Abstract
Wheat production is sensitive to minor temperature changes, and thus the identification of indicators of temperature tolerance is of great importance. In the present study, shoots of 20 d old plants of six wheat (Triticum aestivum L.) cultivars, namely, Millat-2011, Galaxy-2013, Fsd-2008, Sahar-2006, Lasani-2008 and Shafaq-2006 were exposed to heat stress (37 °C) for 6, 12, 24 and 48 h in the growth incubator while the temperature of root was maintained at 25 °C. The root and shoot temperature of control plants was set at 25 °C. The results indicated that short-term heat stress (STHS) significantly decreased photosynthetic pigments, leaf relative water contents (RWC) and peroxidase (POD) activity. By contrast, the membrane permeability, hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents were increased. In addition, an increase in the activities of catalase (CAT) and ascorbate peroxidase (APX), and the concentrations of anthocyanins, ascorbic acid and proline was recorded irrespective of cultivars under heat stress. Among the cultivars, Galaxy-2013 followed by Millat-2011 had higher chlorophylls, activities of CAT and APX, along with higher RWC and anthocyanins in the shoot exposed to STHS. Further, Galaxy-2013 and Millat-2011 had relatively higher levels of phenolics, flavonoids, soluble proteins and soluble sugars both in the shoot and root under STHS. In contrast, spatiotemporal STHS severely affected membrane permeability, root and shoot metabolism and antioxidant activities in the Shafaq-2006. Taken together, Galaxy-2013, Millat-2011 and Shafaq-2006 proved to be tolerant, moderately tolerant and sensitive to heat stress, respectively. The physio-biochemical traits in the shoot rather than in the root were linked with tolerance to spatiotemporally applied STHS possibly due to the reason that root was incubated at 25 °C irrespective of shoot temperature.
Razia Gulnaz, Muhammad Iqbal. (2021) STUDY OF PHYSIOLOGICAL AND BIOCHEMICAL INDICATORS OF TEMPERATURE TOLERANCE IN WHEAT (Triticum aestivum L.) IN RESPONSE TO SHORT-TERM SPATIOTEMPORAL TEMPERATURE VARIATION, Pakistan Journal of Agricultural Sciences, Volume 58, Issue 2.
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