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The basic information on gene action and inheritance of quantitative traits, which is necessary to develop future breeding programme, is not widely studied in pigeonpea because it is a long duration crop and widely affected by stresses (biotic & abiotic). Therefore, present study was conducted among six generations in five pigeonpea crosses to know significance of additive-dominance model, gene action involved in inheritance of quantitative traits. These six population (P1, P2, F1, F2, BC1 and BC2) of five cross combinations of pigeonpea were studied during Kharif, 2014-15 for plant height, number of primary and secondary branches, pods plant-1, pod length, seeds pod-1, 100-seed weight and Seed yield plant-1.Significant deviation of scale(s) (A, B, C & D) from zero in all the crosses for most of the traits were evidence of presence of epistasis and hence further subjected to six parameter model to estimate the main gene effects (additive [ ] and dominance [hˆ] ) and their digenic interactions (additive × additive [iˆ] , additive × dominance [ ˆj] and dominance × dominance [lˆ] ). The estimates of six parameter model revealed that both additive and dominant gene effects were important in all the crosses for almost all the traits. However, the relative contribution of dominant gene effects was much higher than additive gene effects for plant height, pods plant-1, seed pod-1 and seed yield plant-1. Higher frequency of duplicate type of epistasis also confirms the prevalence of dominance gene effects for above traits except for seed yieldplant-1.

Eight intraspecific (four each of mungbean x mungbean and urdbean x urdbean) and 24 interspecific (eight each of mungbean x urdbean, mungbean x ricebean and urdbean x ricebean) crosses were made at five different dates of ten days intervals i.e., September 11-20, 21-30, October 1-10, 11-20 and 21-30 during kharif/late kharif seasons, 2015 to obtain a total of 32 crosses. The per cent crossability at five different dates indicated that it was the highest during October 1-10 in both intra - (mungbean x mungbean, 72.27%, urdbean x urdbean, 55.55%) and interspecific (mungbean x urdbean, 43.24%, mungbean x ricebean, 16% and urdbean x ricebean, 9.92%) crosses. Similarly, the percent ovule fertility recorded was also the highest during October 1-10 in both intra - (mungbean x mungbean, 90.00%, urdbean x urdbean, 83.33%) and interspecific (mungbean x urdbean, 75.00%, mungbean x ricebean, 71.42% and urdbean x ricebean, 60.00%) crosses. Optimum temperature (~22˚C) , followed by low humidity (49.0) and comparatively enhanced sunshine (>8.5 hours) might be responsible for accelerating the highest pod sett during October 1-10 and thus may be suggested as appropriate period for obtaining highest pod setting in Vigna species studied.

International audience; The management of Potato virus Y (PVY) in potato crops poses a con-tinual challenge due to the non-persistent mode of transmission of the virus and the propagation of seed potato tubers over several generations in the field. While PVY- resistant cultivars remain the most efficient way to protect potato crops against PVY, a vast majority of cultivars grown do not display significant resistance to PVY. Due to the short time period for PVY transmission by non-colonising aphid vectors, efficient control of PVY relies on preventing aphids landing on a crop and on adopting precautionary measures by ensuring that crops are grown in areas of low aphid and low virus pressure and limiting field generation. Prophylactic mea-sures such as roguing and early haulm destruction limit PVY spread but are not efficient alone. Among all existing control methods, spraying potato crops with mineral oils can offer significant protection against PVY spread, but their efficacy do vary in field conditions. The combination of several control methods such as mineral oil treatments, crop borders, intercropping, straw mulching or insecticide treatments can increase protection. These emphasise the importance of controlling virus through appropriate monitoring methods and crop management enforced by seed certification schemes through the use of ‘clean’ input seed and, when possible, the segregation of seed and ware crops to minimise the risk of virus transmission. This chapter presents and discusses the most widely used techniques of control and management of PVY, their effectiveness and their mode of action. This chapter also presents the history, objectives and principles of seed potato certification schemes and their role in minimising the spread of viruses within potato crops worldwide.