Fine root turnover of alfalfa in different soil horizons under different nitrogen and phosphorus levels

doi:10.11686/cyxb2021340

Abstract

Abstract:

This research explored the dynamics of fine root turnover and distribution in different soil horizons of alfalfa （Medicago sativa） under different nitrogen and phosphorus application conditions in a field experiment with a two-factor randomized block design in which the relationships between the indexes of fine root turnover were analyzed. Four phosphorus application levels ［0 （P₀）， 50 （P₁）， 100 （P₂） and 150 kg·ha^-1P₂O₅ equivalent （P₃）］ and two nitrogen application levels ［0 （N₀） and 120 kg·ha^-1 （N₁）］ were included in a total of 8 treatments. The turnover characteristics of fine roots in 0-60 cm soil horizon were monitored through minirhizotron. It was found that： 1） With the same rate of N application， alfalfa standing biomass， root surface area density， and fine root production and death rate were typically maximized at P₁ or P₂， with values for P₂ significantly greater than those for P₀ （P<0.05）. 2） With the rate of P application， values for the N₁ treatment were significantly greater than those for the N₀ treatment （P<0.05）. In different soil horizons， under the same nitrogen application conditions， alfalfa fine root mass in the 0-30 cm soil horizon initially increased and then decreased with successive rises in the rate of P application. In the 0-15 cm soil horizon， alfalfa fine root mass in treatment P₂ was significantly higher than that in other treatments （P<0.05）. In the different treatments， alfalfa fine roots were mainly found in the 15-30 cm soil horizon. Under the same nitrogen application rate， the fine root turnover of alfalfa initially decreased and then increased with successive increases in phosphorus application rate. Among the measured parameters， the fitting effect was best and the correlation coefficient was greatest between fine root death and root turnover. In conclusion， optimal of root mass and root surface area density of alfalfa fine roots were observed in the treatment combination N₁P₂， and this management regime is recommended for the promotion of root turnover and growth in alfalfa.

Key words: alfalfa, fine root turnover, nitrogen, phosphorus

Jun-wei ZHAO, Sheng-yi LI, Yan-liang SUN, Xuan-shuai LIU, Chun-hui MA, Qian-bing ZHANG. Fine root turnover of alfalfa in different soil horizons under different nitrogen and phosphorus levels[J]. Acta Prataculturae Sinica, 2022, 31(9): 118-128.

Figures/Tables 7

References 37

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处理 Treatment	TFRB （cm·cm^-3）	RSAD （cm²·cm^-2）	FRB （cm·cm^-3）				FRP （cm·cm^-3）	FRM （cm·cm^-3）
处理 Treatment	TFRB （cm·cm^-3）	RSAD （cm²·cm^-2）	0~15 cm	15~30 cm	30~45 cm	45~60 cm	FRP （cm·cm^-3）	FRM （cm·cm^-3）
茬次Cut
第一茬First cut	1.639	1.524	1.162	2.128	1.777	1.488	-	-
第二茬Second cut	1.471	1.611	0.909	1.847	1.664	1.465	0.114	0.282
第三茬Third cut	1.136	1.690	0.739	1.431	1.318	1.057	0.125	0.460
第四茬Fourth cut	0.968	1.889	0.836	1.164	1.096	0.777	0.261	0.429
SE	0.135	0.265	0.157	0.371	0.271	0.297	0.067	0.078
氮Nitrogen （N）
N₀	1.180	1.479	0.737	1.748	1.467	0.767	0.140	0.388
N₁	1.428	1.877	1.086	1.537	1.460	1.627	0.193	0.392
SE	0.124	0.199	0.175	0.105	0.003	0.430	0.027	0.002
磷Phosphorus （P）
P₀	0.915	1.040	0.627	1.196	1.332	0.505	0.169	0.267
P₁	1.684	1.813	0.756	2.429	1.892	1.657	0.151	0.461
P₂	1.689	2.868	1.521	2.263	1.570	1.404	0.186	0.497
P₃	0.927	0.992	0.741	0.682	1.061	1.221	0.161	0.336
SE	0.383	0.760	0.356	0.729	0.306	0.428	0.013	0.093
P值P value
茬次Cut	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
氮Nitrogen （N）	<0.001	<0.001	<0.001	<0.001	0.339	<0.001	<0.001	0.037
磷Phosphorus （P）	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
茬次×氮Cut×N	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
茬次×磷Cut×P	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
氮×磷N×P	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
茬次×氮×磷Cut×N×P	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001

