土壤水分胁迫对设施番茄根系及地上部生长的影响

The effects of soil moisture stress on the growth of root and above-ground parts of greenhouse tomato crops

为了研究土壤水分胁迫对番茄生长的影响,以番茄‘金粉2号’(Jingfen 2)品种为试材,于2013年5—8月间在南京信息工程大学可控试验温室设计正常灌溉(T1)、轻度胁迫(T2)、中度胁迫(T3)、重度胁迫(T4)4个土壤水分处理,观测不同处理番茄植株根系及地上部分的生长状况。结果表明:不同处理的番茄根系生长指标(根系总长度、总表面积、总平均直径、根尖数)的最大值均表现为:T2>T3>T1>T4,比较峰值发现,T2、T3和T4的根系总长度分别为T1的1.8、1.0和0.4倍,总表面积分别为T1的2.3、1.1和0.4倍,总平均直径分别为T1的1.3、1.1和0.6倍,根尖数分别为T1的1.1、1.0和0.5倍;T1、T2和T3处理的番茄根系均集中分布在5—10 cm土层内,而在T4处理下根系集中分布在15—25 cm土层内;番茄的株高、茎粗和叶面积指数大小表现为:T1>T2>T3>T4,T2、T3和T4的番茄株高分别比T1下降11.49%、28.6%和43.98%,茎粗以T4处理最低,为T1的73.57%,T2、T3和T4的叶面积指数分别为T1的81.33%、64.62%和43.37%,各处理间叶面积指数在5%水平下呈现显著性差异。相关分析表明,番茄地上部分和地下部分各项生长指标与土壤体积含水率呈正相关。研究认为轻度土壤水分胁迫对番茄植株地上部分的生长影响不显著,利于根系生长,中、重度土壤水分胁迫明显抑制了番茄植株地上部分的生长,降低根系在土壤中的分布层,研究为设施番茄水分管理提供科学依据。

Soil moisture plays a key role in determining tomato growth, yield, and quality. Soil moisture directly or indirectly affects the growth and distribution of the root system. Under soil moisture stress, plant water and nutrient uptake depend on root size, morphology, and competition. It is important to study tomato root growth under different soil moisture treatments to optimize water and nutrient utilization efficiency. Previous studies have mostly investigated the physiological and biological effects of soil moisture on tomato fruit, and many studies have discussed certain aspects of individual mechanisms. In this study, the growth of both roots and all above-ground parts of tomato plants under each moisture treatment was observed. Soilmoisture data were combined with whole plant growth status to reveal dynamic changes in tomato roots and above-grounds part in response to soil moisture stress. We used the tomato （Lycopersicon esculentum ） cultivar ＇ Jingfen 2＇ in our experiment, which was performed in a controlled environment greenhouse at the Nanjing University of Information Science and Technology from May to August of 2013. Four soil moisture treatments were applied：normal water supply （T1）, mild water stress （ T2）, moderate water stress （ T3 ）, and severe water stress （T4）. The growth of roots and above-ground parts of tomato plants were observed. Among the four soil moisture treatments, measurements of four root growth parameters （total root length, total root surface area, average root diameter, and number of root tips） were in the following descending order ： T2〉T3〉T1〉T4. Maximum total root length in T2, T3, and T4 was 1.8-, 1.0-, and 0.4-fold that of T1, respectively. Total root surface area in T2, T3, and T4 was 2.3-, 1.1-, and 0.4-fold that of T1, respectively. Average root diameter in T2, T3, and T4 was 1.3-, 1.1-, and 0.6-fold that ofT1, respectively. Root tip number in T2, T3, and T4 was 1.1-, 1.0-, and 0.5-fold that of T1, respectively. In T1, T2, and T3, tomato roots were distributed mainly in the 5--10 cm soil layer, but in T4 most roots were in the 15--25 cm layer. Plant height, stem diameter, and leaf area index （LAI） of tomato plants decreased with increasing soil moisture stress. Compared with T1, plant height in T2, T3, and T4 was reduced by 11.49%, 28.60%, and 43.98%, respectively. The minimum stem diameter was found in T4, which was 73.57% of the tomato stem diameter in T1. LAI differed significantly （P 〈 0.05 ） among soil moisture treatments; LAI in T2, T3, and T4 was 81. 33%, 64.62%, and 43.37%, respectively, of that in T1. Soil moisture was positively correlated with growth indices of root and above-ground parts, and soil moisture content in the 20-cm layer had the highest correlation with root growth indices. The mild water stress treatment （T2） did not significantly affect the growth of above-ground parts, while it benefited root growth. The moderate and severe water stress treatments （T3 and T4） significantly inhibited the growth of above-ground parts and decreased the extent of root distribution in the soil. The results of this study may provide a scientific basis for water management in greenhouse tomato production.