毛竹叶片衰老过程的叶重量、叶面积及元素内吸收率的动态

对福建永春毛竹(Phyllostachys pubescens Mazel ex H.de Lehaie)叶片衰老过程的叶重量、叶面积及元素内吸收率的动态进行了研究,并对元素内吸收率RE_1(以元素的干重含量为计算单位,mg/g)、RE_2(以单位叶片的元素含量为计算单位,mg/leaf)以及RE_3(以单位叶面积的元素含量为计算单位,mg/cm~2)进行了比较。叶片衰老过程中,平均叶重量、叶面积及比叶重分别下降了19.55％、15.16％和5.07％。叶重量与叶面积下降百分率的季节变化趋势一致,说明毛竹叶片存在一定的重量与面积比率。在不同的元素内吸收率比较中,N和K的元素内吸收率均为正,Ca均为负,表明叶片衰老过程中N和K的元素含量从衰老叶片中转移至植株的其他部位,而Ca在老叶中累积。N、P、K、Ca和Mg 5种元素平均的元素内吸收率高低顺序均为RE_2>RE_3>RE_1,反映出以元素的干重含量为计算单位和以单位叶面积的元素含量为计算单位的元素内吸收率偏低。

Dynamics of Leaf Mass, Leaf Area and Element Retranslocation Efficiency During Leaf Senescence in Phyllostachys pubescens

Dynamics of leaf mass (LM), leaf area (LA) and element retranslocation efficiency during leaf senescence was investigated in Phyllostachys pubescens Mazel ex H. de Lehaie in Yongchun, Fujian, China. Comparison of differences in element retranslocation efficiencies (RE) based on per gram leaf dry weight, per leaf and per LA during leaf senescence was carried out. With leaf senescence, the mean decreases of LM, LA and specific leaf mass (SLM) were 19.55%, 15.16% and 5.07%, respectively. The seasonal changes in decrease percentage of LM and LA were similar, indicating that certain mass to area ratios occurred in P. pubescens leaves. On different bases, RE of N and K was positive, while RE of Ca was negative, suggesting that with leaf senescence, N and K were translocated out of senescing leaves to other parts of plant, while Ca accumulated in senescing leaves. For the mean RE of N, P, K, Ca and Mg on different bases, the rank order was RE_2 (mg element/leaf)>RE_3 (mg element/cm~2 leaf)>RE_1 (mg element/g), therefore, RE on the basis of leaf weight or LA would be underestimated.