| Effects of nitrogen application timing on photosynthetic physiology and endogenous hormones in grape leaves |
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| DOI：10.7606/j.issn.1000-7601.2020.05.13 |
| Key Words: nitrogen application time grape photosynthetic parameters fluorescence parameters endogenous hormones content |
| Author Name | Affiliation | | MA Zonghuan | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | MAO Juan | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | WEI Jucan | Nanhua Ecological Construction Bureau, Bailongjiang Forestry Administration of Gansu Province, Zhangye, Gansu 734000, China | | CHU Mingyu | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | LI Wenfang | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | ZHOU Qi | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | YANG Shijin | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | CHEN Baihong | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China |
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| Abstract: |
| 10-year-old wine grapevine ‘Cabernet Gernischet’ was used as material. Drip irrigation of fertigation was applied at 300 kg·hm-2 urea at germination stage (S1), vigorous growth of new shoots stage (S2), flowering stage (S3), the first stage of fruit expansion (S4), and secondary shoot growth stage (S5), respectively. No nitrogen was applied for control (CK) during the whole growth period. The photosynthetic characteristic index of leaves was measured separately at 50 days after anthesis (DAF50), 85 days after anthesis (DAF85), and 120 days after anthesis (DAF120), and collected leaf samples were analyzed photosynthetic physiology and endogenous hormone levels during the period of nitrogen (N) application. The results showed that N application increased Pn and Fv/Fm of leaves during the whole growth period, and the increase of Pn and Fv/Fm of leaves before anthesis was the most significant, reaching 18.22 μmol·m-2·s-1 and 0.854, respectively. The stomatal conductance (Gs) and transpiration rate (Tr) of leaves at different growth stages were significantly increased by applying N during S1, S2, and S3. While the most significant one was at 85 days after anthesis when N application was at S2, Gs and Tr increased by 18.5% and 10.8%, respectively, compared with control. The intercellular CO2 concentration (Ci) and non photochemical quenching coefficient (NPQ) of leaves were significantly reduced when nitrogen application was at S3, S4, and S5. There was no significant difference between N fertilizer at S1 and CK. Applying N fertilizer before the first fruit expansion stage can significantly increase the quantum efficiency of PSⅡ electron transfer (ФPSⅡ) and photochemical quenching coefficient (qP), the highest values were 0.889 and 0.959, respectively. It can be seen that applying N fertilizer in different timings could affect the absorption, transmission, dissipation, and distribution of light energy in leaves by changing the parameters related to photosynthetic fluorescence, so as to improve the efficiency of light energy utilization. Application N fertilizer before S4 significantly increased the quantum efficiency of PSⅡ electron transfer (ФPSⅡ) and photochemical quenching coefficient (qP), the highest values were 0.889 and 0.959, respectively. Therefore, N fertilizer in different stages could affect the absorption, transmission, dissipation, and distribution of light by changing the parameters related to photosynthetic fluorescence, so as to improve the light efficiency of leaves. The application period of N affected the content of endogenous hormones in leaves at different growth stages. Compared with CK, the N application significantly increased the content of ZT in leaves after DAF85, increased by 21.9% at least. The content of IAA in leaves when N application after flowering maintained above 34.9 μg·g-1 during the fruit harvest. The GA3 content was the highest when N application at S4 and S2, 7.11 μg·g-1 and 6.49 μg·g-1 respectively. Therefore, N application at different stages can promote the accumulation of growth hormone and inhibiting the accumulation of growth\|inhibiting hormone. |
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