处理 Treatment	TFRB （cm·cm^-3）	RSAD （cm²·cm^-2）	FRB （cm·cm^-3）				FRP （cm·cm^-3）	FRM （cm·cm^-3）
处理 Treatment	TFRB （cm·cm^-3）	RSAD （cm²·cm^-2）	0~15 cm	15~30 cm	30~45 cm	45~60 cm	FRP （cm·cm^-3）	FRM （cm·cm^-3）
茬次Cut
第一茬First cut	1.639	1.524	1.162	2.128	1.777	1.488	-	-
第二茬Second cut	1.471	1.611	0.909	1.847	1.664	1.465	0.114	0.282
第三茬Third cut	1.136	1.690	0.739	1.431	1.318	1.057	0.125	0.460
第四茬Fourth cut	0.968	1.889	0.836	1.164	1.096	0.777	0.261	0.429
SE	0.135	0.265	0.157	0.371	0.271	0.297	0.067	0.078
氮Nitrogen （N）
N₀	1.180	1.479	0.737	1.748	1.467	0.767	0.140	0.388
N₁	1.428	1.877	1.086	1.537	1.460	1.627	0.193	0.392
SE	0.124	0.199	0.175	0.105	0.003	0.430	0.027	0.002
磷Phosphorus （P）
P₀	0.915	1.040	0.627	1.196	1.332	0.505	0.169	0.267
P₁	1.684	1.813	0.756	2.429	1.892	1.657	0.151	0.461
P₂	1.689	2.868	1.521	2.263	1.570	1.404	0.186	0.497
P₃	0.927	0.992	0.741	0.682	1.061	1.221	0.161	0.336
SE	0.383	0.760	0.356	0.729	0.306	0.428	0.013	0.093
P值P value
茬次Cut	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
氮Nitrogen （N）	<0.001	<0.001	<0.001	<0.001	0.339	<0.001	<0.001	0.037
磷Phosphorus （P）	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
茬次×氮Cut×N	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
茬次×磷Cut×P	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
氮×磷N×P	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
茬次×氮×磷Cut×N×P	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001

处理 Treatments	年细根生产量 Annual production of fine root （cm·cm^-3·a^-1）	年细根死亡量 Annual mortality of fine root （cm·cm^-3·a^-1）	年细根最大现存量 Maximum annual standing crop of fine root （cm·cm^-3）	周转率 Turnover rate （a^-1）
N₀P₀	0.546±0.013B	0.964±0.043E	1.564±0.050D	0.344±0.012C
N₀P₁	0.415±0.010F	1.402±0.063B	1.916±0.060B	0.213±0.010D
N₀P₂	0.310±0.010G	1.348±0.053C	1.880±0.070C	0.162±0.007E
N₀P₃	0.436±0.010E	0.944±0.043E	0.817±0.030E	0.526±0.022B
N₁P₀	0.482±0.010D	0.637±0.023F	0.683±0.025F	0.697±0.032A
N₁P₁	0.504±0.010C	1.365±0.043C	2.330±0.085A	0.214±0.010D
N₁P₂	0.820±0.019A	1.634±0.073A	2.359±0.093A	0.343±0.014C
N₁P₃	0.545±0.013B	1.069±0.043D	1.562±0.050D	0.344±0.015C
N	**	ns	**	**
P	**	**	**	**
N×P	**	**	**	**

处理 Treatments	年细根生产量 Annual production of fine root （cm·cm^-3·a^-1）	年细根死亡量 Annual mortality of fine root （cm·cm^-3·a^-1）	年细根最大现存量 Maximum annual standing crop of fine root （cm·cm^-3）	周转率 Turnover rate （a^-1）
N₀P₀	0.546±0.013B	0.964±0.043E	1.564±0.050D	0.344±0.012C
N₀P₁	0.415±0.010F	1.402±0.063B	1.916±0.060B	0.213±0.010D
N₀P₂	0.310±0.010G	1.348±0.053C	1.880±0.070C	0.162±0.007E
N₀P₃	0.436±0.010E	0.944±0.043E	0.817±0.030E	0.526±0.022B
N₁P₀	0.482±0.010D	0.637±0.023F	0.683±0.025F	0.697±0.032A
N₁P₁	0.504±0.010C	1.365±0.043C	2.330±0.085A	0.214±0.010D
N₁P₂	0.820±0.019A	1.634±0.073A	2.359±0.093A	0.343±0.014C
N₁P₃	0.545±0.013B	1.069±0.043D	1.562±0.050D	0.344±0.015C
N	**	ns	**	**
P	**	**	**	**
N×P	**	**	**	**

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