Vasfilov S P
Zh Obshch Biol. 2015 May-Jun;76(3):225-43.
Higher plants show a wide range of leaf lifespan (LL) variability. LL is calculated as a sum of functional LL(f) (corresponding to the time of active photosynthesis and CO2 accumulation in the leaf) and nonfunctional LL(n) (the time of photosynthetic activity absence). For evergreen species of boreal zones, LL(n) corresponds to the period of winter rest. Photosynthetic potential of leaf (PPL), interpreted as the maximum possible amount of CO2 that can be fixed during its life, can be estimated on the basis of maximum photosynthesis rate (P(a)) dynamics during LL(f); the maximum (P(a max)) being achieved in mature leaf. Photosynthetic potential depends on LL(f) more strongly than on P(a max). The PPL/LL(f) ratio is indicative of the rate of PPL realization over leaf lifespan. As LL(f) shows strong positive correlation with LL, the latter parameter can also characterize the rate of PPL realization. Long LL(f) in evergreen species provides higher PPL, which is advantageous by comparison with deciduous ones. In evergreen species, the PPL itself is realized slower than in deciduous ones. The increase in LL(f) and LL is accompanied by the increase in leaf constructional cost (LCC(a)) as well as the decrease in photosynthesis rate. At that, photosynthesis rate per unit of dry weight (P(m)) decreases much faster than that per unit of leaf area (P(a)). Apparently, when considering dry leaf weight, the apoplast share seems to be much higher in long-living leaves of evergreen species than in short-living leaves of deciduous species. The leaf payback (LP) may be stabilized by unidirectional shifts in PPL and LCC(a). Species with short/long LL(f) and high/low PPL realization rate are typical for early/late succession stages and for habitats with the environmental conditions favorable/adverse for photosynthesis and growth. If the conditions for photosynthesis and growth are favorable, high PPL realization rate provides advantage in competition. The PPL realization rate is coupled with the rate of leaf senescence.
高等植物的叶片寿命（LL）具有广泛的变异性。LL的计算方式为功能性叶片寿命（f）（对应于叶片进行活跃光合作用和积累二氧化碳的时间）与非功能性叶片寿命（n）（光合作用活动缺失的时间）之和。对于北方地区的常绿树种，LL（n）对应于冬季休眠期。叶片的光合潜力（PPL），被解释为叶片一生中能够固定的最大可能二氧化碳量，可以根据功能性叶片寿命（f）期间最大光合速率（P（a））的动态变化来估算；最大值（P（a max））在成熟叶片中实现。光合潜力对功能性叶片寿命（f）的依赖程度强于对最大光合速率（P（a max））的依赖。PPL/功能性叶片寿命（f）的比值表明了PPL在叶片寿命期间的实现速率。由于功能性叶片寿命（f）与叶片寿命（LL）呈现出强正相关，后一个参数也能够表征PPL的实现速率。常绿树种中较长的功能性叶片寿命（f）能提供更高的PPL，与落叶树种相比这具有优势。在常绿树种中，PPL本身的实现速度比落叶树种慢。功能性叶片寿命（f）和叶片寿命（LL）的增加伴随着叶片构建成本（LCC（a））的增加以及光合速率的降低。此时，单位干重的光合速率（P（m））下降得比单位叶面积的光合速率（P（a））快得多。显然，在考虑干叶重量时，常绿树种长寿叶片中的质外体比例似乎比落叶树种短寿叶片中的高得多。叶片回报（LP）可能会通过PPL和叶片构建成本（LCC（a））的单向变化而稳定下来。功能性叶片寿命（f）短/长且PPL实现速率高/低的物种典型地出现在早期/晚期演替阶段以及光合作用和生长环境条件有利/不利的栖息地。如果光合作用和生长条件有利，高PPL实现速率在竞争中具有优势。PPL实现速率与叶片衰老速率相关联。
