Dry-Matter Allocation and Nutrient Uptake Dynamic in Pepper Plant Irrigated with Recycled Water by Different Nitrogen and Potassium Rate

As a consequence of increasing water demand, lack of natural water resources, and use of high amounts of fertilizers in the greenhouse crops in arid and semi-arid areas, the use of reclaimed municipal wastewaters is a valuable option, although the knowledge of plant nutritional requirements becomes more important to avoid imbalances caused by the nutrients present in reclaimed wastewater and to attain efficient nutrient use. An experiment was conducted with greenhouse-grown sweet pepper (Capsicum annuum L. var. Aifos) on a sand-mulched sandy loam soil and fertigation with recycled municipal wastewater and inorganic fertilizer treatments. Five treatments were applied: control with no nitrogen (N) or potassium (K) supplied (N0K0) and four different doses of N and K as the mean elements with possible imbalances: N1K1, N1K1.5, N1.5K1, and N1.5K1.5. N(1)K(1)was the recommended rate under local conditions (125 kg N ha(-1) and 193 kg K ha(-1)). Eight plants per treatment were collected at five growth stages (0, 56, 84, 113, and 155 days after the seedling transplant, DAT). Dry matter (DM) and N, phosphorus (P), K, calcium (Ca), and magnesium (Mg) concentrations in fruit, leaf, stem, and pruning wastes were measured for each sampling date. For all treatments, the period of largest extraction of nutrient by plant occurred from 113 to 155 DAT, which coincides with the greatest accumulation of dry matter. Plant nutrient distribution showed that fruit is the largest sink of N, K, and P. The NK levels showed no effect on DM and nutrient uptake in the periods of vegetative growth, fruiting, and fruit growth. Nutrient uptakes by the plant were not affected by NK level applied. The NK rates could be lowered significantly without reducing DM and nutrient total uptake by plant during vegetative growth, flowering, and early fruit development periods, when using reclaimed municipal wastewater. The fertigation with greater rates of N and K for the harvest period can be considered as an adequate and sustainable procedure to grow greenhouse pepper.