agriculture Article
Design and Implementation of a Rainfed Matrix for Cotton James Mahan * and Paxton Payton Cropping Systems Research Laboratory, 3810 4th Street, Lubbock, TX 79415, USA;
[email protected] * Correspondence:
[email protected]; Tel.: +1-806-723-5221 Received: 4 October 2018; Accepted: 30 November 2018; Published: 7 December 2018
Abstract: Global production of agricultural products must continue to increase if shortages are to be avoided. While irrigated production is substantial since water available for both current and future production is limited, rainfed production will become increasingly important. In-season weather variability results in instability in rainfed production and in order to gain information on the mechanisms involved and their potential mitigation, it is important to monitor production over a range of possible environmental scenarios. We designed and implemented a rain matrix experimental approach for cotton based on a series of sequential plantings coupled with a rain-simulation protocol. The rain matrix in two years produced 56 growing environments with rain and thermal variability and 44 yield:environment comparisons. The yield:rain relationship was not strong (R2 = 0.35) Analysis of heat units over the matrix indicated (1) heat units varied with planting date and (2) heat units were sufficient to achieve maturity. Plantings reached maturity with
