冬前积温对北部冬麦区小麦苗期生长的影响

Effect of accumulated temperature before overwintering on wheat seedling growth status in north winter wheat area of China

为探究全球气候变化对我国北部冬麦区适宜播期的影响,于2019—2021年2个小麦生长季在中国农业科学院作物科学研究所北京试验基地进行小麦播期试验。选用2个不同分蘖力小麦品种为试验材料,设置4个不同播期:9月25日(J)、10月5日(S0)、10月15日(S1)和10月25日(S2),作为冬前不同积温处理,研究冬小麦苗期群体质量、个体性状和茎蘖生理对冬前积温差异的响应。结果表明:随着播期的推迟,小麦越冬前积温及相邻播期间积温差呈逐渐降低趋势。J和S0播期下冬前积温均超过550℃,满足小麦冬前形成壮苗的基本条件,播期S1和S2较S0冬前积温平均减少148.0和282.4℃,不利于冬前小麦壮苗的形成;在4个不同播期条件下,播期每推迟10 d,积温平均分别下降204.0、148.0和134.4℃。播种至出苗的天数受到日平均温度的影响,当日平均温度低于15℃时,随着播期的推迟,播种至出苗的天数逐渐增加,当日平均温度高于15℃时,播种至出苗的天数为恒定值。小麦群体总茎数、叶面积指数、干物质重、氮素积累量和单株分蘖数也随着冬前积温的减少而降低。苗期可溶性糖含量、硝酸还原酶活性随着冬前积温的减少均呈先升后降的变化趋势,而可溶性蛋白含量和谷氨酰胺合成酶活性对积温的响应存在品种间差异。综合冬前小麦群体质量和个体性状,在4个不同播期中,10月5日播种条件下小麦冬前群体总茎数和单株分蘖数与我国北部冬麦区冬前壮苗标准最为接近,冬前积温有利于壮苗的形成。因此,当日平均气温为15~17℃时为北京冬小麦最佳播种期。

To explore the impacts of global climate change on the suitable sowing date for winter wheat in north winter wheat area of China,we carried out a wheat sowing date experiment during growing seasons of 2019-2021 at the Beijing Experimental Base of the Institute of Crop Sciences,CAAS.Two winter wheat cultivars with different tillering powers were selected as experimental materials.Four different sowing dates were set:September 25th(J),October 5th(S0),October 15th(S1)and October 25th(S2),to examine the responses of population quality,individual characters,and stem and tiller physiology to the accumulated temperature difference before overwintering.The results showed that with the delay of sowing date,the accumulated temperature before winter and their difference between the adjacent sowing dates decreased gradually.The accumulative temperature at the sowing J and S0 both exceeded 550℃,which met the basic condition for the formation of strong wheat seedlings before winter.The average accumulated temperature at sowing S1 and S2 was 148.0 and 282.4℃lower than that of S0,which was not conducive to the establishment of strong wheat seedlings before winter.The average accumulated temperature decreased by 204.0,148.0 and 134.4℃,when the sowing date was delayed by 10 days under the four different sowing dates,respectively.The days from sowing to emergence were affected by the average daily temperature.The days from sowing to emergence gradually increased with the delay of sowing date when the daily average temperature was lower than 15℃,while the days from sowing to emergence were constant when the daily average temperature was higher than 15℃.The total stem number,leaf area index,dry matter weight,nitrogen accumulation and tiller number per plant of wheat also decreased with the decreases of pre-winter accumulated temperature.The soluble sugar content and nitrate reductase activity at the seedling increased first and then decreased with the decreases of accumulated temperature before winter,while the soluble protein content and glutamine synthetase activity to accumulated temperature performed differently among varieties.According to the population quality and individual traits of wheat before winter,among the four different sowing dates,the total stem number and tiller number per plant of wheat before sowing on October 5 were the closest to the standard of strong seedlings before winter in north winter wheat area.The accumulated temperature before winter is conducive to the formation of strong seedlings.When the daily average temperature is 15-17℃,it is the best sowing time for winter wheat in Beijing.