Critical Evaporative Demands for Differential Stomatal Action in Peanut Grown in Narrow and Wide Row Spacings¹

Abstract

Induced stomatal closure behavior of irrigated peanut (Arachis hypogeoe L. cv. Comet, a bunch type) as related to row spacing and evaporative demand has been previously demonstrated as real and repeatable. The objective of this research was to determine the magnitude of evaporative demand that induced stomatal closure in narrow-row plantings. Stomates in wide rows tended to show far less closure on the same days. The differences were not noted on days with low evaporative demand. Concurrent measurements of net radiation, dry-and wet-bulb temperature, and horizontal wind velocity were made every IS min. Estimates of environmental evaporative demand were made. No distinct peak or cumulative evaporative demand levels were found that separated stomatal differential action days from nonaction days. However, analysis of the cumulative advective energy component of cumulative evaporative demand showed a threshold above which stomatal closure responses were noted. This threshold was 8.S MJ m-2 • Further detailed analysis of the factors involved in the cumulative advective energy component indicated stomatal closure was dominated by neither horizontal wind velocity, integrated over time, nor integrated vapor pressure deficit.Additional index words: Evapotranspiration, Advective energy.

Stomatal Response to High Evaporative Demand in Irrigated Grain Sorghum in Narrow and Wide Row Spacing

“…Stone et al (1985) reported the occurrence of stomatal action in peanut on 26% of the data collection days. Integrated advected energy was a triggering effect for stomatal action noted for peanut by Erickson et al (1986); 8.5 MJ m-2 was the estimated critical level. The principal micrometeorological factors that led to increases in stomatal resistance in peanut were wind velocity and vapor pressure deficit.…”

“…The reading days were classed by evaporative demand in accordance with the procedure of Erickson et a!. (1986); i.e., evaporative demand was assumed to be represented by the potential evapotranspiration of Van Bavel (1966).…”