Studies on Combining Ability and Heterosis in Table Pea (Pisum Sativum Spp. Hortense L.) Using Half Diallel Mating System

Abstract

Vegetable pea is a very common and nutritious vegetable grown in cool season. It is a self-pollinated vegetable crop. Informations on the different aspects of genetic architecture shall provide a guideline to formulate efficient breeding programme for improvement of the crop and selection of . elite parents for the development of improved varieties. Keeping all these points in mind, the study entitled "Studies on Combining Ability and Heterosis in Table Pea (Pisum sativum spp. Hortense L.) Using Half Diallel Mating System." was formulated. The experiment was conducted with 45 F1s developed through 10 parent diallel cross technique excluding reciprocals during the year 2010-11 in a Randomized Block Design. The data on 10 quantitative and 4 qualitative traits were recorded. The analysis of variance revealed highly significant differences for all characters among parent and F1's except no. of branches per plant, width of pod and ash content. Highly significant variance was noted for days to flowering, length of first fruiting node, dry matter and yield per plant. Mean performance of F1's was higher than parent for plant height, seed/shell ratio, protein content and dry matter. The estimated value of additive genetic variance was highly significant for all the characters except width of pod. The component of variance due to dominance (H1) was highly significant for days to flowering, plant height, length of first fruiting node, no. of first fruiting node, no. of branches per pod, length of pod, no. of seeds per pod, seed/shell ratio, no. of pods per plant, protein content, dry matter, ash content while non significant for width of pod. The component of variance due to dominance (H2) revealed significance for all the characters under study except width of pod. Positive and highly significant value of F component was recorded for all characters except days to flowering, width of pod, no. of seeds per pod, seed/shell ratio, protein content, dry matter and ash content. The estimated value of h2 was found positive and highly significant for days to flowering and no. of seeds per pod while non-significant for remaining characters. The estimated value of E was non-significant for all traits. The value of average degree of dominance (H1/D)0 · 5 reflected recessive alleles for all the characters under study. The ratio of dominance and recessive (4DH1)·05 +F/(4DH1)·05-F being greater than unity for no. of branches per plant, seed/shell ratio, dry matter, ash content and yield per plant indicated that dominant genes were more frequent than recessive genes for these characters. The ratio h2/H2 was less than unity for all characters suggesting thereby at least one of the major gene group was responsible for controlling the inheritance of these traits which might be due to complementary gene interaction causing depression in the ratio. The mean sum of square due to gca revealed highly significant value for all characters except no. of branches per plant, length of pod, width of pod and ash content. The sea variance revealed highly significant value for days to flowering, plant height, length of first fruiting node and yield per plant. The sea effect for yield per plant was plotline and significant for 3 crosses viz, AP-2xAP-3, AP4xE-6 and AP-1 xAP-4. The percentage of heterosis was worked out over superior and mid parent. The crosses KS-501 xE-6, KS- 156xE-6, AP-3xE-6 and AP-3xE-6 and AP-1 xE-6 over superior parent and AP-2xAP-3, AP-4xE-6, AP-2xE-6 and KS-149xAP-2 over mid parent exhibited superior in terms of heterosis along with the mean performance. The estimate of heritability in narrow sense was found low for with of pod, moderate for days to flowering, plant height, length of first fruiting node, no. of first fruiting node, length of pod, seed/shell ratio, no. of pod per plant, protein content, dry matter, ash content while high for remaining characters like yield per plant, no. of branches per plant and no. of seeds per pod. Genetic advance in percent of mean in F 1 generation was observed high for days to flowering, plant height, length of first fruiting node, no. of branches per plant, no. of seeds per pod, no. of pod per plant, yield per plant while other traits exhibited moderate genetic advance. The characters like plant height, length of first fruiting node, no. of first fruiting node, width of pod, no. of seeds per pod, seed/shell ratio, no. of pod per plant, protein content, dry matter, ash content and yield per plant are controlled through non-additive genetic variance and as such breeding methodology like pedigree method may be applied for improvement of these characters. Therefore, it is concluded that pedigree method, recurrent selection, single seed decent method as well as simple selection would be more beneficial for improvement of seed yield and its components in Table Pea. However, the best three crosses showing significant sea effects ilil order of merit for yield per plant were AP-2xAP-3, Af?-4xE-6 and AP-1 xAP-4. It is therefore suggested that these ttlree crosses may be utilized for selection of superior lines from segregating populations.