Interactive Effects of Organic Fertilizers and Drought Stress on Growth and Nutrient Content of Brassica juncea at Vegetative Stage

Addisie Geremew,Charles Carpenter,Aruna Weerasooriya,Elisha Peace,Selamawit Woldesenbet,Laura Carson

doi:10.3390/su132413948

Abstract

With the ongoing climate change scenario and alarmingly increased land degradation, understanding complex interactions of drought stress and organic fertilizers on morpho-physiological traits and dynamics of nutrient concentration is pivotal for sustainable production leafy vegetables such as mustard (Brassica juncea). Thus, this study evaluated the effect of drought stress and organic fertilizers on B. juncea growth, physiology, and dynamics of nutrient concentration at the vegetative stage. The plants were exposed to three water stress levels (well-watered (100% field capacity, FC), mild (50% FC), and severe (25% FC) supplemented with three organic fertilizers (chitosan, ultra green, and home-grown natural vegetable foods) either individually or in combination during the vegetative growth stage. Water stress had a negative effect on growth and physiological traits, and macro- and micronutrients of mustard. However, the ameliorative effects of fertilizer application were revealed by improved plant height, leaf area, relative water content, membrane stability index, and chlorophyll content from 9.7% to 26.9%, 28% to 32.72%, 7.97% to 39.51%, 7.93% to 39.66%, and 29.68% to 56.53%, respectively. Analysis of variance revealed a significant effect of soil moisture level, fertilizer type and their interaction on content of macronutrients (Ca, K, P, N, C, S, Na, Mg) and micronutrients (Fe, Zn) in mustard leaves. However, there was no significant effect detected for Cu across all factors as well the interaction effect on Mn. Overall, our results indicated that application of organic fertilizers enables mustard plant to withstand the deleterious effect of drought stress, resulting in improved growth and physiological traits as well as leaf nutrient content.

Highlights

This study highlights the deleterious effect of drought on growth and physiological traits and leaf nutrient content of B. juncea at vegetative stage
We found that application of combined organic fertilizers mitigates the adverse effects of drought on the mustard plants synergistically by increasing plant height, leaf area, relative water content, chlorophyll content, membrane stability, and shoot biomass, but not root biomass
The present study showed a significant effect of soil moisture level, fertilizer type, and their interaction on content of macronutrients (Ca, K, P, N, C, S, Na, Mg) and micronutrients (Fe, Zn) in mustard leaves

Summary

Introduction

The species is a remarkable source of several macro- and micronutrients and nutraceuticals which are used to prevent and cure an array of chronic and non-communicable diseases [1,2,3]. Despite these economic and health benefits, low water availability and poor soil fertility during vital stages of its seed germination, growth, flowering, and pod filling severely impact crop yield [4,5,6]. Plant growth and crop productivity may be adversely altered depending on the genotype, plant phenological stage, as well as intensity, timing, and duration of water stress [8,9]

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