Effects of soil applied and foliar fertilizers on growth, nutrient uptake, yield and quality of tomato (Lycopersicon esculentum Mill. cv. Peto 86) grown on Vertisols of Central Sudan

The Vertisols of central Sudan is known to be deficient in nitrogen, available phosphorus, potassium and some micronutrients. Crops response to added nitrogen and foliar fertilizers was well recognized. However, for tomatoes discrepancy among various reports calls for authentication endeavors. The present study was conducted, therefore, to test the efficiency of different fertilizer types as source of nitrogen and various ratios of two types of foliar fertilizers for tomato production under the conditions of the Vertisols soils of central Sudan. Two sets of trials were conducted in the Gezira Research Station Farm during winter seasons of 2005/06 and 2006/07. The tomato variety 'Peto 86' was sown in the first to the second week of November in the two trials and raised under optimum management conditions. In the first trial plants received either 0 or 86 kg N/ha, supplied as ammonium nitrate (AN), ammonium sulphate (AS), ammonium sulphate nitrate (ASN), NPK (20:20:20+Tr) or urea. The soil added nitrogen was supplemented or not with four foliar sprayings of a compound micronutrients foliar formulation at moderate spraying ratio. For the second trial, three spraying ratios of the compound micronutrient foliar type were compared with similar ratios of a complete foliar formulation in plots receiving 43 kg N/ha as ASN. Results indicated a significant response of tomatoes to added nitrogen and foliar fertilizers for dry matter, total and marketable yields and nutrient uptake. NPK stood out to be the optimum nitrogen source for tomato production in the Vertisols of Central Sudan, followed by ASN and then urea. The higher responses obtained for NPK suggested further investigations in ways and means of applying phosphorus and potassium to tomato in the Vertisols of central Sudan. The erratic response of tomato to the sulphur containing fertilizers (AS and ASN) indicated the importance of soil test for available sulphur before deciding on the nitrogen source to be used for tomato production. The use of compound micronutrients as foliar fertilizers for tomato was justified, and complete foliar fertilizers were proved to supply luxurious macronutrients that cause no harm to the tomatoes. Moderate foliar spraying ratios proved to be the most favorable for optimum tomato yield and high ratios produced more leafy plants at the expense of fruit yield. Fertilizers application within the studied rates and ratios had no effect on tomato nutritional (physiological) disorders or tomato quality except for slight decline in sugars