Sensitivity of Southern Peas to Plant Water Deficit at Three Growth Stages¹

Abstract

Response of southern peas (Vigna sinensis L. Endl. var. Burgundy) to different levels of water deficit at three different stages of growth was measured in a greenhouse. In each stage, plants were stressed to three levels of leaf water potential: — 14 bars, — 21 bars, and —28 bars. Crop susceptibility factors (fractional reductions in yield compared to a nonstressed treatment) were determined for each stage of growth and level of plant water deficit. The flowering period was found to be the most sensitive stage, regardless of deficit level. The pod development stage was found to be least sensitive to level of deficit. A water deficit of — 28 bars, however, caused a yield reduction of greater than 50% for all growth stages. Stress‐day index values were calculated and related to crop yield. The use of the stress‐day index concept in irrigation scheduling is discussed. Leaf water potential varied linearly with soil water potential between 0 and — 15 bars. Leaf diffusion resistance became high and transpiration was negligible after the leaf water potential reached — 10 to — 12 bars; the corresponding soil water potential was — 5 bars. Water‐use efficiencies were highest for the nonstressed treatment and the treatment with the low deficit level during the first stage.

Plant growth, nutrient acquisition and mycorrhizal symbioses of a waterlogging tolerant legume (Lotus glaber Mill.) in a saline-sodic soil

“…For all the variables measured on plant and soil (growth, morphological, nutrient uptake, AM fungi and soil) in waterlogged and non-waterlogged treatments we estimated a Susceptibility Index (SI) was calculated (Hiler et al, 1972):…”

Vertical Gradients of Water Potential and Tissue Water Relations in Sitka Spruce Trees Measured with the Pressure Chamber

“…Other studies have shown that stomatal resistance can be largely unaffected by water potential over a wide range before increasing sharply over a quite narrow range of potentials (Tinklin & Weatherley 1966Miller, Gardner & Golz 1971;Hansen 1971;Hiler et al 1971;Kriedemann & Smart 1971;C. The physiological significance of these responses is at present largely unknown.…”

Deficit and excess of soil water impact on plant growth of Lotus tenuis by affecting nutrient uptake and arbuscular mycorrhizal symbiosis

“…For all the measured plant and soil variables, we computed a Susceptibility Index (SI; Hiler et al 1972):…”