水分和氮素对玉米苗期生长、根系形态及分布的影响

doi:10.3864/j.issn.0578-1752.2019.01.004

摘要/Abstract

摘要：

【目的】东北地区春旱频发严重影响玉米出苗与苗期生长,明确水分、氮素对玉米苗期生长和根系发育的影响及其耦合效应,可为东北春玉米水、氮调控措施的优化提供依据。【方法】 2016—2017连续2年设置水分、氮素两因素盆栽试验,土壤相对含水量设4个水平,分别为重度干旱（W0,30%）、适度干旱（W1,50%）、水分适宜（W2,70%）和水分过量（W3,90%）;施氮量设3个水平,分别为不施氮（N0,0）、低氮（N1,0.12 g N·kg ^-1土）和高氮（N2,0.24 g N·kg ^-1土）。【结果】水分、氮素均显著影响玉米苗期的植株生长、根系发育、氮素吸收与利用,且两因素对植株干重、根系形态、吸氮量和氮肥利用率交互作用显著。土壤水分亏缺或过量均抑制了植株生长、干物质累积、根系发育和氮素吸收。W0处理的负面影响最为严重,其地上部干重、根系干重和植株吸氮量与W2处理相比分别降低55.5%、60.1%和47.4%,氮肥利用率下降6.4个百分点,根长和根表面积分别减少58.2%和59.5%。施氮显著促进玉米苗期植株生长与氮素吸收,降低根冠比,且不同水分条件下氮肥效应及对根系发育的影响存在明显差异。水分适宜条件下施氮促进根系生长,显著增加根长、根表面积和根体积,植株干重和吸氮量增幅最高。干旱胁迫条件下施氮抑制了根系发育,显著降低根长和根表面积,氮肥效应偏低。水分过量条件下施氮改善根系生长,但施氮效应仍低于W2处理。各水分条件下,N1处理的根长和根表面积均高于N2处理,而体积接近或更小,说明低氮增加了细根的比例。水分、氮素不仅显著影响根系形态,也导致根系空间分布出现明显差异。干旱胁迫促进根系下扎,增加深层土壤的根长分布,W0和W1处理0—12 cm土层根长比例相比W2处理分别下降11.0和8.3个百分点,而24—36 cm土层分别提高9.5和6.9个百分点。与干旱胁迫相反,水分过量趋向于增加根系在表层土壤的聚集。施氮显著促进表层土壤的根系分布,N1和N2处理0—12 cm土层根长比例相比N0处理分别增加16.3和13.7个百分点,而24—36 cm土层分别下降11.5和12.5个百分点。所有水-氮处理中,W1N1处理根系的空间分布最为均衡。【结论】水分、氮素对玉米苗期生长和根系发育有显著的耦合效应,适宜的水、氮措施可优化根系形态与空间分布,增加植株干重和氮素吸收利用。春玉米生产中建议降低氮肥基施用量以发挥水氮耦合效应,促进根系下扎和细根增殖,提高植株耐旱性和氮肥利用率。

关键词: 玉米, 水分, 氮素, 根冠比, 根系形态, 根系分布

Abstract:

