The study examined the influence of light quality on the growth and nutritional status of romaine lettuce grown in deep water culture with a floating raft system using two different nutrient solutions. Four spectra of LED light were used with different ratios of R, G, and B lights (80:10:10, 70:10:20, 60:10:30, and 70:18:12). Two nutrient solutions with a low (A) and moderately high (B) nutrient content were used. Regardless of the nutrient solution, the RGB 70:18:12 light promoted the production of leaf biomass as well as inhibited the accumulation of K and Mg in the leaves. Moreover, those plants were characterized by a low Nitrogen Balance Index (NBI) and a high flavonol index. In the last week of cultivation, there was a strong decrease in K, P, and nitrates in the nutrient solution, and an increase in Ca. In the final stage of growth, symptoms of withering of the tips of young leaves (tipburn) were observed on the plants. The most damage was observed on the plants growing under 70:10:20, 70:18:12, and with the higher concentration of minerals in the solution (B).

The correct fertilization of vegetable crops is commonly determined on the basis of soil and plant costly destructive analyses, demanding more sustainable non-invasive optical detection. Here, we tested the ability of the combined transmittance/fluorescence leaf clip Dualex device for determining the nitrogen (N) status of cabbage plants. Fully developed leaves from plants grown under different N rates of 0; 100; 200; 300 kg N ha⁻¹ in 2018 and 2019 were measured in the field by the Dualex sensor twice a year in July and October. The chlorophyll (Chl) and nitrogen (nitrogen balance index, NBI) indices and the flavonols (Flav) index of the sensor were positively and negatively correlated to leaf nitrogen, respectively. Merging the two-years data, the NBI versus leaf N correlation was less point dispersed in October than July (R² = 0.76 and 0.64, respectively). NBI was also correlated to cabbage yield, better in July than October. Our results showed that the multiparametric Dualex device can be used as precision agriculture tool for the early prediction of plant N and cabbage yield with economic advantage for the growers and reduced environmental contamination due to nitrate leaching.

Effects of LED and HPS lighting on the growth, seedling morphology and yield of greenhouse tomatoes and cucumbers | Jacek Dyśko, Kaniszewski Stanisław | Agricultural Journals

The Influence of pH of Nutrient Solution On Yield and Nutritional Status of Tomato Plants Grown in Soilless Culture System: The aim of the studies conducted in the years 2004-2006 was determination the influence of nutrient solution of different pH on the yield and nutritional status of tomato plants grown in soilless culture in organic and inert medium. Tomato plants were grown on slabs made of shredded rye straw and on slabs of peat and rockwool. The plants were fertilized with standard nutrient solution of different pH: 4.5, 5.0, 5.5, 6.0, 6.5. Nutrient solution pH and the kind of applied growing substrates were exerted significantly influence on the height of total and marketable yield of tomato cv. Blitz F¹. Early yield was not depended on pH of nutrient solution and the kind of using substrates. The highest total and marketable yield was observed in tomato grown in rockwool slabs. For all the growing media, the highest yield of tomatoes was obtained after feeding the plants with the nutrient solution of pH 5.5. The kind of growing substrates and pH of nutrient solution were significantly differenced the nutritional status of tomato plants. Despite of considerable differentiation of means concentration of mineral nutrient in tomato leaves, the plant growth and development were proper. Concentration of mineral nutrients was comprised at the optimum range of nutritional status of tomato plants. The pH of nutrient solution at the range of 4.5-6.0 was not exerted significantly influence on nutritional status of tomato plants with nitrogen, potassium and magnesium. With the increase of the pH nutrient solution the average phosphorus, iron and manganese content was decreased. The higher concentration of nitrogen, calcium and magnesium was occurred in tomato plants cultivated in organic substrates than in rockwool. The phosphorus and manganese content was higher in the leaves of tomato plants grown in rockwool compared to those in the organic media. Tomato plants grown in the straw substrate contained lower concentrations of potassium and iron and more calcium in comparison to peat.

The aim was to determine the suitability of various substrates for application in a closed system of soilless tomato cultivation, based on the potential fitness of drainage waters from these substrates for recirculation. Four substrates were used: rockwool, coir substrate, lignite substrate (Carbomat) and biodegradable organic substrate (Biopot). Tomato plants grown in these substrates were fertilized with the same amount of nutrient solution, containing the same concentration of nutrients. The characteristics of drainage water from these substrates were analyzed during cultivation. The highest amount of drainage water was collected from the lignite substrate Carbomat. However, these leachates showed good properties for further recirculation: low electro conductivity and turbidity, high nutrient content, moderate microbial load with high population of Trichoderma fungi, and being beneficial for plant growth. Moreover, Carbomat produced the highest tomato yield compared to other substrates. This indicates that this organic substrate is an efficient alternative to rockwool and its drainage water may be reused in a recirculation system. On the contrary, the drainage water from the Biopot substrate showed the worst qualities: high pH and low EC, low concentration of nitrate nitrogen and phosphorus, very high turbidity and a high number of microorganisms. These parameters do not qualify Biopot drainage waters for reuse.

There is insufficient information on the effects of drip irrigation and drip fertigation with nitrogen on growth and development of onions. The aim of the present work was to investigate the possibility of using these techniques in connection with fertilization, where nitrogen is split into preplant and side-dress application, that is used in onion (Allium cepa L.) production. Yield of spring sown onion (cvs. Riviera F1 and Utopia F1 in 1999 and cv. Riviera F1 only in 2000), were investigated in field experiments on a sandy-loam soil. Nitrogen fertilization consisted of a preplant application of 50 kg·ha−1 N incorporated in all treatments, and a side-dress application of: (1) 50 kg·ha−1 N in dry form without irrigation, (2) 50 kg·ha−1 N in dry form plus drip irrigation, or (3) 50, or (4) 150, or (5) 250 kg·ha−1 N in surface fertigation, applied through drip lines, and (6) 150 kg·ha−1 N in subsurface fertigation, applied through buried drip lines. In comparison with the not irrigated or fertigated...