Abstract: Effects of different sowing dates on growth,development and the formation of seed yield of P.cornutum were studied from 2003 to 2004,the study were based on the experiment during 1998 to 2002.Used direct-seeding method,the seed was sowed every fifteen days,there were twelve sowing dates in all.The results showed that the initial temperature and effective accumulated temperature were 12.56℃and 69.07℃,respectively.With sowing dates delayed,plant height,number of total leaves,plant extending diameter,stem thick,number of primaries per-panicle,the re-greening rate and seed yield were decreased,and if sowing dates were too late,seedling emergence stage was postponed to next year.The seedling age that could be over-winter and be bolting in next year were exceed 59 days,at the same time morphological index of seedling were 9.6cM plant height,15.5cM extending diameter,5.8 pieces of leaves,over 0.8cM stalk thick.The growth potential and seed yield of biennial seedlings were positively correlated with the growth potential of annual seedlings.The course of growth and development of biennial plant was accord with annual plant,the period of growth development of P.cornutum was divided into vegetative growth stage,dormant period and reproductive stage.The optimum sowing date of P.cornutum for cultivation or harvesting seed were in the mid May in spring,sowing date of over-winter cultivation using germinated seed was in the early October in Inner Mongolia.The study clarified the optimum sowing date of artificial cultivation and the youngest seedling age over-winter cultivation of P.cornutum,it will be useful for artificial cultivation and breeding of P.cornutum.

Key words: P cornutum, Growth development, Seed yield, Sowing date

CLC Number: 

• S641