遮阴处理对多花黄精光合蒸腾特性的影响

Photosynthesis and Transpiration Characteristics of Polygonatum cyrtonema Under Different Shading Treatments

以多花黄精盆栽苗为研究对象,设置全光照(CK)、透光率83%±5%(T1)、透光率为61%±5%(T2)、透光率为38%±5%(T3)4个遮阴处理,测定多花黄精的光合蒸腾指标及主要环境因子,研究不同遮阴处理下多花黄精叶片的光合蒸腾特性差异及其与环境因子间的关系。试验表明:(1)4种遮阴处理下多花黄精的净光合速率日变化均呈单峰曲线变化,均未出现"光合午休"现象,且不同处理间全天基本表现为T1>T2>T3>CK。(2)CK、T1和T2处理下多花黄精蒸腾速率日变化为双峰曲线,而T3处理下多花黄精蒸腾速率日变化为单峰曲线。(3)4个处理10:00—14:00多花黄精净光合速率下降都是由气孔因素引起的,而14:00—16:00多花黄精净光合速率下降均是由非气孔因素引起的。(4)遮阴强度的增加,改变了蒸腾速率与环境因子的相关关系,且遮阴强度越大,蒸腾速率与光合有效辐射(PAR)的相关性越强。研究表明,增加黑色遮阳网数量在一定范围内可以提高多花黄精的光合与蒸腾能力,改善多花黄精的生长状况,且以1层黑色遮阳网和2层黑色遮阳网效果相对好。本研究为多花黄精的人工栽培提供了一定的理论依据。

Potted seedling of Polygonatum cyrtonema was used as experiment material,and four treatments were designed,i.e.full illumination(CK),light transmittance 83%+5%(T1),light transmittance 61%+5%(T2)and light transmittance 38%+5%(T3).We measured the photosynthesis and transpiration physiological indices of the P.cyrtonema and the major environmental factors,then compared the differences in photosynthesis and transpiration rates of P.cyrtonema as well as their relationship with environmental factors.The results showed that:(1)the diurnal variation of the net photosynthetic rate of P.cyrtonema under four shading treatments showed a single-peak curve,and no‘midday photosynthetic break’was observed,and the diurnal variation of net photosynthetic rate of P.cyrtonema under different shading treatments was T1>T2>T3>CK;(2)the diurnal variation of transpiration rate of P.cyrtonema under CK,T1 and T2 treatments was a bimodal curve,while that under T3 treatment was a single-peak curve;(3)the decrease of net photosynthetic rate of P.cyrtonema in the four treatments from 10:00 to 14:00 was caused by stomatal factors,while that from 14:00 to16:00 was caused by non-stomatal factors;(4)with the increase of shading intensity,the correlation between transpiration rate and environmental factors was changed,and the greater the shading intensity,the stronger the correlation between transpiration rate and photosynthetic effective radiation(PAR).Our results indicate that increasing the black shading nets in a certain range could improve the photosynthetic and transpiration capacity of P.cyrtonema,and improve the growth of P.cyrtonema,and the effect of one layer of black shading nets and two layers of black shading nets is relatively good.