Heat tolerant, high yielding wheat varieties will be critical in building resilience into wheat production systems under the threat of climate change in Central Asia. Two studies were conducted in three years to identify heat tolerant wheat genotypes. The first study was conducted in Karshi, Uzbekistan in three years (2013–2015) using 105 winter wheat genotypes of diverse genetic background and origin. Late planting was undertaken to expose the crop to high temperatures during grain-filling. The temperatures during grain-filling of the late planted crop reached up to 43°C confirming heat stress. Heat tolerance was assessed through changes in morpho-physiological traits under normal and late planting. Arrays of genotypic variations were found for traits related to heat tolerance. The 10 genotypes classified tolerant showed lower reductions (4 to 10%) in grain yield compared to the 10 sensitive genotypes (37 to 55%). The late seeded crop matured in 171 days compared to 209 days for timely seeded crop. The rate of decrease in NDVI (normalized difference vegetation index, a measure of leaf greenness and chlorophyll content) was faster in late compared to timely seeded crop. This suggests association between higher ambient temperature and chlorophyll breakdown. Genotypes exhibiting lower reductions in grain yield had slower rate of NDVI decline compared to heat sensitive genotypes. Average number of spikes and spike length didn’t differ significantly between timely and late seeded crops. Lower reductions in grain yield were associated with higher 1000-kernel weight, taller plant height, and slower rate of NDVI reduction. Several genotypes (‘Alvd//Aldan/Ias58/3/Col.No.3617/4/Zarrin77’, ‘Alamoot/3/Alvd//Aldan"s"/IAS58/4/Alamoot/Gaspard’, and ‘Elomon’), identified as heat tolerant could be further evaluated for identifying new varieties or utilized as improved parents.

The second experiment involved evaluation of 24 spring wheat genotypes from ICARDA which had been selected for heat tolerance outside Central Asia. Several genotypes planted in March, considered an extremely late planting time, matured between 80 and 90 days with grain yield ranging from 3.3 to 5.6 t ha-1 on medium saline soils under >40°C temperatures grain-filling in Aral Sea region. These fast maturing genotypes are viewed as valuable wheat material to be cultivated in winter frost-prone environments of Central Asia and other regions where similar conditions preclude the cultivation of winter wheat.Three winter wheat varieties (‘Davlatle’, ‘Chimbay’ and ‘Amudarya’) have been identified for cultivation under terminal heat conditions. ‘KR-SP2014-21’ (Angi-2/Hubara-3) and ‘KRJ-SP2015’ (Qimma-12/Pastor-6//Qimma-12), have been identified as early maturing, heat tolerant spring wheat cultivars.