Nutrient deficiencies under stress in legumes: An overview - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 53

Chapter 3

Nutrient deficiencies under stress
in legumes: An overview

Fakiha Afzal 1 , Tahira Khan 1 , Ammarah Khan 1 , Saifullah Khan 1 , Hammad Raza 1 , Ayesha Ihsan 1 ,
Mohammad Abass Ahanger 2 and Alvina Gul Kazi 1
1 Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology (NUST), Islamabad, Pakistan
2 School of Studies in Botany, Jiwaji University, Gwalior, India

3.1 Introduction

In the continuously varying environment, plants
are exposed to numerous environmental fluctuations
that alter every physiological process and biochemical
pathway. 'Stress' refers to any environmental condition
that affects normal plant growth, metabolism and
development. Stress factors may be from natural sources
such as temperature, high irradiance (photo-inhibition,
photo-oxidation), osmotic imbalance, flooding, mineral
deficiency or pest attack, or be anthropogenic (i.e., due
to human activities). Plants need to cope with these
stresses in order to ensure their survival. Global envi-
ronmental changes are causing a rise in temperature
that will lead to floods, melting ice caps, and variability
and unpredictability of rainfall and drought. Surface
water scarcity will lead to the utility of groundwater
that is not safe. This will contribute towards the increase
in salinity of soil and will have a negative impact on
crops. In this regard, legumes will be affected the most
because of their sensitivity.
The minerals needed by plants are categorized into
two groups on the basis of their quantitative require-
ments. Macronutrients include six elements (N, P, K,
S, Mg and Ca) and are found as major components of
the plant tissues (George et al., 2008). Micronutrients
usually work as regulators of different metabolic
processes and the enzymes involved in efficient
running of these processes. Many different factors like
temperature, water availability, pH and mineral defi-
ciency can affect the nitrogen-fixing ability of the
legumes.

Legumes are a diverse and biologically significant group
of plants belonging to the family Fabaceae encompass-
ing about 18,000 to 19,000 species in about 650-750
genera. They are second only to the Gramineae in their
value to humans (Bouchenak & Lamri-Senhadji, 2013).
Various legumes such as alfalfa, peanuts, peas, green
beans, soybeans, dry beans, dry peas, chickpeas, broad
beans, lentils and many others represent an important
component of human diets in several areas of the world
and are a principal source of protein for many. In
addition, because of their nitrogen-fixing capability in
association with soil bacteria they add to soil fertility
and hence help crop growth as well as yield. Many
pharmacological products are derived from legumes.
The presence of many bioactive compounds including
saponins, oligosaccharides, lectins, phytoestrogens and
phenolic compounds which have significant physiological
and metabolic roles in humans, is well documented
(Vavilov, 1995; Postgate, 1998).
Proper mineral supplementation is one of the
essential and basic strategies for ensuring proper
growth, development and yield in crop plants.
Nutritional deficiency in plants leads to a number of
physiological, biochemical and molecular changes
such as stunted growth, necrosis, synthesis and
accumulation of protective compounds, and changes
in expression of genes responsible for crop performance
(Ahanger et al., 2014).