Water Conservation Strategies Utilizing Primed Acclimation.

Water conservation in agricultural production is a common priority across both the Southwest and the Southeast U.S., even though annual rainfall totals in the Southeast would appear to be more than adequate to meet crop demand.  However crop water deficits are a problem in the Southeast because of the predominantly sandy soils and rainfall distribution patterns that do not provide adequate water when crop demand is high and yield impacts are greatest.  In addition, droughts in the past decade have brought declining aquifers and exacerbated water resource competition with expanding urban centers in this region.  To address this issue, research was originated in the Southeast examining regulated deficit irrigation schedules that capitalized on a physiological phenomenon known as priming.  This process involves exposure to an initial, often mild level of stress that primes or prepares the crop for subsequent stresses which may occur during the critical reproductive stages.   This priming stress has the potential to bring about an acclimated state so that the crop is better able to withstand ensuing stress and maintain yield.  Early research indicated that peanut was especially responsive to this water conservation strategy and the method was termed primed acclimation (PA).  While this work originated in the Southeastern U.S., subsequent testing expanded to other crops and production regions including several areas of Texas, and it was demonstrated that these priming strategies may be useful in both humid and semi-arid environments.  PA has now been tested over several years and regions and with crops including peanut, cotton, corn, and potato.  Common mechanisms among crops in response to PA include: deeper and more extensive rooting architecture, upregulation of gas exchange responses, and indications that gene expression is altered during the initial priming response.  Future work will further explore the direct sensing of stress levels appropriate for successful priming; application of “cross priming” or the use of different types of priming stress to enhance drought tolerance; screening of genotypes for their priming capacity; and expansion of the PA concept to other crops.  This presentation will provide an overview of the work accomplished to date and the ongoing projects exploring PA in agronomic systems.