透湿性反光膜覆盖对柑橘树体微环境、新梢生长及果实发育的影响

Effects of vapor-permeable reflective film mulching on citrus tree microenvironment, shoot growth and fruit development

【目的】探索透湿性反光膜覆盖对柑橘冠层微域环境、新梢生长及果实品质的影响,为柑橘提质增效提供新的参考模式。【方法】以3 300 m^2、32 a生‘宫川’温州蜜柑为试材,树冠下地面全面覆盖白色透湿性反光膜后,选取树势一致的植株,测定冠层光辐射特征、土壤理化性质、树体生长及果实品质等。【结果】覆盖透湿性反光膜没有显著影响果实发育过程中的树体生长。柑橘冠层反射光强度、可见光光质及叶片的净光合速率均得到了显著提升。覆膜不同深度的土壤含水量均有变化,10 cm处降低了7.55%,20 cm差异不大,30 cm降低了2%,40 cm降低了6%。覆膜过程中柑橘叶片中多种元素含量及采收期根际土壤的细菌、真菌数量均有明显变化。采收时,果实纵横径大幅下降;果实亮度提高,着色加强;果皮叶绿素a含量下降17%,类胡萝卜素总量提升了36%;可溶性固形物含量显著提升,可滴定酸含量显著降低;葡萄糖、果糖、蔗糖及总糖含量均有明显提升;维生素C含量提升了22%。【结论】透湿性反光膜可改善光照条件,调节土壤微环境,影响树体生长及光合作用,最终提升温州蜜柑的果实内外在品质。

【Objective】The study is to explore the effects of vapor-permeable reflective film mulching on canopy microenvironment, shoot growth and fruit quality of Satsuma mandarin（Citrus unshiu Marc.）, and provide a new reference model for citrus cultivation.【Methods】The experimental material was 32-yearold Satsuma mandarin（C. unshiu Marc.） trees. Plants with consistent vigor in the open field were selected and white vapor-permeable reflective film mulching was carried out in the late July 2015. Internal and external fruit qualities, canopy light characteristics and light quality, soil physical and chemical properties,and tree growth were measured. For fruit quality evaluation, fruit vertical and horizontal diameters, fruit color, peel pigments, TSS, and contents of titratable acids, sugars and vitamin C were determined. For canopy light characterization, reflected light intensity and quality were analyzed, and for determinations ofsoil physical and chemical properties, rhizosphere soil microbes and water content were measured.【Results】The growth of shoots during the fruit development was less affected by mulching with vapor-permeable reflective film. The treatment significantly improved photosynthetic rate, which was constantly higher than in the control. Vapor-permeable reflective film mulching also significantly increased the reflected light intensity by 2-7 times at ground level, canopy bottom and the middle of the crown, and the absolute radiation of visible light at the three positions was also significantly improved. The treatment significantly reduced the soil moisture at three depths, 10 cm, 30 cm and 40 cm in the open field, where soil moisture declined by 7.55%, 2% and 6%, respectively. At the depth of 20 cm, the water content in mulching treatment was significantly higher at 0 day. However, it gradually reduced to a level similar to that in the control at harvested. Meanwhile, mulching saw a greater number of bacteria and fungi, which increased by77% and 233%, respectively, while the quantity of actinomycetes had no significant change. Mulching had the biggest influence on the number of fungi. Many nutritional elements in citrus leaves increased. At60 days of mulching, N, P, Ca and Mg had increased to some extent while K decreased. Trace elements Zn and B increased as well. Fruit vertical and horizontal diameters were decreased by 13% and 10% by mulching, respectiveluy. Vapor-permeable reflective film mulching significantly improved the fruit color,luminance value（L） and the red-green value（a＊） of the fruit, with L and a＊values increased by 10% and18%, respectively, while blue-yellow value（b＊） displayed a slight increase. The content of peel chlorophyll a also decreased significantly by nearly 17% and total carotenoids increased by 36%. Mulching significantly increased fruit TSS content by nearly 3%, while decreased titratable acids by 0.2% with significant difference. Glucose and fructose were both increased by about 30%, sucrose by 20% and total sugar by 26%. In the open field, vitamin C content in mulching treatment at harvest was 29.55 mg·100 g-1,which was 22% higher than the control.【Conclusion】It turned out that mulching with vapor-permeable reflective film significantly improved the tree microenvironment, including light environment and rhizosphere environment, which is favorable for fruit development. At the same time, mulching improved the photosynthesis while inhibited shoot growth. All of the above changes finally contributed to the improvement of fruit quality.