[Variation in seed yield components among varieties of Poa pratensis]

Seed yield and its characteristics of 28 varieties of Poa pratensis in field plots at Lanzhou, China were evaluated in 2001. The results showed that the seed yields among the varieties were significantly different (P < 0.01) by LSD test. The highest yield was 643.4-650.2 kg.hm-2 obtained from varieties of Balin and Monoply, the lowest was 90.1 kg.hm-2 obtained from Elysee, and the other varieties were in the middle groups with the yields varied from 114.7 kg.hm-2 to 435.1 kg.hm-2. Correlation analysis between seed yield and yielding characteristics indicated that the main factors affecting seed yield were the number of fertile tillers per plant (r = 0.785), the height of fertile tiller (r = 0.712), the length of inflorescence (r = 0.743), and the number of spikelets/fertile tiller (r = 0.786). Cluster analysis for seed production capacity based on seed yield and above-mentioned 4 main characteristics showed that the 28 varieties could be divided into 6 grades.