65ª Reunião Anual da SBPC

E. Ciências Agrárias - 1. Agronomia - 4. Fitotecnia

CHLOROPHYLL A/B AND N/K2O RATIOS IN EGGPLANT (Solanum melongena L.) EXPOSED TO DIFFERENT SOURCES AND LEVELS OF POTASSIUM "tags"

Raquel Passabom Lemos - Universidade Federal Rural da Amazônia- UFRA Odyone Nascimento da Silva - Universidade Federal Rural da Amazônia- UFRA Argemiro Pereira Martins Filho - Universidade Federal Rural da Amazônia- UFRA Douglas José Marques - Departamento de Ciência do Solo, Universidade Federal de Lavras Fernando Broetto - Departamento de Química e Bioquímica, Universidade Estadual Paulista Allan Klynger da Silva Lobato - Universidade Federal Rural da Amazônia- UFRA

INTRODUÇÃO:

The main potassium fertilizer used in agriculture is potassium chloride followed by potassium sulphate to a lesser extent. Potassium sulfate is less “salty” than the potassium chloride. Its salt content per unit of K2O is half the rate of potash, which makes it more suitable for soils with a tendency to salinization. Potassium has in plants a number of duties related to energy storage. Other aspect of potassium is linked to assimilation, because under adequate supplement in soil, the plant absorption of potassium can be four times higher than that of phosphorus, and equal to or greater than nitrogen, in which there are three macronutrients absorbed in large amounts in higher plants. O Growth and adaptation of a species to environment is related with your reproductive efficiency, and this aspect also is linked to photosynthetic pigments. Researches have used chlorophyll level to evaluate plant nutritional state in relation to nitrogen (N), because chlorophyll molecule is constituted by nitrogen, and there is high relationship between chlorophyll and nitrogen level.

OBJETIVO DO TRABALHO:

The aim of this study was to investigate the influence of different sources and levels of potassium on photosynthetic pigments, as well as to measure nitrogen status in leaf.

MÉTODOS:

Study was conducted in Departamento de Produção Vegetal-Horticultura of Universidade Estadual Paulista. The eggplant seeds of cv. Embu were placed to germinate in containers with sterile substrate denominated Plantmax® and watered with distilled water. The seedlings were transplanted from container to pot in 35th day after experiment implementation, in which 3 or 4 definitive leaves were present. The experimental design used was factorial scheme with randomized blocks, 2 potassium sources (KCl/K2SO4) combined with 4 potassium levels (250/ 500/ 750/1000 kg K2O).The fertilization of surface started on 15th day after transplanting and promoted in constant intervals of 15 days. The fertilization of surface was performed using as N source calcium nitrate. The fertilization for K was made from two sources, chloride and potassium sulphate. Chlorophyll a and b were quantified using a spectrophotometer. The tissue used in nitrogen and potassium determinations was leaf localized in plant medium region. Leaves were harvested 50 and 110 days after transplanting. Data were subjected to analysis of variance (F test), applying the test of second-order polynomial regression for those cases, in which there was a significant effect. Standard errors were also calculated in all treatments evaluated.

RESULTADOS E DISCUSSÃO:

Chlorophyll a/b ratio in eggplant leaf presented significant interaction, and this parameter was modified due to potassium excess. In this study, greater concentration of potassium can have induced the reduction in chlorophyll ratio of eggplant. These results on photosynthetic pigments suggest that potassium levels studded affect partially pigment production in eggplant. In other words, reductions showed in this species under salt stress can be strongly related with lower capacity of synthesis or higher chlorophyll degradation. Seedlings conserve, in part, your capacity of chlorophyll synthesis, due to constant process of degradation and synthesis during growth and development. Results linked to N/K2O ratio in leaf describes decrease in N accumulation produced by increase in K2O, and higher value showed in this study was obtained in 250 Kg K2O ha-1. Therefore, other levels evaluated cause negative effects that probably can be explained by salinity.

CONCLUSÕES:

This study revealed that eggplant exposed to potassium excess presented not interference negative under chlorophyll a/b ration, as well as nitrogen concentration in leaf was significantly lower due to increase in potassium level.

Palavras-chave: Nitrogen, Chlorophyll, ,Potassium.