6th Global Summit on Plant Science
Universidade José do Rosário Vellano, Brazil
Title: Differential responses of root system and gas exchange in contrasting tomato genotypes under phosphorus starvation
Biography: Douglas J Marques
Phosphorus (P) is an essential macronutrient for the development of plants. Although it is not always required in larger amounts, its presence is often limited, since the Brazilian and other soils of the world are generally poor in this element. Introduction of tomato plants with greater efficiency in the absorption of phosphorus have been identified. Study conducted by Hochmuth et al., (1985) evaluated more than 200 tomato types (Solanum lycopersicum), with at least two of these introductions being highly efficient in extracting P from the poor-P solution. In one of these introductions (PI 121665 was described as Globonnie cultivar), the efficiency in the extraction of phosphorus was associated with a morphological characteristic in the roots, when this type was cultivated in nutrient solution containing a low content of P. This characteristic, called "cottony root", showed up in simple heritage (a recessive gene, termed crt) and is associated with a large number of roots that can be observed in a microscope after being stained with carmine acetic, when plants are grown in solutions with low content (2 ppm) P, while that this response is not observed when higher concentrations of P (8 ppm) are used. The objective of the research was to evaluate the development of the root system, gas exchange and efficiency in the absorption of phosphorus in contrasting tomato genotypes. The experimental design was a randomized block in the factorial scheme with three tomato genotypes (Globonnie, Tom-598 and F1) and four phosphorus levels (0.2, 30, 60 and 100 mg L-1) with four replications. By evaluating the root morphology, it was observed that the genotype Globonnie produced the highest length, surface area and volume of the root at dose 0.2 mg L-1 of P. For the gaseous exchange there was a higher photosynthetic rate, perspiration and stomatal conductance for Globonnie at the lowest dose of P. For the concentration of P in the leaf and root Globonnie also presented higher content at the dose of 0.2 mg L-1 of P. It was concluded with the research that Globonnie and F1 presented better performances at the dose of 0.2 mg L-1 of P, due to higher root production and gas exchange. Here, we reveal a possible reduction of phosphorus and consequent production costs in tomato agriculture. The Globonnie genotype has the expression of its gene under the conditions of lack of P.