Effect of nitrogen application on photosynthetic daily variation， leaf morphology and dry matter yield of alfalfa at the early flowering growth stage

doi:10.11686/cyxb2021343

Abstract

Abstract:

In this research， studies on leaf morphological characteristics and the diurnal changes of photosynthesis in a drip-irrigated alfalfa （Medicago sativa） crop were monitored under different nitrogen levels and the relationships between the daily changes of photosynthesis， leaf morphology， and dry matter yield were analyzed in order to better understand the mechanism of the impact of nitrogen on alfalfa dry matter yield development. The study thus provides a theoretical framework for optimizing the nitrogen management strategy of alfalfa in commercial production. The study used a single factor randomized complete block design with four nitrogen application levels of 0 （CK）， 60 （N₁）， 120 （N₂）， and 180 kg N·ha^-1 （N₃）. At the early flowering growth stage， daily photosynthetic variation， leaf morphology， leaf nitrogen content， and yield components were of the alfalfa were measured. It was found that the net photosynthetic rate， transpiration rate， and water use efficiency of alfalfa leaves under the nitrogen application treatments were higher than those under the non-nitrogen application treatment， and the intercellular CO₂ concentration of alfalfa leaves under the nitrogen application treatments was lower than that under the non-nitrogen application treatment. The environmental factor that had the greatest combined effect on net photosynthetic rate and transpiration rate was photosynthetic effective radiation. The leaf length， leaf width， leaf area， and specific leaf weight of alfalfa， as well as leaf dry weight， stem dry weight， dry matter yield， leaf nitrogen content， starch， and soluble sugar content all showed a pattern of initial increase and then decrease with successive increments of N application. For different nitrogen concentrations， leaf area was the most significant factor affecting leaf morphological structure， followed by leaf specific weight， leaf length， and leaf width. The effects on dry matter yield of alfalfa were， in descending order， leaf nitrogen content>net photosynthetic rate>leaf area>transpiration rate>specific leaf weight. The decrease in photosynthetic rate in the zero-N and high-N treatments was primarily due to the inhibition of photosynthetic activity； This is a non-stomatal factor. Based on a principal component analysis， the highest overall score for dry matter yield， leaf morphology and photosynthesis was obtained in the N₂ treatment， followed by N₃， N₁ and CK treatments. Therefore， nitrogen fertilization promoted the synergistic improvement of photosynthetic rate and photosynthetic area in alfalfa. It facilitated the production of photosynthetic products， thereby increasing alfalfa dry matter yield， especially at the nitrogen application rate of 120 kg·ha^-1.

Key words: alfalfa, nitrogen, leaf morphology, diurnal variation of photosynthesis, dry matter yield

Yan-liang SUN, Jun-wei ZHAO, Xuan-shuai LIU, Sheng-yi LI, Chun-hui MA, Xu-zhe WANG, Qian-bing ZHANG. Effect of nitrogen application on photosynthetic daily variation， leaf morphology and dry matter yield of alfalfa at the early flowering growth stage[J]. Acta Prataculturae Sinica, 2022, 31(9): 63-75.

Figures/Tables 12

Fig.1 Daily variation of environmental factors in the field

Fig.2 Daily variation of net photosynthetic rate of alfalfa leaves under different levels of nitrogen application

Fig.3 Daily average values of photosynthetic parameters of alfalfa leaves under different levels of nitrogen application

Fig.4 Daily variation of transpiration rate of alfalfa leaves under different levels of nitrogen application

Fig.5 Daily variation of intercellular CO2 concentration in alfalfa leaves under different levels of nitrogen application

Fig.6 Daily variation of stomatal limitation value of alfalfa leaves under different levels of nitrogen application

Fig.7 Daily variation of water use efficiency of alfalfa leaves under different levels of nitrogen application

Table 1 Changes in morphological structure of alfalfa leaves under different levels of nitrogen application

