ABSTRACT. Mungbean improvement via hybridization requires the identification of true F 1 hybrids from controlled crosses before further generations of selfing/crossing and selection. We utilized inter-simple sequence repeat (ISSR) markers for identifying putative F 1 hybrids from six cross combinations whose morphological characteristics were very similar to those of their respective female parents and could not be visually discriminated from the self-pollinated progeny. Based on 10 ISSR primers, polymorphisms were found between female and male parents of all six cross combinations. The highest value of genetic differentiation (21.4%) was found between male and female parents of the SUT3 x M5-1 cross. These 10 ISSR primers gave 2.8-25.0% polymorphism between male and female parents, with a mean of 12.1%, and 0-13.0% polymorphism between F 1 hybrid and female parents, with a mean of 4.8%. F 1 hybrids of all six cross combinations could be differentiated from the self-pollinated progeny of their female parents by using only either ISSR 841 or 857 primers, together with the ISSR 835 primer. We conclude that ISSR markers are useful and efficient for identifying mungbean F 1 hybrids in controlled crosses

This study was conducted to determine the variability, heritability and correlations among agronomic and physiological characters of mungbean (Vigna radiata (L.) Wilczek) and to identify their direct and indirect effects on seed yield. Fifty six mungbean accessions were evaluated at Suranaree University of Technology Farm, Nakhon Ratchasima, Thailand using a randomized complete block design with 4 replications. Fourteen characters were collected and analyzed for genotypic coefficient of variation, phenotypic coefficient of variation, environmental coefficient of variation, heritability estimates in broad sense, phenotypic and genotypic correlation coefficients and path coefficients. It was found that genotypes differed significantly for all characters studied. The highest heritability values were recorded on days to flowering and pod length. Seed yield was significantly and positively correlated with pods per plant, clusters per plant, total dry matter (TDM), seeds per pod, seeds per plant, biomass, leaf area index and branches per plant, and negatively correlated with days to maturity. Clusters per plant showed the highest positive direct effect on seed yield followed by 100 seed weight, seeds per pod, TDM and pods per plant. However, the effect of 100 seed weight was substantially minimized by the negative indirect effects of clusters per plant, pods per plant and seeds per pod. These results demonstrate that clusters per plant, seeds per pod, TDM and pods per plant should be used as selection criteria for yield improvement in mungbean.

ABSTRACT. Heterotic effects of mungbean hybrids from 25 crosses between parents differing in 9 agronomic and physiological traits were evaluated for various selected traits and seed yield. Significant heteroses were observed in most selected traits, except for the number of seeds per plant. When the heterosis of seed yield was evaluated in these hybrids, significant heterosis was found in 9 crosses, which were selected based on the number of pods per plant, number of clusters per plant, pod length, number of seeds per pod, total dry matter, and root length density. These crosses may be exploited for mungbean yield improvement. Nine F 8 lines from 2 of these 9 crosses (KPS 1 x V 2106 and SUT 1 x V 4785), a selection based on significant heterosis for seed yield and high seed yield of F 1 and F 2 , which possessed a higher seed yield than their respective certified variety parents, were identified and these may be useful in future breeding programs.

To study the genetics of seven agronomic and physiological characters (total dry matter (TDM), number of pods per plant, seed weight per plant, 100-seed weight, number of seeds per pod, pod length and root length density) which were correlated with yield, eight crosses of mungbean were made, and the agronomic and physiological characters were evaluated in the six basic generations (P1, P2, F1, F2, BC1 and BC2) of each cross. It was found that most characters including TDM, number of pods per plant, seed weight per plant and root length density showed additive, dominance and epistatic gene effects, except for 100-seed weight, number of seeds per pod and pod length. One hundred-seed weight and number of seeds per pod possessed only additive gene effects, while pod length was controlled by both additive and dominance gene effects. The duplicate epistasis revealed the presence of a large number of non-additive gene actions controlling TDM, number of pods per plant, seed weight per plant and root length density that may hinder the improvement of these characters, and confirmed that selection of these characters in later generations would be more feasible.