International Journal of Plant and Animal Sciences

International Journal of Plant and Animal Science. Vol. 1 (2), pp. 021-029, April, 2013. © International Scholars Journals

Full length research Paper 

Phosphorus fertilization improves soybean growth under salt stress

Rafael de Souza Miranda* ¹, Viviane Ruppenthal², Lineker Sousa Lopes², Cynthia Fontenele Vieira¹, Virna Braga Marques², Marlos Alves Bezerra³ and Claudivan Feitosa Lacerda⁴

¹Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.

²Departamento de Fitotecnia, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.

³Embrapa Agroindústria Tropical and Instituto Nacional de Ciência e Tecnologia em Salinidade (INCTSal/CNPq), Fortaleza, Ceará, Brazil.

⁴Departamento de Engenharia Agrícola, Instituto Nacional de Ciência e Tecnologia em Salinidade (INCTSal/CNPq), Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.

Accepted 26 December, 2012

Abstract

Soybean is one the most important crop in the world. This crop has expanded its cultivated area for regions with saline soils in several parts of the world. This fact occurs because of the large increase of the soybean productivity in recent decades, in parallel with an increasing demand for food. This work aimed to evaluate the salinity effects on the plant growth, and the interaction of phosphorus fertilization versus irrigation water salinity in soybean plants. The experiment was conducted in a greenhouse using recipients contained 6.0 dm³ of mixture sand and commercial substrate (1:1 v/v). Five salinity levels in the irrigation water (0.8, 2.2, 3.6, 5.0 and 6.4 dS m^-1) and two levels of phosphorus fertilization (0 and 300 mg L^-1) were evaluated. After 36 days, the salt stress promoted reductions in the most of the growth variables, such as stem diameter, plant height, number and average length of branches, root length, shoot and root dry mass, and absolute growth rate. On the other hand, it increased the chlorophyll relative index, chlorophyll a and total content, and shoot/root dry mass ratio. The phosphorus-supplemented plants had higher stem diameter, number of branches, shoot dry mass and absolute growth rate. The salt stress-phosphorus interaction showed that the phosphorus attenuated the salt stress deleterious effects only on leaf area after 5 dS m^-1 of saline water. Soybean plants can be irrigated using water with electrical conductivity up to 1.9 dS m^-1 without disturbing its biomass components. The phosphorus fertilization improves the growth soybean subjected to salt stress but not reduce the salinity deleterious effects.

Key words:  Glycine max, irrigation water, soybean, phosphorus, salinity stress.