处理Treatment	叶面积Leaf area （cm²）	叶长Leaf length （mm）	叶宽Leaf width （mm）	比叶重SLW （g·m^-2）
CK	1.80±0.01d	25.12±0.18c	10.62±0.40c	52.40±0.30c
N₁	1.85±0.01c	25.80±0.18b	11.42±0.28b	53.11±0.13b
N₂	1.95±0.01a	26.33±0.46a	12.10±0.25a	54.15±0.09a
N₃	1.90±0.02b	26.27±0.32a	11.94±0.45a	53.54±0.27b
F值F-value	36.855**	19.725**	18.934**	32.175**

Table 2 Dry matter yield components， photosynthetic products and nitrogen content of leaves of alfalfa at different nitrogen application levels

处理 Treatment	干物质产量 Dry matter yield （t·hm^-2）	叶干重 Leaf dry weight （t·hm^-2）	茎干重 Stem dry weight （t·hm^-2）	茎叶比 Stem/leaf	叶片氮含量 Nitrogen content of leaf （%）	淀粉 Starch （% DM）	可溶性糖 Soluble sugar （% DM）
CK	4.67±0.07c	2.17±0.03c	2.50±0.04b	1.16±0.01a	4.06±0.02c	5.46±0.04c	5.59±0.03c
N₁	4.98±0.02ab	2.37±0.03ab	2.61±0.02a	1.10±0.02b	4.28±0.10b	5.80±0.13b	6.00±0.13ab
N₂	5.09±0.07a	2.43±0.04a	2.66±0.03a	1.10±0.01b	4.57±0.04a	5.99±0.17a	6.12±0.12a
N₃	4.93±0.02b	2.34±0.02b	2.59±0.03a	1.11±0.02b	4.28±0.03b	5.58±0.03c	5.71±0.21bc
F值F-value	26.411**	29.828**	9.913**	7.044*	34.330**	18.909**	7.483*

Fig.8 Principal component analysis of dry matter yield， leaf morphology and photosynthesis of alfalfa under different levels of nitrogen application

Fig.9 Integrated analysis of the relationship between major environmental factors and net photosynthetic rate and transpiration rate based on structural equation model

Fig.10 Integrated analysis of leaf nitrogen content， major photosynthetic properties and leaf morphological indicators in relation to dry matter yield based on structural equation model

