遮光处理对三种钝叶草的生长习性与光合特性的影响

钝叶草属(StenotaphrumTrin.)的3个种,普通钝叶草(Stenotaphrum helferi)、森特钝叶草(Stenotaphrum secundatum)和金边钝叶草(Stenotaphrum secundatumcv.varietgatum)均为耐荫性草种。光合测定结果显示,3种钝叶草的光合作用在中午均未出现光抑制,其净光合速率日变化呈现“单峰”曲线型;除金边钝叶草外,森特钝叶草与普通钝叶草在75%遮光下的净光合速率要高于全光照下的。野外观测发现,金边钝叶草与森特钝叶草一直维持在营养生长阶段,而普通钝叶草的生长发育周期最短,在大约3个月就完成了从营养生长到生殖生长的全过程,包括抽穗、开花和结实。光照下森特钝叶草生长最好,而在遮光下普通钝叶草长势最好。在75%的遮光条件下,3种植物都保持了较好的生长状况,并且保持终年常绿的景观效果。总的来说,3种钝叶草都表现出了耐荫能力,而普通钝叶草的耐荫性最强,在遮光条件下生长迅速,叶片呈现翠绿色,因而是一种非常理想的阴生草坪草种;金边钝叶草是生长最为缓慢的品种,但它的叶片黄绿相间,能给人焕然一新的视觉感受。

Effects of shading on growth and photosynthesis of three species of the genus Stenotaphrum

Three grasses of the genus Stenotaphrum,S.helferi,S.secundatum and S.secundatum cv.varietgatum are all shade-resistant species.The photosynthetic characteristics of the three species showed that their photosynthesis had no light inhibition under strong radiation at noon,and all presented a single apex in the diurnal variation of net photosynthetic rate.Except S.secundatum cv.varietgatum,S.helferi and S.secundatum had a higher net photosynthesis rate in 75% shading than under full light.Field observations showed that S.secundatum cv.varietgatum and S.secundatum kept their growth in the vegetative stage all the year around,while S.helferi completed its lifecycle including vegetative growth,earring,flowering and seeding within 3 months.Among the three species,S.secundatum grew best under full sunshine,whereas S.helferi grew best in the shading situation.All tested species still kept pretty good growth situation under 75% shading,and maintained evergreen in the whole year.On the whole,all the three species assumed shade-tolerant ability;among them,S.helferi had the strong shade-tolerant ability,which grew rapidly under the condition of shading,and its leaves revealed emerald color.Thereby,it was a very ideal sciophilous turfgrass.S.secundatum cv.varietgatum grew slowest but had yellow strips on its leaves and,therefore,presented beautiful scenery at any time.