Drought resistance in spring wheat cultivars. II.* Effects on plant water relations

Abstract

We studied cultivar and drought effects on the water relations of a large set of cultivars of bread wheat (Triticum aestivum L.), durum wheat (T. turgidum), triticale (X Tritosecale Wittmack) and barley (Hordeum vulgare L.), grown in field plots in north-western Mexico in the presence and absence of simulated late drought. Leaf water potential (Ψ) and osmotic potential (π), and leaf permeability (LP) to viscous air flow were measured between 1000 and 1600 hours on many dates; leaf turgor potential (p) was calculated. Drought caused associated reductions in Ψ, π and LP. Cultivar effects on these variables were usually significant on given dates, and reasonably consistent between dates and drought intensities in the case of Ψ, but less so for π and LP. There were consistent positive phenotypic correlations between Ψ and LP, and Ψ and anthesis date, and a negative correlation between Ψ and stature in the absence of drought. The relationship of LP to Ψ for different cultivars differed significantly: in particular, tall bread wheats had lower LP than dwarf cultivars at high values of Ψ, whereas at low Ψ they had higher LP than the dwarf cultivars. There was general osmotic adjustment, and a tendency for the relationship of p to Ψ to vary between cultivars. Irrespective of statistical significance, the effects of cultivar were generally small relative to those of drought intensity.

Analysis of Water Stress in Different Varieties of Maize (Zea mays L.) at the Early Seedling Stage

“…In this study, higher percentages of germination 67% and 58% recorded by inbred lines SRIKAR 3555 and TMMH 806 respectively which indicate that these two genotypes were relatively able to maintain better plant water status within the water-stressed period during which measurement was taken. This shows that inbred lines SRIKAR 3555 and TMMH806might not have only tolerated the drought but also might have avoided the drought as defined by Fisher and Sanchez [29] and also Otoole and Chang [30] that avoidance of drought is the ability of a plant to maintain relatively high water status despite the low moisture condition within the entire plant environment. According to González and González-Vilar [31], the subjective value accepted for LRWC is ≥ 80%.…”

Genetic variation in osmoregulation in bread and durum wheats and its relationship to grain yield in a range of field environments

“…Kaul(1969) presented the data as means rather than as a response of osmotic potential to change in water potential from which some estimate of osmoregulation could be obtained. Although Fischer and Sanchez (1979) did estimate the water potential at zero turgor, which differed between genotypes, the differences were found to be nonsignificant because of variability in the responses of turgor pressure to water potential. The results of Sojka et al (1981), however, do show relationships between mean midday water potentials and yields which were specific for particular cultivars.…”

RESISTANCE TO DROUGHT AND DENSITY STRESS IN CANADIAN AND EUROPEAN MAIZE (Zea mays L.) HYBRIDS

“…Selection of genotypes which yield well under drought stress is a stated objective of many breeding programs, including those in maize (Castleberry and Lerette 1980 (Blum 1974;O'Toole and MoYa 1978;Fisher and Sanchez 1979;Fisher et al 1983). Stomatal conductance has been monitored for a similar purpose (Jones 197 9).…”