| Abstract |
- Two experiments were conducted on wine grapes 'Chardonnay' and
'Gewurtztraminer' (Vitis vinifera L.) in 1986 and 1987 to
investigate the performance of grapes in competition with perennial
ryegrass (Lolium perenne L.) 'Manhattan 11' sod, the competition
between sod and grapes for nutrients and moisture and the effects
of nitrogen fertilization and water supply on this competition.
Three vineyard floor vegetation management methods, bare floor,
mowed sod and unmowed sod, were used to establish three levels of
competition between sod and grapes. Nitrogen fertilization at 0,
137 and 274 kg/ha and soil moisture varied with and without
irrigation were used to evaluate certain limiting resources.
Sods, whether mowed or not, significantly reduced grape growth
in both 1986 and 1987 and yield in 1987. Fruit soluble solids were
increased by unmowed sod treatment in 1987. The sod did not affect
grape leaf P, K, Mg, Cu and Zn concentrations but reduced grape
leaf N and Fe in 1986 and S, Ca, B and Mn concentrations in 1987.
The sod also decreased total amounts of all nutrients measured in
grape leaves. Soil moisture within grape rows was not reduced by
sod in mid-July, but soil moisture measured in late July and
September between grape rows was reduced by the sod. Nitrogen
fertilization enhanced grape growth in 1987 but did not affect
grape yield and quality. Nitrogen fertilization increased grape
leaf N in 1986 and grape leaf Mg and Mn concentrations in 1987, but
decreased grape leaf P, K, S, B in both 1986 and 1987, Ca in 1986
and Cu, Zn concentrations in 1987. Nitrogen fertilization
increased total amounts of N, S, Ca, Mg, Mn, Fe and Zn but did not
affect total amounts of P, K, Cu and B in grape leaves. Vineyard
floor vegetation management and nitrogen fertilization interacted
significantly when evaluated by measuring grape leaf nitrogen
concentration in 1987. Nitrogen fertilization at the rates used
can compensate for the reduction of nitrogen in grape leaves caused
by the sod. Nitrogen fertilization and water supply enhanced each
other in affecting grape growth. Irrigation had no significant
effect on grape leaf N, P, Ca, Mg, Mn and Fe concentrations but
increased K, S, Cu, B and Zn concentrations and total amounts of
all nutrients except Fe measured in mowed sod plots receiving no
nitrogen fertilizer. Grass growth was not reduced by mowing,
consequently mowed and unmowed sod treatments were not
significantly different from each other as measured by grape
growth, yield and nutrient status. Grass growth was enhanced by
nitrogen fertilization.
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