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Effect of Drip Irrigation, N-Fertigation and Cultivation Methods on the Yield and Quality of Carrot In the years of 2004-2006 research on influence of surface and subsurface drip irrigation on yield and quality of carrot grown on ridges and on the flat ground was investigated. Irrigation was started at soil water potential of 30-40 kPa. Nitrogen fertilizers (100 kg.ha-1) were applied in two rates. The first rate was preplant applied, the second was used by fertigation. In the control treatment without irrigation, the second rate of nitrogen was applied by broadcasting. Surface and subsurface drip irrigation significantly increased the yield of carrot. In cultivation on ridges higher yield of the carrot was obtained when surface drip irrigation was applied as compare to subsurface method. Carrot cultivated on ridges produced significantly longer roots than cultivated on flat ground. Generally the surface and subsurface drip irrigation decreased dry matter content and total N content in carrot roots. Drip irrigation at both cultivation methods increased pH and decreased the salt concentration of the soil.

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.