'Miguang' Grape Response to Pergola and Single-Curtain Training Systems.

Background and Aims: Grapevine shoot growth and light utilization are typically adjusted through the use of canopy management strategies that are adapted to the local climate. In this study, we analyze the effects of a pergola (PER) and single-curtain training system (SCT) on the microclimate, light interception, photosynthetic capacity, and assimilate distribution of 'Miguang' grape in a rainy region of China. Methods and Results: We measured light interception, spectral absorptance, leaf area, chlorophyll content, photosynthetic rate, soluble sugar and starch content per cane, assimilate distribution berry weight, soluble solids, and titratable acid content. SCT produced a higher photosynthetic photon flux density in the cluster region, a canopy light absorptance in the 450–800 nm wavelength range, higher chlorophyll content, and larger leaf area of the middle node leaves. It produced lower basal and top leaves leaf areas. At berry expansion (E-L-31) and veraison (E-L-35), the net photosynthetic capacity of the leaves from the base to the middle nodes was higher with SCT than with the PER, and the net photosynthetic capacity of leaves near the top was reduced with SCT. At the harvest period, the net photosynthetic rate of the middle and top node leaves and the shoot photosynthetic rate were higher with SCT than with the PER. The distribution of assimilates to the fruit was higher with SCT. In addition, SCT produced a higher shoot soluble sugar and lower internode length from the fourth to sixth nodes, and it produced a higher shoot starch content and internode diameter in the fourth internode. Conclusions: SCT significantly improved photosynthetic photon flux density in the cluster, promoted assimilate distribution to fruit, decreased vegetative growth, increased chlorophyll content, increased the leaf size of the middle node on the primary shoot, and increased shoot soluble sugar from the fourth to sixth nodes. Significance of this Study: The results of this study can provide a relevant theoretical basis and technical support for grape canopy management. [ABSTRACT FROM AUTHOR]