**6. Production constraints**

Traditionally, mungbean has been grown during kharif season. Development of short duration and disease resistant varieties has led their cultivation during spring/summer season in North and central India and during winter (rice fallows) in the coastal peninsula. The major constraints in achieving higher yield are lack of exploitable genetic variability, absence of suitable ideotypes for different cropping systems, poor harvest index, and susceptibility to biotic and abiotic stresses, besides non-availability of quality seeds of improved varieties. The major yield limiting harriers are lack of seedling vigour, excessive flower production, flower drops, poor pod setting, poor harvest index, monocarpic senescence, low response to inputs, narrow adaptation, indeterminate growth habit, staggered maturity and sensitivity to photoperiods and temperature. The phenomenon of compensation among yield components is considered to be main yield limiting factor. Limited variability has been exploited in varietal development programmes of these crops. Pedigree analysis of the released cultivars indicated that a small number of parents with high degree of relatedness were repeatedly used in crossing programmes. Diseases and insect pests cause considerable yield losses to mungbean. Mungbean yellow mosaic virus (MYMV), cercospora leaf spot (*C. canescens*, *C. cruenta*) and powdery mildew (*Ertisiphe polygoni* DC) are of considerable economic importance. Mungbean yellow mosaic virus and leaf crinkle during kharif and mungbean yellow mosaic virus during spring in North India and powdery mildew during winter season in coastal peninsula are the major diseases. During the vegetative stage, defoliators like hairy caterpillars, semi-looper and caterpillar are the common pests. Activity of thrips starts at the bud stage and poses serious problems when the crop attains peak flowering, resulting in heavy flower drop. There is no resistant variety against these insect pests. Pre-harvest sprouting especially in mungbean poses a serious threat to timely sown crop during rainy season. Intense heat and hot winds during May-June lead to flower drop and poor pod set in spring/summer crop.
