外源褪黑素對高溫脅迫下西瓜幼苗生理特性的影響

劉若溪 曹歌 王琪 張涵洋 李愛

摘? ? 要：西瓜作為重要的園藝經濟作物，在中國各地栽培，品種甚多。高溫是限制西瓜夏季育苗成活率的主要原因之一，為探究外源褪黑素對高溫脅迫下西瓜幼苗生理特性的影響，選用‘北抗1號西瓜為試驗材料，將西瓜幼苗進行常溫、40 ℃高溫脅迫、外施褪黑素后40 ℃高溫脅迫3個處理，測定植株株高、葉長、葉寬、莖節數等形態指標和組織含水量、光合特性、抗氧化酶活性、滲透調節能力等生理生化指標。結果表明：與常溫處理相比，高溫脅迫處理降低了西瓜幼苗的葉長、葉寬、葉片數等形態指標，外源褪黑素能有效緩解高溫對西瓜幼苗生長的抑制作用，與40 ℃高溫脅迫下植株相比，外施褪黑素后西瓜幼苗的光合色素含量增加21.93%，丙二醛含量降低19.38%，超氧化物歧化酶（SOD）活性升高10.20%，過氧化物酶（POD）活性升高18.52%，脯氨酸含量升高25.52%，可溶性蛋白含量升高29.41%。由此可知，外源褪黑素能夠通過改變滲透調節物質含量，增強抗氧化酶活性，抑制膜質過氧化，從而增強西瓜幼苗的抗高溫脅迫能力。

關鍵詞：西瓜；高溫脅迫；褪黑素；生理生長

中圖分類號：S651? ? ? ? ? ? 文獻標志碼：A? ? ? ? ? ?DOI 編碼：10.3969/j.issn.1006－6500.2023.06.002

Abstract： As an important horticultural cash crop， watermelon is cultivated throughout China with a wide range of varieties. High temperature is one of the main reasons limiting the survival rate of watermelon seedlings in summer. To explore the effect of exogenous melatonin on the physiological characteristics of watermelon seedlings under elevated temperature stress，this thesis chose 'Beikang No.1' watermelon as the test material. The watermelon seedlings were subjected to three treatments： normal temperature， high temperature stress at 40 °C and high temperature stress at 40 °C after external melatonin application， and then determined morphological indicators such as plant height， leaf length， leaf width and number of stem nodes， and physiological and biochemical indicators such as tissue water content， photosynthetic properties， antioxidant enzyme activity and osmoregulatory capacity. The results were as follows：? compared with normal temperature treatment， high temperature stress reduced the morphological indexes of watermelon seedlings， such as leaf length， leaf width， leaf number， etc. Exogenous melatonin could effectively alleviate the inhibitory effect of high temperature on the growth of watermelon seedlings， compared with plants under high temperature stress at 40 ℃， the photosynthetic pigment content of watermelon seedlings increased by 21.93% ， the malondialdehyde content decreased by 19.38% ， the superoxide dismutase activity increased by 10.20% ， the peroxidase activity increased by 18.52% ， proline content increased by 25.52% and soluble protein content increased by 29.41% respectively. In conclusion， exogenous melatonin can enhance the resistance of watermelon seedlings to high temperature stress by changing the content of osmoregulatory substances， enhancing the activity of antioxidant enzymes and inhibiting membrane peroxidation.

Key words：watermelon; high temperature stress; melatonin; physiological growth

收稿日期：2023-02-24

基金項目：國家級大學生創新創業訓練計劃項目（202110061008）；國家自然科學基金（31800572）

作者簡介：劉若溪（2001—），女，河南安陽人，在讀本科生，主要從事園藝植物生理和分子生物學研究。

通訊作者簡介：李愛（1984—），女，河北石家莊人，副教授，博士，主要從事園藝植物生理和分子生物學研究。

西瓜（Citrullus lanatus）是葫蘆科西瓜屬一年生蔓生藤本，是一種重要的經濟作物，在中國各地栽培，目前栽培面積已達152.81萬hm2，品種甚多[1]。……