鹽生植物營養(yǎng)是鹽生植物研究領域中的一個重要課題,，其中氮素營養(yǎng)顯得尤為重要,，因為氮是植物生長發(fā)育必不可少的的營養(yǎng)元素,，是植物體內(nèi)蛋白質(zhì),、核酸,、酶、內(nèi)源激素及葉綠素的組成成分,。另外,，氮化合物是一種適宜的溶質(zhì)，存在于植物體細胞的液泡,、細胞質(zhì),、基質(zhì)等各部位，是植物體內(nèi)重要的滲透劑,，在逆境下對植物有明顯的滲透調(diào)節(jié)作用,，對植物的生長發(fā)育和逆境的適應有極其重要的作用。
氮素缺乏可能是鹽堿地區(qū)植物生長的主要限制因素之一,，因此,，在鹽堿地區(qū)施加氮有利于提高一年生鹽生植物對鹽脅迫的抵抗能力。鹽脅迫下增加氮素營養(yǎng)提高植物耐鹽性的研究,，以植物地上部分的較多,。植物最先感受逆境脅迫的器官是根系。逆境脅迫下根系形態(tài)上的變化是最為直觀的,，但根系卻是最不被人們了解的植物器官,。根系的形態(tài)特征在決定植物對氮的吸收方面起著重要作用，而有關鹽生植物根系的研究相對較少，究其原因是對根系的作用和功能的認識不足,，以至于對鹽生植物根系的認識滯后于地上部。
中科院新疆生態(tài)與地理研究所原俊鳳博士以鹽生植物的根系發(fā)育和形態(tài)變化為切入點,，研究了鹽生植物囊果堿蓬（Suaeda physophora）的離子吸收,、氮的累積與根系的關系。研究發(fā)現(xiàn),，鹽脅迫下硝態(tài)氮對囊果堿蓬根系的生長的促進作用顯著大于地上部,，導致根冠比的增大。這一研究結果與大部分非鹽生植物根系對氮的反應不同,，相對于地上部生長而言,，高氮通常導致非鹽生植物的根系生長降低，引起根冠比的降低,。為了有效地利用有限的資源,，高等植物的生長方式體現(xiàn)出“經(jīng)濟法則”，即光合作用產(chǎn)生的生物量有效地在根系和地上部分配,。因此,，高鹽下增加硝態(tài)氮營養(yǎng)促進囊果堿蓬的側(cè)根發(fā)育，導致根冠比增加,，使植物根系獲得更多的養(yǎng)分和水分,，可能是囊果堿蓬提高耐鹽能力的一種適應策略。（生物谷Bioon.com）
生物谷推薦原文出處：
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.
