Effects of nutritive solution electrical conductivity and plant density on growth, yield and quality of sweet basil grown in gullies by subirrigation

Abstract

The increasing demand for basil in the last decade has arisen from consumer tendency towards high nourishing produce. Soilless growing of this crop is a current farm strategy and the quality targets are affected by nutritive solution as well as by plants density per pot. Research was carried out with the aim of assessing plant growth, yield and leaves quality of basil (Ocimum basilicum L., cv. Gecom FT) grown in pots (peat-lapil) and fed by subirrigation inside plastic gullies, under a heated greenhouse. Comparisons were made of four electrical conductivities (EC: 2.2, 2.5, 2.8, 3.1 mS·cm-1) in factorial combination with four plant densities (9, 12, 15, 18 plants per pot) and a split plot design was arranged with three replicates. The 2.8 mS.cm-1 EC resulted in the best yield, growth indexes and biometrical parameters values. Water absorption was highest under the 2.8 mS.cm-1 EC, whereas the highest nutrient consumptions as well as the best quality indicators and chemical composition corresponded to the 2.8 to 3.1 mS.cm-1 EC range. The 12 plants per pot density gave the best results, in terms of yield, growth indexes and biometrical parameters, also showing the highest plant water and nutrient uptakes. The leaves quality attributes and chemical composition always displayed decreasing trends as a function of the plant density increase, the highest values corresponding to 9 and 12 plants per pot; only the nitrates concentration showed an opposite trend compared to the other nutrients. In conclusion, the 2.8 mS.cm-1 nutritive solution and the 12 plants per pot density resulted in the best yield and leaves quality. Further enhancement of both experimental factors level even caused the reduction of water and nutrient efficiency use.