水分胁迫对‘赤霞珠’不同叶龄叶片光合特性的影响

【目的】探究水分胁迫对葡萄不同叶龄叶片光合及荧光变化规律的影响。【方法】以3 a(年)生‘赤霞珠’葡萄(Vitis vinifera‘Cabernet Sauvignon’)为试材,由黎明前叶片水势(ψb)反映胁迫程度,设置对照(无水分胁迫,CK)、中度水分胁迫(T1)和重度水分胁迫(T2)三个处理,测定‘赤霞珠’葡萄新梢不同叶龄叶面积、叶片光合参数、叶绿素荧光参数及Ru BP活化酶和果糖-1,6-二磷酸酯酶活性。【结果】葡萄叶片叶龄为80 d时,叶面积趋于稳定,T2显著降低了各叶龄叶片的面积,T1与CK无显著性差异;葡萄叶片SPAD值随叶龄的增加而增大,且T1增加了各叶龄叶片SPAD值,T2则降低;Pn、Gs、Tr、Ru BP活化酶和果糖-1,6-二磷酸酯酶活性随葡萄叶片叶龄的增加均呈先上升后下降的趋势,并且随水分胁迫程度的增加下降程度增大;水分胁迫不同程度地降低了各叶龄叶片Fv/Fm、Yield、ETR、q P,而Fo显著增加,T2增加了各叶龄叶片的NPQ,但随着叶龄的增加,T2叶片NPQ又显著低于其他两个处理。【结论】随‘赤霞珠’葡萄叶片叶龄的增加,光合能力呈先上升后下降的趋势,当葡萄叶片叶龄为60~90 d时,光合能力最强。水分胁迫降低了各叶龄叶片的光合效率,重度水分胁迫会阻碍葡萄幼龄叶片的正常发育,并加速老龄叶片的衰老。

Effects of water stress on photosynthetic characteristics of 'Cabernet Sauvignon' at different leaf ages

【Objective】A study was carried out on photosynthetic and fluorescence characteristics of grape leaves under water stress.Grapes are mainly planted in the arid and semi-arid areas in China.The photosynthetic function of leaves is different in different leaf ages.Therefore,to explore the changes of photosynthesis and chlorophyll fluorescence of grape leaves at different leaf ages under water stress is of great significance to the water-saving cultivation of grape in China.【Methods】The experiment was carried out in 2018 in a glass greenhouse in Yuquanying Farm of Ningxia Agricultural Reclamation Group and the experimental station of the National Grape Industry Technology System.The ranges of temperature in the glass greenhouse was 24-38℃,humidity 38%-58%,and air CO2 concentration 300-500μmol·mol-1.3-year-old‘Cabernet Sauvignon’grape(Vitis vinifera L.)vines were used as the materials.Theψb was measured with a 3005 pressure chamber(Soil Moisture Equipment Company,USA)after water stress treatment,which was carried out on June 20,2018.The daily irrigation time was controlled by a time controller,and theψb was used to reflect the stress degree.During the shoot growth period in mid-April 2018,the first unfolded leaves on the annual branches were marked on April 20,April 30,May 10,May 20 and May 30,and named as Leaf 1,Leaf 2,Leaf 3,Leaf 4 and Leaf 5,respectively.The day(d)was used as the measurement unit of leaf age,and the unfolding date was regarded as the initial leaf age(0 d).By June 20,Leaf 1-5(leaf age 60 d,50 d,40 d,30 d and 20 d).Three water treatments were set including no water stress(CK),moderate water stress(T1),and severe water stress(T2),with water potential range of-0.2 MPa≤ψb,-0.60 MPa≤ψb≤-0.40 MPa andψb≤-0.60 MPa,respectively.Changes in leaf area,leaf photosynthetic parameters,chlorophyll fluorescence parameters and the activities of Rubisco and fructose-1,6-bisphosphatase in the new shoots of‘Cabernet Sauvignon’grape were measured.【Results】There were significant differences in leaf indexes among different leaf ages under water stress.The leaf area of grape increased with the increase of leaf age,and the order of leaf area was Leaf 1>Leaf 2>Leaf 3>Leaf 4>Leaf 5.There was no significant difference between T1 and CK,but T2 significantly decreased leaf area at each leaf age(p<0.05).The results indicated that severe water stress inhibited the increase of leaf area at all leaf ages.The value of SPAD showed a similar trend.T1 increased the SPAD values in all leaf ages but there was no significant difference with CK,while T2 significantly decreased the SPAD value of leaves of all leaf ages(p<0.05).With the increase in leaf age,Pn,Gs and Tr all increased at first and then decreased,and decreased with the severity of water stress.T2 significantly reduced Pn and the activities of Rubisco and fructose-1,6-bisphosphatase in leaves of each leaf age,but there was no significant difference between T1 and CK.Water stress decreased Fv/Fm,Yield,ETR,qP,and significantly increased F0 of all leaf ages.T2 increased NPQ in leaves of all ages,but with the increase in leaf age,NPQ of T2 leaves was significantly lower than that of the other two treatments.Among the measured indexes,Leaf 1,Leaf 2 and Leaf 5 were greatly affected,indicating that both the old and young leaves were greatly affected by water stress,while the mature leaves were less affected and became the main contributors to photosynthesis.Grape leaves at the ages of 60-110 days were less susceptible to water stress as reflected by relatively high photosynthetic capacity under water stress.【Conclusion】With the increase in leaf age of‘Cabernet Sauvignon’grape,the photosynthetic capacity increased at first and then decreased,and was highest in leaves at the age of 60-90 days.Water stress reduced photosynthetic efficiency of leaves of all ages,while severe water stress hindered the normal development of the young leaves and accelerated the senescence of old leaves.This study provides a theoretical basis for grape defoliation practice and water-saving cultivation in grape production.