By the extent of the damage done to the crops, drought is one of the global problems of agriculture. Notwithstanding an insignificant depressive effect of drought on morpho-physiological traits of plants, its influence on grain yield and quality is quite significant. Development of drought-resistant and high yielding varieties becomes, thus, one of the primary objectives of agriculture in the dryland areas. Breeding for varieties with the complex tolerance to a wide range of unfavorable environmental conditions is conducted through selection of germplasm whose morphological traits are less susceptible to depression. Such germplasm may be also used as parental material in crosses. Water-use-efficiency, or in other words the amount of water consumed per biomass unit formation, depends on genotype and is a valuable trait in breeding. Transpiration adjusts temperature ofthe plant and creates favorable conditions for the course of other physiological processes. From this standpoint, studying the intensity and productivity of transpiration facilitates more purpose-focused selection of the best germplasm. Trials to assess transpiration intensity under optimum irrigation and moisture deficiency conditions were carried out on the experimental station of the Azerbaijani Research Institute of Agriculture, located on the Absheron peninsula. The study material included several wheat varieties with different morphological traits. To maintain soil humidity at the level of70-80% of the total moisture holding capacity, the field was irrigated 2-3 times during the crop season. In the variant with moisture deficiency, soil humidity was within 35-65%. Transpiration was measured by weighing of f1ag leaves (Ivanov, 1950). Varieties differing by heading time and architectonics ofleaves (vertical or horizontal) were selected for the study: comparatively early heading Giymatli-2/17 (horizontal leaves), Azemetli-95 (vertical leaves), late-heading Akinchi-84 (horizontal leaves) and Girmizi gul (vertical leaves). The study results suggest that the transpiration intensity in the varieties with horizontal leaves was higher, irrespective of heading date and moisture availability. As shown in the table, at the earlier stage of plant development, difference between the variants (irrigated versus non-irrigated) for the varieties with horizontal leaves was as high as 28- 32%, while it made up 22-26%.for the varieties with vertical leaves. Later, when the moisture deficit increased, the difference between the irrigated and dry variants reached 35-37% and 28- 31% for the varieties with horizontal and vertical leaves respectively. By the end ofMay the difference between variants turned out to be 45-47%, and 32-38% forthe varieties with horizontal and vertical leaves respectively. The data suggests that the early heading genotypes are characterized by lower transpiration than the late-heading genotypes, which can be explained by reduced functioning of the root system and lower humidity of leaves in the early heading genotypes. In general, it may be concluded that water- use-efficiency is an important biological and morphological trait that is determined by genotype and using parental forms with vertical leaves can contribute to development of drought-resistant and high yielding varieties.

English

0407|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection