棚架下垂叶幕与水平叶幕对香百川葡萄叶片光合特性的影响

Comparison of leaf photosynthetic characteristics of pendulous canopy and horizontal canopy in Chambourcin grape

【目的】比较棚架下垂叶幕和水平叶幕下葡萄叶片臭氧伤害状况以及对光合性能的影响。【方法】以5年生的葡萄品种香百川为试材,利用臭氧监测仪监测7—9月份栽培环境中臭氧浓度,采用CIRAS-3便携式光合作用测定仪和Handy PEA测定2种叶幕叶片的净光合速率和荧光特性。【结果】下垂叶幕缓解了臭氧伤害情况,其主梢叶片发生臭氧伤害的比例在6月和7月均低于水平叶幕。成熟期时下垂叶幕主副梢叶片叶绿素总含量均显著高于水平叶幕。下垂叶幕主梢中部功能叶片净光合速率在转色期和成熟期分别高于水平叶幕13%~56%和28%~99%。水平叶幕的PSⅡ最大光化学量子产量(F_(v)/F_(m))在转色期时比下垂叶幕低3.08%;水平叶幕叶片单位面积内有活性反应中心的数量(RC/CS_(m))与反应中心吸收的光能用于电子传递的量子产额(φ_(Eo))在转色期和成熟期均显著低于下垂叶幕;水平叶幕J点相对可变荧光(V_(j))与用(F_(m)–F_(o))进行标准化后K点相对可变荧光(W_(k))在转色期和成熟期时均高于下垂叶幕,其PSⅡ受体侧及放氧复合体受到的伤害程度更高。【结论】棚架下垂叶幕减少了强光直射时间,从而缓解了臭氧对PSⅡ的伤害,增加了叶片的叶绿素含量和叶片净光合速率。

【Objective】This study compared the ozone damage and photosynthetic performance of grape leaves in pendulous canopy and horizontal canopy.【Methods】Five-year-old Chambourcin grapevines were selected as the experimental materials.Ozone concentration in the air was monitored from July to September using an ozone monitor,and ozone damage in pendulous canopy and horizontal canopy was recorded according to the degree of damage on the leaves.Determinations of leaf area and total chlorophyll content in leaves of primary and lateral shoots from both canopy types were conducted at berry maturity stage.The net photosynthetic rate and fluorescence characteristics of leaves from the two canopy types were measured using a CIRAS-3 portable photosynthesis meter and a Handy PEA.【Results】During the experiment,the air ozone concentration at the Taian Zhongqing winery site(117.21°E,36.17°N) was monitored in real time,and the daily maximum ozone concentration ranged from 14 n L·;1to 56 n L·;1from June to September,with the highest ozone concentration occurring on July 4th and the lowest on June 28th.The average daily maximum ozone concentration from June to September was 30.6 n L·;1,and the ozone concentration decreased after the commence of rainy season in late July.The ozone damage was mitigated by adopting pendulous canopy,and the ozone injury incidence in leaves of primary shoots of the pendulous canopy was lower than that of the horizontal canopy in June and July.The degree of ozone injury to leaves of the primary and lateral shoots of the pendulous canopy was significantly lower than that of the horizontal canopy in June,and the number of leaves in the primary and lateral shoots without injury was 169.34%and 4.66%higher than that of the horizontal canopy,respectively.The difference in leaf area in the primary shoots between the two canopy types was not significant,while leaf area in the lateral shoots in the pendulous canopy was significantly(53.25%) higher than that of the horizontal canopy.The total chlorophyll content in leaves of the primary and lateral shoots of the pendulous canopy was 131.18%and 59.52%significantly higher than those of horizontal canopy,respectively.The net photosynthetic rate of the leaves at the middle node of the primary shoots of pendulous canopy was 13%-56%and 28%-99%higher than that of horizontal canopy at the veraison and berry maturity stages,respectively.The O-J-I-P curve pattern of Chambourcin grapevine leaves in the pendulous canopy differed significantly from those in the horizontal canopy,and the relative variable fluorescence (F_(m)) at the P point in the pendulous canopy was higher than that of the horizontal canopy at veraison and maturity stages,indicating that the pendulous canopy leaves have a higher capacity to absorb light energy.Both canopy types showed a clear J point (2 ms) on July 31st and September 6th.The injury degree at the PSII receptor side in the horizontal canopy was significantly higher than in pendulous canopy,indicating that electrons from Q^(-)_(A)to Q^(-)_(B)was restricted.The maximum photochemical quantum yield of PSII (F_(v)/F_(m)) of the horizontal canopy was 3.08%lower than that of pendulous canopy at veraison stage.The number of active reaction centers per unit area (RC/CS_(m))was 12.79%and 23.58%lower than that of the pendulous canopy at veraison and maturity stages,respectively.The quantum yield of light energy absorbed by reaction centers for electron transfer (φ_(Eo)) in the horizontal canopy leaves was 19.02%and 26.08%lower than that in the pendulous canopy at the two stages.The relative variable fluorescence of J points (V_(j)) in the horizontal canopy was 12.25%and24.98%higher than that in the pendulous canopy on July 31st and September 6th,respectively.The W;in the horizontal canopy was 5.92%higher than in the pendulous canopy on July 31st.The initial slope of relative fluorescence (M_(o)) had no significant difference between the two canopy types at both veraison and maturity stages.【Conclusion】Pendulous canopy alleviated the ozone damage on grape leaves,increased chlorophyll content in leaves,and improved net photosynthetic rate in leaves at the middle node of the primary shoots compared with the horizontal canopy.