No abstract

The SO4= toxicity in gypsiferous soils, which represent more than 100 million hectares worldwide, constitutes one of the major problems limiting world agricultural output. Currently, phytoremediation of SO4= is regarded, from agricultural and environmental standpoints, as one of the most effective alternatives for the decontamination and recovery of these soils. In this study, we analyzed the behavior of five plant species characteristic of gypsiferous soils (Gypsophila struthium, Helianthemun alypoides, H. squamatum, H. syriacum, and Lepidium subulatum) in order to establish the variability of these plants in terms of S-extraction mechanisms. Our results indicate that the species best adapted and with the densest population was Lepidium subulatum. This plant showed the highest concentration of total S and the greatest organic S, as well as the highest levels of amino acids and proteins. In this study, we propose that the incorporation of S into organic compounds is the essential metabolic process determining the tolerance of Lepidium subulatum to gypsiferous soils. In conclusion, the foliar accumulation of organic S could be defined a priori as one of the key characteristics in developing plants with a potential for regenerating zones with high SO4= concentrations.

The effect that application of nitrogen−phosphorus (NP) rates exerts on some parameters of nitrogen metabolism and on yield in aubergine plants (eggplant, Solanum melongena cv. Bonica) was studied. All plants were grown under controlled conditions in an experimental greenhouse. The treatments consisted of the combination of three rates of N in the form of KNO3 (N1:  15 g m-2, N2:  22.5 g m,-2 and N3:  30 g m-2) together with two rates of P in the form of H3PO4 (P1:  24 g m-2 and P2:  36 g m-2), for a total of six treatments. Results indicate that regardless of the P rate applied, an increase in the N fertilizer increased NO3- assimilation as well as total and commercial yield. Use of the P2 rate favored all of these processes in comparison with the results obtained with the P1 rate, in addition to notably reducing the foliar levels of NO3- and noncommercial yield. Keywords: Solanum melongena L.; NP fertilization; nitrogen assimilation; yield

Aubergine plants (Solanum melongena cv. Bonica) were grown under controlled greenhouse conditions on a soil substrate supplied with organic fertilizers (15 kg/m 2 ) mixed with calcium sulfate (CaSO 4 at 500 g/m 2 ), with different doses of nitrogen (N as N 1 = 15, N 2 = 22.5, N 3 = 30 g/m 2 ) in the form of ammonium nitrate (NH 4 NO 3 ), and phosphorus (P as P 1 = 24, P 2 = 36 g/m 2 ) as phosphorus acid H 3 PO 4 ). Plants were sampled every 15 days, and the pigments chlorophyll a, chlorophyll b, total (a+b) and ratio (a/b), carotene, licopene, and anthocyanins were determined in the leaves. The results showed that increases in rhizosphere N led to increases in foliar concentrations of chlorophyll a and b, both individually and as total chlorophyll, independently of the dose of P applied. Total chlorophyll concentrations were directly correlated with the level of P fertilization. Carotene and licopenes reflected the influence of increasing doses of N, whereas P did not affect these pigments. Anthocyanin levels were affected by both N and P. l.

The effect that application of nitrogen−phosphorus (NP) rates exerts on some parameters of phosphorus metabolism in eggplant (Solanum melongena cv. Bonica) was studied. All plants were grown under controlled conditions in an experimental greenhouse. The treatments consisted of the combination of three rates of N in the form of KNO3 (N1 = 15 g m-2; N2 = 22.5 g m-2; and N3 = 30 g m-2) together with two rates of P in the form of H3PO4 (P1 = 24 g m-2 and P2 = 36 g m-2), for a total of six treatments. The results obtained show a positive effect of NP fertilization on the nutritional status of P in the plants, clearly reflected in the response of bioindicators of the P (acid phosphatase activity and carbohydrates). The plants treated with N3P2 registered greater integration or assimilation of inorganic P to organic P, a fact that may be related to the maximum total and commercial yield in these plants and minimum noncommercial yield. Keywords: Solanum melongena L.; NP fertilization; phosphorus metabolism; bioindicators