Modeling purple nutsedge sprouting under soil solarization

Abstract Sprouting percentage was estimated for purple nutsedge tubers in the field from daily fluctuating soil temperatures. Tuber sprouting under alternating temperatures ranging from 20 to 45 C for 14 d responded quadratically to alternations of high and low temperature. A response surface regression of the cumulative sprouting percentage accounted for 88% of the variation. The cumulative sprouting percentage curves were sigmoidal, and the Richards function satisfactorily regressed the characteristics of the curves. A simulation model was developed for the cumulative sprouting percentage by estimating sprouting from daily high and low temperatures and accumulating daily increments of tuber sprouting. Five weeks of soil solarization with clear polyethylene film at Waimanalo, Hawaii raised the mean soil temperature at 15-cm depth by 5.8 C in spring and by 7.2 C in summer. Solarization also increased the mean daily temperature difference from 1.5 to 3.7 C in spring and from 2.3 to 3.8 C in summer. Solariz...