[Effects of acetochlor on the photosynthetic and fluorescence characteristics and chloroplast structure of grape leaves].

Taking one-year old sand-cultured Kyoho (Vitis vinifera x Vĩtis labrusca) grapevines as test materials, this paper studied the effects of spraying acetochlor on the grape leaves photosynthetic and fluorescence characteristics and chloroplast ultra-structure. On the 13th day after spraying acetochlor, the net photosynthesis rate and stomatal conductance of upper-node leaves decreased significantly, so as the maximal photochemistry of PSII and the quantum yield of PSII electron transport. The relative variable fluorescence in the J step and K step of the chlorophyll fluorescence transients had an obvious increase, while the performance index (PI(ABS)) had a marked decrease. The damages to the PSII reaction center and oxygen-evolving complex of upper-node leaves were more severe, as compared to middle-node leaves, but the damage degree was alleviated along with treatment time. On the 60th day after spraying acetochlor, the differences in the photosynthetic and chlorophyll fluorescence parameters between upper- and middle-node leaves diminished. The responses of bottom-node leaves appeared later than those of the upper- and middle-node leaves. The damage of PSII reaction center and oxygen-evolving complex, the rise of relative variable fluorescence in the J step and K step, and the decline of PI(ABS) of bottom-node leaves were much greater than those of the upper- and middle-node leaves. On the 60th day after spraying acetochlor, the leaf sugar and starch contents increased, but the pigments in the upper- and middle-node leaves decreased significantly, the chloroplast membrane was impaired, the size of chloroplasts decreased, and the lamellae became fuzzy or the gap between lamellae increased. As a whole, acetochlor could be transmitted to the aboveground part of grapevine, and result in the damage of leaf photosynthetic apparatus and the decrease of PSII activity and photosynthetic rate.