Initial development of cowpea plants under salt stress and phosphate fertilization

Francisco Vanies Da Silva Sá,Miguel Ferreira Neto,Hans Raj Gheyi,Nildo Da Silva Dias,Emanoela Pereira De Paiva,Yuri Bezerra De Lima

doi:10.4136/ambi-agua.2070

Francisco Vanies Da Silva Sá, Miguel Ferreira Neto + Show 4 more

Open Access

https://doi.org/10.4136/ambi-agua.2070

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Abstract

The objective of this work was to study the effects of irrigation with saline water associated with phosphate fertilization on the emergence and early growth of cowpea plants. The assay was conducted in the greenhouse of the Department of Environmental Sciences and Technology of the Federal Rural University of the Semi-Arid (UFERSA) in Mossoró-RN, during October and November of 2015. The study adopted a randomized block with treatments arranged in a 5 x 3 grid, corresponding to five levels of water salinity (0.5, 1.5, 2.5, 3.5 and 4.5 dS m-1) and three doses of superphosphate, based upon the soil analysis (60%, 100% and 140% of the recommended dose for the crop 60 kg P2O5 ha-1), with five repetitions. The cowpea plants, cv. Paulistinha, were grown in lysimeters with capacity of 8 dm3. During the first 15 days of the initial stage of development the plants were evaluated for emergence, growth and biomass accumulation. The increase in water salinity above 1.5 dSm-1 reduced the emergence, growth and dry matter accumulation of cowpea plants. The increase of 40% in the recommendation of phosphorus fertilization of cowpea increased the growth and biomass accumulation of shoot plants, regardless of salinity.

Highlights

Cowpea, Vigna unguiculata (L.) Walp., is a socioeconomically important crop in Brazil, supplementing food supplies and employing farm workers, especially in the North and Northeast regions (Rocha et al, 2009)
Irrigation water salinity affected the emergence of cowpea plants, with reductions of 21.1% in the emergence of plants cultivated at the lowest salinity level (0.5 dS m-1) in comparison to those at the highest level (4.5 dS m-1) (Figure 1A)
For mean time of emergence (MTE), there was an increment in the time required for total emergence, so that plants irrigated with high saline level (4.5 dS m-1) required 12.4% more time to emerge, in relation to the control (0.5 dS m-1) (Figure 1B)

Summary

Introduction

Vigna unguiculata (L.) Walp., is a socioeconomically important crop in Brazil, supplementing food supplies and employing farm workers, especially in the North and Northeast regions (Rocha et al, 2009). The Northeast is the main producing region, accounting for 90% of the Brazilian cowpea crop (Bezerra et al, 2010), the limited availability of water, in the northeastern semi-arid portion, means the crops must be irrigated to achieve satisfactory yields. The high sensitivity of cowpea plants to water deficiencies in the soil, combined with differing amounts of variations in rainfall in different years and cultivation areas, causes great variations in the annual yields of this crop (Mousinho et al, 2008). Inadequate irrigation management increases the salt content of the soil, promoting its salinization, which in turn reduces the capacity of plants to absorb water, causing metabolic alterations identical to those caused by water stress (Munns and Tester, 2008). Inadequate irrigation has indirect effects such as toxicity by specific ions, for example, salts of sodium and chlorine (Syvertsen and Garcia-Sanchez, 2014)

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