混合盐碱胁迫对燕麦幼苗矿质离子吸收和光合特性的影响

刘建新; 王金成; 王瑞娟; 刘秀丽

Effect of complex saline-alkali stress on the mineral ions absorption and photosynthetic characteristics of oat seedlings

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DOI：10.7606/j.issn.1000-7601.2017.01.27

Key Words: oat complex saline-alkali stress ion absorption and transport photosynthetic parameters chlorophyll fluorescence

Author Name	Affiliation
LIU Jian-xin	College of Life Science and Technology, Longdong University/University Provincial Key Laboratory for Protection and Utilization of Longdong Bio-resources in Gansu Province, Qingyang, Gansu 745000, China
WANG Jin-cheng	College of Life Science and Technology, Longdong University/University Provincial Key Laboratory for Protection and Utilization of Longdong Bio-resources in Gansu Province, Qingyang, Gansu 745000, China
WANG Rui-juan	College of Life Science and Technology, Longdong University/University Provincial Key Laboratory for Protection and Utilization of Longdong Bio-resources in Gansu Province, Qingyang, Gansu 745000, China
LIU Xiu-li	College of Life Science and Technology, Longdong University/University Provincial Key Laboratory for Protection and Utilization of Longdong Bio-resources in Gansu Province, Qingyang, Gansu 745000, China

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Abstract:

In order to reveal the physiological adaptation of a new variety of oat Dingyou 6 to saline-alkali stress, oat seedlings were exposed to 0, 25, 75 mmol·L^-1 of complex saline-alkali stress (molar ratio of NaCl∶Na₂SO₄∶NaHCO₃∶Na₂CO₃=12∶8∶9∶1) in a pot experiment, and then the growth, mineral ions absorption and photosynthetic performance of oat seedlings were measured after the stress treatment for 10 days. The results showed that the dry weight of oat seedlings were not affected under 25 mmol·L^-1 complex saline-alkali stress, while the dry weight of oat seedlings were significantly decreased under 75 mmol·L^-1 complex saline-alkali stress for 10 days. Under 25 mmol·L^-1 complex saline-alkali stress, the K⁺/Na⁺, Ca²⁺/Na⁺ and Mg²⁺/Na⁺ in both roots and shoots of oat seedlings were decreased, and the contents of K⁺, Ca²⁺ and Mg²⁺ selective absorbed by roots from outside and the transport of K⁺ and Ca²⁺ from roots to shoots were increased. Moreover, the Mg²⁺ transport was inhibited, resulting in higher K⁺/Na⁺ and Ca²⁺/Na⁺ but lower Mg²⁺/Na⁺ of shoots than that of roots. Compared to 25 mmol·L^-1 complex saline-alkali stress, the above changes further increased under 75 mmol·L^-1 complex saline-alkali stress significantly. Under 25 mmol·L^-1 complex saline-alkali stress, the content of chlorophyll (a+b) in leaves of oat seedlings was significantly decreased, while chlorophyll a/b ratio and carotenoid content were increased significantly, net photosynthetic rate (Pn), stomatal conductance(Gs), intercellular CO₂ concentration(Ci), transpiration rate(Tr) and stomatal limitation value(Ls) had no significant changes; Compared with 25 mmol·L^-1 complex saline-alkali stress, 75 mmol·L^-1 complex saline-alkali stress significantly reduced the contents of chlorophyll (a+b) and carotenoid, Pn, Gs, Tr, and Ls, but with no significant difference in the chlorophyll a/b ratio. Under 25 mmol·L^-1 complex saline-alkali stress, the maximum fluorescence efficiency (Fv/Fm) and non-photochemical quenching coefficient (NPQ) in leaves of oat seedlings were significantly decreased, while regulated thermal energy dissipation (Φ_NPQ) was increased significantly, the minimal fluorescence (F₀), actual photochemical efficiency (Φ_PSII), photochemical quenching coefficient (qL), non-regulatory energy dissipation (Φ_NO), the deviation from full balance between PSI and PSII (β/α-1), and Hill reaction activity had no significant changes. Compared with 25 mmol·L^-1 complex saline-alkali stress, 75 mmol·L^-1 complex saline-alkali stress significantly improved the F₀, Φ_NO, β/α-1, while decreased Fv/Fm, Φ_PSII, qL, NPQ, Φ_NPQ and Hill reaction activity. Collectively, these results indicated that it was an important mechanism of oat seedlings adapt to the saline-alkali stress that the high values of K⁺/Na⁺ and Ca²⁺/Na⁺ in shoots were maintained by regulating the uptake and transportation of mineral ions, the structure damage in PSII reaction center was main cause for decreasing of photosynthetic rate, dissipation of excessive light energy might be a critical approach for protecting photosynthetic structure in oat seedlings under high concentration of complex saline-alkali stress.