EXCISED-LEAF WATER RETENTION CAPABILITY AS AN INDICATOR OF DROUGHT RESISTANCE OF <i>Triticum</i> GENOTYPES

Abstract

Excised-leaf water retention was studied in 25 Triticum aestivum and 16 T. turgidum var. durum genotypes, as well as in 52 lines from a cross of high- and low-retention durums. A system of tared dishes, carrier trays and a data entry device interfaced with an electronic balance was used to facilitate handling large numbers of samples. At each sampling, four of the newest fully expanded leaves were taken from each plot, weighed, and then re weighed at intervals after standing in a control led-environment room and after oven drying. Weighing of leaves 24 h after excision resulted in poor separation of genotypes, particularly late in the season. A 6- to 10-h interval improved differentiation between genotypes. Initial leaf water content tended to decline over the growing season, while the amount of water lost in 24 h tended to remain relatively constant. In the hexaploid cultivars Columbus lost water slowest, while NB112 lost water fastest; in the durums, Pelissier was slowest, Hercules was fastest. Fifty-two lines from a Hercules × Pelissier cross exhibited a range of retention capabilites between the parental values. There was a low-order, but significant, positive correlation between yield and flag-leaf water retention in this material.