Effects of intercropping on photosynthetic rate and net photosynthetic nitrogen use efficiency of maize under nitrogen addition

doi:10.17521/cjpe.2018.0033

Abstract

Abstract:

Aims The aim of this study was to explore the response of photosynthetic carbon assimilation and photosynthetic nitrogen (N) use efficiency (PNUE) of maize to intercropping system of maize and potato under different N addition, which has a great significance for the N regulation and N fertilizer management for the increase in intercropping yield.

Methods In order to analyze the effects of intercropping and additional N level on leaf characteristics, photosynthetic parameters, PNUE and yield of maize, field experiment with mono- and inter-cropping system under four N addition levels (N0, 0 kg·hm ^-2, N1, 125 kg·hm ^-2, N2, 250 kg·hm ^-2 and N3, 375 kg·hm ^-2) treatments were set up.

Important findings The results showed that inter-cropping planting significantly increased leaf dry mass of maize and leaf mass per area compared with maize monoculture. Among different N treatment levels (except N3), leaf area of maize under intercropping close to potato increased compared with that under maize monoculture. Intercropping also increased the light saturation point of photosynthesis and dark respiration rate of maize compared with maize monoculture. PNUE decreased as the increasing of N levels in monoculture maize, intercropping maize leaves close to potato (I-P) and leaves close to maize of other row (I-M), and the largest decline was found in I-P. At the same N level (less than 250 kg N·hm^-2), PNUE and photosynthetic rate (P_n) of maize in I-P were significantly higher than those in M and I-M system. Intercropping system significantly improve the yield of maize (land equivalent ratio > 1). This study concluded that higher PNUE and P_nof maize close to the potato contributed to the increase of intercropped maize yield under less than or equal to 250 kg N·hm^-2 addition.

Key words: intercropping, nitrogen level, leaf nitrogen content, photosynthetic rate, photosynthetic nitrogen use efficiency

ZHU Qi-Lin, XIANG Rui, TANG Li, LONG Guang-Qiang. Effects of intercropping on photosynthetic rate and net photosynthetic nitrogen use efficiency of maize under nitrogen addition[J]. Chin J Plan Ecolo, 2018, 42(6): 672-680.

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Figures/Tables 6

References 38

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氮水平 N level (kg·hm^-2)	产量 Yield		生物量 Biomass		土地当量比 Land equivalent ratio
氮水平 N level (kg·hm^-2)	I	M	I	M	土地当量比 Land equivalent ratio
0 (N0)	7.54 ± 0.23^Aa	5.18 ± 0.71^Aa	17.62 ± 1.01^Aa	14.88 ± 1.24^Aa	1.46
125 (N1)	12.30 ± 1.57^Ab	9.99 ± 1.63^Ab	25.69 ± 0.52^Ab	21.84 ± 0.73^Bb	1.23
250 (N2)	14.40 ± 1.67^Ab	11.69 ± 1.97^Bb	28.82 ± 1.88^Ac	24.90 ± 2.73^Bc	1.23
375 (N3)	14.29 ± 1.47^Ab	11.92 ± 1.11^Bb	28.63 ± 2.33^Ac	25.20 ± 1.75^Bc	1.20

氮水平 N level (kg·hm^-2)	产量 Yield		生物量 Biomass		土地当量比 Land equivalent ratio
氮水平 N level (kg·hm^-2)	I	M	I	M	土地当量比 Land equivalent ratio
0 (N0)	7.54 ± 0.23^Aa	5.18 ± 0.71^Aa	17.62 ± 1.01^Aa	14.88 ± 1.24^Aa	1.46
125 (N1)	12.30 ± 1.57^Ab	9.99 ± 1.63^Ab	25.69 ± 0.52^Ab	21.84 ± 0.73^Bb	1.23
250 (N2)	14.40 ± 1.67^Ab	11.69 ± 1.97^Bb	28.82 ± 1.88^Ac	24.90 ± 2.73^Bc	1.23
375 (N3)	14.29 ± 1.47^Ab	11.92 ± 1.11^Bb	28.63 ± 2.33^Ac	25.20 ± 1.75^Bc	1.20

