Seasonal trends in leaf photosynthesis and stomatal conductance of drought stressed and nonstressed pearl millet as associated to vapor pressure deficit

Abstract

Single leaf photosynthesis (Pn) and stomatal conductance (Cg) of drought stressed and nonstressed pearl millet [Pennisetum americanum (L.) Leeke] were measured across growth stages to determine if a pattern exists in Pn and Cg during the growing season and to evaluate the influence of air vapor pressure deficit (VPDa) on the seasonal variations of Pn and Cg. Leaf photosynthesis and Cg were measured independently on pearl millet plants grown at the driest (drought stressed) and wettest (nonstressed) ends of a line-source irrigation gradient system. Well defined and predictable variations in both Pn and Cg were found across two growing seasons. Leaf photosynthesis of the nonstressed plants declined from a maximumof 25.8 μmol m(-2) s(-1) at the flag leaf emergence (48 days after planting, DAP) to a minimum of 14.5 μmol m(-2) s(-1) at physiological maturity. Stomatal conductance of the nonstressed plants peaked at the flowering and early grain fill stages and declined as plants approached maturity. In contrast, Pn and Cg of the stressed plants declined from a maximum at flag leaf emergence to a minimum at flowering and increased as plants approached maturity. High VPDa during the flowering and grain fill stages induced stomatal closure and decreased Pn in the stressed plants. High mid-season VPDa did not induce stomatal closure and did not reduce leaf photosynthesis in nonstressed plants. The lack of sensitivity of Pn to VPDa in the nonstressed treatment suggests large air VPD such as that prevalent in southern Arizona does not limit the growth of irrigated pearl millet by limiting CO2 assimilation.

PHOTOSYNTHESIS AND BIOMASS PRODUCTION BY MILLET (PENNISETUM GLAUCUM) AND TARO (COLOCASIA ESCULENTA) GROWN UNDER BAOBAB (ADANSONIA DIGITATA)AND NÉRÉ (PARKIA BIGLOBOSA) IN AN AGROFORESTRY PARKLAND SYSTEM OF BURKINA FASO (WEST AFRICA)

“…The average P N of millet (24.3 ± 5.01 μmol CO 2 m −2 s −1 ) recorded in the control plot in the present study was within the range of values of 4.4–62.94 μmol CO 2 m −2 s −1 reported by previous studies (Boegh et al ., 1999; McPherson, 1973; Masojidek et al ., 1991; Tewolde et al ., 1993; Warner and Edwards, 1988). The average P N of taro in the control plot (13.8 ± 1.18 μmol CO 2 m −2 s −1 ) was also within the range of values (4.1–30.93 μmol CO 2 m −2 s −1 ) reported by Sato et al .…”

Transcriptome analysis of Pennisetum americanum × Pennisetum purpureum and Pennisetum americanum leaves in response to high-phosphorus stress

“…This often leads to the problem of excessive application of phosphorus fertilizer. Existing research on Pennisetum predominantly addresses abiotic stresses such as drought and oxidative stress [23,24], while research on phosphorus stress, especially high phosphorus is relatively scarce. This study, therefore, investigates P. americanum × P. purpureum and P. americanum under hydroponic conditions with varying P levels.…”