The Effects of Saline Water Drip Irrigation on Tomato Yield, Quality, and Blossom-End Rot Incidence --- A 3a Case Study in the South of China

Abstract

Saline water resources are abundant in the coastal areas of south China. Most of these resources still have not been effectively utilized. A 3-year study on the effects of saline water irrigation on tomato yield, quality and blossom-end rot (BER) was conducted at different lower limits of soil matric potential (-10 kPa, -20 kPa, -30 kPa, -40 kPa and -50 kPa). Saline water differing in electrical conductivity (EC) (3 dS/m, 4 dS/m, 4.5 dS/m, 5 dS/m and 5.5 dS/m) was supplied to the plant after the seedling establishment. In all three years, irrigation water with 5.5 dS/m salinity reduced the maximum leaf area index (LAIm) and chlorophyll content the most significantly when compared with other salinity treatments. However, compared with the control treatment (CK), a slight increase in LAIm and chlorophyll content was observed with 3~4 dS/m salinity. Saline water improved tomato quality, including fruit density, soluble solid, total acid, vitamin C and the sugar-acid ratio. There was a positive relationship between the overall tomato quality and salinity of irrigation water, as analyzed by principal component analysis (PCA). The tomato yield decreased with increased salinity. The 5.5 dS/m treatment reduced the tomato yield (Yt) by 22.4~31.1%, 12.6~28.0% and 11.7~27.3%, respectively in 2012, 2013 and 2014, compared with CK. Moreover, a significant (P≤0.01) coupling effect of salinity and soil matric potential on Yt was detected. Saline water caused Yt to increase more markedly when the lower limit of soil matric potential was controlled at a relatively lower level. The critical salinity level that produced significant increases in the BERi was 3 dS/m~4 dS/m. Following the increase in BERi under saline water irrigation, marketable tomato yield (Ym) decreased by 8.9%~33.8% in 2012, 5.1%~30.4% in 2013 and 10.1%~32.3% in 2014 compared with CK. In terms of maintaining the Yt and Ym, the salinity of irrigation water should be controlled under 4 dS/m, and the lower limit of soil matric potential should be greater than -20 kPa.

Optimization of irrigation-drainage scheme for tomato crop based on multi-index analysis and projection pursuit model

“…Higher yield was in correspondence with higher irrigation quota, this result agreed with the findings of Zhai et al (2015). The yield-increase effects by drip irrigation were also reported in Ayars's and coauthors (1999) study.…”

“…For each fruit, 10 g of tomato flesh was taken along the longitudinal axis and then homogenized for quality measurements. The following components contributed greatly to the tomato quality: volume, density, soluble solids, total acid, vitamin C and sugar:acid ratio (Zhai et al, 2015). At each harvest time, the number and weight of tomato was recorded, and the tomato yield was calculated at the end of the last harvest.…”

Effect of Water Quality and Deficit Irrigation on Tomatoes Yield and Quality: A Review

“…Zhai et al [12] emphasized as water is an important impact factor influencing yield and quality of tomato and indicated as yield decreased with increased salinity and recommended that salinity of irrigation water should be controlled under 4 dS/m. In addition, Rahil et al and Magan et al [10,13] reported that total and marketable fruit yield reduced with increasing salinity level.…”

Irrigation water quality of River Kulfo and its implication in irrigated agriculture, South West Ethiopia

“…For instance, in the study conducted in China, it was confirmed that irrigation water more than 5 Ds/m significantly affect the fruit yield of tomato (Zhai et al, 2015). The associated effect of salt in irrigation is attributed to decreased turgor pressure, a lowered speed of cell expansion and damage to chloroplasts, thus reducing the growth rate and photosynthesis.…”

“…The use of saline irrigation directly affects the soil profile and the dissolved salts may cause changes in the salt balance of the soil system. Zhai et al (2015) reported that the salt concertation in the soil profile under tomato production was increased by 47% for the use of saline water more than 5 dS/m.…”