光照强度对雪茄烟叶片组织结构及内源激素含量的影响

遮荫栽培是雪茄外包皮烟叶生产的关键栽培技术。为明确低光强对叶片形态结构的影响及其生理机制，在室内模拟条件下，以雪茄品种H382为材料，设置高中低3个光照强度，分别为T200[200±15μmol/（m²·s）]、T100[100±15μmol/（m²·s）]和T50[50±15μmol/（m²·s）]，研究了光强对雪茄叶片的形态特征、叶片组织结构及内源激素含量的影响。结果表明，随光强降低，叶长、叶宽、叶面积及比叶面积显著增加，单叶干质量和比叶重显著降低，植株干物质积累量显著降低。低光照强度（T50）的叶片叶绿素含量低于中、高光照强度处理。中、低光强的叶片上、下表皮厚度低于高光强处理，随光强减弱栅栏组织变薄，海绵组织厚度表现为T200 > T50 > T100，T50处理叶片的海绵组织细胞间隙大，组织疏松。光强减弱，叶片生长素（IAA）和脱落酸（ABA）含量显著降低，但赤霉素（GA₃）含量却增加，而玉米素（Zt）含量呈先增加后降低趋势。可见，低光强一方面提高GA₃含量，降低ABA含量，促进叶片发育；另一方面降低IAA含量和叶绿素含量，最终叶片变薄，干物质积累量减少。

Effects of Light Intensity on Growth and Development and Endogenous Hormone Content of Cigar Leaves

Shading is a key cultivation technique in cigar tobacco production. A laboratory experiment was carried out to clarify the effect of low light on leaf morphological structure and its physio-biochemical characteristics. The different light intensities were set as higher T200[200±15 μmol/(m²·s)], middle T100[100±15 μmol/(m²·s)], and lower T50[50±15 μmol/(m²·s)] using cigar cultivar H382. The effects of different light intensities on the morphological characteristics, leaf structure, and endogenous hormone contents were studied. The results revealed an increment in leaf length, leaf width, leaf area, and specific leaf area while a reduction was witnessed in single leaf dry mass and specific leaf weight as light intensity decreased. Similarly, the chlorophyll content was also decreased under low light intensity. Additionally, the size of the upper and lower epidermis and palisade tissues was decreased. The size of spongy tissues was also decreased in the order T100 < T50 < T200 with larger intercellular spaces. Finally, the auxin (IAA) and abscisic acid (ABA) contents in the leaf were significantly reduced, gibberellin (GA₃) content was increased while Zeatin (Zt) was firstly increased and then dcereased under low intensities. Our results uncovered two different effects of various light intensities on a cigar tobacco leaf. One was, as it improved GA₃ content, reduced ABA content, and promoted leaf development via higher leaf area. The second effect was a decrease in the IAA content, leaf tissue thickness, chlorophyll content, and dry matter accumulation.