遮荫处理对罗汉果果肉组织中罗汉果苷和糖分含量的影响

该研究以罗汉果品种“永青1号”为材料，在果实发育后期进行不同强度的遮荫处理，测定遮荫处理下果肉组织中罗汉果苷各组分含量、各种糖分的积累及其相关糖代谢酶活性、叶片光合特性的变化。结果表明：重度遮荫(70％遮荫)会导致果实中罗汉果甜苷Ⅴ含量显著提高，遮荫60 d(授粉后90 d)，对照与70％遮荫处理果实中罗汉果甜苷Ⅴ含量分别为4.83％、5.79％，差异达极显著水平( P<0.01)；70％遮荫处理下果实中葡萄糖、果糖含量也明显高于对照( P<0.05)。与罗汉果甜苷Ⅴ、葡萄糖、果糖含量的变化不同，遮荫60 d，70％遮荫处理下罗汉果果实中可溶性糖、蔗糖的含量分别显著(P<0.05)和极显著(P<0.01)低于对照。另外，遮荫处理导致罗汉果叶片净光合速率下降，遮荫40 d，70％遮荫处理下叶片的净光合速率显著低于对照( P<0.05)。综上说明，重度遮荫处理可以引起罗汉果果实品质的改变；光合速率下降是遮荫处理下可溶性糖含量降低的主要原因；SPS、AI、SSC活性的改变则是遮荫导致蔗糖含量降低及葡萄糖、果糖含量上升的重要因素；重度遮荫条件下，荫棚中温度降低可能是罗汉果果实中甜苷Ⅴ含量增高的关键诱因。该研究结果为罗汉果的生产及品质调控提供了理论依据。

Effects of shading on contents of mogrosides and sugars in fruit flesh of Siraitia grosvenorii

With the common Siraitia grosvenorii variety of“Yongqing 1” as experimental material, we measured the chan-ges of concentrations of mogrosides monomers, soluble sugars, glucose, fructose, sucrose and starch in the fruit flesh, as well as the activities of sucrose metabolism enzymes, including acid invertase(AI), neutral invertase (NI), sucrose syn-thase (in synthesis direction, SSS;in cleavage direction SSC), sucrose phosphate synthase (SPS) and the net photosynthet-ic rates, during the late development stage of fruit under different shading treatments. The results indicated that in compari-son with control, severe shading (70%shading) resulted in significant increase of mogroside V content:60 d after shading (90 d after pollination), the content of mogroside V in the fruit flesh of 70% shading treatment was 5.79%, significantly higher than that of control group (4.83%, P<0.01). Meanwhile, the concentrations of glucose, fructose were also much higher than those of controls (P<0.05). On the contary, the changes of concentrations of total soluble carbohydrates and su-crose were far different from those of mogroside V, glucose and fructose:60 d after shading, the levels of total soluble car-bohydrates, sucrose in the fruit flesh of 70%shading treatment were significantly ( P<0.05 ) , extremely significantly ( P<0.01) lower than those of controls, respectively. On the other hand, shading treatment led to a decrease of net photosynthet-ic rate (Pn):40 d after shading, Pn of leaves under 70%shading treatment was significantly (P<0.05) lower than that of controls. The above results implied that severe shading treatment could result in the improvement of fruit quality of S. grosve-norii. In additon, under shading treatment, the decrease of photosynthetic rate could be the major reason for the decline of soluble sugar content, while changes of sucrose, fructose and glucose contents should be mainly resulted from the changes of activities of SPS, AI and SSC. In addition, under severe shading treatment, fall of temperature could be regarded as the probable cause for the increase of mogroside V content. The research provides the theoretical basis for the production tech-niques and the quality control of S. Grosvenorii fruit.