Abstract
BackgroundNitrogen (N) metabolism plays an important role in plant drought tolerance. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) regulates many aspects of plant development; however, the effects of DCPTA on soil drought tolerance are poorly understood, and the possible role of DCPTA on nitrogen metabolism has not yet been explored.ResultsIn the present study, the effects of DCPTA on N metabolism in maize (Zea mays L.) under soil drought and rewatering conditions during the pre-female inflorescence emergence stage were investigated in 2016 and 2017. The results demonstrated that the foliar application of DCPTA (25 mg/L) significantly alleviated drought-induced decreases in maize yield, shoot and root relative growth rate (RGR), leaf relative water content (RWC), net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr), and nitrate (NO3−), nitrite (NO2−), soluble protein contents, and nitrate reductase (NR), nitrite reductase (NiR), isocitrate dehydrogenase (ICDH), alanine aminotransferase (AlaAT) and aspartate aminotransferase (AspAT) activities. In addition, the foliar application of DCPTA suppressed the increases of intercellular CO2 concentration (Ci), ammonium (NH4+) and free amino acid contents, and the glutamate dehydrogenase (GDH) and protease activities of the maize. Simultaneously, under drought conditions, the DCPTA application improved the spatial and temporal distribution of roots, increased the root hydraulic conductivity (Lp), flow rate of root-bleeding sap and NO3− delivery rates of the maize. Moreover, the DCPTA application protected the chloroplast structure from drought injury.ConclusionsThe data show, exogenous DCPTA mitigates the repressive effects of drought on N metabolism by maintained a stabilized supply of 2-oxoglutarate (2-OG) and reducing equivalents provided by photosynthesis via favorable leaf water status and chloroplast structure, and NO3− uptake and long-distance transportation from the roots to the leaves via the production of excess roots, as a result, DCPTA application enhances drought tolerance during the pre-female inflorescence emergence stage of maize.
Highlights
Nitrogen (N) metabolism plays an important role in plant drought tolerance. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) regulates many aspects of plant development; the effects of DCPTA on soil drought tolerance are poorly understood, and the possible role of DCPTA on nitrogen metabolism has not yet been explored
Compared with the well-watered treatment, in the drought+DCPTA treatment, the grain number decreased by 14.01% in 2016 and by 16.55% in 2017, and the grain yield decreased by 17.98% in 2016 and by 20.54% in 2017
Compared with the well-watered treatment, in the DCPTA treatment, the grain number increased by 5.97% in 2016, and the grain yield increased by 7.31% in 2016 and by 8.02% in 2017
Summary
Nitrogen (N) metabolism plays an important role in plant drought tolerance. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) regulates many aspects of plant development; the effects of DCPTA on soil drought tolerance are poorly understood, and the possible role of DCPTA on nitrogen metabolism has not yet been explored. Nitrogen (N) metabolism plays an important role in plant drought tolerance. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) regulates many aspects of plant development; the effects of DCPTA on soil drought tolerance are poorly understood, and the possible role of DCPTA on nitrogen metabolism has not yet been explored. Crops are frequently exposed to drought during the growth period because of limited and erratic rainfall patterns due to global climate change, which leads to restrictions on agricultural productivity worldwide [1]. By 2050, the world population will reach 9 billion people, resulting in a high demand for maize (projected to double); at that time, drought will severely restrict crop growth for more than 50% of the cultivated land [4]. The application of plant growth regulators has been considered an effective way to enhance crop drought resistance [6]. As far as we know, very few studies of DCPTA have focused on crops, and the effect of DCPTA on crops exposed to soil drought are still unclear
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