Effects of Coverlys TF150® on the growth and photosynthetic characteristics of grape plants

Abstract:【Objective】China has a marked continental monsoonal climate. The rainfall and heat appear during the same season. So fungal vine diseases caused by high rainfall are important concerns in China. Rain-shelter cultivation is a common kind of canopy management to reduce disease, and has been widely used in many places in China so far. In this article, the effects of the shelter film Coverlys TF150® on the growth and photosynthetic characteristics of grape plants were studied.【Methods】One year old potted Kyoho and Cabernet Sauvignon grape nursery trees were put under the Rain shelter covered with PO film and Coverlys TF150®, the rain shelter height was 2 m. Then the chlorophyll fluorescence, photosynthesis indicators, and leaf and branch growth and development indicators of the leaves of Kyoho and Cabernet Sauvignon were determined.【Results】The value of the Fv/Fm, ΦPSⅡ, ETR and qP of the Kyoho and Cabernet Sauvignon leaves under Coverlys TF150® treatment peaked at 10:00 and 14:00, and the value at 10:00 was generally higher than that at 14:00. Compared with the PO film, the Coverlys TF150® significantly increased the Fv/Fm of the Kyoho and Cabernet Sauvignon leaves from10:00 to 14:00, but decreased the Fv/Fm at 08:00 and 16:00. At 10:00, 12:00 and 14:00, the Fv/Fm of Kyoho was increased significantly by 7.41%, 5.00% and 3.61%, respectively under the Coverlys TF150® treatment, and the Fv/Fm of the Cabernet Sauvignon was increased significantly by 4.76%, 5.00% and 6.17%, respectively. From 10:00 to 14:00, the ΦPSⅡ, ETR and qP of the Kyoho and Cabernet Sauvignon leaves under the Coverlys TF150® were higher than that under the PO film, and lower than that under the PO film at 08:00 and 16:00. Compared with the value under the PO film, the ΦPS Ⅱ of the Kyoho leaves under the Coverlys TF150® treatment was increased by 7.14%, 13.64% and 17.39%, respectively, at 10:00, 12:00 and 14:00; The ΦPS Ⅱ of the Cabernet Sauvignon leaves was increased by 7.14% , 8.70% and 12.50%, respectively. The net photosynthetic rate (Pn), intercellular carbon dioxide (Ci), stomatal conductance (Gs) and transpiration rate of the grape leaves (Tr) under the Coverlys TF150® were higher than those under the PO film from 10:00. to 14:00, and lower than those under the PO film at 08:00 and 16:00. The net photosynthetic rate of the leaves of Kyoho under the Coverlys TF150® treatment was 18.80%, 24.65% and 25.34% higher than that ounder the PO film at 10:00, 12:00 and 14:00 and the net photosynthetic rate of Cabernet Sauvignon was 20.00%, 30.18% and 20.00% higher than that under the PO film, respectively. The diurnal variation area of the net photosynthetic rate under the Coverlys TF150® treatment was 13.80% and 12.21% higher than that under the PO film, respectively; At 12:00 and 14:00, the intercellular carbon dioxide concentration under under the Coverlys TF150® treatment significantly was increased by 27.35% and 19.31% , respectively in Kyoho, and significantly was increased by 21.30% and 14.76% in Cabernet Sauvignon, respectively. At 10:00, the leaf stomatal conductance of Kyoho and Cabernet Sauvignon under the Coverlys TF150® was significantly increased by 27.75% and 38.06% compared with that under the PO film, respectively. And transpiration rate was significantly increased by 50.94% and 27.31% , respectively. At 12:00, the stomatal conductance of the Kyoho and Cabernet Sauvignon leaves under the Coverlys TF150® was significantly increased by 38.34% and 36.40% compared with that under the PO film. The leaf transpiration rate under the Coverlys TF150® was increased by 15.48% and 24.81%, respectively. Compared with the values under the PO film, the leaf weight, leaf area and chlorophyll content of Kyoho and Cabernet Sauvignon under the Coverlys TF150® were significantly increased by 31.60% and 10.35%, respectively, and leaf area was significantly increased by 8.77% and 15.01%. The leaf chlorophyll content was increased by 31.45% and 9.41%, respectively. Meanwhile, the Coverlys TF150® significantly increased the leaf thickness by 14.81% in Kyoho, while the leaf thickness of the Coverlys TF150® treatment had no significant difference with that of the PO film treatment in Cabernet Sauvignon. Compared with the PO film, the Coverlys TF150® significantly improved the fresh shoot mass and fresh root mass of the grape plants, the fresh shoot mass and root mass were increased by 10.73% and 17.83% in Kyoho, and they were increased by 19.33% and 19.96% in Cabernet Sauvignon, respectively, and the root-shoot ratio was also improved. Compared with the PO film, the TF150® significantly increased the length the Kyoho shoots by 14.49%, and the new shoots diameter was significantly increased by 19.96% in Cabernet Sauvignon. The Coverlys TF150® treatment also increased the soluble sugar and starch content in the shoots, the content of soluble sugar was increased by 25.00% in Kyoho, and the content of starch was increased by 25.00% and 21.21%, respectively in Kyoho and Cabernet Sauvignon.【Conclusion】Compared with the PO film, the Coverlys TF150® improved the photosynthetic capacity of the grape leaves and reduced the photosynthetic inhibition, which was beneficial to the growth and development of the grape plants and promoted the accumulation of storage nutrients in the branches.