EFFECT OF POTASSIUM SUPPLY ON THE BEHAVIOUR OF TWO PROCESSING TOMATO CULTIVARS AND ON THE CHANGES OF FRUIT TECHNOLOGICAL CHARACTERISTICS

The effect of three levels of potassium (K) supply on the yield components and the technological traits of two processing tomato cultivars (Lycopersicon esculentum Mill.) were studied in Algeria during two seasons in open field with a factorial and randomized design. The plants were grown in loamy soil poor in organic matter (1.18%) and in K (75 ppm K₂O). Numerous variables were measured over time and mainly at harvest: the number of stems, stem diameter at collar level, plant height, number of flowers, total number of fruit, mean fruit weight, fruit size of fruit, pH of fruit juice, acidity of fruit juice, vitamin C, brix and the concentration of lycopene pigment. The main registered results have shown that total fruit weight per plant, mean fruit weight per plant, total number of flowers, total number of fruit were positively affected by potassium fertilization. Moreover, fruit juice acidity and fruit juice refractive index were positively affected by potassium fertilization while juice pH was not affected. However, the number of stems per plant, the mean stem diameter at collar level as well as the plant height and total bunch number were positively affected by potassium fertilization. One level of potassium fertilization seemed to positively influence fruit juice vitamin C content and acidity. Results about lycopene concentration seemed to be negatively affected by K fertilization.