旱田几种禾本科杂草结实期光合特性的研究

通过对稗草Echinochloa colonum、虎尾草Chloris virgata、金狗尾草Setaria glauca、马唐Digitaria sanguinalis等4种禾本科杂草结实期的光合作用指标及微气象条件的测定分析,得出其在光能利用和水分利用上的差异.4种杂草的净光合速率日变化均呈现出双峰曲线,第1个高峰都出现在10:00;第2个高峰除稗草出现在13:00外,其他3种杂草均出现在15:00.稗草的净光合速率受微气象条件的影响最小,其峰值最高,上午最高时的净光合速率比虎尾草、马唐、金狗尾草分别高16.6%、41.3%、53.4%;虎尾草下午的净光合速率最高,受温光的影响最大,下午最高时光合速率分别比马唐、金狗尾草、稗草高31.8%、9.8%和31.2%.在水分利用上,稗草的水分利用效率最高.

Photosynthetic Characteristics of Several Gramineous Weeds During Fructification Period in Dry Farmland

Photosynthetic indexes and micrometeorologic conditions of four weed species Echinochloa colonum(L.)Link,Chloris virgata Swartz,Setaria glauca(L.)Beauv.,Digitaria sanguinalis(Linn) Scop.were detected during their fructification period.The differences of photic utilization and water utilization were concluded respectively.The daily change of net photosynthetic rate(Pn) of four weed species followed double apex curve.The first apex all appeared at 10:00,and the second one emerged at 15:00(except) Echinochloa colonum whose apex all appeared at 13:00.The Pn of Echinochloa colonum whose apex value is the highest had the weakest influence of micrometeorologic conditions.The highest Pn of Echinochloa colonum exceeded Chloris virgata,Digitaria sanguinalis,Setaria glauca 16.6%,41.3%,53.4% respectively during morning.However Chloris virgata whose Pn was the highest in the afternoon was extremely influenced by temperature and light.The highest Pn of Chloris virgata exceeded Digitaria sanguinalis,Setaria glauca,Echinochloa colonum,31.8%,9.8%,31.2% respectively during afternoon.Echinochloa colonum had the highest water utilization efficiency.