干熱河谷番茄苗期葉片光合效率的土壤水分閾值效應

李建查 閆幫國 潘志賢 張雷 岳學文 何光熊 樊博 史亮濤 方海東

摘 ?要 ?本文以番茄植株為供試材料，采用旱棚盆栽人工給水后自然耗水獲得系列土壤水分梯度的方法，利用Li-6400光合測定系統測定不同水分條件下番茄光合生理特性。通過光合參數與土壤水分回歸分析，結合數學模型求解，研究了番茄苗期葉片光合效率的土壤水分閾值效應。結果表明：番茄葉片凈光合速率（Pn）、蒸騰速率（Tr）、水分利用效率（WUE）及光合參數具有明顯的水分臨界效應。Pn、Tr、WUE和氣孔限制值（Ls）均隨土壤水分的降低先升高后下降，但是各指標水分臨界值表現不同步，其中Tr和Pn的水分飽和點分別為20.68%和18.18%，WUE最高點為15.83%，Ls最高點為10.74%。當土壤含水率低于10.74%，番茄莖和葉片SOD活性均顯著提高。土壤含水率10.74%是番茄葉片光合結構損傷的臨界點，也是干熱河谷番茄苗期生長所允許的土壤水分最大虧缺程度。而土壤含水率15.83%～18.18%為番茄苗期高產高效水含量，此時番茄幼苗葉片具有較高的光合能力和高效生理用水特性，是確保干熱河谷番茄高產高效節水管理的關鍵區間之一。

關鍵詞 ?干熱河谷;番茄;光合特性;土壤水分;閾值效應

中圖分類號 ?Q945.79 ? ? ?文獻標識碼 ?A

Abstract ?Tomato plants were selected as the experimental material. Soil water gradients were obtained by the balances between water provision and consumption in experimental pots in a covered shed. The Li-6400 portable photosynthesis system was used to measure the photosynthetic efficiency parameters under different soil water conditions. It was found that the net photosynthetic rate （Pn）， transpiration rate （Tr）， water use efficiency （WUE） and photosynthetic parameters of tomato leaves had clear thresholds of soil moisture. Pn， Tr， WUE and stomatal limiting value （Ls） first increased and then decreased with decreasing soil water content， but their thresholds were different. The water saturation points of Pn and Tr were 18.18% and 20.68% respectively， the water efficiency point of WUE was 15.83%， and the maximum soil moisture of Ls was 10.74%. SOD activities of tomato roots and leaves increased significantly when soil water moisture was below 10.74%. The soil water of 10.74% was a critical point that the photosynthetic structure of tomato leaves was impaired， and it was also the maximum thershold point of soil water deficit allowed tomato seedling growth in the dry-hot valley. Soil moisture from 15.83% to 18.18% was classified as the intervals of high productivity and high efficiency; in this range， tomato had high photosynthetic capacity and efficient physiological characteristics for water consumption. This range of soil water meets to tomato production with high productivity and high efficiency in the dry-hot valley.

Keywords ?dry-hot valley; tomato; photosynthetic characters; soil moisture; threshold effect

DOI ?10.3969/j.issn.1000-2561.2019.11.025

光合參數是反映植物對逆境生理過程響應的主要指標，通過研究植物光合作用與土壤水分的關系，有助于闡明植物在環境變化中的生理適應性[1-2]。土壤水分是影響植物生理過程和植物分布的重要生態因子，對植物光合作用和水分利用效率的影響較大[3-5]。……