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Effect of Heat Stress on the Photosynthetic Characteristics in Flag Leaves at the Grain‐Filling Stage of Different Heat‐Resistant Winter Wheat Varieties
Author(s) -
Feng B.,
Liu P.,
Li G.,
Dong S. T.,
Wang F. H.,
Kong L. A.,
Zhang J. W.
Publication year - 2014
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/jac.12045
Subject(s) - photosynthesis , cultivar , heat stress , agronomy , horticulture , chemistry , biology , botany , zoology
Heat stress has become an increasingly important factor in limiting wheat yields. In northern C hina, high temperature (>30 °C) during the grain filling is one of the major constraints in increasing wheat productivity. We used two winter wheat ( T riticum aestivum L.) cultivars with different sensitivities to heat stress (Jimai 22 ‘ JM 22’, low sensitivity and Xinmai 26 ‘ XM 26’, high sensitivity) to study the various aspects of photosynthetic characteristics during the grain filling stage under heat stress. The results showed that photosynthesis rates ( P n ) in flag leaves of XM 26 decreased faster than in JM 22 under heat stress during the grain‐filling stage. P n decreased more rapidly under heat stress than without stress, by up to 69.9% and 59.3%, respectively, at 10 days following heat stress (10 DAS ). This decline of P n was not caused by heat‐induced stomatal limitation, but rather by a decline in Rubisco activity and a functional drop in photosystem II ( PSII ). After heat stress, the grain yield of JM 22 decreased by 6.41%, but XM 26 decreased by 11.43%, when compared with their respective controls. Heat stress also caused an alteration of mesophyll cell ultrastructure. Injury caused by heat stress to organelles in XM 26 was more severe than JM 22. Moreover, the JM 22 cultivar showed some self‐repair capacity following heat stress injury. These results indicate that declines in photosynthetic performance caused by heat stress were cultivar‐dependent. Compared with XM 26, the JM 22 cultivar had superior heat stability in terms of PSII function and carboxylation activity, both of which are susceptible to heat stress.