Abstract
ABSTRACT Sweet potato [Ipomoea batatas (L.) Lam.] has wide adaptability to different climatic conditions. However, its yield can be affected by prolonged periods of drought. Application of exogenous jasmonates can modulate several physiological and biochemical processes, improving plant tolerance to abiotic stress. This study sought to evaluate the role of exogenous application of methyl jasmonate (MeJA) in attenuating the adverse effects of drought stress by physiobiochemical analyses and their impact during the early initiation of tuberous roots. The experimental design was completely randomized and arranged in a 2 x 2 factorial, comprised of two concentrations of a MeJA plant regulator [without (0 µmol·L-1) and with (13 µmol·L-1) application] and two water regimes (optimum and drought conditions, corresponding to a field capacity of 100 and 40%, respectively). Plants treated with MeJA showed a reduction in total leaf area and leaf dry biomass but increased adventitious root dry biomass. In addition, MeJA application in sweet potato plants affected photosynthetic performance and increased and antioxidant phenolic compounds, carotenoids, anthocyanins, and proline. The evaluated response mechanisms showed that the severity of drought was more prominent than the positive effects of MeJA, since the increases on antioxidant pigments and secondary metabolites were not sufficient to mitigate stress caused by drought, which was reflected in the reduced tuberous root production.
Highlights
Ipomoea batatas (L.) Lam. is a starchy tuberous root containing several vitamins, minerals, and proteins (Shigematsu et al 2017), which is why it is one of the seven major food crops cultivated worldwide (Li et al 2018)
Plants cultivated under drought showed reductions in A, gs, Ci, E, and Ψw on the 3rd, 6th, and 9th day (Table 1)
In plants treated with methyl jasmonate (MeJA), reductions were observed in A, gs was not altered, which shows that the reduction in A was due to cumulative limitations in carboxylation reactions, as verified by the lower EiC (Tables 1 and 2)
Summary
Ipomoea batatas (L.) Lam. (sweet potato) is a starchy tuberous root containing several vitamins, minerals, and proteins (Shigematsu et al 2017), which is why it is one of the seven major food crops cultivated worldwide (Li et al 2018). Recent research has reported that sweet potato, when included in the human diet, is beneficial for preventing many diseases (Esatbeyoglu et al 2017), making it a functional food This is due to high contents of polyphenolic compounds and carotenoids (Albishi et al 2013; Esatbeyoglu et al 2017; Wang et al 2018). The formation of tuberous roots in sweet potatoes can begin within four weeks after planting the branch, depending on the cultivar and environmental conditions In this phase it is ideal to have favorable conditions in terms of soil moisture and temperature (Gajanayake and Reddy 2016)
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