Soil Salt Distribution and Tomato Response to Saline Water Irrigation under Straw Mulching

Smart control of soil water and salt content for improving irrigation management of tomato crop field: Kairouan area

A good assessment of soil water and salt content is required for sustainable irrigation with brackish/saline water. The use of the Internet of Things (IoT) has been initiated for the tomato crop (Savera variety) as part of the PRIMA MEDITOMATO project. An experiment was carried out between February and June 2022 at a farmer's site. For continuous soil water and salt content assessment, TEROS (11/12) probes were implemented at depths of 0, 10, 20, 30, and 60 cm. The data logging process was performed by a ZL6 device and delivered by the ZENTRA Cloud web application (METER GROUPE Company). For the accuracy of the introduced sensors, calibration tests were first processed. Results of the calibration of the probes in the laboratory and in situ showed linear relationships between the humidity values measured by ZL6 (θZL6) and those determined by the gravimetric method, with high correlation coefficients (R2) of 0.86 and 0.96, respectively. There were also strong linear relationships between the ECbulk(ZL6) and the ECe measured on saturated paste extract with high correlation coefficients (R2) of 0.96 and 0.95. Corrected data, according to the determined linear regression equations, present the real-time assessment of soil water and salt content over the entire growth stage of tomatoes. The results of this monitoring showed that soil water content remained close to its status at field capacity (32%) at the beginning of the assessment and increased with the intensification of irrigation, reaching 46 and 54% at 20 and 30 cm, respectively, around mid-April. The salinity level was greater with depth. Indeed, it was low in topsoil with the increase in irrigation frequency and higher at 30 and 60 cm toward the end of the tomato cycle. According to this study, real-time data given by ZENTRA Cloud allows us to adjust irrigation management on time.

Effects of drip tape modes on soil hydrothermal conditions and cotton yield (Gossypium hirsutum L.) under machine-harvest patterns

Background

The layout of drip tapes under mulch has changed in Xinjiang, China, with the development of machine-harvest cotton (Gossypium hirsutum L.) planting technology. This study aims to demonstrate the effects of drip tape modes on soil hydrothermal conditions, cotton yield, and water use efficiency (WUE) of machine-harvest cotton under mulch in Xinjiang.

Methods

A field experiment was conducted to set up two machine-harvest cotton planting patterns (T1: the cotton planting model with one film, two drip tapes and six rows; T2: the cotton planting model with one film, three drip tapes and six rows), and a conventional planting mode (T3: the cotton planting model with one film, two drip tapes and four rows) as a control.

Results

Our results showed that the heat preservation and warming effects of the cotton planting model with one film, two drip tapes and six rows and the cotton planting model with one film, three drip tapes and six rows were better than that of the conventional planting mode. Soil temperature under the mulching film quickly increased and slowly decreased, which was beneficial to the early growth and development of cotton. The mean soil moisture content of the 0–60 cm soil layer in the cotton planting model with one film, three drip tapes and six rows was significantly higher than the other two treatments at the middle and late stage of cotton growth (90 days after sowing (DAS) and 135 DAS). Moreover, the water holding capacity of the middle and upper part of the tillage layer in the cotton planting model with one film, three drip tapes and six rows was the best. At the medium cotton growth stage, the main root layer in the cotton planting model with one film, three drip tapes and six rows formed a desalination zone. At the late cotton growth stage, the soil salinity content of the 0–60 cm soil layer showed that the cotton planting model with one film, three drip tapes and six rows was the lowest, the cotton planting model with one film, two drip tapes and six rows was the highest, and the conventional planting pattern was in the middle. Among these three modes, the cotton planting model with one film, three drip tapes and six rows was more efficient in controlling soil salt accumulation. The agronomic traits and cotton quality in the cotton planting model with one film, three drip tapes and six rows were better than that for the other two treatments. Compared with the other treatments, the cotton yield in the cotton planting model with one film, three drip tapes and six rows increased by 6.15% and 11.0% and 8.1% and 12.3%, in 2017 and 2018, respectively, and WUE increased by 17.4% and 22.7% and 20.9% and 22.8%, in 2017 and 2018 respectively. In conclusion, the cotton planting model with one film, three drip tapes and six rows can be recommended for machine-harvest cotton planting for arid areas in Xinjiang, considering water conservation and improving cotton yield.

A Review on the Beneficial Role of Silicon against Salinity in Non-Accumulator Crops: Tomato as a Model

Salinity is an abiotic stress that affects agriculture by severely impacting crop growth and, consequently, final yield. Considering that sea levels rise at an alarming rate of >3 mm per year, it is clear that salt stress constitutes a top-ranking threat to agriculture. Among the economically important crops that are sensitive to high salinity is tomato (Solanum lycopersicum L.), a cultivar that is more affected by salt stress than its wild counterparts. A strong body of evidence in the literature has proven the beneficial role of the quasi-essential metalloid silicon (Si), which increases the vigor and protects plants against (a)biotic stresses. This protection is realized by precipitating in the cell walls as opaline silica that constitutes a mechanical barrier to the entry of phytopathogens. With respect to Si accumulation, tomato is classified as a non-accumulator (an excluder), similarly to other members of the nightshade family, such as tobacco. Despite the low capacity of accumulating Si, when supplied to tomato plants, the metalloid improves growth under (a)biotic stress conditions, e.g., by enhancing the yield of fruits or by improving vegetative growth through the modulation of physiological parameters. In light of the benefits of Si in crop protection, the available literature data on the effects of this metalloid in mitigating salt stress in tomato are reviewed with a perspective on its use as a biostimulant, boosting the production of fruits as well as their post-harvest stability.