Induction of Thermotolerant Tomato Plants Using Salicylic Acid and Kinetin Foliar Applications

Abstract

The fruit yield of tomato plant cultivated in summer season where air temperature was exceeded 32°C produce the lowest yield comparing with different growing seasons during the year. This field experiment was carried out to assess the role of foliar applications of kinetin (kin) at 0.05 & 0.1 mM and salicylic acid (SA) at 0.25 & 0.5 mM on ameliorating the deleterious effects of natural heat stress during 2012 and 2013 summer seasons. The both levels of SA significantly increased plant height, plant f.w, branches and leaves no./plant. These positive effects on vegetative growth reflected on enhancing reproductive growth especially for clusters no./plant, fruits no./plant and fruit yield, which directed from the increase in free amino acids and proline. SA at 0.5 mM recorded the lowest value of total phenolics and peroxidase activity while for phenylalanine ammonia-lyse (PAL) was recorded the highest activity. The maximum percentage in fruit set was recorded by kin at 0.1 mM, regardless the lowest value of fruit fresh weight. The highest fruit yield was achieved by SA at 0.5 and 0.25 mM, respectively. Whereas the lowest fruit yield recorded with the application of kin at 0.1 and 0.05 mM, respectively