The effects of drought on barley growth: models and measurements showing the relative importance of leaf area and photosynthetic rate

Abstract

In a field experiment on the effects of drought on spring barley the crop was protected from rain by automatic rain shelters. Various plots received irrigation at different times to give a range of drought treatments from full irrigation to no irrigation between emergence and harvest. The foliage area, light interception, stomatal resistance and leaf photosynthesis rate of five treatments were measured throughout the growing season, and a mathematical model has related the computed whole canopy photosynthesis to the measured total dry-matter yields at harvest. Hence, it was possible to estimate tha independent influences of drought on radiation interception, efficiency of use of intercepted radiation, and respiration. The analysis shows that for all treatments the decrease of intercepted radiation was the major factor in reducing yield, and it accounted for a loss of 30-40% for treatments that were stressed from the beginning of the season, and of 10-20 % for treatments that were stressed after mid-May. Stomatal closure caused a reduction of up to 11 % in daily photosynthesis, and the maximum effect was on plants that acquired a large leaf area before being stressed. However, the effect of stomatal closure integrated over the whole season was only 6 % or less. Our measurements of internal resistance to carbon dioxide transfer were not precise enough to show significant differences between treatments; but increases of internal resistance, caused by stress, may have contributed to loss of yield. AGS 93

EFFECT OF REDUCED SOIL MOISTURE AVAILABILITY ON LEAF MORPHOLOGY AND IN VITRO DRY MATTER DIGESTIBILITY OF FESTUCA ARUNDINACEA GENOTYPES WITH CONTRASTING LEAF TENSILE STRENGTH

“…In the field, changes in leaf dimensions in response to water shortage can be the main cause of declines in crop photosynthesis because of their influence on leaf area index (Leafe, Jones and Stiles, 1980;Legg et al, 1979). In the present experiment, the low watering treatment was effective in inducing similar adaptive morphological changes in F. arundinacea to those reported by Grace and Russell (1977), e.g.…”

Variability in adaptive mechanisms to water deficits in annual and perennial crop plants

“…One of the most obvious plant responses to water deficits is a reduction in leaf arca (Hsiao, 1973) with concomitant decreases in intercepted radiation and yield (Legg et al, 1979). The effects of water stress on leaf growth are considered to be mediated by reductions in turgor pressure ('~<p) a11 the leaf water potential ('Ir) decreases (Hsiao, 1973).…”

Effect of early blight(Alternaria solani)and different nitrogen inputs on radiation interception, radiation use efficiency, and total dry matter production in potatoes(Solanum tuberosum)grown in Canterbury, New Zealand

“…In many situations RUE and harvest index (HI) are stable, and thus yield can be related to RI alone. However some abiotic stresses, like water stress (Biscoe et al 1975;Moorby et al 1975;Gallagher & Biscoe 1978;Legg et at. 1979;Shekhar & Iritani 1979) and nutrient deficiency (Gallagher & Biscoe 1978;Green 1984;Muchow & Sinclair 1994) may also affect RUE which must then be accounted for in yield models (Shah et al 2004a).…”