干旱对碧玉杨幼苗水氮利用与同化物分配的影响

doi:10.13866/j.azr.2022.03.22

摘要/Abstract

摘要：

为进一步明确杨树对土壤干旱生理生态响应过程和树种间抗旱策略差异,以盆栽碧玉杨（Populus × euramericana ‘Biyu’）插条苗为试验材料,研究了持续2 a干旱胁迫下碧玉杨叶片光合特性、水氮利用与同化物分配的响应变化。结果表明：（1）干旱下一年生碧玉杨幼苗的叶片变小变厚,气孔导度和蒸腾速率变化不大,净光合速率受到非气孔限制,从而使得瞬时水氮利用效率同时下降。（2）二年生碧玉杨叶片更小更厚且碳氮比增大,而叶氮含量不变,有利于提高叶片抗旱性;干旱下净光合速率略有增加,瞬时水氮利用效率未降低,且中度干旱显著提高了碧玉杨的整株氮利用效率。（3）连续2 a干旱处理下碧玉杨的生长大幅降低,向茎器官分配了更多的干物质和非结构性碳,导致根冠比降低,这可能不利于其根系水氮吸收和整株抗旱性。综上,干旱下碧玉杨幼苗虽然可通过叶片变小以降低蒸腾耗水,并维持较高的叶氮含量,但同时也降低了光合面积导致整株生长大幅降低,且根系同化物分配降低,初步表明碧玉杨抗旱性较差,不适宜在干旱半干旱地区大面积造林。

关键词: 杨树, 干旱, 叶片气体交换, 水氮利用, 同化物分配

Abstract:

The ecophysiological response of poplar to soil drought and drought resistance strategies among species remained unclear. In this study, Populus×euramericana ‘Biyu’ cuttings grown in pots were used as materials. Changes of leaf gas exchanges, water and nitrogen use traits, growth, and carbohydrate allocation among organs under 2-year drought were investigated. Results showed that the leaves of 1-year-old poplar cuttings became smaller but thicker under drought with stable stomatal conductance, and transpiration rate. The net photosynthesis rate decreased by non-stomatal inhibition, and the transient water and nitrogen use efficiency significantly decreased. In the second year, the leaves became even smaller and thicker with a higher carbon and nitrogen ratio. However, leaf nitrogen contents remained unchanged, which could improve leaf drought resistance. The net photosynthesis rate increased slightly, and transient water and nitrogen use efficiency remained stable. Moreover, moderate drought significantly increased whole-plant nitrogen use efficiency. Under a 2-year drought treatment, the growth significantly decreased. More biomass and non-structural carbohydrates allocated into the stem but not in the root system, and the root and shoot ratio became smaller, which are detrimental to the water and nitrogen uptake in the root and whole-plant drought resistance. Therefore, P.× euramericana ‘Biyu’cuttings can reduce water consumption in smaller but thicker leaves under drought, with high leaf nitrogen content, but this response could reduce the leaf area used for photosynthesis, resulting in decreased growth and smaller roots. These results indicated that P.×euramericana ‘Biyu’ has low drought resistance, which is not suitable for large-scale afforestation in arid and semi-arid areas.

Key words: poplar, drought, leaf gas exchanges, water and nitrogen use efficiency, carbohydrate distribution

尚佳州,赵瑜琦,王卫锋,高钿惠,宗毓铮. 干旱对碧玉杨幼苗水氮利用与同化物分配的影响[J]. 干旱区研究, 2022, 39(3): 893-899.

SHANG Jiazhou,ZHAO Yuqi,WANG Weifeng,GAO Tianhui,ZONG Yuzheng. Response of drought on water and nitrogen utilization and carbohydrate distribution of Populus × euramericana ‘Biyu’ cuttings[J]. Arid Zone Research, 2022, 39(3): 893-899.

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指标		2016年			2017年
指标	CK	MS	SS	CK	MS	SS
叶干重/g	17.24±2.03ab	9.33±0.91cd	7.24±0.71d	19.13±1.53a	15.27±2.09b	10.38±2.66c
茎干重/g	36.22±2.24c	25.30±5.34d	22.02±2.24d	54.37±4.94b	63.93±6.41a	40.66±5.38c
根干重/g	46.21±10.01c	24.27±6.95e	16.31±3.12e	83.97±9.54a	59.11±5.89b	36.26±4.24d
植株总干重/g	99.67±10.19c	58.91±11.99e	45.58±4.80f	157.47±10.35a	138.30±9.82b	87.30±10.06d
株高/cm	88.89±12.97c	68.00±5.50d	63.22±12.92d	123.00±6.20a	100.50±4.59b	86.00±5.76c
基径/cm	0.96±0.12d	0.84±0.07d	0.75±0.13d	11.03±0.52a	10.26±0.76b	9.23±0.73c
根冠比	0.87±0.20b	0.70±0.14bc	0.56±0.10c	1.15±0.17a	0.75±0.11b	0.72±0.08bc
单叶面积/cm²	84.95±17.22a	49.26±7.72b	37.52±7.43c	28.84±1.65d	27.39±0.35d	17.56±0.61e
比叶重/(g∙m^-2)	74.47±10.08d	95.91±6.01c	97.19±4.15c	138.26±4.08a	129.98±4.66ab	121.13±3.28b

参数		2016年			2017年
参数	CK	MS	SS	CK	MS	SS
叶碳含量/%	33.35±0.36c	32.77±0.56c	32.74±0.72c	40.25±1.79b	41.44±0.33b	44.15±1.88a
叶氮含量/%	1.61±0.10a	1.38±0.17b	1.48±0.06ab	0.93±0.04d	1.11±0.08c	1.17±0.04c
叶碳氮比	21.30±1.25c	22.92±2.16c	22.16±0.57c	43.36±3.39a	37.34±2.78b	37.82±0.95b
单位叶面积氮含量/(g∙m^-2)	1.20±0.07b	1.33±0.17ab	1.44±0.06a	1.29±0.05ab	1.45±0.07a	1.41±0.03a
光合氮利用效率/(μmol∙g^-1∙s^-1)	10.86±0.53a	6.25±0.69b	4.86±0.21c	5.84±0.25b	5.99±0.31b	6.07±0.14b
整株氮利用效率/(g∙g^-1)	424.68±20.73b	442.01±49.03ab	426.31±18.57b	409.06±74.17b	485.71±46.39a	401.94±64.15b