Differences in phosphorus absorption and utilization in two tomato (Solanum lycopersicum L.) cultivars

Abstract

Phosphorus (P) deficiency is one of the common nutritional disorders in crop and horticultural plants. Various species and genotypes differ in tolerance to P deficiency. In this research, effects of low P supply were studied in two tomato (Solanum lycopersum L.) cultivars (Behta and Piazar) in hydroponics in order to introduce the most tolerant cultivar to P deficiency. In addition, we studied some involving mechanisms for differences in P deficiency tolerance between the two studied cultivars. Phosphorus deficiency caused reduction of shoot and root dry weight. Growth reduction due to P deficiency was greater in Behta than Piazar. Leaf pigments, chlorophyll fluorescence parameters and net assimilation rate were influenced by P deficiency more pronouncedly in Behta than Piazar. Low P supply caused accumulation of soluble carbohydrates, starch and free amino acids but resulted in reduction of soluble protein concentration. Concentration of P was decreased under low P conditions and relative allocation of P to the leaves, stems and roots were different between two cultivars, being higher for the leaves in Piazar and for the stems in Behta. Concentration of P in the old leaves decreased 58-67% while increased in the young leaves up to 220-350% which reflected the re-translocation of P from the former to the latter leaves. Although cultivars did not differ in the extent of re-translocation, it was higher under low phosphorus compared with adequate P supply. Our results suggested that, different tolerance to P deficiency in the two studied cultivars could be attributed to both differences in P acquisition and internal P use efficiency.

Keywords

• Non-structural carbohydrates
• Photosynthesis
• non
• structural carbohydrates
• Use efficiency
• Acquisition efficiency
• P deficiency
• Tomato