影响丰花草种子萌发和幼苗生长的主要环境因子

The Main Environmental Factors Affecting Seed Germination and Seedling Growth of Borreria stricta(L.f) G. Mey

运用培养皿滤纸法和盆栽法,分别研究温度、光照和水分条件对热带常见杂草丰花草种子萌发和幼苗生长的影响.结果表明：丰花草种子萌发温度范围广泛（5 -40℃）,随温度升高,丰花草幼苗的鲜质量和生长长度均呈现先升高后降低的趋势;恒温下30 t 为其种子萌发的最适温度,其发芽率、发芽指数、活力指数均相对较高,而平均发芽时间最短;25 T 时生长的幼苗最健壮,其芽长、根长和芽鲜质量、根鲜质量均显著高于其他温度时的对应值.而变温条件更有利于丰花草种子萌发,12 hD/12 h L 、5℃/15℃时发芽率达55.63%,15℃/25℃时发芽率〉90%,25 T /35 T 时的种子萌发率、幼苗长度、幼苗鲜质量均最大.光照不是影响丰花草种子萌发的关键因子,但光照可能有利于促进丰花草幼苗生物量向根部分配,光暗交替（12 h D/12 h L）条件下丰花草幼苗生长情况相对最好（长度根冠比为1.05 ： 1;鲜质量根冠比为0.51 ： 1）.水分是决定丰花草种子能否萌发的关键因素,25℃、12 h D/12 h L 条件下,在土壤最大持水量60%时丰花草种子萌发和幼苗生长状况均最佳.

An experiment was carried out to determine the effect of temperature, light and water conditions mimicking those found in tropical farmland and forest land on the germination and seedling growth of a common weed [ Borrenia stricta （ L. f. ） G. Mey] by using petri - dish with filter paper and pot culture methods. B. stricta seeds had a wide germination temperature range （5 -40 ℃）; the fresh weight and growth length of stricta seedlings increased at first and then decreased with temperature increase. Under constant temperature conditions, 30℃ was optimal for germination temperature at which germination rate,germination index and vigor index were highest,and mean germination time was shortest. Seedling growth,however,was most robust at 25℃ because of the seedling shoot length, root length, shoot fresh weight, and root fresh weight were significantly higher than the corresponding values at other temperature treatment. Fluctuatingtemperature improved seed germination of B. stricta thus seed germination rates were, respectively, 56% and 〉 90% at 5/15 °C and 15/25 °C under 12hdarkeness/12 h light conditions. The maximum seed germination rate, seedling length and seedling fresh weight were obtained at 25/35 . Light was not thekey factor controlling seed germination of B. stricta,but light may be conducive to allocation of biomass to root,and the best seedling growth of B. stricta was observed under the alternation of light and darkness （12h D/12h L） ,with root - shoot ratios of length and fresh weight of 1.05 ： 1 and 0.51 ： 1, respectively. Water was the key factor in control-ling B. stricta seed germination. Seed germination and seedling growth of B. stricta were both best when soil moisture was 60% of the maximum water - holding capacity under the condition of 25 and 12 h D/12 h L.