Stomatal Closure Behavior Induced by Row Spacing and Evaporative Demand in Irrigated Peanuts¹

Abstract

Peculiar stomatal action has been suggested as one causal factor for observed differences in water use between peanuts (Arachis hypogaea L.) grown in narrow and wide rows. This study was designed to characterize stomatal action in narrow‐ and wide‐row plantings on a Udic Argiustoll soil. Measurements of stomatal diffusive resistance (Rs) and leaf‐water potential (Ψw) were made daily at half hour intervals on irrigated peanuts grown in narrow‐row (NR) and wide‐row (WR) spacings during periods of flowering to pod development in 1979,1981, and 1982. Measurement days were classified as low, moderate, and high evaporative demand days according to respective daily meteorological conditions. In both NR and WR treatments the relationship between Rs and Ψw was generally linear. On certain days, however, NR‐Rs increased to much higher values earlier in the afternoon at a given Ψw than WR‐Rs. The effect was most pronounced on high evaporative demand days and was never noted on low evaporative demand days. Data for 3 years reveal the NR stomatal closure effect was real and repeatable.

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

“…A DIFFERENTIAL stomatal closure behavior in well watered peanut (Arachis hypogaea L. cv. Comet, a bunch type) was reported in a previous paper (Stone et al, 1985). Stomates on adaxial surfaces of fully illuminated leaves tended to close earlier in the day on plants grown in narrow rows than corresponding stomates on plants grown in wide row spacings.…”

“…In the previous study (Stone et al, 1985) of differential stomatal action in peanut, the days on which stomates in leaves on narrow row planting tended to close more than stomates in wide-row plots were called action days (AD); days with no discernable differences in stomatal action were nonaction days (NAD); days with intermediate effect were called intermediate action days (lAD). This paper reports the micrometeorological measurements made during the previous observations of stomatal actions.…”

“…Therefore, the differential stomatal closure behavior observed between narrow-row and wide-row plants was probably independent of Z 0 • Measurements of narrow-row LAI and wide-row LAI were initiated 37 days after planting (DAP) in 1982 ( Fig. 4), whereas stomatal resistance and leaf water potential measurements (Stone et al, 1985) were initiated 54 DAP. All observed AD, indicated by arrows in Fig.…”

“…Even if the turbulent air structure over the canopies were the same, as suggested int he discussion of Z 0 above, the differences in LAI could result in different reactions by individuals in the two treatments. The previous paper by Stone et al (1985) included the observation that the plants in narrow rows were slimmer than those in wide rows and had the leaflets closer to the extremity of the branches. This might result in a different vascular system.…”

“…The techniques for measuring stomatal diffusive resistance, leaf-water potential, and the methods for plot mamagement are detailed by Stone et al ( 1985). Only the specific methods and instruments used to obtain environmental data presented are discussed here.…”