Evaluation of Different Concentrations of Nitrogen for Tomato Seedling Production (Lycopersicon esculentum Mill.)

This study was aimed at evaluating the different concentrations of nitrogen for tomato seedling production (Lycopersicon esculentum Mill.), hybrid Loreto. Five concentrations of nitrogen were analyzed: 0, 4, 8, 12 and 16 mEq / L, using as a basis the Steiner nutrient solution. A pilot randomized block design was used with six replications and five treatments. Thirty-five days after sowing, the following variables were analyzed: seedling height, stem diameter, fresh stem weight, fresh leaf weight, leaf area, dry steam weight, dry leaf weight, dry root weight and total nitrogen content. An ANOVA analysis (p <0.05) with post-hoc Tukey test was performed to compare each treatment variables. The results showed that the increase in the concentration of nitrogen has a positive effect on organ growth. The treatment with the highest values in the morphological variables was 16 mEq / L, which shortened the production time of seedlings ready for transplant

Evaluation of Different Concentrations of Nitrogen for Tomato Seedling Production (Lycopersicon esculentum Mill.)

This study was aimed at evaluating the different concentrations of nitrogen for tomato seedling production (Lycopersicon esculentum Mill.), hybrid Loreto. Five concentrations of nitrogen were analyzed: 0, 4, 8, 12 and 16 mEq / L, using as a basis the Steiner nutrient solution. A pilot randomized block design was used with six replications and five treatments. Thirty-five days after sowing, the following variables were analyzed: seedling height, stem diameter, fresh stem weight, fresh leaf weight, leaf area, dry steam weight, dry leaf weight, dry root weight and total nitrogen content. An ANOVA analysis (p <0.05) with post-hoc Tukey test was performed to compare each treatment variables. The results showed that the increase in the concentration of nitrogen has a positive effect on organ growth. The treatment with the highest values in the morphological variables was 16 mEq / L, which shortened the production time of seedlings ready for transplant

Polyamine Function in Plants: Metabolism, Regulation on Development, and Roles in Abiotic Stress Responses

Polyamines (PAs) are low molecular weight aliphatic nitrogenous bases containing two or more amino groups. They are produced by organisms during metabolism and are present in almost all cells. Because they play important roles in diverse plant growth and developmental processes and in environmental stress responses, they are considered as a new kind of plant biostimulant. With the development of molecular biotechnology techniques, there is increasing evidence that PAs, whether applied exogenously or produced endogenously via genetic engineering, can positively affect plant growth, productivity, and stress tolerance. However, it is still not fully understood how PAs regulate plant growth and stress responses. In this review, we attempt to cover these information gaps and provide a comprehensive and critical assessment of the published literature on the relationships between PAs and plant flowering, embryo development, senescence, and responses to several (mainly abiotic) stresses. The aim of this review is to summarize how PAs improve plants' productivity, and to provide a basis for future research on the mechanism of action of PAs in plant growth and development. Future perspectives for PA research are also suggested