Mazurenko N. Improvement of yield quality in cv White Muscat by applying a short-term water stress under conditions of the South Coast of the Crimea.

Research objects: yield quality of cv White Muscat, irrigation strategies, a short-term stress as a means to increase yield quality. Research objective: to investigate the possibilities of increasing yield quality of cv White Muscat in irrigated vineyards by applying a short-term water stress of certain severity. Methods: field and lysimetric studies of irrigation strategies; refractometry and direct titration for determining sugar content and titratable acidity of grapeberries; am-pelometry for determining the leaf surface area; the use of a pressure chamber for determining leaf water potentials; mathematical statistics for assessing the confidence of re-sults obtained; calculation and comparison method for as-sessing the economical effectiveness of monitoring the water regime of plants. Theoretical and practical results: implementation of a physiological algorithm of the water regime control in cv White Muscat which relies on monitoring leaf water potential and performing irrigations after berry setting has been completed and the level of leaf water potential of -0.5 MPa has been achieved, not later than a month prior to the planned terms of harvest. This leads to an increase in sugar content of grapeberries by 1.0-2.0 g per 100 cm3. Novelty: the possibility of increasing yield quality of cv White Muscat on the South Coast of the Crimea by applying a short-term water stress has been studied. It has been established that a short-term water stress applied in the first period of the growth stage immediately after berry setting has been completed may lead to an increase in yield quality of the study cultivar. The desired stress se-verity has been determined, based on the cultivar, in terms of leaf pre-dawn water potentials ( 0.5 to 0.6 MPa). It has been found that such irrigation strategy using a short-term stress of the given severity lead to an intense sugar accumulation of grapeberries, desired changes in the structure of the cluster and reduction in fungal infection. Implementation degree: the algorithm of determining the terms of irrigation for cv White Muscat has been implemented in vineyards planted to this cultivar on an area of 3.45 ha on the state farm Taurida on the South Coast of the Crimea. Effectiveness: an improved yield quality arising from applying the irrigation strategy suggested leads to an annual economical effect of 225.3 and more hrn. per ha. Sphere, branch of use: agriculture, viticulture.