Effect of winter low temperature on flowering and fruit set in Loquat

Effect of low temperature in winter on loquat flowering and fruit set were investigated during 2004 and 2005 in order to evaluate the possibility of cultivating loquat in Shanghai. Fruit set under low temperatures difference among cultivars. 'Baiyu' and 'Guanyu', the main cultivars in Shanghai region, bloomed early, and their flowers were exposed to low temperatures. All young fruit turned brown and aborted when temperatures dropped to -5--7 degrees C, but flower buds were not influenced. The fruit set ratios of 'Baiyu' and 'Guanyu' were 2.23 and 5.05%, respectively. 'Tianzhong' and 'Yedaozaosheng' appeared to have a higher tolerance to low temperatures compared to other cultivars. Within a panicle, the flowers at lower position had a smaller chance to confront the deadly low temperatures than the upper flowers. Hence, particles could be thinned leaving five lower lateral flowers, which would be enough for desirable yield. 'Tianzhong' had a long blooming period and high fruit retention in late February.