Member - Alan N. Lakso, Dept. of Horticultural Sciences, email anl2@cornell.edu

Cooperators - Terence L. Robinson, Pomology, Cornell, Geneva

Robert M. Pool, Viticulture, Cornell, Geneva

Gerry White, Ag. Economics, Cornell, Ithaca

Martin Goffinet, Plant Anatomy, Cornell, Geneva

David Eissentstat, Root Biology, Penn. State Univ.

Terry Bates, Viticulture, Cornell, Fredonia

Richard Dunst, Viticulture, Cornell, Fredonia

Objective 1 - To evaluate and refine microirrigation management strategies to promote natural resource protection and optimal crop production.

In the NY grape production region along the east end of Lake Erie, we have conducted irrigation trials with Concord juice grapes.

Concord Pruning X Irrigation Interactions. In its 12th year, this trial examines the interactions of supplemental irrigation and vine pruning severity in a deep gravel soil with conservative soil management by herbicides. Balance-Pruned (BP) vines (quite severely each year to 45 buds per kg of pruning weight) are compared to Minimally-Pruned (MP) vines that receive almost no pruning except for a low cut under the canopy. A much more rapid canopy development of the MP compared to BP vines due to much higher shoot numbers (typically 350-400 in MP versus 60-90 in the BP) leads to higher early season and total yearly water use. Therefore, we hypothesized that irrigation in dry years would have a greater benefit to the MP vines due to their higher water use and greater sensitivity to stress. In dry years irrigation has benefited growth, yields, and ripening of the crop, with the greatest effects on the MP vines. Year-to-year differences were strong due to varying rainfall and patterns of dry and wet years as perennial crops carry stress effects from year to year. After 12 years the supplemental gave no increase in yields of normally-pruned vines, but supported an increase a yearly average of 1 ton/acre in minimally-pruned vines. Economic analysis of these results suggest that drip irrigation would be close to profitable for minimally-pruned vines unless the cost of obtaining water was excessive. These results of course depend on the percent of dry years. Also the economics of irrigation would certainly be better in a poorer site, especially with competing cover crops.

Root Production and Life Span as Affected by Irrigation. Within the Concord project, we have developed in the past 4 years a cooperative project with D. Eissenstat, root biologist at Penn State. Seasonal root dynamics of mature Concord vines in the Lake Erie region were monitored with minirhizotrons under the BP and MP vines, with and without irrigation. The results from 4 years of study are: (1) seasonal patterns of root production are extremely variable from year to year; (2) root production drought reduces the total numbers of new roots produced in the summer months by as much as 30-40%; (3) two consecutive years of drought stress reduced the root production in the second year to only about 30% of the irrigated treatment; and (4) effects of irrigation on median root life span (7-9 weeks in this study) were not consistent in all years, but generally extended root life span. Thus, irrigation clearly benefited Concord root production and generally benefited root life span.

Objective 2 - To improve, modify and evaluate microirrigation system design and components for natural resource protection and optimal crop production.

No activities in this objective.

Objective 3 - To assess and develop decision criteria for adoption of microirrigation technologies.

We have been attempting in various ways to obtain good estimates of water use by apple orchards and grape vineyards in the Northeast to advise growers on irrigation system design and irrigation amounts. We are suspicious of crop coefficients from arid climates due to the complexity of the microclimate of large discontinuous canopies, internal physiological factors affecting conductances, and different advective components (from cool lakes vs hot dry hills). Estimating water use accurately by soil moisture monitoring is difficult due to (a) competing cover crops in our orchards and vineyards: (b) extremely extensive, but low density and erratic root distributions, and (c) frequent rainfalls. In 2001 we began estimating water use by apple trees with sap flow gauges calibrated for shorter periods with whole canopy gas exchange chambers. The estimates were compared to estimates of ET for a reference grass (by the current FAO modified equation) and to published apple crop coefficients. Although there was not a tight correlation between daily estimates by sap flow vs (Eto x Kc), the overall correlation indicated that the published Kc values as published for apples are approximately 30% too high for the Northeast. This will need to be confirmed but it does support.

Objective 4 - To promote appropriate microirrigation technologies through formal and informal educational activities.

The results of the irrigation and water stress physiology studies have been communicated to growers via popular publications (see below) and seminars presented at growers meetings in the Northeast region. Also results have been incorporated into the fruit crop physiology component of a graduate class on Woody Crop Physiology at Cornell University.

Potential Impact

This work on grape irrigation has led more grape growers to put in drip irrigation systems, especially for newly planted Niagara grapes that is a growth component of the industry. Also there has been a significant increase in grower interest in irrigation systems for wine grapes in New York and elsewhere in the Northeast.

Recent Relevant Publications

Comas, L.H., D.M. Eissenstat and A.N. Lakso. 2000. Assessing root mortality and decomposition in a study of canopy pruning in Concord grape. New Phytologist 147:171-178.

Lakso, A.N. and R.M. Pool. 2001. Water status in vineyards in erratic climates: effects on productivity and wine quality. Proc. 16th Midwest Regional Grape and Wine Conf. pp. 1-9.

Eissenstat, D.M., L.H. Comas, L.J. Anderson, and A.N. Lakso. 2001. Root Biology in Grapes: A Case Study of the Effects of Canopy Pruning and Irrigation on Concord Root Dynamics. Penn. Fruit News (in press).

Lakso, A.N. and R.M. Pool. 2001. The effect of water stress on vineyards and wine quality in Eastern climates. Wine East (in press).

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