盐生植物营养是盐生植物研究领域中的一个重要课题，其中氮素营养显得尤为重要，因为氮是植物生长发育必不可少的的营养元素，是植物体内蛋白质、核酸、酶、内源激素及叶绿素的组成成分。另外，氮化合物是一种适宜的溶质，存在于植物体细胞的液泡、细胞质、基质等各部位，是植物体内重要的渗透剂，在逆境下对植物有明显的渗透调节作用，对植物的生长发育和逆境的适应有极其重要的作用。
氮素缺乏可能是盐碱地区植物生长的主要限制因素之一，因此，在盐碱地区施加氮有利于提高一年生盐生植物对盐胁迫的抵抗能力。盐胁迫下增加氮素营养提高植物耐盐性的研究，以植物地上部分的较多。植物最先感受逆境胁迫的器官是根系。逆境胁迫下根系形态上的变化是最为直观的，但根系却是最不被人们了解的植物器官。根系的形态特征在决定植物对氮的吸收方面起着重要作用，而有关盐生植物根系的研究相对较少，究其原因是对根系的作用和功能的认识不足，以至于对盐生植物根系的认识滞后于地上部。
中科院新疆生态与地理研究所原俊凤博士以盐生植物的根系发育和形态变化为切入点，研究了盐生植物囊果碱蓬（Suaeda physophora）的离子吸收、氮的累积与根系的关系。研究发现，盐胁迫下硝态氮对囊果碱蓬根系的生长的促进作用显着大于地上部，导致根冠比的增大。这一研究结果与大部分非盐生植物根系对氮的反应不同，相对于地上部生长而言，高氮通常导致非盐生植物的根系生长降低，引起根冠比的降低。为了有效地利用有限的资源，高等植物的生长方式体现出“经济法则”，即光合作用产生的生物量有效地在根系和地上部分配。因此，高盐下增加硝态氮营养促进囊果碱蓬的侧根发育，导致根冠比增加，使植物根系获得更多的养分和水分，可能是囊果碱蓬提高耐盐能力的一种适应策略。（生物谷Bioon.com）
生物谷推荐原文出处：
Pedosphere doi:10.1016/S1002-0160(10)60043-4
Effect of Nitrate on Root Development and Nitrogen Uptake of Suaeda physophora Under NaCl Salinity
Jun-Feng YUANa, b, Gu FENGc, Hai-Yan MAa, b and Chang-Yan TIANa, ,
a Key Laboratory of Oasis Ecology and Desert Environment, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011 (China)
b Graduate University of Chinese Academy of Sciences, Beijing 100049 (China)
c College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China)
The effects of NaCl salinity and NO?3 on growth, root morphology, and nitrogen uptake of a halophyte Suaeda physophora were evaluated in a factorial experiment with four concentrations of NaCl (1, 150, 300, and 450 mmol L?1) and three NO?3 levels (0.05, 5, and 10 mmol L?1) in solution culture for 30 d. Addition of NO?3 at 10 mmol ?1 significantly improved the shoot (P < 0.001) and root (P < 0.001) growth and the promotive effect of NO?3 was more pronounced on root dry weight despite the high NaCl concentration in the culture solution, leading to a significant increase in the root:shoot ratio (P < 0.01). Lateral root length, but not primary root length, considerably increased with increasing NaCl salinity and NO?3 levels (P < 0.001), implying that Na+ and NO?3 in the culture solution simultaneously stimulated lateral root growth. Concentrations of Na+ in plant tissues were also significantly increased by higher NaCl treatments (P < 0.001). At 10 mmol L?1 NO?3, the concentrations of NO?3 and total nitrogen and nitrate reductase activities in the roots were remarkably reduced by increasing salinity (P < 0.001), but were unaffected in the shoots. The results indicated that the fine lateral root development and effective nitrogen uptake of the shoots might contribute to high salt tolerance of S. physophora under adequate NO-3 supply.
