浅埋滴灌下水氮运筹对春玉米根系衰减特性及产量的影响

Effects of water and nitrogen application on root attenuation characteristics and yield of spring maize under shallow buried drip irrigation

为探明浅埋滴灌下水氮运筹对春玉米产量及吐丝后根系衰减特性的影响,2017—2020年在通辽市科尔沁区农牧业高新科技示范园区,以传统畦灌常规施氮(W:4000 m^(3) hm^(–2),N:300 kg hm^(–2))为对照(CK),以滴灌定额为主处理,设传统畦灌常规灌量40%(W1:1600 m^(3)hm^(–2))、50%(W2:2000 m^(3) hm^(–2))、60%(W3:2400 m^(3) hm^(–2))3个水平,以施氮量为副处理,设常规施氮量50%(N1:150 kg hm^(–2))、70%(N2:210 kg hm^(–2))和常规施氮量(N3:300 kg hm^(–2))3个水平,测定不同水氮运筹下春玉米产量的变化,2019年和2020年采用BTC-100微根监测系统对春玉米吐丝后0-50 d时段内0-100 cm土层的根系进行定点连续动态监测。结果表明,春玉米产量连续4年均为W3N3显著高于CK,与W3N2、W2N3、W2N2处理差异不显著,氮肥农学效率连续4年均为W3N2较高。与CK相比,浅埋滴灌W3N30-60 cm土层根长密度、总根表面积和根系平均直径增加,80-100 cm土层根长密度降低,总根表面积和根系平均直径差异较小;吐丝后0-50 d根长密度、总根表面积和根系平均直径衰减幅度较CK低,其中20-40 cm土层根长密度吐丝后0-50 d时段W3N32年分别降低10.29%和8.83%,CK分别降低了15.04%和14.08%,平均根系衰减率W3N3较CK降低5.23%和4.43%。浅埋滴灌下,根长密度、总根表面积和根系平均直径W3N3、W3N2高于其他处理,且吐丝后0-50 d时段内0-60 cm土层衰减幅度较低,80-100 cm土层差异较小;吐丝后0-50 d时段内0-100 cm土层平均根系衰减率W3N3与W3N2差异不显著,W3N2较W2N2和W1N22年分别低5.68%、5.44%和9.75%、11.98%,较W3N1低7.16%和6.77%。方差分析表明,滴灌量和施氮量对产量和氮肥农学效率均有显著影响,滴灌量对吐丝后0-50 d时段内0-60 cm土层根长密度、总根表面积和平均根系衰减率影响显著,施氮量对吐丝后0-50 d时段内0-60 cm土层根长密度、吐丝后0-30 d时段内0-60 cm总根表面积和吐丝后0-50 d时段内0-40 cm土层平均根系衰减率影响显著。综上,浅埋滴灌下W3N3和W3N20-60 cm土层根长密度、总根表面积和根系平均直径较高,且吐丝后0-50 d时段内降低幅度小,平均根系衰减率低,二者产量差异不显著,但W3N2氮肥农学效率更高,推荐W3N2为西辽河平原灌区玉米节水高产高效栽培适宜的水氮管理模式。

In order to explore the effects of shallow drip irrigation on the yield and root decay characteristics of spring corn after silking,in the Agricultural and Animal Husbandry High Tech Demonstration Park of Horqin District,Tongliao City from 2017 to 2020,traditional border irrigation conventional nitrogen application(W:4000 m^(3) hm^(–2),N:300 kg hm^(–2))was used as the control(CK),and drip irrigation quotas were used as the main treatments.Three levels of traditional border irrigation conventional irrigation were set:40%(W1:1600 m^(3) hm^(–2)),50%(W2:2000 m^(3) hm^(–2)),and 60%(W3:2400 m^(3) hm^(–2)),Using nitrogen application rate as the secondary treatment,three levels of conventional nitrogen application rate[50%(N1:150 kg hm^(–2)),70%(N2:210 kg hm^(–2)),and conventional nitrogen application rate(N3:300 kg hm^(–2))]were set up to determine the changes in spring maize yield under different water and nitrogen treatments.In 2019 and 2020,the BTC-100 micro root monitoring system was used to continuously monitor root system of spring maize in the 0–100 cm soil layer at the 0–50 days stage after silking.The results showed that the yield of spring maize was significantly higher in W3N3 than CK for four consecutive years,and there was not significant difference compared with W3N2,W2N3,and W2N2 treatments.The nitrogen agronomic efficiency of W3N2 was also the highest at the same time.Compared with CK,root length density,the total root surface area,and the average root diameter of W3N3 all increased in 0–60 cm soil layer while root length density,the total root surface area,and the average root diameter were less in 80–100 cm soil layer;the decrease in root length density,the total root surface area,and the average root diameter was lower from 0 d to 50 d after silking in two years,in which the root length density of W3N3 and CK decreased by 10.29%and 8.83%,and 15.04%and 14.08%and the average root decay rate of W3N3 decreased by 5.23%and 4.43%compared with CK.Under the shallow buried drip irrigation,the root length density,the average diameter,and the total root surface area of W3N3 and W3N2 were both higher than those of other treatments,whose decrease extent of average root decay rate were lower in 0–60 cm soil layer and differences were less in 80–100 cm soil layer from 0 day to 50 days after silking;During the 0–50 day stage after silking,the difference of average root decay rate between W3N3 and W3N2 was not significant,and W3N2 decreased by 5.68%and 5.44%,9.75%and 11.98%,7.16%and 6.77%,respectively,compared with W3N1,W2N2,and W1N2 in two years.The variance analysis showed that both drip irrigation and nitrogen application had a significant impact on yield and nitrogen fertilizer agronomic efficiency.The drip irrigation amount had a significant impact on the root length density,the total root surface area,and the average root decay rate of the 0–60 cm soil layer at the 0–50 day stage after silking.Nitrogen application amount had a significant impact on root length density of the 0–60 cm soil layers at the 0–50 day stage after silking,the total root surface area of the 0–60 cm soil layers at the 0–30 day stage after silking,and the average root decay rate of the 0–40 cm soil layer at the 0–50 day stage after silking.In summary,the root length density,the total root surface area,and the average root diameter of the 0–60 cm soil layers of W3N3 and W3N2 under shallow burying drip irrigation were relatively higher,and the decrease was lower within the 0–50 day stage after silking,the average root decay rate was low,and the yield difference between the two was not significant,however,W3N2 had higher nitrogen agronomic efficiency,which could be recommended as a suitable water and nitrogen application mode for water-saving,high-yield,and efficient cultivation of corn for the irrigation area of the Xiliaohe plain.