31-12-2010, 11:55 AM
BY:Kyaw Swar Win, Soe Win, Aung May Than
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ABSTRACT
Field experiments were conducted in pre-monsoon and monsoon seasons, 2008 at Food Legumes Section, Department of Agricultural Research (DAR) to select the suitable lines for pre-monsoon and monsoon seasons, to estimate the genetic variability, heritability and genetic advance for yield and agronomic characters among the tested mungbean breeding lines and to study the association of yield and agronomic characters among these lines.
Ten selected mungbean breeding lines obtained from National Mungbean Breeding Program of Food Legume Section, DAR, were planted in randomized complete block design with four replications in both seasons using Yezin-9 and Yezin-11 as checks. Genetic parameters and correlation studies were computed.
In pre-monsoon season, only 11 genotypes were recorded due to severe infection of mungbean yellow mosaic virus on Yezin-9. Pre-monsoon season gave high variation in the characters among the tested breeding lines. The line-2 (YM-03-2-2), line-7 (YM- 01-1-7), line-8 (YM-01-1-8) and line-5 (YM-03-2-5) should be selected as promising lines for pre-monsoon because of high yield performance and high mean of their yield components. And line-2 (YM-03-2-2), line-7 (YM-01-1-7), line-8 (YM-01-1-8) and line- 5 (YM-03-2-5) showed highly resistant to mungbean yellow mosaic virus in premonsoon season. In the monsoon season, line-6 (YM-03-2-6) and line-4 (YM-03-2-4) had better yield performance and higher yield performance than check variety (Yezin-9). Thus these two lines could be used as promising lines for monsoon. Mean performance of observed characters in monsoon season were higher than those of pre-monsoon season. This indicated that monsoon season is more preferable for the production of mungbean. All the observed characters except number of seeds per pod were significantly different in both seasons.
In pre-monsoon, the selection of the early flowering variety with larger number of pods per plant will lead to yield improvement because yield per plant is negatively correlated with days to 50% flowering and positively correlated with pods per plant. In monsoon season, pods per plant and plant height could be considered yield contributing characters for monsoon season.
INTRODUCTION
Mungbean belongs to the family Leguminosae and botanically recognized as Vigna radiata L. Wilczek syn. Phaseolus radiatus L., P. aureus Roxb (Wilczek 1954; Verdcourt 1970). Mungbean probably originated in India (De Candole 1886; Zhukovsky 1950; Bailey 1970) or the Indo-Burmese region (Valvilov 1951; Singh and Jain 1970). Annual mungbean production world wide is about 2.5 to 3.0 million metric tons harvested from about 5.0 million hectares. About 45% of the world mungbean production is in India. Mungbean is the most important grain legume in Thailand and Philippine, and in Sri Lanka it ranks second, while in India, Myanmar, Bangladesh and Indonesia it is the third most important grain legume (Poehlman 1991). Mungbean is a highly valuable short duration crop having many desirable characters like high protein content, wide adaptability, low input requirement and ability to improve soil fertility (Makeen et al. 2007).
Mungbean is one of the major pulses in Myanmar. It occupied the largest area about 24.46% (one million hectare) of the total area of legumes. Annual production of mungbean was about 108,000 metric tons in 2007-2008. The largest mungbean growing areas are found in central Myanmar where pre-monsoon sowing (February - March) and monsoon sowing (May - September) are most prevalent. The rest are found in lower Myanmar where mungbean is grown in post-monsoon season (Mid October – Mid December) after rice harvest (MOAI 2008).
The target yield in Myanmar is 1600 kg per hectare, but the yields of premonsoon, monsoon and post-monsoon in 2006-2007 were 500 kg per hectare, 965 kg per hectare and 1143 kg per hectare, respectively (MOAI 2008). Therefore, it is needed to attempt to reach national target yield. The production constraints in mungbean are low yield potential, lack of yield stability, susceptibility to major diseases and pests, narrow adaptability due to photoperiod and temperature sensitivity and susceptibility to abiotic stresses such as drought, flood, nonsynchronous maturity and pod shattering (Fernandez and Shanmugasundaram 1988).
Seed yield is an important trait as it measures the economic productivity in mungbean, but its inheritance is extremely complex. The breeding systems that make use of additive genetic variance will be effective breeding procedures for improving the mungbean seed yield but very little basic information is available on all types of gene effects controlling the seed yield and its components in mungbean (Khattak et al. 2001). The efficacy of selection depends upon the magnitude of genetic variability for yield and yield contributing traits, and the knowledge of heritability and genetic advance for these traits guides the breeders to select superior genotypes to initiate an effective and fruitful crossing program, but in highly self pollinated crops like mungbean, natural variation is narrow resulting in limited opportunity (Khan et al. 2004).
Correlation study gives an idea about the contribution of different characters to seed yield. The analysis of correlation provides the information of interrelationship of important plant characters and hence, leads to a directional model for direct and/or indirect improvement in seed yield (Vandana and Dubey 1993).
Therefore, this study was undertaken with the following objectives:
1. to select the suitable lines for pre-monsoon and monsoon seasons,
2. to estimate the genetic variability, heritability and genetic advance for yield and agronomic characters among the tested mungbean breeding lines and
3. to study the association of yield and agronomic characters among the tested mungbean breeding lines.
