Effect Of Elevated Temperature On Maize Stem Growth,Microstructure And Lodging Resistance Characters

With global climate change,the effects of elevated temperature on maize production system are increasingly complex.Lodging resistance plays an important role on the completely mechanized maize production system in present and the future.Thus,studying on the characteristics of maize stem and lodging resistance responding to gradient warming during the whole season could provide theoretical and practical basis to the adaptive cultivation approach in response to climate change in the future.ZD958 and XY335 were tested as materials.And three temperature gradient of CK,CK+2℃,CK+4℃ were conducted in the greenhouse to study the effect of gradient warming on stem growth and development,material composition,stem mechanics characters,lodging resistance characters and grain yield.The main findings were as follows:1.The temperature increment shortened the nutrition growth period.From planting to jointing,CK+4℃ and CK+2℃ decreased 3-4 days and 2 days,respectively,compared with CK;increase the reproductive growth period of time,CK+4℃ and CK+2℃ increased by 6-8 days and 4-5 days,respectively,compared with CK.Under temperature elevated makes plants grow faster,and the leaf area index was significantly higher than that of control,plant height,ear height,the third internode length,internode length and long peduncle were significantly higher than that of control,and CK+2℃ increased on average by 10.80%,37.29%,16.87%,17.11% and 17.78%,respectively,compared to CK;CK+4℃ increased on average by 20.82%,54.17%,37.11%,28.48% and 35.84%,respectively,compared to CK.Temperature increment significantly increased the ear coefficient and stalk width coefficient,thick stalk width and moment of inertia of small,the greater the risk of lodging.2.Temperature increment significantly decreased the number and area of vascular bundles of stems.CK+4℃ and CK+2℃ decreased the number of central vascular bundles of third internode by43.29% and 22.59%,respectively,compared to CK.CK+4℃ and CK+2℃ decreased total vascular bundle area by 40.33% and 28.68%.The effect of temperature increment on the number and area of central vascular bundle was greater than that of peripheral vascular bundle.In terms of cell morphology and number,the lengthwise cell length was significantly increased by heating treatment,and the number of cell layers was significantly decreased with the increase of cell length.The total width of parenchyma cells,epidermal cells and cortical cells decreased.3.Temperature increment significantly decreased the thrust resistance,puncture strength and crushing strength.With maize growing process,and 2 cultivars of aboveground third internode stem thrust resistance were a single-peak curve variation,25 days after spinning,the average maximum thrust resistance was 161.89 N,then stem thrust resistance drop,CK+4℃ and CK+2℃ significantly decreased the thrust resistance by 50.75% and 43.75%.Puncture strength along with the birth process showed a trend of decline curve change after the first increases,maximum value appeared in the mature period before and after puncture strength,CK+4 and CK+2℃ significantly decreased the thrust resistance by 25.41% and 29.59%.The change trend of stem crushing strength was consistent with that of thrust resistance,which increased first and then decreased.The peak value of crushing strength appeared from 25 days after spinning to the maturity stage,CK+4℃ and CK+2℃significantly decreased the thrust resistance by 22.41% and 23.58%.4.The changing trend of IAA/ABA ratio of the two cultivars under different growth stages and different temperature treatments was not consistent.The ratio of IAA/ABA of ZD958 reached its peak at 7 days after jointing,and then showed a decreasing trend.Compared with CK,the ratio of ZD958 showed a larger change range.In XY335,the variation trend of CK and CK+2℃ is consistent,while CK+4℃ presents a bimodal trend.The change trend of ZR/ABA ratio in ZD958 was consistent with that of the control.CK+4℃ and CK showed a bimodal trend.In XY335,the change trend of CK+2℃ and CK+4℃ were consistent,while CK+4℃ showed a bimodal trend.GA3/ABA showed the same trend in the warming treatment,showing a single peak trend of increasing first and then decreasing.5.The thrust resistance of stem was significantly negatively correlated with plant height,ear height,and length of the third internode,and positively correlated with stem diameter,moment of inertia,number and area of edge vascular bundle,and number and area of central vascular bundle.The puncture intensity of stem was negatively correlated with plant height,ear height,and the length of the third internode,and positively correlated with stem diameter,number and area of peripheral vascular bundle,and number and area of central vascular bundle.The crushing strength of stem was negatively correlated with plant height,ear height,and the length of the third internode in the aboveground,and positively correlated with stem diameter,number and area of peripheral vascular bundle,and number and area of central vascular bundle.According to the correlation analysis between the ratio of stem ganglia hormone and the cell microstructure and agragrical characters,the longitudinal cell layer number,epidermal cell width,parenchyma cell total width,cortical cell total width and long and short axis width were all negatively correlated with IZG/ABA,while the longitudinal cell length was positively correlated with the length of the third internode.