昆明西山滇青冈林内滇青冈种子库动态的研究

通过对昆明西山滇青冈林内滇青冈种子库的跟踪取样调查和种子埋藏试验，对滇青冈种子库的动态进行了研究。昆虫在种子成熟前侵入种子，经种子雨进入种子库时已有71.8%的种子失去萌发能力。种子雨输入种子库的绝大部分种子停留在表面种子库，其中48.55%的种子被虫害,25.36%被某些非生物或生物搬运，17.39%的腐烂，8.7%的被动物当场取食，没有种子萌发，影响种子库动态的各种因子的作用大小在时间上是变化。被搬运的种子中，有4.9%的由表面种子库转移到埋藏种子库。土层是滇青冈种子的安全生境，土壤种子库的存在时间超过250天。埋入土壤的试验种子一直处于静止状态，到6月雨季后有80%种子萌发，20%的腐烂。萌发种子数是当年产种子的0.26%。滇青冈林内的滇青冈种子库是季节性的，种子库对种群个体的补充作用是有限的。

Nod Factors(Lipo-Chito-Oligosaccharides)Research Pessrogr

Nod factors are a novel general class of signal molecules produced by rhizobia,which play a key function in the initial steps of nodulation.Research has shown that different substitutions on a lipochito oligosacchride(LCO)backbone play a role in deciding the specificity between bacteria and the host plants.The nod genes of rhizobia,which contain the genetic basis for this structural variety,include a set of nodulation genes encoding the enzymes that synthesize LCOs.