Interaction of soil moisture and excess of boron and nitrogen on lettuce growth and quality

A study of the effects of boron (10 mg/kg as H3BO3) and nitrogen (0-0.15-0.30-0.45-0.60 g/kg) fertilization in combination with soil water capacity (40% and 70%) on lettuce growth and nutritional value was performed. The effects of the simultaneous application of N and B depend on the soil moisture, since lower water in the soil reduced lettuce growth and quality. Linear correlation was found between N fertilization and lettuce yield and quality at the two water soil capacities. Only when N fertilization exceeded 0.45 g/kg the fresh and dry biomass, photosynthesis, sugars and ascorbic acid showed negative influence as compared to the control. The toxic effects of B in lettuce cultivation were alleviated by the presence of high N doses, since a competition between N and B ions was revealed. Overall, the management of irrigation and N fertilization is very important in soils with boron toxicity.