Environment-Sensitive Male-Sterility in some Food CropsK BSaxenaauthorMBharathiauthorFlowering is an indispensable phenomenon of natural reproduction. To enter in the reproductive phase, most plant species get critical signals from different environmental factors which facilitate the conversion of their vegetative buds into reproductive tissues. The major factors that influence the appearance of flowers are moisture stress, temperature, photoperiod and irradiation. According to Bernier et al. (1993) these factors are perceived by different plant parts. For example, leaves are affected by photoperiod and irradiation; while temperature is perceived by all plant parts. Similarly, vernalization affects shoot apex and moisture availability is perceived by roots. These external determinants do not act independently and their interaction is inevitable and a particular factor may alter or substitute the direct effect of the other factors; and this may change the threshold level of individual factor in inducing flowering. Since at a given point of time,these environmental factors may act on different parts of the plant in their own way, the interaction among their gene products (proteins) may decide the transition of the vegetative buds into reproductive buds. Once flowering is induced in the plants, the further development of reproductive parts leads to differentiation into male/female gametes which participate in the natural reproduction. In this processes also, certain environmental factors play an active role and any departure from the normal process of microsporogenesis/ megasporogenesis leads to disorders such as male or female sterility.In this chapter the authors have not attempted a thorough review of male sterility systems of food cops but restricted to environment-sensitive male sterility with brief description of their origin, possible variants, maintenance and utilization in two-parent hybrid breeding...CerealsPlant GrowthLegume Crops2015Daya Publishing HouseBook Section