**2.4 Reproductive ecology of alfalfa**

Reproductive success in alfalfa occurs through interaction between development and organization of flower, pollination, fertilization, seed formation, dispersal and other ecological factors. Flowering onset is an intricate progressive evolution that could be activated by various pathways [64]. Diverse ecological and plant internal factors like day length, temperature, light quality and age of plant mediate this transition [65–67]; temperature and photoperiod are important signals in alfalfa flower induction [68, 69]. Alfalfa is a long day plant, requiring 12–14 h of minimal brightness to induce flowering [70]. Alfalfa is solely an insect pollinated crop, which is pollinated only by a small group of insects, especially bees. Each alfalfa bloom is pollinated by a single insect in a single time. The pollinator species, the genotype of alfalfa and the nectar content can affect the pollination process of alfalfa. The predominant pollinators of alfalfa are honey bees (*Apis mellifera*), leaf cutter bees *(Megachile rotunda*) and alkali bees (*Noma melanderi*). Alfalfa seed requires 4–6 weeks to develop into a viable seed [71]. The environmental factors such as rainfall and low temperature during maturing process will decrease the viability of the seeds, ultimately producing seeds of poor quality. The seedling vigor will be reduced and the germination quality will be minimized due to fungal infection or premature seed sprouting [72]. Genetic differences between varieties also affect seed maturity.
