Two California native perennial grasses, nodding needlegrass [Nassella cernua (Stebbins & R.M. Love) Barkworth] and California barley [Hordeum brachyantherum Nevski ssp. californicum (Covas & Stebbins) Bothmer, N. Jacobsen & Seberg], were compared with a conventional grass cover crop, ‘Blando’ brome (Bromus hordeaceus L.), as well as resident (weedy) vegetation and a clean cultivated control for effects on growth and yield of cultivated grape (Vitis vinifera L. cv. Barbera). Statistical analyses did not reveal yield differences between treatments with floor vegetation (the native grasses, ‘Blando’ brome, and resident vegetation) and clean cultivation, the cover crop treatments (the native grasses and ‘Blando brome’) and clean cultivation, nor the native grass treatments versus treatments with non-native floor vegetation (‘Blando’ brome and resident vegetation). However, there was a significant difference between the two native grasses with the average yield of nodding needlegrass 26.2% higher than that of California barley. Treatments did not differ in 8Brix, berry weight, or pruning weight. At the end of the study, vine trunk diameter was 7.1% higher under the cover crop treatments than resident vegetation. Given these results, in vineyards where a neutral effect on growth or yield is desired, nodding needlegrass would be suitable as a permanent cover crop, whereas California barley would not.
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