Abstract only

Majority of the country's cropland, especially in southern areas, is affected by soil and air moisture stresses. Soil moisture stress is usually accompanied by high air temperatures, leading to rapid decrease of moisture both in soil and the plants. Study of the dynamics of leaf area formation and dry biomass accumulation in various wheat varieties under drought is of great practical impor- tance. We have attempted to study the effect of the moisture stress on the leaf area formation dynamics and dry biomass accumulation during the onto- genesis. Two local wheat varieties Garagilchin-2 and Baraketli-95 were used as the study material. It should be noted that fast increase in the leaf area for both genotypes was observed at the beginning of the ontogenesis in both variants: moisture stress and irrigated (check). Maximum values for the leave area of Garagilchin-2 and Baraketli-95 were recorded in the 2nd decade of may, at the end of booting. Leaf area for the variants with irrigation (check) and moisture stress were 62 and 46 thousand m2/ha in Garagilchin-2, and 60 and 41 thousand m2/ha in Baraketli-95, respectively. The differences between the variants were equal to 26% and 32% for Garagilchin-2 and Baraketli-95, respectively. Reduction of leaf area is observed starting from the heading date. At the end of the first decade, leaf area dropped to 37 and 16 thousand m2/ha in Garagilchin-2 and to 32 and 14 thousand m2/ha in Baraketli-95, for the irrigated and water stress variants, respectively and the difference between the variants for Garagilchin- 2 and Baraketli -95, made up 56% and 57%, respectively. The area of stems kept increasing until the grain filling stage, reaching its maximum values 68 and 54 thousand m2/ha in Garagilchin-2, and 67 and 53 thousand m2/ha in Baraketli-95 in the irrigated and water stress variants, respectively. The difference between the variants was 20% and 21 % for Garagilchin-2 and Baraketli-95, respectively. The difference became slightly higher by the end of ontogenesis and was estimated as 22% and 25% for Garagilchin-2 and Baraketli-95, respectively. In both varieties the spike area increases under irrigation more rapidly than under water stress, reaching its maximum in the mid-may after the spike is fully formed. Maximum values of spike area are 28 and 19 thousand m2/ha in Garagilchin-2, and 27 and 20 thousand m2/ha in Baraketli-95, for irrigated and water stress variants, respectively. The difference between the variants is 32% and 27% for Garagilchin-2 and Baraketli-95, respectively. The difference between the variants by the end of ontogenesis is estimated as 33% and 36% for Garagilchin-2 and Baraketli-95, respectively. The study data suggests that in varieties Garagilchin-2 and Baraketli-95 the leaf area under drought tends to reduce to a greater extent than that of the stems and spikes. The aboveground dry biomass accumulation dynamics is the same than that of the leaf area. It should be noted that maximum values for dry biomass in leaves in irrigated and water stress variants in both varieties are observed in the early may amounting to 42 and 30 ton/ha in Garagilchin-2, and 44 and 34 ton/ha in Baraketli-95, for the irrigated and water stress, respectively. Maximum values of dry biomass in stems are observed in the third decade of may, at the milk stage, while maximum values of dry biomass in spikes are recorded at the wax stage. The following maximum values were recorded for Garagilchin- 2 for stem dry mass 13.0 and 9.0 ton/ha, and spike dry mass 13.4 and 7.2 ton/ha, in the irrigated and water stress, respectively. In Baraketli-95, 12.6 and 9.1 ton/ha were recorded for the dry stem biomass, and 12.8 and 9.0 ton/ha for the spike dry mass, in the irrigated and water stress variants, respectively. It was found that dry biomass accumulation in spikes proceeds more evenly than in the stems and leaves. Thus, the obtained data provides evidence that the leaf area and the leaf dry biomass accumulation dynamics are influenced not only by the plant development stage and genotype, but also by environment, especially by such strong factor as water stress.

English

0409|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection