Abstract

Water stress and high temperature variability are the major constraints for wheat crop productivity and food security in the context of climate change. Impact of high temperature and water stress at anthesis stage of spring wheat was studied through field experiments conducted during 2008 to 2009 and 2009 to 2010. Five wheat varieties of diverse origin namely Tatara, National Agricultural Research Centre (NARC)-2009, Sehar-2006, SKD-1 and F-Sarhad were sown in randomized complete block design (RCBD) replicated four times. Physiological parameters that is, net photosynthesis (A_n), transpiration rate (E), SPAD chlorophyll contents and prolines were recorded at anthesis stage. The results indicated reduction of A_n and increased E due to high temperature and moisture stresses. Among genotypes, maximum photosynthetic rate was recorded for Tatara (30.52 μ mole/m²/s) followed by NARC-2009. The E recorded maximum in Sehar-2006 (2.80 mole/m²/s) which had low photosynthetic activity whereas minimum E observed in Tatara (2.27 μ mole/m²/s) followed by NARC-2009. Maximum SPAD value observed in Tatara (53.17) followed by NARC-2009 (49.00) where as Sehar-2006 (37.17) depicted less chlorophyll contents and ultimately reduced photosynthesis and productivity. The highest proline contents were recorded in Tatara (59.69 µg g^-1) followed by NARC-2009 (55.05 µg g^-1) as compared to SKD-1 (46.27 µg g^-1) and F-Sarhad (50.58) which might be due to genetic potential and physiological adaptability of Tatara cultivars against stress conditions. Water stress and high temperature at anthesis led to reduction in photosynthesis resulting reduced biomass and limited yield. Therefore, genotypes having better physiological performance under biotic stresses need to be considered for cultivation under changing environment. Since Tatara performed best in our study, it is recommended for cultivation under high temperature and moisture stresses. The values of all physiological attributes (A_n and E) were higher during first year (2008 to 2009) as compared to second year (2009 to 2010) which was due to relatively high temperature and low moisture availability during the second year.

Key words: Temperature, water stress, photosynthesis, transpiration, proline, SPAD chlorophyll, anthesis, wheat.

Abbreviation

Abbreviations: A_n, Net photosynthesis; E, transpiration rate; NARC, National Agricultural Research Centre.