向日葵是异花授粉作物，花盘内有1000～3000朵结实小花，但结实率一般都不高。空壳率约占30％左右，严重影响向日葵产量。其除了品种因素造成的以外，主要原因是授粉不良。下面介绍预防方法。（一）选用优良品种应选用提纯复壮的“匈牙利4号”作为食用品种；“白葵2号”或‘伯 Sunflower is a cross-pollination crop, there are 1000 ~ 3000 flowers face flower, but the seed setting rate is generally not high. Shell rate of about 30%, seriously affecting the yield of sunflowers. Apart from the variety of factors caused by its outside, the main reason is poor pollination. Here’s how to prevent it. (A) selection of fine varieties should be used to purify and rejuvenate the “Hungarian No. 4” as food varieties; “White Kwai 2” or "Bo