Cold stress effects on reproductive development in grain crops: An overview

Cold temperatures are the cause of enormous agricultural losses, especially in sub-tropical and temperate grain crops. The reproductive period is a vital phase in the life cycle of all annual plants, and metabolism during this phase ultimately determines crop yield. Plants exposed to cold temperature during reproduction show reduced metabolic rates leading to low yields. In this review, we describe the effects of low temperature on various stages of the reproductive phase, from meiosis to grain filling, and temperature sensitivity of different reproductive organs. Cold temperature induces flower abortion, pollen and ovule infertility, causes breakdown of fertilization and affects seed filling, leading to low seed set and ultimately low grain yield. Physiological and metabolic bases of cold stress, including the role of phytohormones (especially ABA) and sugar-induced regulation are reviewed, and future research directions investigating molecular and metabolomic changes during the development of the gynoecium during cold stress suggested.