Canopy microclimate of Shiraz 06/1103P grapevines were altered and exposed to Regulated Deficit Irrigation (RDI) with varying severity and timing to mitigate the crop load. Four crop load levels were imposed by dormant pruning the vines to 22 spurs (control) with no further manipulation, and mechanically pruning others to 4? hedges and mechanically thinning the canopy to a density of 7 count shoots/foot of row (CLL); 9 count shoots/foot of row (CLM); and mechanically box pruning to a 4-inch hedge with no shoot thinning (CLH), respectively. Control vines were irrigated to 70%of ET until harvest (RDIC). Other vines either received 70%of full vine ET until to veraison, after which the rate was cut to 50%of ET (RDIL) or had their irrigation cut to 50%of ET before veraison (RDIE), but not thereafter. Application of shoot thinning at Stage 17 of the E-L scale by removing 25%of the total shoots exposed with the CLM resulted in exposing about 32000 shoots per acre with count shoots spaced about 2? along the cordon. This exposure translated to about 4 leaf layers and about 13 m2 of leaf area to ripen the clusters retained on the vines. The leaf area to fruit ratio achieved with the CLM treatment exposes just enough leaf area to ripen the crop level retained on the vines. The combination of the CLM and RDIE treatments decreased the berry weight harvest by 12%without any decrease in harvest weight compared to hand-pruned control resulting ~ 10 tons/acre yield in 2010. The resultant crop harvested from this treatment combination was harvested 4 days later than the hand-pruned control irrigated with RDIC. The combination of CLM with RDIE resulted in wines with higher total iron-reactive phenolics (1510 mg/L CE eq.), higher tannin concentration (520 mg/L) and similar anthocyanin concentration (250 mg/L CE eq.) to hand-pruned control with RDIC. This project at the end of its second year provides valuable information to growers by indicating dormant pruning and shoot thinning can be done efficiently and precisely with mechanization while saving irrigation resources. The identified treatment combinations (CLM with RDIE) results in smaller berry size without adversely affecting yield with preferable wine phenolic composition in the San Joaquin Valley of California.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF2010-10-16 06:41:462017-10-16 06:42:26Interactive Effects of Mechanical Canopy Management and Regulated Deficit Irrigation on Shiraz Grapevines