Abstract
Abiotic stress such as drought and agrochemicals leads the drastic reductions in legume yields, hence, in order to mitigate the loss of yields due to abiotic stresses, the production of stress tolerance genotypes of the legumes could be a rewarding approach. Therefore, the aim of the present study was to evaluate the drought and herbicide stress effects under ex-vitro conditions on seed germination and early seedling growth in a legume crop mung bean (Vigna radiata L.). To begin with, drought stress was induced by employing various concentrations of mannitol (50mM, 100mM, 250mM, 500mM, 750mM, and 1000mM) and polyethylene glycol (PEG-5%, 10%, 15%, 20%, and 25%) while during herbicide stress experiments, dicamba (3,6-dichloro-2-methoxybenzoic acid) and picloram (4-Amino-3,5,6-trichloro-2-pyridine carboxylic acid) were considered in various concentrations (5mg/L, 25mg/L, 50mg/L, and 100mg/L) of each. Moreover, data were collected as partial and full seed germination after 3- and 7-days of stress treatments respectively. After 7-days of mannitol stress treatments, results reveals that even the high concentration of mannitol (500mM) could be proved as weak osmotic stressor for seed germination (35%±0.14) in comparison to control (91%±0.74) while further increase in mannitol concentration (750mM) was proved to be lethal, toxic and inhibits seed germination completely. Furthermore, in comparison to mannitol, PEG turns out as strong osmotic stressors and (15%) of PEG was proved to very lethal for seed germination. Even during early seedling growth, increased concentrations of both mannitol and PEG were found to be inhibitory. Among two herbicides, the result shows that both herbicides (dicamba and picloram) were proved to be completely toxic and lethal even at very low concentrations (5mg/L) and induced abnormal seed germination and inhibited completely seedling growth. However, the inhibitory response of picloram herbicide stress on seed germination was found to be more pronounced and severe than dicamba herbicide. Hence, the present study reveals that in comparison to mannitol, PEG turns out as a strong osmotic stressor while picloram proves to be a relatively more toxic herbicide than dicamba for seed germination. Additionally, drought stress induced seedlings on transfer to soil exhibit inhibited growth under continuous irrigation with either mannitol or PEG solutions.
Highlights
Pulses have been treated as the most cultivated and consumed legumes and some of them such as cowpea (Vigna unguiculata), green gram (Vigna radiata), black gram (Vigna mungo), pigeon pea (Cajanus cajan), lentil (Lens culinaris), and grass pea (Lathyrus sativus) are being grown as alternative staple crops in marginal and harsh areas of the world (Deikman et al, 2012; Araujo et al, 2015)
*Corresponding Author: Vikrant drvikrant@dhtepdy.edu.in; dr.s.vikrant@gmail.com. Abiotic stress such as drought and agrochemicals leads the drastic reductions in legume yields, in order to mitigate the loss of yields due to abiotic stresses, production of stress tolerance genotypes of the legumes could be a rewarding approach
Seed germination and growth of mung bean seedlings were significantly affected by drought stress induced by various concentrations of mannitol and polyethylene glycol (PEG)
Summary
Pulses have been treated as the most cultivated and consumed legumes and some of them such as cowpea (Vigna unguiculata), green gram (Vigna radiata), black gram (Vigna mungo), pigeon pea (Cajanus cajan), lentil (Lens culinaris), and grass pea (Lathyrus sativus) are being grown as alternative staple crops in marginal and harsh areas of the world (Deikman et al, 2012; Araujo et al, 2015). In recent past, it has been experienced that salinity and drought stresses minimize the food and fodder production worldwide and continuous increase in dry climatic conditions globally causes frequent occurrence of drought even on fertile and agriculture lands (Hu & Schmidhalter, 2005; Lieu et al, 2015). These stresses have been considered as the primary causes of legume crops failures in India. Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made
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