C. G. Werneck

Dry matter production and nutrient accumulation after successive crops of lettuce, tomato, rice, and andropogongrass in a substrate with zeolite

SUMMARY Zeolites are hydrated crystalline aluminosilicate minerals of natural occurrence, structured in rigid third dimension net that can be used as slow release plant-nutrient source. The main objective of this study was to evaluate the effects of plant growth substrate under zeolite application, enriched with N, P and K, on dry matter yield and on nutrient contents in consecutive crops of lettuce, tomato, rice, and andropogon grass. The experiment was carried out in a greenhouse, with 3 kg pots with an inert substrate, evaluated in a randomized block design with three replications. Treatments consisted of four types of enrichment of concentrated natural zeolite: concentrated zeolite (Z) only, zeolite + KNO3 (ZNK), zeolite + K2HPO4 (ZPK) and zeolite + H3PO4 + apatite (ZP), and a control grown in substrate fertilized with a zeolite-free nutrient solution. Four levels of enriched zeolite were tested: 20, 40, 80, and 160 g/pot. Four successive crops were grown on the same substrate in each pot: lettuce, tomato, rice, and andropogon grass. Results indicated that N, P and K enriched zeolite was an adequate slow-release nutrient source for plants. The total dry matter production of above-ground biomass of four successive crops followed a descending order: ZP > ZPK > ZNK > Z.

Crescimento e nutrição mineral do porta-enxerto limoeiro 'Cravo' cultivado em substrato com zeólita enriquecida com NPK

The main objective of this research was to evaluated the growth, dry matter production, leaf area, N, P and K levels and exportation and chlorophyll levels of Rangpur Lime (Citrus limonia Osbeck) grown in a substrate with NPK enriched zeolite. Rootstocks were cultivated during 93 days in 150cm3-dibble tubes containing composted organic substrate of cocopeat and vegetal coal (3:1) with zeolite addition. Treatments comprised 4 levels (0, 2.5, 5, 10 and 15 g per plant) of a NPK-enriched zeolite, which was a mix of H3PO4/apatite-zeolite (70%) and KNO3 - zeolite (30%). Results indicated that the supply of nutrients through the mineral zeolite enriched with NPK added to the organic substrate was a viable alternative for citrus rootstock production in protecting environment. The supply of 6,4 g of enriched zeolite significantly increased dry matter production, leaf area, height and steam diameter. These increases were 37,5% in relation to the control without zeolite. N, P and K foliar levels increased with zeolite enriched with NPK. Chlorophyll levels were related to N levels, pointed out to be a useful tool for Rangpur Lime nutritional status evaluation.

Produção e qualidade de frutos de tomateiro cultivado em substrato com zeólita

Yield and fruit quality of tomato grown in substrate with zeolite We evaluated yield and quality of tomato fruits, cv. Finestra, grown in a zeolite substrate enriched with N, P and K. Treatments comprised four levels (20; 40; 80 and 160 g per pot) of zeolite enriched with H 3 PO 4 /apatite, KNO 3 and KH 2 PO 4 , and a control grown in a nutrient solution. Fruit production, firmness, total soluble solids, pH, titratable acidity and ascorbic acid were evaluated from 80 to 90 days of plant cultivation. Nutrients supplied through the mineral zeolite enriched with N, P and K was an adequate alternative to increase the production. Higher fruit production was obtained with addition of P and K and higher zeolite dosis (160 and 80 g per pot). Fruit production was 11% and 17% higher when compared to the plants grown in nutritive solution (check treatment). Positive effects were observed in P-enriched zeolites in relation to fruit firmness, and negative effects over fruit pH. Fruit firmness varied 104% among treatments, from 7.06N (ZNK 160) to 14.38N (ZPK 40). The increase of potassium availablity increased the ascorbic acid levels of the fruits.

Produção, aparência e teores de nitrogênio, fósforo e potássio em alface cultivada em substrato com zeólita

ABSTRACT Yield, appearance and content of nitrogen, phosphorus andpotassium in lettuce grown in substrate with zeoliteIn this research we evaluated and related yield and tissue levelsof N, P and K in shoot tissues and appearance of lettuce plants grownin a substrate with N, P and K enriched with zeolite. Treatmentscomprised of four levels (20; 40; 80 and 160 g/pot) of zeolite enrichedwith H 3 PO 4 /apatite, KNO 3 and KH 2 PO 4 , and a control grown in anutrient solution. Lettuce yield and N, P and K levels in the shoottissues were evaluated. Ordering test was carried out to compare theappearance of the samples. Lettuces grown in substrate with zeoliteenriched with phosphorus sources showed higher yield, andequivalent visual quality in comparison with the control. There weresignificant correlations between N level in tissues and the sensoryattributes of plant color and size, and between the P levels and thesize of the plant. The sensory analysis of the appearance was anadequate tool to identify the quality of lettuce.Keywords: Lactuca sativa , stilbite, sensory analysis, preference test.