不同光照度生境对海芋块茎形态、淀粉含量及叶绿素含量的影响

Effect of light intensity on tuber morphology,starch content and leaf chlorophyll content of calla lily

【目的】了解海芋Alocasia macrorrhiza对不同光照度生境的响应,明确在海芋试验中叶绿素仪测定叶绿素的精确度,以期为大面积的成龄胶园林荫下土地资源利用及叶绿素仪在海芋生理试验中正确应用提供理论依据和技术支持。【方法】采用SPAD-502叶绿素仪和乙醇-丙酮浸提法对不同光照度下海芋不同叶片的SPAD值、叶绿素a、叶绿素b和总叶绿素含量进行测定。【结果】与自然光照下的海芋相比,林荫下海芋的块茎长度增加了12.11%,茎围和淀粉含量则分别降低了15.08%和12.96%。自然光照下海芋的SPAD值、叶绿素a、叶绿素b及总叶绿素含量均比在林荫下生长的海芋低,但叶绿素a与叶绿素b含量的比值要高。自然光照下海芋叶片SPAD值呈现从倒1叶至倒5叶逐渐增加的趋势(倒3叶除外)。林荫下生长的海芋叶片SPAD值从倒1叶至倒2叶是增加的,从倒3叶至倒5叶逐渐降低,最大值在倒2叶。光照强度对不同叶片的叶绿素a、叶绿素b及总叶绿素含量的影响趋势与SPAD值的影响趋势一致,只是影响幅度不同。【结论】光照有利于海芋淀粉的合成。光照不足的情况下,海芋会通过增加叶片(特别是上层叶片)的SPAD值、叶绿素a、叶绿素b及总叶绿素含量来捕获光能。在自然光照下,利用海芋倒4叶的SPAD值更能准确地预测其叶绿素的绝对含量,而在林荫下生长的海芋倒5叶的SPAD值更能准确地预测其叶绿素的绝对含量。

[ Objective ] In order to understand the response of calla lily, Alocasia macrorrhiza L. , to dif- ferent light intensities, verify the accuracy of SPAD chlorophyll meter in chlorophyll measurements of cal- la lily, and provide a theoretical basis and technical supports for utilizing large land resources under ma- ture rubber plantation and using chlorophyll meter correctly in physiological experiments of calla lily. [ Method ] SPAD value, chlorophyll a, chlorophyll b and total chlorophyll contents of different calla lily leaves under different light intensities were determined using SPAD-502 chlorophyll meter and alcohol-ac- etone extraction methods. [ Result ] Compared with calla lily grown under natural light, tuber starch con- tent and girth of calla lily under tree-shade decreased by 15.08% and 12. 96% respectively, while tuber length increased by 12. 11%. SPAD value, chlorophyll a, chlorophyll b and total chlorophyll contents of calla lily under natural light were lower than those of calla lily under tree-shade, while chlorophyll a/b ratio was higher. SPAD value of calla lily under natural light increased gradually from the first-top-leaf to the fifth-top-leaf （ except the third-top-leaf）. SPAD value of calla lily under tree-shade increased gradu- ally from the first-top-leaf to the second-top-leaf reaching the maximum, and then decreased gradually from the third-top-leaf to the fifth-top-leaf. Light intensity influenced chlorophyll a, chlorophyll b and to- tal chlorophyll contents of different leaves in the same way as it did for SPAD value, but in different de- gree. [ Conclusion] Light is conducive to starch synthesis in calla lily tubers. Calla lily can capture more light energy through increasing SPAD value, chlorophyll a, chlorophyll b and total chlorophyll contents of leaves, especially the upper leaves, under limited light conditions. The SPAD value of the fourth-top-leaf is the best estimation for the chlorophyll contents of calla lily under natural light, while the SPAD value of the fifth-top-leaf is the best estimation for the chlorophyll contents under tree-shade.