| Late Spring Coldness(LSC)is one of the major agrometeorological disasters which harm the high yield and quality of wheat in Huang-Huai wheat region.It is urgent to improve the ability of disaster prevention and reduction.With the global warming,the growth and development of wheat is accelerated.LSC is more likely to occur in spring,especially in Huang-Huai wheat region.LSC prone period coincides with the most sensitive period of wheat to low temperature,which makes the yield loss of semi winter wheat more serious.In this experiment,Yannong 19 and Xinmai 26 were selected from different varieties of anti cold winter wheat.In this experiment,the intelligent low temperature climate incubator was used to treat wheat at 2 ℃ and-2 ℃ for 4h/1d at the stage of anther interval formation in wheat.The processing time is from 1:00 to 5:00 in the morning.It is to study the effects of low temperature stress on the upper internode,spike morphology and yield per spike of wheat at the anther interval formation stage,in order to explore the morphological indexes of wheat tolerance to LSC and provide theoretical basis for the construction of evaluation system of wheat tolerance to LSC.The main results are as follows:(1)The plant height and barycenter height of Yannong 19 and Xinmai 26 were significantly decreased by low temperature stress during the anther interval formation stage,and the decrease would gradually increase with the increase of low temperature stress.The plant height and the height of center of gravity of different varieties with cold resistance were different under low temperature stress.Under the low temperature stress treatment at 2℃ for 4h /1d,the plant height and height of gravity center of Yannong 19 decreased by 23.86% and 27.93% than that of CK respectively,while that of Xinmai 26 decreased by 18.09% and 39.30% than that of CK respectively.Under the low temperature stress treatment at-2℃ for 4h/1d,the plant height and height of gravity center of Yannong 19 decreased by 32.12% and 46.93% than that of the CK respectively,while that of Xinmai 26 decreased by 27.76% and 47.73% than that of CK respectively.(2)Low temperature stress significantly reduced the length and dry weight of the internode under spike and the penultimate internode of Yannong 19 and Xinmai 26 at the stage of anther interval formation,and the decrease would gradually increase with the aggravation of low temperature stress,but had no significant effect on the thickness of the internodes under spike and the penultimate internode of Yannong 19 and Xinmai 26.The effects of low temperature stress on the length and dry weight of internode under spike and the penultimate internode of different varieties with cold resistance in late spring were different.Under the low temperature stress treatment at 2℃ for 4h /1d,the length and dry weight of the internodes under spike of Yannong19 were reduced by 44.02% and 36.67% than that of CK respectively,while the length and dry weight of the penultimate internode decreased by 37.79% and 39.62% respectively,and the length and dry weight of the internodes under spike of Xinmai 26 were reduced by 35.56% and 40.00%than that of CK respectively,while the length and dry weight of the penultimate internode were reduced by 46.20% and 36.59% than that of CK respectively.Under the low temperature stress treatment at-2℃for 4h/1d,the length and dry weight of the internodes under spike of Yannong 19 decreased 59.73% and 46.67% than that of CK respectively,while the length and dry weight of the penultimate internode decreased by 52.53% and 45.28% than that of CK respectively,and the length and dry weigh of the internodes under spiket of Xinmai 26 decreased 59.18% and 64.44%than that of CK respectively,while the length and dry weight of the penultimate internode decreased 51.30% and 46.34% than that of CK respectively.(3)Low temperature stress at anther interval formation stage reduced the spike width and dry weight per spike of Yannong 19 and Xinmai 26,which were significantly different from those of CK,but had no significant effect on the spike length of the two varieties.Under the low temperature stress treatment at 2 ℃ for 4h /1d,the spike width and dry weight per spike of Yannong 19 were 19.41% and 42.35% lower than CK respectively,while that of Xinmai 26 was46.80% and 85.41% lower than CK respectively.Under the low temperature stress treatment at-2 ℃ for 4h /1d,the spike width and dry weight per spike of Yannong 19 were 56.43% and77.20% lower than CK respectively,while that of Xinmai 26 were 58.60% and 81.85% lower than CK respectively.(4)The grain number per spike and yield per spike of Yannong 19 and Xinmai 26 were significantly decreased by low temperature stress at the stage of anther interval formation,and the decline would be significantly increased with the aggravation of low temperature stress,and the effect of Xinmai 26 was more severe than that of Yannong 19.Under the low temperature stress treatment at 2℃for 4h /1d,the grain number per spike and yield per spike of Yannong 19 were54.76% and 50.66% lower than CK respectively,while that of Xinmai 26 were 95.04% and96.67% lower than CK respectively.Under the low temperature stress treatment at-2℃for 4h /1d,the grain number per spike and yield per spike of Yannong 19 were 98.10% and 98.24% lower than CK respectively,while that of Xinmai 26 were 98.24% and 98.75% lower than CK respectively. |
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