夏播小麦栽培生理初探——Ⅱ.穗部灌浆过程的生长分析

前文研究了品种和播期对夏播小麦籽粒产量和产量构成因素的影响。本文对穗部灌浆过程作了生长分析。开花后,每隔两天取样,烘干后称取穗重,直至收获。试验资料符合一元三次回归方程:f(t)=a+bt+ct~2+dt~3,由此计算出穗干物质积累速度。并根据生长曲线求得灌浆速度和持续时间。夏播小麦对播期反应很敏感。在试验条件下,播种日期每推后4天,全生育期平均温度便下降1℃,灌浆阶段的平均温度下降1.5℃。而灌浆阶段平均温度每下降1℃,籽粒灌浆时间延长3.1天。夏播小麦籽粒产量和千粒重的主要限制因素是灌浆期的温度。这一阶段的平均温度既决定灌浆速度,又影响持续时间。而最终的籽粒产量主要取决于灌浆速度。

A preliminary Study on the physiological Characteristics of Soring wheat Cultured in Summer.Ⅱ.Dry matter accumulation in ears during the grain filling period.

A split plot experiment with three replications was conducted in unirr- igated hilly fields at an altitude of 1000 metres in mid-Shanxi in 1982.The purpose of the experiment was to study the effects of sowing date ongrain filling in spring wheat varieties out of season.Two varieties of wheat were used:Jinchun No.3(Shanxi Shring wheat No.3),an early-maturing variety; Xiamai No.1(Summer wheat No.1),a late variety.The sowing dates were July 10,14 and 18 respectively.Each plot consisted of 5 rows 3.3 metres in length and row spacing of 0.2 metres. The plant samples were harvested from each plot 12 days after anthesis and again at three day intervals until the end of grain filling.Ears,stems, leaves and roots from each plot were separated and weighed.For each tr- eatment combination,the relationship between ear dry weight and days from anthesis was calculated by fitting a cubic polynomial of the form:f(t)= a+bt+ct~2+dt~2,where f(t)is ear dry weight(mg),t is time(days from an- thesis).The average rate of dry matter accumulation in ear in the interval from the beginning to the end of filling can be defined as1/(t_2-t_1) integral from t_1 to t_2(df(t)/dt)=(W_2-W_1)/(t_2-t_1),where W_1 is the estimated ear weight (mg)at the 12th day from anthesis,and W_2 is the es timated maximum ear weight(mg).The duration and average rate of dry matter accumulation in ears were evaluated from the cubic polynomial and derivative. Both varieties of summer-sowing wheat were susceptible to changes of sowing date and the range of opportune sowieg time was very narrow and limited.Under the conditions of this experimsnt,both varieties seeded on July 10 and 14 ripened.Those seeded on July 18 did not.The averege temp- erature from emergence to maturity(TEM)dropped 1~*C,and the average te- mperature during grain filling period(TGF)drobbed 1.5℃,as the sowing date was put off 4days.As1~* C drop in TGF caused a 3.1 day increase in the duration of the grain filling period.The grain yield was fundamentally dependent upon the filling rate but not the duration of the grain filling period and the filling rate was mainly dependend upon the TGF.