Effect of covering on photosynthetic characteristics of flag leaf during post-anthesis and yield in winter wheat
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DOI:10.7606/j.issn.1000-7601.2019.03.25
Key Words: bundled-straw cover  winter wheat  photosynthetic performance  kinetic parameters of chlorophyll fluorescence  dry matter accumulation and translocation  yield
Author NameAffiliation
CHEN Ying-hui Gansu Provincial Key Laboratory of Aridland Crop Science /College of Life Science and Technology, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
CHENG Hong-bo Gansu Provincial Key Laboratory of Aridland Crop Science /College of Life Science and Technology, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
LIU Yuan Gansu Provincial Key Laboratory of Aridland Crop Science /College of Life Science and Technology, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
CHANG Lei College of Agronomy, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
CHAI Shou-xi College of Agronomy, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
YANG De-long Gansu Provincial Key Laboratory of Aridland Crop Science /College of Life Science and Technology, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
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Abstract:
      In order to accurately understand the characteristics of photosynthesis and accumulation and remobilization of shoot dry matter for yield improvement of dryland wheat grown under bundled-straw covering condition, a wheat cultivar of Longzhong 2 was used as material to determine differences in photosynthesis of flag leaf, chlorophyll fluorescence dynamic parameters, accumulation and remobilization of shoot dry matter during post-anthesis and grain yield among the different treatments including bundled straw covering cultivation (BS), plastic film mulching cultivation (PF) and cultivation without any covering (CK) in the semiarid rain-fed region of Gansu Province. The result showed that BS and PF significantly improved photosynthetic potential, chlorophyll and carotenoid content, and ratio of chlorophyll to carotenoid of flag leaf during post-anthesis, compared with CK. The effects of BS was more remarkable than those of PF, especially in the late growth period. The leaf photosynthetic rate and stomatal conductance were higher under BS than that under CK during the whole growth stage. In this case, PF just showed positive effects in earlier growth stage, but negative effects in mid-later growth stage. The intercellular CO2 concentration in early and middle stage and the instantaneous water use efficiency in mid-later growth stage under BS were higher than those under both PF and CK. The former increased by 2.8%~8.2% and 6.7%~11.3%, respectively, while the latter increased by 30.3%~44.8% and 27.5%~39.3%, respectively. The Fv/Fm, F′v/F′m, ΦPSⅡ, qP and ETR of flag leaf increased but the NPQ decreased before the middle grain-filling stage under PF and during the whole growth period under the BS. Compared with both PF and CK, BS significantly raised the input amount of dry matter to kernels by 2.6% and 1.0% and the contribution rate to grain weight by 14.2% and 8.6% during post-anthesis, respectively. BS greatly increased spike number per unit area and thus enhanced yield by 35.4%. It was indicated that BS treatment could significantly improved photosynthetic efficiency and accumulation and transportation of dry matter, and consequently increased grain yield of dryland winter wheat.