Effects of Salt Stress on Plant Growth, Nutrient Partitioning, Chlorophyll Content, Leaf Relative Water Content, Accumulation of Osmolytes and Antioxidant Compounds in Pepper (Capsicum annuum L.) Cultivars

Mathias J Hand,Tekam L Meguekam,Alphonse E Nouck,Emmanuel Youmbi,Brice Tonfack,Victor D Taffouo,Kitio P.J Nyemene

doi:10.15835/nbha45210928

Abstract

The salinity of soil is among the most important abiotic stresses which limit agricultural productivity worldwide. The effects of salinity on growth, nutrient partitioning, chlorophyll, leaf relative water content, osmolytes accumulation and antioxidant compounds of pepper (Capsicum annuum L.) cultivars (‘Granada’, ‘Goliath’ and ‘Nobili’), widely used in Cameroon, were investigated. Plants were subjected to four levels of NaCl (0, 50, 100 and 200 mM) at early seedling growth stage of plant development. Application of NaCl treatment led to a significant increase in total soluble sugars, proline; soluble proteins; total free amino acids content, peroxydase and superoxide dismutase activity and total phenolic content in salt-tolerant ‘Granada’ and ‘Nobili’ compared to salt-sensitive ‘Goliath’ and untreated plants, on the contrary, decreased in root dry weight, shoot dry weight, number of leaves, shoot length, stem diameter, total leaf area, chlorophyll and leaf relative water content in ‘Goliath’ at low salinity level. Flavonoid content, K, Ca and Mg concentrations were significantly reduced with increasing salinity in all cultivars. The highest Na concentrations were detected in the leaves while the lowest were recorded in the roots of ‘Goliath’ at high salinity level. The salt sensitivity of ‘Goliath’ seems to be increased osmotic adjustment through the strongly accumulation of Na in leaves while the salt tolerance of ‘Granada’ was related to its induce of antioxidative enzyme system more efficiently, resulting in higher osmolytes accumulation under salinity. ‘Granada’ was more tolerant and stable in physiological and biochemical traits suggesting that it could be grown in salt-affected soils.

Highlights

Salinity is a major environmental factor determining plant productivity in most arid and semi-arid areas of the world
Plant growth Pepper growth was estimated by measuring RDW, SDW, SL, SD, NL and TLA of three cultivars plants under four NaCl concentrations at vegetative stage (42 DAP)
The main effect of NaCl on plant growth parameters was that plants of ‘Granada’ and ‘Nobili’ under 50 mM NaCl remained almost unaffected for SDW, SL, NL and TLA and presented significantly increased values for RDW and SD as compared to those of untreated plants while the main effect of the cultivar on the majority of growth parameters determined was that ‘Goliath’ was negatively affected by NaCl treatment and presented significantly lower values compared to ‘Granada’ whereas ‘Nobili’ showed intermediate ones

Summary

Introduction

Salinity is a major environmental factor determining plant productivity in most arid and semi-arid areas of the world. It affects more than 10% of arable land and salinization is rapidly increasing on a global scale, declining average yield for most major crop plants by more than 50% (Bray et al, 2000). Salt stress occurs in areas where soils are naturally over salted and precipitation is low and/or where irrigation, hydraulic lifting of salty underground water, or invasion of sea water in coastal areas brings salt to the surface soil that inhabit plants (Neumann, 1995). Received in revised form: 20 Jul 2017.

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