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The preferable N source for tropical grasses and its effects on the nutritional status are still matters of priority investigation. This study aimed to explore the effects of N sources and N deprivation on growth and uptake of elements in a newly-released ruzigrass cultivar, BRS Integra. Plants were grown under controlled conditions in vermiculite and were supplied with nutrient solution containing either NH4+, NH4++NO3-, NO3- or no N added in solution making. Plant biomass, chlorophyll content, transpiration, N status, and levels of selected elements were evaluated. NH4+ improved biomass production and aboveground N contents. Other elements exhibited high (N, K and Na), medium (Mn), low (Ca, Cd, Cr, Cu, Mg, Ni and Zn) or non-detected (Al and Fe) translocation. Cd was included in the study because of its hazardous concentrations in agricultural soils in Brazil and its influence on N uptake and translocation in the genus Urochloa. All N sources increased the uptake of whole plant Cu and K and Al, and root Fe and Mg. Other favorable relations prevailed in the roots, specifically of NO3- on Ca and Ni, NH4+ and NH4++NO3- on Cr, and NH4+ on Cd. Removal of N supply caused increases on Mn and Na aboveground and Zn in roots. Overall, the more evident N source-induced uptakes were, in order of decrease, of NO3- on Ca, NH4++NO3- on Ni, and NH4+ on Cr, Cu and Mn. It is concluded that NH4+ is more efficient for fertilizing ruzigrass by improving growth and N uptake compared to NH4++NO3- or NO3-. In addition, the diverse effects of varying N sources on the uptake of 12 elements indicate such interactions should be taken into account to further improve fertilizer formulations. [ABSTRACT FROM AUTHOR]

In this study, two experiments were conducted to evaluate the plant response of Brachiaria brizantha cv. MG5 to nitrogen forms and different pH of nutrient solution. For this, nutrient solutions containing ammonium and ammonium nitrate were fixed at pH 4, 6 or 8, and nutrient solution containing nitrate was fixed at pH 6. The pH adjustment was done by different compounds including MES, calcium hydroxide, calcium carbonate and sulfuric acid. In another experiment the seedlings were grown in nutrient solution with different N forms, but without pH adjustment. The results showed that plants in ammonium or ammonium nitrate at pH = 4 had better growth and performance, followed by pH = 6, compared to plants grown at pH = 8 (buffered with calcium carbonate). Calcium carbonate (bicarbonate) especially in higher amounts in nutrient solution (pH = 8) significantly reduced plant growth particularly root growth as the toxic effects were visible on the roots. The adverse effect of carbonate at high pH was more than those at low pH. High concentration of carbonate in presence of ammonium also was toxic for plants probably due to additional toxic effect of ammonia. However, plants were able to grow normally with different N forms under hydroponics culture, independent of pH effect. When pH was not controlled under different N-forms, there was no significant difference between root and shoot biomass production or leaf SPAD value and protein concentration. So, the presence of carbonate but not pH, was determined as an inhibiting factor for growth of Palisadegrass plants. [ABSTRACT FROM AUTHOR]

The response of pepper (Capsicum annuum L.) to Ammonium-N was studied in a multispan greenhouse under soilless culture using coir fiber as substrate. Ammonium-N application rates were 0, 2, 4, 6 and 8 mM with a total-N concentration of 13 mM. The total content of the rest of all macronutrients in the nutrient solution was maintained from the beginning of the experiment until the end. The highest water uptake was recorded at 2 mM ammonium concentration in the nutrient solution. Compared to nitrate, ammonium nitrogen caused a decrease in nitrate absorption, but led to an increase when applying 8 mM ammonium. Despite a progressive increase in ammonium content in the nutrient solution, potassium absorption was constant below the ammonium concentration of 8 mM. Under a high N-NH4 content (from 6 to 8 mM) in the nutrient solution, high toxicity was found, deriving in the appearance of deformed or noncommercial fruits. There was a significant benefit by the use of ammonium as a component in the nutrient solution. The optimum yield ammonium concentrations were found in the range from 2 to 4 mM. Nevertheless, concentrations higher than 6 mM led into a decrease in commercial production, with the production of increasing deformed fruit, out of size and/or blossom-end rot. [ABSTRACT FROM AUTHOR]

Ammonium (NH4+) is a major nitrogen source for tea plant growth. Although NH4+-induced growth of tea plants were reported, it was still unclear to elucidate the mechanism of proteins in tea plants in responding to NH4+ resupply. In the present study, the proteomic profiles of tea leaves under N deficiency/resupply were investigated by using LC-MS/MS and PRM technique. Compared with N deficiency, there were 247 and 328 proteins significantly expressed after 3 h and 3d of N resupplied, respectively. And compared with 3 h of N resupplied, there were 186 proteins significantly expressed after 3d of N resupplied. According to bioinformatics analysis, the results showed that different expressed proteins participated in various biological processes, such as PsbO, Pbs27, PsaN, and PsaF were involved in photosynthesis, ADH1, AOC3, URE, GDH1-2, and argD were involved in amino acid metabolism, CHI and ANR were involved in flavonoid biosynthesis, GSTF9, APX, and GSS were involved in glutathione metabolism, and PdxT and PdxS were involved in vitamin B6 metabolism. Through PPI analysis, the results showed that the interactions between different expressed proteins mainly occurred in the photosynthetic pathway. Ammonium supply has a profound impact on photosynthesis, amino acid metabolism, flavonoid biosynthesis, glutathione metabolism, and vitamin B6 metabolism. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the most produced cereals in the world. Among the essential nutrients required by this crop, nitrogen (N) is of paramount importance to achieve optimum yields. In paddy fields, ammonium (NH4+) represents the main source of N. This work aimed to evaluate the root morphology, ammonium uptake kinetics and N accumulation in two upland rice varieties, Piauí and Manteiga from Maranhão – Brazil. The varieties were cultivated in hydroponic conditions and submitted to three different doses of ammonium: 1 – constant treatment with 0.2 mM NH4+, 2 – constant treatment with 1 mM NH4+ and 3 – constant treatment with 1 mM NH4+, followed by N starvation during 72 h and resupply with 1 mM NH4+. The varieties present contrasting behaviors when submitted to different doses of NH4+. Piauí showed higher biomass and root length under the treatment with 0.2 mM NH4+. The favorable kinetics parameters observed contributed to a higher N accumulation by Piauí in low dose of NH4+. Under 1 mM NH4+, a higher root biomass and favorable kinetics parameters was recorded by Manteiga. This variety presented a better performance with higher doses of N. Under the treatment of N resupply, Piauí variety showed to be more adapted, due to the greater root plasticity observed. For one hand, the results suggest that Piauí variety presents greater growth in environments with low dose or seasonal flux of NH4+. On the other hand, Manteiga variety presents better growth when submitted to higher levels of NH4+. [ABSTRACT FROM AUTHOR]

This study was done to evaluate the growth responses of tomato plants (Lycopersicon esculentumMill.) to foliar application of ammonium sulfate in different concentrations of 0, 50, 100, or 200 mM once per week, as well as 50 mM in every other day under greenhouse and hydroponic culture system. The results showed that foliar application of ammonium restricted the plant height, yield, and vitamin C content of fruits, but it increased the chlorophyll content in treated plants. The highest and the lowest yield were obtained from zero (control) and 200 mM treated plants, respectively. Fruit hardness was not affected by treatments, while blossom end rot disorder was increased by higher concentrations of ammonium sulfate. In general, the result indicated that tomato plant is rather sensitive to foliar application of ammonium sulfate particularly to higher concentrations and application numbers. [ABSTRACT FROM PUBLISHER]