Rosalinda Mendoza-Villarreal

Tolerance of Lisianthus to High Ammonium Levels in Rockwool Culture

Nitrogen (N) by form of nutrition, ammonium (NH4+) or nitrate (NO3−), affects metabolic and physiological processes of plants. In general, a high proportion of N in NH4+ form results in poor growth. Nonetheless, a number of species exhibit optimum growth when high levels of NH4+ are provided. In the present study, lisianthus [Eustoma grandiflorum (Raf.) Shinn] was grown in rockwool cultures and irrigated with nutrient solutions containing 15 mM N with varying proportions of NH4+ and NO3−. The results showed that an increase in NH4+-N form increased plant height, number of flowers and leaves, leaf area, and shoot, stem, and leaf dry weight. The proportion of NH4+ also affected leaf concentration of phosphorus, potassium (K), calcium (Ca), and magnesium (Mg), although leaf N concentration was unaffected. Potassium leaf concentration was higher when a low proportion of NH4+ was supplemented in the nutrient solution; however, plants exhibited a decrease in leaf K concentration and a decrease in leaf Ca as the proportion of NH4+-N increased. Shoot dry weight was higher with low leaf K whereas high leaf Ca was associated with high shoot dry weight. Net photosynthesis rate was higher in plants irrigated with solutions containing 75% of total N in NH4+ form than in those irrigated with solutions of 0 or 25%. The results suggest that lisianthus can tolerate high levels of NH4+, probably associated with a higher assimilation of Ca.

Efectividad del lodo textil en la producción y composición química del fruto de tomate

The aim of this study was to determine the e f fect of textile sludge applied on a substrate of peat moss and perlite on production and chemical composition of tomato fruit ( Solanum lycopersicum ). The sludge was characterized with the NOM-004-SEMARNAT-2002 and NOM-021- 2000-RECNAT. Tomato of the variety Rio Grande was transplanted into 14 liter plastic-pots with peat moss and perlite (70:30 by volume) in which was added and mixed textile sludge in concentrations of 0, 5, 10, 15 and 20% based on the volume. Nutrition was made with the Steiner solution. The sludge showed characteristics suitable for agricultural use by NOM-004-SEMARNAT-2002. Fruit production was not modified by the application of textile sludge. The concentration of mineral elements in the fruits increased by 0.14% for Na and 15 and 223 mg kg -1 for Zn and Fe, respectively. On the other hand, K decreased by 0.58% as well as for Mn with a value smaller of 22 mg kg -1 . The content of N, P, Ca, Mg and Cu showed no significant changes at all. The pH of the fruits do not vary by effect of the treatments, while vitamin C and total soluble solids showed an increase up to 36% and 52%, respectively, in the sludge treatments an effect attributed to the contribution of the sludge ?s soluble salts. There was no evidence of transferring of heavy metals and fecal colifor m of the textile sludge to the fruits beyond those permitted by the environmental and health standards. However, we detected the presence of helminth eggs in higher values than those allowed by the standard in the fruits of plants treated with the highest concentration of sludge.