【Objective】 The frequent spring drought has severely negative impacts on seed emergence and seedling growth in the maize production of Northeast China. It is necessary to understand the coupling effects of soil water condition and nitrogen (N) rate on maize plant and root growth at the seedling stage, and further to provide reference for optimizing water and N management in maize production of Northeast China. 【Method】In this study, two pot experiments were conducted in 2016 and 2017, with a two factor factorial design of soil water and N rates. The soil water condition included 30%, 50%, 70% and 90% of field capacity, respectively, representing severe water-stress (W0), moderate water-stress (W1), well-watered (W2) and over-watered (W3), respectively. The N rates included 0, 0.12 and 0.24 g·kg ^-1 soil, representing N-omission (N0), low N (N1) and high N (N2), respectively. 【Result】 Soil water and N rate had significant individual effects on maize plant and root growth at the seedling stage, and showed interactive effects on dry matter (DM), root morphology, N uptake, and N fertilizer use efficiency (NUE). Both soil water deficit and excess had negative impacts on maize plant growth, DM accumulation, root development, and N uptake at the seedling stage, and was especially serious under W0 treatment. Compared with W2 treatment, on average in two years, shoot and root DM and plant N uptake under W0 treatment decreased by 55.5%, 60.1% and 45.8%, respectively, NUE decreased by 7.8 percentage points. And root length (RL) and root surface area (RSA) decreased by 58.2% and 59.5%, respectively. The N fertilization improved significantly maize plant growth and N uptake but reduced root/shoot ratio at the seedling stage. Moreover, the plant and root growth responses of N fertilizer differed obviously with the different soil water conditions. The N fertilization improved root growth in terms of higher RL, RSA and root volume (RV) under W2 treatment, and therefore showed the highest plant DM and N uptake. However, N fertilization limited root growth and decreased significantly RL and RSA under W0 and W1 treatments. The N fertilization also improved root growth under W3 treatment, but the N fertilizer response was still lower than that under W2 treatment. Across all the soil water conditions, maize plants showed higher RL and RSA under N1 treatments than that under N2 treatments, but the RV was equal or smaller, indicating that low N supply induced fine root development at the seedling stage. Soil water and N rate not only affected significantly maize root morphology, but also had great effects on root system spatial distribution. The water-stress induced deeper root growth and RL distribution in subsoil. Compared with W2 treatment, on average, the distribution ratio of RL in 0-12 cm soil layer decreased by 11.0 percentage points under W0 treatment and 8.3 percentage points under W1 treatment, but their distribution ratio in 24-36 cm soil layer increased by 9.5 and 6.9 percentage points, respectively. In contrast to soil water-stress condition, maize root system showed a concentrated trend in topsoil under over-watered condition. The N fertilization improved significantly root distribution in topsoil. Compared with N0 treatment, the RL distribution ratio increased by 16.3 and 13.7 percentage points higher in 0-12 cm soil layer under N1 and N2 treatments, respectively, and the distribution ratio decreased by 11.5 and 12.5 percentage points lower in 24-36 cm soil layer, respectively. Across all the soil water-N treatments, maize root system showed the more balanced spatial distribution under the W1N1 treatment.【Conclusion】Soil water condition and N rate had significant coupling effects on maize seedling growth and root development. The appropriate soil water and N management could optimize root morphology and spatial distribution, and improve plant DM accumulation and N uptake. Therefore, we suggested reducing basal N rate to stimulate deeper root growth with more fine root by inducing the water-N coupling effect, and further to enhance plant resistance to drought stress and to improve NUE in spring maize production of Northeast China.

Key words: maize, water, nitrogen, root/shoot ratio, root morphology, root spatial distribution

张馨月,王寅,陈健,陈安吉,王莉颖,郭晓颖,牛雅郦,张星宇,陈利东,高强. 水分和氮素对玉米苗期生长、根系形态及分布的影响[J]. 中国农业科学, 2019, 52(1): 34-44.

ZHANG XinYue,WANG Yin,CHEN Jian,CHEN AnJi,WANG LiYing,GUO XiaoYing,NIU YaLi,ZHANG XingYu,CHEN LiDong,GAO Qiang. Effects of Soil Water and Nitrogen on Plant Growth, Root Morphology and Spatial Distribution of Maize at the Seedling Stage[J]. Scientia Agricultura Sinica, 2019, 52(1): 34-44.

