摘要:柽柳是滨海重盐碱地改良与景观绿化和固碳(C)的重要树种, 春季灌溉咸水被认为是快速缓解柽柳干旱与盐胁迫的有效措施。针对滨海重盐碱地土壤缺氮(N)、贫磷(P)、干旱与盐胁迫的突出问题, 以促进柽柳固碳排盐、快速生长、改良盐碱地为目标, 围绕利用当地咸水资源缓解春季干旱与返盐双重危害的核心问题开展研究。在华北低平原区的滨海重盐碱地布设了为期4年的咸水灌溉与施肥的2因素定位试验。试验设不灌水和灌溉地下咸水(盐分为8.02~9.34 g?L?1, W)条件下的不施肥(CK、WCK), 单施氮(N、WN)和施氮磷(NP、WNP)共6个处理。研究结果表明: 柽柳的生长与蘖枝萌发主要发生在春—夏季, 长高、增粗与分蘖同期但不同步, 株高的生长速率呈斜坡状下降, 分蘖速率呈先升后降的趋势, 6月达最高峰; 柽柳基茎增粗的速率先快后慢。首次灌溉咸水极显著地降低柽柳植株含水率、植株鲜重与叶干重, 但不影响茎干重; 连续3年灌溉咸水抑制柽柳长高与增粗, 降低茎杆与叶片的N含量, 但叶片P含量平均提高11.8%, 柽柳的分蘖率显著提高。灌溉咸水条件下施氮磷肥(WNP)能减缓春—夏季(5—6月)柽柳长高与增粗速率的下降, 加速蘖枝萌发, 提高叶片N、K含量, 促进Ca2+和Mg2+由茎杆向叶片转移, 改变Ca2+、Mg2+离子在茎叶的分布。灌溉咸水条件下WNP处理可通过加速分蘖、促进养分吸收和盐基离子运输来缓解连续灌咸水抑制柽柳生长的负面影响。研究结果可为重盐碱地柽柳的合理灌溉咸水和科学施肥提供依据。
关键词:柽柳/
生长节率/
灌溉咸水/
NP营养/
咸水耦合施肥/
离子
Abstract:Saline irrigation is a highly effective method of elimination of salt and drought stress in spring in the coastal severe saline-alkali soils. Tamarix chinensis, a salt-tolerant plant, plays an important role in reforming the ecological landscape of the coastal wetlands in northern China. However, the responses of plant growing rhythm of T. chinensis to long-term saline irrigation-associated fertilization remain unclear. To promote the rapid growth of T. chinensis for carbon (C) fixation, landscape construction, and saline-alkali soils reclamation, an experiment involving irrigation with local phreatic saline resources and application of nitrogen (N) and phosphorus (P) was conducted to alleviate spring drought and salt stresses, and solve the prominent problems of soil N and P deficiencies in the coastal severe saline-alkali soil. The experiment was consisted of two factors of saline irrigation and N and P fertilization over a four-year period in the coastal saline-alkali soil in the low plain of North China. Six treatments included no fertilizer as control (CK, WCK), only applying N (N, WN), applying both N and P (NP, WNP), each corresponding to no irrigation (the first) and irrigation with local phreatic saline water containing 8.02?9.34 g?L?1 salt (the second), respectively. The results showed that the growth and resprouting of T. chinensis occurred mainly in spring till to summer, but plant height and diameter increase and resprouting did not synchronized simultaneously. The trends of rates of plant height growing, resporuting and stem diameter thickening of T. chinensis during the growth season were as sloping shapes, triangle, and up fast following down slowly, respectively. In the first year of saline irrigation, soil water content, fresh weight of plant and leaf dry weight of T. chinensis was reduced significantly (P<0.01); but the stem dry weight was not impacted. However, after three-year saline water irrigation, the plant height and diameter growth was inhibited, the N content of stem and leaf were decreased significantly (P<0.05), but the P content of leaf increased by 11.8% on average, and branch numbers of T. chinensis increased significantly (P<0.05). The WNP treatment, i.e. saline irrigation and applying NP, retarded the decline of growth rate of plant height and stem diamter during spring to summer (May?June), not only accelerated the resprouting rate, but also increased the N and K contents of leaves, and promoted the transfer of Ca2+ and Mg2+ from stem to leaves, which resulted in a distribution change of ion in stem and leaf. WNP can alleviated the negative effect of continuous saline irrigation on the growth of T. chinensis by accelerating resprouting, promoting nutrient absorption and ion transport. The results provides a support for rational saline water irrigation and fertilization for T. chinensis in the costal serious saline-alkali soil.
Key words:Tamarix chinensis/
Growth rhythm/
Saline irrigation/
Nitrogen and phosphorus nutrients/
Saline irrigation-associated fertilization/
Ion
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