The different basis of heterosis consists of (i) relative heterosis over mid parent (ii) heterobeltiosis on better parent basis and (iii) standard heterosis based on existing superior local variety, are equally important in their own way. In the present paper all the three bases of heterosis were studied in rice and presented. The standard heterosis was worked out taking MDU.5 as the standard variety. Eight strains of rice were crossed in a L X Tmethod and 16 hydrids were obtained (4 lines and 4 testers). The lines were Nootripattu, Poongar, Seengani, and Vellaichithiraikar and testers were ADT.36, IR.20, IR.50 and MDU.5. The sixteen hybrids and eight parents were evaluated during 1998 rabi season at Agricultural College and Research Institute, Madurai. The experiment was conducted in a randomized block design with two replications. Each genotype was raised in three rows of 3m length with a spacing of 20cm X 15cm between rows and among plants.The recommended agronomic practices were adopted. Data were recorded on five randomly selected plants in the middle row. The six characters selected for analysis were plant height, number of productive tillers per plant, panicle length, number of spikelets per panicle, number of grains per panicle and single plant yield.