Morphological and physiological responses of different wheat genotypes to chilling stress: A cue to explain yield loss

Citation

Li, P.F., B.L. Ma*, Y.C. Xiong, and W.Y. Zhang. 2017. Morphological and physiological responses of different wheat genotypes to chilling stress: A cue to explain yield loss. J. Sci. Food Agric. (in press).

Plain language summary

Cold stress is one of the limiting factors inhibiting crop growth and development, resulting in the loss of grain yield. Plants tend to undergo innumerable changes under chilling stress. In most cases, cold stress can decrease the viable leaf area and the carbohydrate production and accumulation, eventually negatively affecting the final yield. Is the source (size of leaf area for carbohydrate production) or the sink (size of the grain/spikes for carbohydrate deposition) restricted by chilling stress? Which factor would play a critical role to cause the yield loss? The two questions remain unclear in the cold-tolerance physiology. We hypothesized that imbalanced source-sink process could be predicted to have a large impact on yield in different wheat genotypes under chilling stress. In the present study, six different genotypes of wheat were selected to test this hypothesis under environment-controlled growth conditions. Our study showed that diploid and tetraploid wheat genotypes obtained larger leaf areas and relatively high photosynthetic rates but eventually produced no or low yield under chilling stress. While in hexaploid genotypes, leaf areas and photosynthetic rates remained at a low level, and water soluble carbohydrates can be stored substantially. This helps to maintain a decent sink size and ensure the supply and translocation of photosynthetic assimilates from source to meet the sink demand, allowing these genotypes to achieve relatively stable grain yields under chilling stress. Thus, these results show that the communication of source to sink is a key factor to guarantee a high and stable grain yield under chilling stress in modern wheat genotypes.

Abstract

BACKGROUND: The eco-physiological mechanism of wheat yield loss resulting from chilling stress is a critical fundamental scientific issue. However, most of the previous studies have focused on hexaploid wheats, and there were few studies on the morphological and physiological plasticity of wheat plants. Six different wheat genotypes were tested under chilling stress to investigate the physio-morphological parameters as well as the loss of grain yield in growth chambers.
RESULTS: Chilling stress resulted in significant loss in grain yield in all genotypes. Under chilling stress, diploid wheats generated zero harvest, and tetraploid genotypes also suffered from a pronounced loss in grain yield compared with control group. In contrast, hexaploid genotypes acquired relatively high maintenance rate of grain yield among three species.
CONCLUSIONS: Diploid and tetraploid wheat genotypes maintained relatively large leaf area and high photosynthetic rates, but they were subjected to greater declines in vascular bundle number and productive tillers as a consequence of the inhibition by sink growth under chilling stress. While hexaploid genotypes were found to have relatively low leaf area and photosynthetic rates, they turned to store more soluble carbohydrates and exhibit stronger sink enhancement, ensuring the translocation and redistribution of assimilates. Our finding provided a new theoretical implication on yield stabilization in the domestication process of wheat genotypes under chilling stress.

Publication date

2017-12-31

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