DOCTOR OF PHILOSOPHY (Agriculture) PLANT BREEDING AND GENETICS INDRA SINGH

Transcription

1 GENETICS OF QUANTITATIVE TRAITS IN COWPEA [Vigna unguiculata (L) WaIp.] A THESIS SUBMITTED TO THE SARDARKRUSHINAGAR DANTIWADA AGRICULTURAL UNIVERSITY IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE A WARD OF THE DEGREE OF DOCTOR OF PHILOSOPHY (Agriculture) IN PLANT BREEDING AND GENETICS BY INDRA SINGH M.Sc.(Agri.) DEPARTMENT OF PLANT BREEDING & GENETICS CHIMANBHAI PATEL COLLEGE OF AGRICULTURE SARDARKRUSHINAGAR DANTIW ADA AGRICUL TURAL UNIVERSITY SARDARKRUSHINAGAR [GUJARAT) SEPTEMBER 2004 {Regn. No }

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3 GENETICS OF QUANTITATIVE TRAITS IN COWPEA [Vigna unguiculata (L.) Walp.] Name of student : Shri INDRA SINGH (Regi.No ) Name of Major Advisor: Dr. S.N. BADA Y A Professor & Head DEPARTMENT OF PLANT BREEDING AND GENETICS CHIMANBHAI PATEL COLLEGE OF AGRICULTURE SARDARKRUSHINAGAR DANTIW ADA AGRICULTURAL UNIVERSITY SARDARKRUSHINAGAR ABSTRACT Heterosis, inbreeding depression, combining ability and genetic components of yield and twelve other traits were studied following diallei analysis involving eight cowpea parents, their 28 hybrids during summer 2003 (EI ) and parents, their F,s and F 2 s during monsoon 2003 (E 2 ) at Main Pulses Research Station, S.D. Agricultural University, Sardarkrushinagar. Observations were recorded on thirteen characters, viz., days to flowering, days to maturity, plant height, branches per plant, number of pods per plant, number of clusters per plant, number of pods per cluster, pod length, nu111ber of seeds per pod, loo-seed weight, grain yield, harvest index and protein content. Data were analyzed following Griffing (1956) Model-I, Method-2 for combining ability and genetic components and graphi~al analysis as per Hayman (I 954a).

4 The analysis of variance revealed significant differences among the genotypes for all the characters studied. The variances due to parents vs' F I were also found significant for all the characters except for days to maturity, plant height, branches per plant and protein content in E J, whereas, in E 2, the variances due to genotypes, parents, F 1, F 2 and parents vs F I were highly significant for all the traits except for days to maturity in parents vs F}, while days to flowering, seeds per pod and IOO-seed weight were non-significant in F I VS F 2. In the pooled analysis, the variance due to G x E interaction were significant for all the traits except seeds per pod. ~he magnitude of heterosis was greater for branches per plant, pods per plant, clusters per plant and grain yield, moderate for pods per cluster, pod length, seeds per pod, IOO-seed weight and harvest index and low for days to flowering, days to maturity, plant height and protein content. It was observed that high heterosis for grain yield was mainly due to heterosis in three yield contributing traits, viz., pods per plant, seeds per pod and 100-seed weight. The crosses which manifested high heterosis for yield and its components also showed high inbreeding depression. The parents TC-99-1, HC and TC were good general combiner for grain yield and most of the other characters and RC-19 and Meterlong for early flowering and maturity which can be used in crossing programme to isolate superior segregants. Per se performance of parents and hybrids can be a good indicator for predicting general combining ability (GCA) and specific combining ability (SCA) effects, respectively. Estimates of variance due to gca (cr 2 gca) and sea (a 2 sca) and predictability ratios along with D and H components revealed that both additive and non-additive gene actions were in operation in the

5 inheritance of all the traits under study, with predominant role of nonadditive gene action. Further, dominance ratio also indicated the presence of over dominance in most of the characters. Graphical analysis, however, revealed partial dolninance for plant height, pod length, I OO-seed weight and protein content in both the environments and generations, complete dominance for days to maturity and grain yield per plant in E,F., pods per cluster in E 2 F, and over dominance for days to flowering, harvest index and branches per plant in both the environments, clusters per plant, grain yield per plant and seeds per pod in E 2 F) and pods per cluster in ElF,. the graphical analysis also showed presence of wide genetic diversity among the parental lines for all the traits. The parents TC-99-1, HC and TC were found to be good combiners for grain yield and its attrib utes. The parental lines, RC-19 and Meterlong were observed to be good sources of genes for earliness. The heritability estimates were high for pod length, moderate for days to flowering, days to maturity, plant height, pods per plant, clusters per plant, pods per cluster, 100-seed weight, grain yield, harvest index and protein content and low for branches per plant. The results of present investigation suggested that reciprocal recurrent selection should be followed which would take care of both types of gene action. Biparental mating may also be used in segregating generation to break undesirable linkage.