Abstract
Due to climate change, temperature in late February and early March raised up which cause heat stress at reproductive stage (terminal growth phase of wheat crop) which has become the major causative factor towards low wheat production in arid and semiarid regions. Therefore; strategies need to be adopted for improving terminal heat stress tolerance in wheat. In this study, we assessed whether foliar application of silicon (Si) (2 and 4 mM) at terminal growth phase i.e. heading stage of wheat imposed to heat stress (37 ± 2 °C) under polythene tunnel could improve the performance of wheat. Results of the study revealed that heat stress significantly reduced the photosynthetic pigments (chlorophyll a, b and a + b and carotenoids) leading to a lower grain yield. However, a 4 mM Si application (foliar applied) at heading stage prominently increased the chlorophyll a, b and a + b and carotenoids of flag leaf by improving the activities of enzymatic antioxidants (catalase, peroxidase and superoxide dismutase) and osmoprotectants (soluble sugar protein and proline) under terminal heat stress. Improvements in the performance of wheat (chlorophyll contents, carotenoids, soluble sugar and proteins and proline and yield) with foliar application of Si were also observed under control conditions. Correlation analysis revealed strong association (r > 0.90) of chlorophyll contents and carotenoids with grain and biological yield. Negative correlation (−0.81 < r > −0.63) of physio-biochemical components (antioxidants, proline, soluble sugars and proteins) with yield revealed that under heat stress these components produced in more quantities to alleviate the effects of heat, and Si application also improved these physio biochemical components. In crux, foliar application of Si alleviates the losses in the performance of wheat caused by terminal heat stress by improving the antioxidant mechanism and production of osmoprotectants.
Highlights
Due to climate change, temperature in late February and early March raised up which cause heat stress at reproductive stage which has become the major causative factor towards low wheat production in arid and semiarid regions
It has been observed from couple of decades that temperature in late February has been raised than the n ormal[4,5] which has become one of the key growths limiting factors during the reproductive stage as it reduces metabolism and photosynthetic partitioning and pollen v iability[1,6]
Wheat plants subjected to foliar Si application under both ambient temperature and heat stress condition upgraded the chlorophyll a, b and a + b and carotenoids contents at 2 mM and 4 mM concentration
Summary
Temperature in late February and early March raised up which cause heat stress at reproductive stage (terminal growth phase of wheat crop) which has become the major causative factor towards low wheat production in arid and semiarid regions. A 4 mM Si application (foliar applied) at heading stage prominently increased the chlorophyll a, b and a + b and carotenoids of flag leaf by improving the activities of enzymatic antioxidants (catalase, peroxidase and superoxide dismutase) and osmoprotectants (soluble sugar protein and proline) under terminal heat stress. Wheat is an important cereal crop of the globe and sensitive to terminal heat stress imposed at reproductive stage[2,3] It has been observed from couple of decades that temperature in late February has been raised than the n ormal[4,5] which has become one of the key growths limiting factors during the reproductive stage as it reduces metabolism and photosynthetic partitioning and pollen v iability[1,6]. They further reported that Si alleviates heat stress by improving photosynthesis, membrane stability, water balance and by enhancing the expression of heat stress responsive genes
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