References 31

1	Gao Y， Sun S N， Xing F， et al. Nitrogen addition interacted with salinity-alkalinity to modify plant diversity， microbial plfas and soil coupled elements： A 5-year experiment. Applied Soil Ecology， 2019， 137（5）： 78-86.
2	Liu X J， Zhao Y J， Hao F， et al. Detection and characterization of nitrogen efficiency in alfalfa. Acta Prataculturae Sinica， 2021， 30（12）： 90-102.
	刘晓静，赵雅姣，郝凤，等. 紫花苜蓿氮效率及其类型特征研究. 草业学报， 2021， 30（12）： 90-102.
3	Weigelt A， Bol R， Bardgett R D. Preferential uptake of soil nitrogen forms by grassland plant species. Oecologia， 2005， 142（4）： 627-635.
4	Kuypers M M M， Boran K H M. The microbial nitrogen-cycling network. Nature Reviews Microbiology， 2018， 16（5）： 263-276.
5	Erisman J W， Bleeker A， Galloway J， et al. Reduced nitrogen in ecology and the environment. Environmental Pollution， 2007， 150（1）： 140-149.
6	Xiao Z X， Wang Y， Liu G F， et al. Effects of fertilizing time in early spring on alfalfa （Medicago sativa） production performance and nutritional quality in mollisol area in cold region. Scientia Agricultura Sinica， 2020， 53（13）： 2668-2677.
	肖知新，王洋，刘国富，等. 寒地黑土区春季施肥期对紫花苜蓿生产性能及营养品质的影响. 中国农业科学， 2020， 53（13）： 2668-2677.
7	Zheng Q， Wang H J， Lv X， et al. Comprehensive method for evaluating soil quality in cotton fields in Xinjiang， China. Chinese Journal of Applied Ecology， 2018， 29（4）： 1291-1301.
	郑琦，王海江，吕新，等. 新疆棉田土壤质量综合评价方法. 应用生态学报， 2018， 29（4）： 1291-1301.
8	Oikawa S， Ainsworth E A. Changes in leaf area， nitrogen content and canopy photosynthesis in soybean exposed to an ozone concentration gradient. Environmental Pollution， 2016， 215（8）： 347-355.
9	Zhang Q Y， Peng S L. Effects of warming on the biomass allocation and allometric growth of the invasive shrub Lantana camara. Acta Ecologica Sinica， 2018， 38（18）： 6670-6676.
	张桥英，彭少麟. 增温对入侵植物马缨丹生物量分配和异速生长的影响. 生态学报， 2018， 38（18）： 6670-6676.
10	Zhang X L， Liu L T， Sun H C， et al. Hyperspectral estimation of the maximum carboxylation rate of cotton leaves under different nitrogen levels. Transactions of the Chinese Society of Agricultural Engineering， 2020， 36（11）： 166-173.
	张鑫磊，刘连涛，孙红春，等. 不同施氮水平下棉花叶片最大羧化速率的高光谱估测. 农业工程学报， 2020， 36（11）： 166-173.
11	Wang S L. Study on the response of different rice varieties to light and nitrogen and its mechanism. Nanchang： Jiangxi Agricultural University， 2016.
	王盛亮. 不同双季稻品种对光氮的响应差异及其机理研究. 南昌：江西农业大学， 2016.
12	Lizana C， Wentworth M， Martinez J P， et al. Differential adaptation of two varieties of common bean to abiotic stress： Effects of drought on yield and photosynthesis. Journal of Experimental Botany， 2006， 57（3）： 685-697.
13	Kunelius H T. Effects of weed control and N fertilization at establishment on the growth and nodulation of alfalfa. Agronomy Journal， 1974， 66（6）： 806-809.
14	Badr M A， Abou-hussein S D， El-tohamy W A. Tomato yield， nitrogen uptake and water use efficiency as affected by planting geometry and level of nitrogen in an arid region. Agricultural Water Management， 2016， 169（5）： 90-97.
15	Li H S. Principles and techniques of plant physiological and biochemical experiments. Beijing： Higher Education Press， 2000.
	李合生. 植物生理生化实验原理和技术. 北京：高等教育出版社， 2000.
16	Stewart K J， Grogan P， Coxson D S， et al. Topography as a key factor driving atmospheric nitrogen exchanges in arctic terrestrial ecosystems. Soil Biology and Biochemistry， 2014， 70（2）： 96-112.
17	Jiang H X， Liu D， Zhai G Y， et al. Effect of fertilizer combinations of nitrogen， phosphorus and potassium on the forage yield of Medicago sativa. Pratacultural Science， 2012， 29（9）： 1441-1445.
