IMPROVEMENT OF TOMATO PERFORMANCE UNDER LOW TEMPERATURE STRESS USING SOME BIO-STIMULANTS COMPARED WITH LOW TUNNEL SYSTEM

Chilling injury is one of climate change challenges which effect negatively on plant growth of warm season crops. Low temperatures can be overcome by utilization high cost protected cultivation systems such as low tunnels. Open field experiment was conducted in Private farm, located in MansouriaDistrict, at North of Giza Governorate, Egypt during two winter seasons of 2019/ 2020 and 2020/2021 to study the response of tomato cv. Platinum under low temperature conditionsfor foliar spray with: 1) Melatonin (100 μM); 2) acetyl salicylic acid (178 mM); 3) potassium silicate(250 mg/L); 4) the mix between acetyl salicylic acid (178 mM) and potassium silicate(250 mg/L); 5) water (control) compared with low tunnel and their effects on agronomic, quality traits and productivity with using of Auxinapplicationas common agricultural recommendation in winter season.Our results revealed that plants of control showed the highest significant injury index on leavesand percentage of injury. All treatments reduced of injury index and injury %, especially the tunnel and the mix treatment.The mix between acetyl salicylic acid and potassium silicatesignificantly enhanced the agronomic traits such as plant height, number of branches, leaf area, shoot fresh weight and number ofleaves/plants. All cold mitigators significantly decreased of total sugars, proline andtotal phenols, exceptacetyl salicylic acid in total sugars in first season,melatonin in proline in first season and potassium silicate in phenols.The highest lycopene and TSS were recorded in the tunnel and the mix treatment, while the highest Vit C were detected forpotassium silicate and followed by the Mix treatment then the tunnel. Except melatonin application in first season only, all cold alleviating compounds clearly increased fruit set, and total yield. Tunnel in first season only and the mix treatment in both seasons produced the highest significant early yield, total yield and number of fruits/ plants which were higher in fruit set percentage than other treatments. We suggested usingthe Mix treatment as low-cost alternative for low tunnels for tomato production under low temperature condition.