Genetics of synchrony in maturity and indeterminate growth in mungbean

Abstract

The research studies reported in this dissertation were conducted at the experimental area of Department of Plant Breeding and Genetics, University of Agriculture Faisalabad, Pakistan. The aim of the investigation was to appraise the inheritance pattern of synchrony in pods maturity, indeterminate plant growth and yield related parameters. For the purpose two screening trials were performed in two different seasons. A multivariate statistical and logarithmic technique was applied for the selection of appropriate parents. Two approved varieties (AZRI-2006 and NM-2006) out of fifty mungbean accessions displayed lowest DDd2 and DDh2 values. The other two accessions (97006 and AUM-9) which were selected had demonstrated the highest values for the said parameters. Two cross combinations were made by utilizing the mentioned four parents. Six basic populations (P1, P2, F1, BC1, BC2 and F2) of two crosses were developed. Genetic variance analysis revealed the existence of additive and environmental components only for the inheritance of all the seventeen traits in both the cross combinations, with the pre-pondrance of additive variance only. Similarly the estimates of narrow sense heritability F2 and F generation were higher for all the traits in both the crosses of mungbean. The results of generation variance and heritability estimates suggested the pre-pondrance of additive component only. Generation mean analysis revealed the pre-pondrance of only additive genetic component for days taken to ninety percent pods maturity, similarly additive and dominance components were important for the inheritance of DDh3 and seed yield per plant in NM-2006 × 97006 cross combination. The involvement of additive, dominance and positive additive × additive digenic interaction was detected for seeds per pod and seed yield per plant in AZRI-2006 × AUM-9 cross and for days to first pod maturity, plant height approaching reproductive phase in NM-2006 × AUM-9. Due to the involvement of fixable genetic components, the proposed breeding methodology for the improvement of mentioned traits could be the use of pedigree, bulk or single seed descendent method of selection for producing early maturing, dwarf type plants, with lowest degree of indetermination of plant height (DDh3) escorted with maximum seeds per pod and seed yield. Heterosis in F1 was greatly pronounced for the traits; DDd1, DDd2, DDd3, DDh1, hundred seed weight and seed yield per plant. The same was useless due to the involvement of negative dominance except for the trait seed yield per plant. Due to pervasiveness of heterosis, direct selection for high yielding plants in early segregating generation may be rewarding. The results signified the engagement of epistasis for most of the traits. A negative dominance for the characters indicated that dominance was towards the reducing effect of traits. For those traits in which epistasis was involved, the purposed breeding strategy may be the use of bi-parental approach, diallel selective mating or recurrent cycles (one or two) of selection among the selected segregants in early generation and final selection may be delayed until the elimination of undesired genes. Similarly interrelationships study was also performed to detect the association of traits with seed yield and among themselves. The same analysis pointed out that number of seeds per pod, hundred seed weight, number of pods per 8 plant, pod clusters per plant, days to first flower, first pod maturity, ninety percent pods maturity, could be utilized as effective criteria for the improvement of seed yield greengram. On the basis of information derived from the above given studies, synchronous maturing, determinate and high yielding mungbean genotypes might be useful in future breeding programmes to increase the crop production, which will ultimately increase the gross domestic product.