Electrical conductivity of the nutrient solution for soilless cultivation of kohlrabi

Abstract

The electrical conductivity of the nutrient solution directly affects production and quality of the plants. We evaluated the electrical conductivity suitable for soilless cultivation of kohlrabi. The experiment was carried out in a completely randomized design, with four replicates and five treatments, composed of different nutrient solution’s conductivities (1.31, 1.71, 2.37, 2.98 and 3.75 dS m-1). We evaluated number of leaves, leaf area, specific leaf area, leaf area ratio, fresh and dry masses of leaves, bulb, roots and total, bulb volume, water content in the bulbs and pH, soluble solids, vitamin C, firmness, titratable acidity and SS/TA ratio of the bulbs. All variables related to growth were affected by the nutrient solutions, showing the highest values with the use of the nutrient solutions with EC close to 2.0 dS m-1. Considering the commercial part of the plant, the most developed bulbs were obtained with EC of 1.96 dS m-1, being 49.9 g and 41.15 cm3 per bulb. On the other hand, except for pH, the other variables responded to the increase of EC. Higher values for pulp firmness and titratable acidity occurred with EC close to 2.0 dS m-1, whereas the other variables showed higher values using a more concentrated nutrient solution.

Production and quality of purple kohlrabi under nutrient solutions of different electrical conductivities

“…The vitamin C contents observed in the present study are close to those obtained by Oliveira et al (2022), who observed highest content (57.40 mg 100g -1 of fresh mass) at the highest EC of the nutrient solution, 3.75 dS m -1 , in white kohlrabi.…”

“…Thus, it can be observed that the negative effect of the highest ECns on LA was due to the reduction in leaf blade expansion since it did not affect the production of new leaves. Other authors have also found a reduction in the leaf area of kohlrabi in response to the increase in electrical conductivity, caused either by the addition of NaCl in the irrigation water (Osman & Salin, 2016) or by the increase in nutrient concentration in the nutrient solution (Oliveira et al, 2022).…”

“…Studies conducted with other crops show that vitamin C content tends to increase in response to increased salinity of the nutrient solution, for instance with lettuce (Carillo et al, 2020), amaranthus (Sarker & Oba, 2019), and tomato (Oliveira et al, 2022). This information is of great importance, as ascorbic acid, a precursor of vitamin C, can contribute to prolonging the shelf life of the product and sustain its nutraceutical value by conferring antioxidant properties (Carillo et al, 2020;Zandi & Schnug, 2022).…”

“…Biswas et al (2016) observed a linear reduction in kohlrabi growth with increasing irrigation water electrical conductivity (ECw), especially with ECw greater than 3.0 dS m -1 . In hydroponic cultivation in coconut fiber, Oliveira et al (2022) observed greater plant development using a nutrient solution with electrical conductivity of 2.0 dS m -1 .…”

Crop Hydroponics, Phyto-hydroponics, Crop Production, and Factors Affecting Soilless Culture

“…The substrate or growing media determines the water use efficiency, nutrient use efficiency, and yield of the crop . Successful cultivation of vegetables and ornamental plants in hydroponic systems using different substrates and nutrient solutions have been reported: for example, carrot in rockwool blocks containing vermiculite with a supply of nutrient solutions through subsurface irrigation in a greenhouse, watermelon grown in aeroponics by NFT, lettuce raised in polystyrene foam + pots with discharge of three nutrient solutions through a floating system in a greenhouse, ginger in pots supplemented coir dust and burnt paddy husk in different proportions with MARDI nutrient solution through irrigation channels in a side-netted rain shelter, green beans in pots supplemented with peat, perlite, and sand with a supply of nutrient solution through subsurface irrigation, broccoli grown in rockwool with supply of Hoagland nutrient solution in a multitunnel greenhouse, kohlrabi ( Brassica oleracea var. gongylodes ) with NFT in a greenhouse, rhododendron flower production in containers containing mixtures of bark, sphagnum peat moss, perlite, and vermiculite, hybrid lily in plastic bags containing cocopeat, perlite, and palm trunk in different proportions with discharge of nutrient solution, mustard in hydroponics and aquaponics, tomato, and tomato, cucumber, eggplant, chili pepper, carrot, lettuce, and spinach in an open roof top system …”