Quantitative responses of tomato yield, fruit quality and water use efficiency to soil salinity under different water regimes in Northwest China
Réponses quantitatives du rendement des tomates, de la qualité des fruits et de l'efficience d'utilisation de l'eau à la salinité du sol sous différents régimes hydriques dans le nord-ouest de la Chine
Abstract
Reduced irrigation and high soil salinity are widely recognized to decrease tomato yield, but they can improve
fruit quality and water use efficiency (WUE) when imposed appropriately. However, the response of plant to
their interaction is still unclear, and the quantitative relationship of WUE and fruit quality with salinity under
different water regimes is also lacking. This study investigated the responses of tomatoes in terms of yield, fruit
quality, and WUE based on yield (WUEy), biomass (WUEb), and leaf (iWUE) to twelve treatments, consisting of
combinations of three water regimes relative to the field capacity (FC) (W0, W1, and W2 refer to 95 % FC, 75 %
FC, and 60 % FC, respectively) and four soil salinity levels (0 g, 2 g, 4 g, and 6 g salt mixtures added to 1000 g air-
dried soil, respectively). Results showed that WUEy and WUEb had a negative correlation with salinity under
different water regimes. Salinity resulted in a greater reduction in yield and biomass than water consumption
compared to the control treatment. Therefore, lower water consumption of plants under W2 treatment alleviated
the decrease of WUEy induced by salinity to a certain extent. From the leaf scale, iWUE was positively and
linearly related with salinity, indicating that stomatal regulation was more prone to reduced stomatal conduc-
tance than the net photosynthetic rate under W0 and W1. Whilst it showed a quadratic relationship under W2,
the results supported that a highly salinity-induced iWUE was dependent on water supply. In addition, although
salinity had a negative correlation with fruit fresh mass (FM), dry matter content, and water content (WC) under
W0 and W1, fruit titratable acidity (TA) and total soluble solids (TSS) were proportional to salinity regardless of
water regimes. The results also showed that W1 increased the sensitivity of TA and TSS to salinity, but W2
resulted in weak sensitivity of FM and WC to salinity. Thus, we deduced that mildly reduced irrigation was an
appropriate strategy to regulate iWUE and fruit quality under high salinity conditions. This study provides a
water regime management basis for comprehensive changes in yield, WUE, and fruit quality of tomatoes grown
in saline soils.