叶片指标 Leaf indexes	种植模式 planting pattern	氮水平 N level (kg·hm^-2)
叶片指标 Leaf indexes	种植模式 planting pattern	0 (N0)	125 (N1)	250 (N2)	375 (N3)
叶面积 Leaf area (cm²·leaf^-1)	M	308 ± 14^Aa	466 ± 26^Ab	493 ± 19^Ab	553 ± 28^Ac
	I-M	283 ± 17^Aa	478 ± 19^Ab	524 ± 13^ABb	562 ± 22^Ac
	I-P	394 ± 8^Ba	498 ± 16^Bb	549 ± 23^Bc	576 ± 12^Ac
叶干质量 Leaf dry mass (g·leaf^-1)	M	1.71 ± 0.09^Aa	2.55 ± 0.08^Ab	2.68 ± 0.10^Ab	2.86 ± 0.22^Ab
	I-M	1.19 ± 0.07^Ba	2.66 ± 0.19^Ab	2.68 ± 0.14^Ab	3.02 ± 0.19^Ac
	I-P	1.44 ± 0.11^ABa	2.90 ± 0.16^Bb	3.30 ± 0.28^Bb	3.62 ± 0.10^Bc
比叶质量 LMA (g·m^-2 )	M	55.72 ± 3.97^Aa	54.90 ± 4.22^Aa	54.41 ± 1.87^Aa	51.82 ± 4.94^Aa
	I-M	42.42 ± 5.11^Ba	58.33 ± 2.16^Abc	63.00 ± 3.86^Bb	53.78 ± 4.60^Ac
	I-P	36.65 ± 2.07^Ba	55.59 ± 4.78^Abc	62.75 ± 2.21^Bc	48.82 ± 3.76^Bb
单位质量含氮量 N_mass(g·kg^-1)	M	14.55 ± 1.30^Aa	21.62 ± 1.04^Ab	31.02 ± 0.89^Ac	34.04 ± 1.15^Ac
	I-M	15.99 ± 0.71^Aa	23.78 ± 1.03^Ab	31.17 ± 0.76^Ac	34.08 ± 0.80^Ac
	I-P	18.68 ± 0.86^Ba	24.86 ± 0.66^Ab	32.97 ± 1.23^Ac	37.12 ± 0.49^Ac
单位面积含氮量 N_area(mg·cm^-2)	M	0.42 ± 0.05^Aa	0.62 ± 0.01^Ab	0.84 ± 0.06^Abc	0.89 ± 0.06^Ac
	I-M	0.34 ± 0.03^Aa	0.69 ± 0.08^Ab	0.82 ± 0.06^Ac	0.92 ± 0.06^Ac
	I-P	0.36 ± 0.03^Aa	0.72 ± 0.05^Ab	0.91 ± 0.01^Ac	0.93 ± 0.02^Ac
光合氮利用效率 PNUE (CO₂ μmol·g^-1·s^-1)	M	49.85 ± 5.24^Aa	32.57 ± 0.48^Ab	32.73 ± 2.37^Ab	32.01 ± 2.39^Ab
	I-M	64.71 ± 6.25^Ba	31.53 ± 2.03^Ab	28.65 ± 0.23^Ab	26.32 ± 5.41^Ab
	I-P	75.58 ± 5.38^Ca	47.14 ± 5.39^Bb	39.29 ± 5.40^Bc	30.28 ± 2.06^Ad

叶片指标 Leaf indexes	种植模式 planting pattern	氮水平 N level (kg·hm^-2)
叶片指标 Leaf indexes	种植模式 planting pattern	0 (N0)	125 (N1)	250 (N2)	375 (N3)
叶面积 Leaf area (cm²·leaf^-1)	M	308 ± 14^Aa	466 ± 26^Ab	493 ± 19^Ab	553 ± 28^Ac
	I-M	283 ± 17^Aa	478 ± 19^Ab	524 ± 13^ABb	562 ± 22^Ac
	I-P	394 ± 8^Ba	498 ± 16^Bb	549 ± 23^Bc	576 ± 12^Ac
叶干质量 Leaf dry mass (g·leaf^-1)	M	1.71 ± 0.09^Aa	2.55 ± 0.08^Ab	2.68 ± 0.10^Ab	2.86 ± 0.22^Ab
	I-M	1.19 ± 0.07^Ba	2.66 ± 0.19^Ab	2.68 ± 0.14^Ab	3.02 ± 0.19^Ac
	I-P	1.44 ± 0.11^ABa	2.90 ± 0.16^Bb	3.30 ± 0.28^Bb	3.62 ± 0.10^Bc
比叶质量 LMA (g·m^-2 )	M	55.72 ± 3.97^Aa	54.90 ± 4.22^Aa	54.41 ± 1.87^Aa	51.82 ± 4.94^Aa
	I-M	42.42 ± 5.11^Ba	58.33 ± 2.16^Abc	63.00 ± 3.86^Bb	53.78 ± 4.60^Ac
	I-P	36.65 ± 2.07^Ba	55.59 ± 4.78^Abc	62.75 ± 2.21^Bc	48.82 ± 3.76^Bb
单位质量含氮量 N_mass(g·kg^-1)	M	14.55 ± 1.30^Aa	21.62 ± 1.04^Ab	31.02 ± 0.89^Ac	34.04 ± 1.15^Ac
	I-M	15.99 ± 0.71^Aa	23.78 ± 1.03^Ab	31.17 ± 0.76^Ac	34.08 ± 0.80^Ac
	I-P	18.68 ± 0.86^Ba	24.86 ± 0.66^Ab	32.97 ± 1.23^Ac	37.12 ± 0.49^Ac
单位面积含氮量 N_area(mg·cm^-2)	M	0.42 ± 0.05^Aa	0.62 ± 0.01^Ab	0.84 ± 0.06^Abc	0.89 ± 0.06^Ac
	I-M	0.34 ± 0.03^Aa	0.69 ± 0.08^Ab	0.82 ± 0.06^Ac	0.92 ± 0.06^Ac
	I-P	0.36 ± 0.03^Aa	0.72 ± 0.05^Ab	0.91 ± 0.01^Ac	0.93 ± 0.02^Ac
光合氮利用效率 PNUE (CO₂ μmol·g^-1·s^-1)	M	49.85 ± 5.24^Aa	32.57 ± 0.48^Ab	32.73 ± 2.37^Ab	32.01 ± 2.39^Ab
	I-M	64.71 ± 6.25^Ba	31.53 ± 2.03^Ab	28.65 ± 0.23^Ab	26.32 ± 5.41^Ab
	I-P	75.58 ± 5.38^Ca	47.14 ± 5.39^Bb	39.29 ± 5.40^Bc	30.28 ± 2.06^Ad

氮水平 N rate (kg·hm^-2)	P_n (%)			N_area (%)			PNUE (%)
氮水平 N rate (kg·hm^-2)	M	I-M	I-P	M	I-M	I-P	M	I-M	I-P
0 (N0)	-	-	-	-	-	-	-	-	-
125 (N1)	-1.8	4.8	16.2	50.2	116.5	86.8	-34.7	-51.3	-37.6
250 (N2)	28.8	18.8	32.5	98.6	172.1	158.6	-34.3	-55.7	-48.0
375 (N3)	27.6	28.9	-3.0	101.9	174.9	173.5	-35.8	-59.3	-59.9