鹽磷脅迫對木麻黃和臺灣相思種子萌發及幼苗生長的影響

袁鋒 羅倩 夏心慧 潘國營 李茂瑾 江傳陽 蘇親桂 陳燦

摘 要：惡劣環境下，人工海防林因面臨養分脅迫而經營困難。為探討鹽、磷脅迫對主要海防林樹種木麻黃和臺灣相思種子萌發及生長的影響，該研究分別用不同濃度的NaCl（鹽）和KH2PO4（磷）溶液處理種子和澆灌幼苗，測定種子萌發和幼苗生長指標。結果表明：（1）高鹽脅迫顯著抑制種子萌發，對幼苗生長有一定影響，但兩種植物影響程度不同；臺灣相思種子萌發耐鹽性高于木麻黃，前者相對鹽害率最大值為23.03%，后者為89.15%；隨著鹽濃度增加，木麻黃和臺灣相思種子的發芽率、發芽勢、發芽指數和活力指數均降低，對應最大值分別為38.70%、34.67%、18.70、0.055和76.67%、62.22%、48.46、6.11。（2）兩種植物的株高和根長隨鹽濃度增加而降低，木麻黃和臺灣相思株高分別為12.29～6.01 mm和48.27～17.33 mm，根長分別為8.57～1.45 mm和33.41～5.88 mm；臺灣相思根、莖、葉生物量及根冠比均隨鹽濃度的增加逐漸減小，木麻黃各處理差異較小。 （3） 臺灣相思的種子和幼苗較木麻黃更耐低磷環境，二者最適磷濃度存在差異；木麻黃種子發芽率（49.33%）、發芽指數（23.12 %）、活力指數（0.093）及根莖葉生物量最大值均在0.1 mmol·L－1磷處理；臺灣相思種子發芽率（81.11%）、發芽勢（62.22%）、發芽指數（38.23）、活力指數（5.07）、株高（54.48 mm）及根長（37.16 mm）最大值均在5 mmol·L－1磷處理，10 mmol·L－1磷處理抑制其萌發。因此，播種海防林種子或種植幼苗時須根據土壤鹽和磷的含量選擇播種或種植方式。

關鍵詞： 養分脅迫， 木麻黃， 臺灣相思， 種子萌發， 幼苗生長

中圖分類號：Q945

文獻標識碼：A

文章編號：1000－3142（2023）04－0587－09

Abstract：Artificial coastal protection forests are difficult to manage because ofnutrient stress in harsh environment. To explore the effects of salt and phosphorus stress on the seed germination and seedling growth of Casuarina equisetifolia and Acacia confusa， we respectively watered the seeds and seedlings of the two kinds of plants with the solutions of NaCl （salt） and KH2PO4 （phosphorus） in different concentrations， and then determined their growth indicators， respectively. The results were as follows： （1） High salt concentration solutions significantly inhibited seed germination and had a certain effect on the growth of seedlings， however， the effects of salt stress on seed gemination and growth were different. The salt tolerance of Acacia confusa seed germination was higher than that of Casuarina equisetifolia. The biggest relative salt damage rate of Acacia confusa was 23.03% and that of Casuarina equisetifoliawas 89.15%. As the concentration of NaCl increased， the germination rate， germination potential， germination index and vitality index of Casuarina equisetifolia and Acacia confusa seeds decreased. And the maximums of the four germination indexes of Casuarina equisetifolia seed were 38.70%， 34.67%， 18.70 and 0.055， and of Acacia confusa seeds were 76.67%， 62.22%， 48.46 and 6.11， respectively. （2） The height and root length of the plants decreased with the increase of salt concentration. The plant heights of Casuarina equisetifolia and Acacia confusa were 12.29 to 6.01 mm and 48.27 to 17.33 mm， and the root lengths were 8.57 to 1.45 mm and 33.41 to 5.88 mm， respectively. The biomass of root， stem and leaf as well as rootshoot ratio of Acacia confusa gradually decreased with the increase of salt concentration， but the differences between the treatments of Casuarina equisetifolia were not obvious. 0.6% and 0.4% salt stress were the thresholds for seed germination and seedling growth of the two plants， respectively. （3）The seed and seedling of Acacia confusa were more tolerant to low－phosphorus environment than Casuarina equisetifolia， and there was a difference in the optimum phosphorus concentration between the two. When the phosphorus concentration was 0.1 mmol·L－1， the seed germination rate（49.33%）， germination index （23.12%） and vitality index（0.093） of Casuarina equisetifolia， as well as the biomass of root， stem and leaf， all reached the maximum. In the 5 mmol·L－1 treatment， the maximums of germination rate（81.11%）， germination potential（62.22%）， gemination index（38.23）， vitality index（5.07）， plant height （54.48 mm） and root length （37.16 mm） of Acacia confusa seeds all appeared， while their germination was inhibited in the treatment of 10 mmol·L－1. Therefore， when sowing the seed of coastal defense forest or planting its seedling， the sowing or planting mode must be selected according to the soil salt and phosphorus contents.

Key words： nutrient stress， Casuarina equisetifolia， Acacia confusa， seed germination， seedling growth

種子順利萌發、成苗是植物能否完成生活史的前提，除受種子自身大小、質量等因素影響外，還受制于土壤養分等環境因素（Rajjou et al.，2012）?！?br>