Water Deficit Effects on Transpiration and Leaf Growth¹

Abstract

Reductions of leaf development and transpiration are closely related to soil water deficits. Few studies have analyzed the effects of water deficits on both processes during different growth stages. A study was conducted to analyze and quantify the effects of water deficits during different growth stages on leaf development (number, extension, and senescence) and transpiration rates of sorghum [Sorghum bicolor (L.) Moench] and cotton (Gossypium hirsutum L.). The study was conducted at the Blackland Research Center at Temple, TX, in a glasshouse using covered pots and in the field using covered lysimeters. In the glasshouse, the sorghum and cotton pre‐flowering treatments were irrigated at 60, 35, 15, and 0% of water used in the control pots. In the lysimeters, water deficit treatments of 50, 30, and 0% plant available water (PAW) were imposed on sorghum during the vegetative period (before panicle initiation and between panicle initiation and anthesis) and after anthesis. Leaf length and transpiration rates were measured two to three times per week. Leaf extension was reduced to 0% of well‐watered sorghum and cotton when the PAW decreased from 50 to 0%. Transpiration per unit leaf area decreased from 100 to 0% of well‐watered sorghum and cotton when PAW decreased from 28 to 0% for each stressed period. Sorghum leaf senescence was enhanced and leaf number increased in the 0% PAW treatments compared to the well‐watered and 30% treatments. These relationships of leaf development, transpiration, and PAW compare favorably with other published results. The PAW threshold values when each process is affected would be useful in developing criteria for scheduling irrigation and in improving the accuracy of crop growth models in estimating leaf development and transpiration.

A practical model for predicting soil water deficit in New Zealand pastures

“…Further work is required to determine the dependence of a on pasture and soil types. If a can be successfully related to pasture species, this may provide a means to study the relative response of alternative pasture species to drought conditions (Parry et al 1992), as plant stress is closely related to ^£7 (McAneney et al 1982;McAneney & Judd 1983;Parfitt et al 1985aParfitt et al , 1985bRosenthal et al 1987;Barker et al 1989;Sadras & Milroy 1996). This would then allow a practical model of plant growth response to water stress to be formulated.…”

Addressing drought conditions under current and future climates in the Jordan River region

“…They showed that the relationship between SPI and NDVI can be explained with a linear relationship as long as the seasonality is taken into account, for example, by conducting correlation analyses individually for each month of the year. Because the relationship between precipitation and vegetation development differs between plant species (Rosenthal et al, 1987), the analyses were conducted separately for different land uses. First, the average SPEI, SPI and NDVI values of all pixels in each land use were determined for each month.…”

Osmolyte accumulation: can it really help increase crop yield under drought conditions?

“…Virtually all major processes contributing to crop yield including leaf gas exchange (Ritchie, Burnett & Henderson 1972;Ritchie 1973;Sinclair & Ludlow 1986;Kuppers, Kuppers & Schulze 1988), leaf growth (Sinclair 1986;Rosenthal et al . 1987;Lecoeur & Sinclair 1996;Muchow & Sinclair 1991) are inhibited late in stage I or in stage II of soil drying.…”