EFFECTS OF PARTICLE FILM TECHNOLOGY ON TOMATO UNDER SALINITY STRESS

Irrigated agriculture is dependent on adequate water supply and its quality. Water used for irrigation can vary greatly in quality, depending upon type and quantity of dissolved salts. They originate from dissolution or weathering of the rocks and soils, and by intrusion of seawater into the river and underground water resources. The problem of saltwater intrusion due to groundwater over-exploitation is one of the major threats in the coastal areas of Italy, as occurs in Apulia region, where the chronic water shortage forces farmers to use saline irrigation water. Salinity is detrimental for many crops because of its negative effects on the physiology and production. The salinity tolerance, as well as the genotype, is influenced by several agronomic and environmental parameters as air temperature and relative humidity (RH). Thus, conditions leading to a reduction of transpiration, as lower temperature and higher RH, can contribute to greater tolerance to salinity. Thus, the techniques that reduce the transpiration rate and heat stress of the crops could have a positive effect on salinity tolerance. Among those there is the kaolin-based particle film technology (Pft) that employs a multi-functional, environmentally friendly material effective in pest control, mitigation of heat stress, and to produce fruit and vegetables of good quality. The presence of mineral particles over leaves and fruit surfaces interferes with physiological processes, mainly with heat and radiation balance and gas exchange. Therefore, it was hypothesized that the Pft could contribute to increasing the salt tolerance. In consideration that the tomato, species moderately sensitive to salinity, is a major vegetable crops present in the areas of Apulia at risk of salinity, to verify the hypotheses, was investigated the effects of Pft on yield and quality, and water use efficiency of field grown tomato. The research was carried out in three years on tomato for processing, irrigated with brackish water, in Southern Italy. Treatments were i) three salinity levels of irrigation water (Electrical Conductivity of water = 0.5, 5, and 10 dS m-1), ii) tomato plants treated or not with kaolin, and iii) two cultivars in each year, arranged in a split plot design with three replications. The salinity increase caused the reduction in yield mainly for declining fruit weight, but the fruit quality was better in terms of dry matter content and total soluble solids. In addition, salinity increased the blossom-end rot mainly on cultivar with elongated fruits. Pft, overall, as average of three years, improved total (12.7%) and marketable yield (17.7%), fruit weight (8.1%) and harvest index (10.3%), and reduced fruit sunburn by 76.4%. In addition, kaolin contributed to the declining in insect attack to the fruit (58.7%), improvement in total solid soluble (6.2%) and redness (10.2% the skin and 16.6% the pulp) of fruits, and increased yield water use efficiency (Y_WUE) (19.7%). Furthermore, kaolin mitigated detrimental effects of salinity on yield, through a minor decrease, between the control irrigated with fresh water and the more saline treatment, as average of three years, in total (22.8%) and marketable yield (34.8%), fruit weight (21.1%), biomass water use efficiency (B_WUE) (22.9%) and Y_WUE (34.7%). The use of kaolin-based particle film technology may be an effective tool to alleviate salinity stress in tomato production in Mediterranean environment.