	姜慧新，刘栋，翟桂玉，等. 氮、磷、钾配合施肥对紫花苜蓿产草量的影响. 草业科学， 2012， 29（9）： 1441-1445.
18	Wang Y Q， Shen Y， Qian J， et al. Effect of nitrogen forms on plant growth， expression of nitrate transporter gene MtNRT1.3， and nitrogen absorption in Medicago sativa L. Acta Agrestia Sinica， 2019， 27（5）： 1172-1180.
	王玉强，沈宇，钱进，等. 不同形态氮肥对紫花苜蓿生长、硝酸盐转运蛋白基因MtNRT1.3表达及氮吸收的影响. 草地学报， 2019， 27（5）： 1172-1180.
19	Husson O. Redox potential （Eh） and pH as drivers of soil/plant/microorganism systems： A transdisciplinary overview pointing to integrative opportunities for agronomy. Plant and Soil， 2013， 362（1）： 389-417.
20	Bailey-serres J， Parker J E， Ainsworth E A， et al. Genetic strategies for improving crop yields. Nature， 2019， 575（7781）： 109-118.
21	Welschmeyer N A， Lorenzen C J. Chlorophyll-specific photosynthesis and quantum efficiency at subsaturating light intensities. Journal of Phycology， 2010， 17（4）： 283-293.
22	Kumari S. Effects of nitrogen levels on anatomy， growth， and chlorophyll content in sunflower （Helianthus annuus L.） leaves. Journal of Agricultural Science， 2017， 9（8）： 208-219.
23	Wang X， Cai J， Zhou Q， et al. Physiological mechanisms of abiotic stress priming induced the crops stress tolerance： A review. Scientia Agricultura Sinica， 2021， 54（11）： 2287-2301.
	王笑，蔡剑，周琴，等. 非生物逆境锻炼提高作物耐逆性的生理机制研究进展. 中国农业科学， 2021， 54（11）： 2287-2301.
24	Han Q F， Jia Z K， Wang J P， et al. Study on diurnal photosynthesis characteristics in different alfalfa leaf layers in Loess Plateau. Acta Agrestia Sinica， 2009， 17（5）： 558-563.
	韩清芳，贾志宽，王俊鹏，等. 黄土高原地区紫花苜蓿不同叶位光合日变化特征研究. 草地学报， 2009， 17（5）： 558-563.
25	Hu S L， Wan S M， Jia Z K， et al. A study on photosynthetic characteristics of alfalfas grown for different lengths of time in the semi-humid area of the Loess Plateau. Acta Prataculturae Sinica， 2008， 17（5）： 60-67.
	胡守林，万素梅，贾志宽，等. 黄土高原半湿润区不同生长年限苜蓿叶片光合性能研究. 草业学报， 2008， 17（5）： 60-67.
26	Mang L， Bao Y T G T， Bu R Q Q G， et al. Diurnal dynamics of photosynthetic and transpiration rates of Medicago falcata L. and their relationships with environmental factors. Acta Agrestia Sinica， 2010， 18（2）： 195-198.
	茫来，宝音陶格涛，布仁其其格，等. 黄花苜蓿光合蒸腾日变化特征及其与环境因子的关系. 草地学报， 2010， 18（2）： 195-198.
27	Flexas J， Carriquí M， Coopman R E， et al. Stomatal and mesophyll conductances to CO₂ in different plant groups： Underrated factors for predicting leaf photosynthesis responses to climate change？ Plant Science， 2014， 226（9）： 41-48.
28	Li J X， Wang W P， Hu Z J， et al. Effects of simulated acid rain conditions on plant photosynthesis and disease susceptibility in tomato and its alleviation of brassinosteroid. Scientia Agricultura Sinica， 2021， 54（8）： 1728-1738.
	李建鑫，王文平，胡璋健，等. 模拟酸雨对番茄光合作用和病害发生的影响及油菜素内酯对其缓解效应. 中国农业科学， 2021， 54（8）： 1728-1738.
29	Zhang J S， Jia Y H， Sun P， et al. Effect of uniform pattern and N application rate on colony， photosynthesis and dry matter accumulation of winter wheat. Journal of China Agricultural University， 2021， 26（7）： 12-24.
	张金汕，贾永红，孙鹏，等. 匀播和施氮量对冬小麦群体、光合及干物质积累的影响. 中国农业大学学报， 2021， 26（7）： 12-24.
30	Zhu T Q， Liu X J， Hao F. Photosynthetic responses of alfalfa leaves to nitrogen. Grassland and Turf， 2017， 37（6）： 31-35.
	朱天琦，刘晓静，郝凤. 2个紫花苜蓿品种叶片对氮的光合响应. 草原与草坪， 2017， 37（6）： 31-35.
31	Wang J， Zhang Y， Huang C Z， et al. Effects of different mulching on soil water-heat and spring maize yield in newly reclaimed land. Chinese Journal of Eco-Agriculture， 2021， 29（5）： 844-854.
	王娟，张瑜，黄成真，等. 不同覆盖方式对新复垦区土壤水热及春玉米产量的影响. 中国生态农业学报， 2021， 29（5）： 844-854.

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