Influence of rootstock and vine spacing on root distribution, vine growth, crop

The effects of seven rootstocks (AxR#l, 110R, 039-16, 5C, 3309, 1616, and 420A) grafted to Cabernet Sauvignon (clone #8) in combination with three between row spacings (2, 3, and 4 m) and two in-row spacings (1 and 2 m) on root distribution, shoot growth, soil water utilization, leaf and fruit composition and crop yield were evaluated this past season in a replicated field plot established at the Oakville Experimental Vineyard in 1987. The most significant new findings obtained in 1993 were the documentation of the differences in the patterns of root growth of the seven rootstocks at two different vine spacings (1 and 2 m) on the basis of root density (number of roots/unit volume) and root sizes at depths between ground level and 2 meters. The root mapping data showed that 039-16 stock had the greatest number of roots, 4m2 of soil surface area, and 1616 and 420A had the lowest root density. There was a positive relationship between the total number of roots per 4m2 of soil surface area and the amount of above ground growth of the different stocks. There were significant differences between stocks for total roots, small roots (< 2 mm root diameter) and large roots (5 to 12 mm and > 12 mm diameters). For all stocks, root density declined with soil depth and with closer vine spacing. However, closer vine spacing did not alter the root distribution of any rootstocks. Root maps by size and number to a depth of 2 m of all seven stocks are presented in the report. The stocks were divided into three groups based on the amount of shoot growth and crop yield; 110R. 039-16, AxR#l. and 1616 had the most shoot growth and highest yield; 5C and 3309 were intermediate, and 420A was lowest. The higher yielding stocks had greater number of shoots and clusters per vine and higher berry and cluster weights than lower yielding stocks. Shoot length, number of primary leaves, and leaf area of spur shoots of 110R, 039-16, and AxR#l were greater than the other four stocks. Pruning weight per vine of the seven rootstocks were in decreasing order of AxR#l, 110R, 039-16, 3309, 5C, 1616, and 420A. Yield: pruning weight ratios ranged between 3.84 and 4.85, all within an acceptable range for balancing shoot growth and crop yield. At harvest, 039-16 fruits were generally higher in pH, malate, and K than fruits form the other six stocks. The levels of malic acid and titratable acidity in fruits at harvest were directly related to the total amount of shoot growth per vine. 420A, 1616. and 5C fruits were ripened earliest, 110R and 3309 ripened intermediate and 039-16 fruits were generally the last to ripen as measured by °Brix. 8 Mineral petiole analysis at bloom and veraison revealed that 039-16 stocks continues to be the highest in K and lowest in Mg, whereas 420A is lowest in K and highest in Mg, the oilier stock ranging in between. Wider spacing between vines within rows increased the level of Ca and Mg and decreased K, however, row spacing had little effect on the mineral content of petioles at bloom and veraison. The average crop yield of 2, 3, and 4 m row spacing were 7.9, 6.0, and 5.2 tons/acre, respectively, and for 1 and 2 m vine spacing were 7.1 and 5.7 tons/acre, respectively. The higher yields were due to greater number of shoots and clusters per acre. Berry weight increased with wider row spacing, but did not differ between 1 and 2 m vine spacing. Closer row and vine spacing delayed accumulation of sugar in fruits and time of harvest. Fruits from 1 m vine spacing had higher levels of malic acid than 2 m fruits at harvest. The level of anthocyanin in fruits was greater at wider row spacing than narrow row spacing. Decreasing row spacing from 4 m to 2 m reduced pruning weight per vine and per meter of canopy length, whereas decreasing vine spacing from 2 m to 1 m reduced pruning weights per vine, but when compared on a per meter of row length basis, 1 m vine spacing had significantly higher pruning weight than 2 m vine spacing. Closer vine spacing within rows, however, did reduce average weight per cane. Wines made from four rootstocks (5C. 110R, 3309, and 039-16) at two vine spacings (2×2 m and 4×2 m) in 1993, differed considerably in composition. However Duo-trio taste comparisons generally did not show rootstock differences between the wines (Tables 17 and 18). 039-16 wine had the highest pH and hue and the lowest litratahle acidity and color at both spacings. whereas 3309 wine was lowest in pH and highest in TA and color.