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土壤水分 Soil water condition	施氮量 N rate	2016年			2017年
土壤水分 Soil water condition	施氮量 N rate	株高 Plant height (cm)	茎粗 Stem diameter (cm)	SPAD	株高 Plant height (cm)	茎粗 Stem diameter (cm)	SPAD
W0	N0	60.4bB	19.7bB	28.8bA	73.4bC	25.3bB	32.0bC
	N1	79.7aB	23.7aB	44.3aA	80.5aC	28.6aC	42.9aB
	N2	82.5aB	23.9aB	45.7aA	83.1aC	30.9aC	44.9aB
W1	N0	71.7bA	31.8bA	32.9bA	82.5bBC	32.6bA	35.2bB
	N1	88.7aB	39.2aA	43.0aA	96.4aB	37.2aB	44.1aB
	N2	91.3aB	40.4aA	45.4aA	101.5aB	38.9aB	47.0aB
W2	N0	79.8bA	32.9bA	29.9bA	93.0bAB	34.4bA	36.7bAB
	N1	117.4aA	42.0aA	45.7aA	124.6aA	40.2aA	45.0aB
	N2	112.3aA	41.8aA	44.5aA	130.3aA	42.6aA	47.2aB
W3	N0	80.3bA	32.1bA	30.1bA	96.7bA	33.8bA	38.7bA
	N1	111.2aA	40.4aA	46.6aA	120.8aA	39.1aAB	48.0aA
	N2	115.3aA	41.8aA	45.5aA	125.1aA	38.0aB	50.1aA
方差分析 ANOVA
水分 W		<0.001 ***	<0.001 ***	0.893 ^ns	<0.001 ***	<0.001 ***	<0.001 ***
氮素 N		0.0016 **	<0.001 ***	<0.001 ***	<0.001 ***	0.032 *	<0.001 ***
水分×氮素 W×N		0.126 ^ns	0.551^ns	0.694 ^ns	0.083 ^ns	0.332 ^ns	0.879 ^ns

土壤水分 Soil water condition	施氮量 N rate	2016			2017
土壤水分 Soil water condition	施氮量 N rate	地上部干重 Shoot dry matter (g)	根系干重 Root dry matter (g)	根冠比 R/S ratio	地上部干重 Shoot dry matter (g)	根系干重 Root dry matter (g)	根冠比 R/S ratio
W0	N0	26.0bB	4.8aB	0.19aA	22.9bC	5.8aC	0.25aAB
	N1	34.9aD	5.3aD	0.15bB	29.7aC	6.0aD	0.20bB
	N2	36.5aD	4.9aD	0.13bB	29.4aC	5.5aC	0.19bA
W1	N0	39.6bA	8.3bA	0.21aA	32.3bB	8.8bB	0.27aA
	N1	63.3aC	12.4aC	0.20aA	43.4aB	10.9aC	0.25abA
	N2	65.7aC	11.2aC	0.17bA	48.4aB	10.7aB	0.22bA
W2	N0	40.5bA	8.4cA	0.21aA	41.7bA	10.8bA	0.26aAB
	N1	92.8aA	16.6aA	0.18bA	72.1aA	15.8aA	0.22bAB
	N2	87.3aA	14.8bA	0.17bA	68.9aA	14.7aA	0.21bA
W3	N0	37.2bA	7.5bA	0.20aA	41.8bA	10.1bAB	0.24aB
	N1	76.1aB	14.1aB	0.19abA	66.1aA	13.6aB	0.21bB
	N2	78.6aB	13.2aB	0.17bA	72.6aA	15.2aA	0.21bA
方差分析 ANOVA
水分 W		<0.001 ***	<0.001 ***	0.003 **	<0.001 ***	<0.001 ***	0.031 *
氮素 N		<0.001 ***	<0.001 ***	0.022 *	<0.001 ***	<0.001 ***	0.001 **
水分×氮素 W×N		<0.001 ***	<0.001 ***	0.846 ^ns	<0.001 ***	0.002 **	0.749 ^ns

土壤水分 Soil water condition	施氮量 N rate	根长 Root length (m)	根表面积 Root surface area (m²)	根体积 Root volume (cm³)
W0	N0	122.1aB	0.75aB	38.5aC
	N1	83.8bD	0.60bD	42.4aD
	N2	75.3bC	0.57bD	39.1aD
W1	N0	164.8aA	1.08aA	66.4cA
	N1	148.5aC	1.12aC	105.5aB
	N2	119.2bB	0.99aC	89.2bC
W2	N0	192.4cA	1.21bA	62.9cAB
	N1	259.7aA	1.81aA	116.8bA
	N2	221.0bA	1.73aA	164.6aA
W3	N0	174.3bA	1.09cA	57.5cB
	N1	221.4aB	1.59aB	93.5bC
	N2	208.9aA	1.43bB	110.3aB
方差分析 ANOVA
水分 W		< 0.001 ***	< 0.001 ***	< 0.001 ***
氮素 N		< 0.001 ***	0.002 **	< 0.001 ***
水分×氮素 W×N		< 0.001 ***	< 0.001 ***	< 0.001 ***