Application of biostimulants promotes growth and productivity of heat-stressed tomato (Solanum lycoperosicum) plants.

: Plant biostimulants are natural substances commonly used in recent decades in the agricultural practices primarily for plant defense and to enhance plant growth, yield and quality of tomato plant. This study was conducted to investigate the effect of biostimulants foliar application on growth, productivity, and fruit quality of tomato plants during the summer season of 2020 and 2021. Tomato plants were sprayed twice (at 15 days interval) with biostimulants i.e., date palm pollen grains extract, bee pollen grains extract, chito boom (5% chitosan, 9% B, 1.15% amino acids and 0.05% Mo), algeno plus (50% Potassium alginate, 0.92% Mg, 1.75% S, 0.52 % Fe, 0.25% Mn, 0.15 % Zn, 0.25% B, 0.004 % Mo and 0.73% cytokines), fast tunic (2.5% NAA and 0.6% sodium nitrophenolate), and water as control. The results indicated that date palm pollen and bee pollen extracts significantly increased plant height when compared to control. Bee pollen and algeno plus significantly increased number of branches. These treatments in addition to chito bom, increased leaf area and leaf perimeter. All biostimulants significantly decreased Malondialdehyde (MDA), while they exhibited a significant increase for peroxides, proline and total phenols, total fruit yield, fruit weight per plant and fruit number per plant. Bee pollen and chito bom improved fruit contents of total sugar, beta-carotene, lycopene and these treatments in addition to date palm pollen increased vitamin C and acidity. Bee pollen grains, and date palm pollen grains extracts, chitosan could be recommended to alleviate high temperature stress on tomato plants.