Effects Of Water On Light Response Characteristics Of Different Leaf Age Leaves And Fruit Quality And Yield Of Tomato

With tomato "Jinpeng No.1" as experimental materials, adopting potted way, based onevaportranspiration(ET) per plant, setting4levels of supplemental irrigation amount(50%ET,75%ET,100%ET,125%ET), two experiments were carried out: flowering period experimentand fruit period experiment. The water treatment in flowering period experiment and fruitperiod experiment began at the beginning of tomato flowering period and fruit period,respectively. The experiments studied the gas exchange and light response parameters oftomato leaves varying with the change of leaf age under different growth stages and differentwater treatment; Meanwhile, the influence of water on chlorophyll fluorescence parametersof tomato leaves, fruit quality and yield and plant dry matter distribution in the fruit periodwere also studied. This study evaluated the photosynthetic characteristics of tomato leavesand obtained the photosynthetic light response parameters for photosynthetic model indifferent leaf age under different water conditions, and clarified the relationship betweenphotosynthetic efficiency and tomato yield. In words, theoretical parameters for establishingphotosynthetic model about water and leaf age and the basis for theoretical watermanagement of tomato cultivation in potted way were obtained in this study.The main results were as follows:1. In the flowering period experiment, with leaf aging, net photosynthetic rate,transpiration rate, stomatal conductance all gradually reduced, water use efficiency increasedfirstly and then declined; the maximum net photosynthetic rate and light saturation pointdecreased with leaf aging under75%ET,100%ET and125%ET treatment; For50%ETtreatment, the maximum net photosynthetic rate and light saturation point increased firstlyand then declined, when leaf age was17d, their values were maximum. As for apparentquantum yield, the relationship between which and leaf age was also parabola, when the leafage was17d, apparent quantum yields were maximum.With the increase of supplementary irrigation amount, net photosynthetic rate,transpiration rate, stomatal conductance, maximum net photosynthetic rate and lightsaturation point all increased, peaking at125%ET treatment, bottoming at50%ET; Therelationship between apparent quantum yield and supplementary irrigation amount was parabola.2. In the fruit period experiment, with the increase of tomato leaf aging, netphotosynthetic rate, transpiration rate, stomatal conductance all gradually reduced, water useefficiency increased firstly and then decreased; When leaf ages were18d and29d, therelation between supplemental irrigation amount and maximum net photosynthetic rate wereparabola, which indicated the optimum supplemental irrigation amount were75%ET and100%ET, respectively. When leaf ages were38d and47d, with the rising of supplementaryirrigation amount, maximum net photosynthetic rate both ascended, peaking at125%ETtreatment. As for apparent quantum yield, the relationship between which and leaf age wasalso parabola, when the leaf age was38d, apparent quantum yields were maximum. And forlight saturation points, they decreased with leaf aging.With the increase of supplementary irrigation amount, the maximal photochemicalefficiency of PSII, photochemical efficiency of PSII, the actual photochemical efficiency ofPSII, photosynthetic electron transport rate and photochemical quenching of tomato leavesand fruit water content, yield and plant dry matter all rose, peaking at125%ET treatment,bottoming at50%ET; However, non-photochemical quenching, fruit hardness, total solublesolid, Vc and organic acids significantly descended as well as the red colour and coloursaturation of peel of tomato fruit, however, the fruit yield increased; field water use efficiencyincreased firstly, peaking at100%ET treatment and then declined.3. The light response parameters of different leaf age tomato leaves under different waterconditions were: in flowering period, when leaf age was10d, Pmaxwas7.17²1.64μmol·m^-2·s^-1, α was0.0477⁰.0653; when leaf age was17d, Pmaxwas9.72¹7.51μmol·m^-2·s^-1, α was0.0556⁰.0681; when leaf age was24d, Pmaxwas3.21⁸.46μmol·m^-2·s^-1,α was0.0370⁰.0452. In fruit period, when leaf age was18d, Pmaxwas20.64²6.73μmol·m^-2·s^-1,α was0.0518⁰.0556; when leaf age was29d, Pmaxwas11.00²4.24μmol·m^-2·s^-1; α was0.0522⁰.0594; when leaf age was38d, Pmaxwas11.77¹8.18μmol·m^-2·s^-1,α was0.0619⁰.0693; when leaf age was47d, Pmaxwas9.09¹8.17μmol·m^-2·s^-1,α was0.0538⁰.0606.In conclusion, photosynthetic light response parameters of different leaf age tomatoleaves were different in flowering and fruit period under different water treatments. With leafaging, increasing supplementary irrigation amount that could delay the fall of leafphotosynthetic capacity. Stomatal limiting factor was the main factor of water influencing onphotosynthesis of tomato leaves; It was stomatal limitation and non-stomatal limitationfactors that caused Pn varying with leaf age. Taking photosynthetic characteristics of tomatoleaves in different leaf age into consideration, the optimum supplementary irrigation amount for flowering period of tomato was125%ET; Taking photosynthetic characteristics of tomatoleaves and fruit yield into consideration, the optimum supplementary irrigation amount forfruit period of tomato was also125%ET.