Cultivo hidropônico de pimenteira ‘biquinho’ com águas salobras

Abstract

In order to generate information about the potential of 'Biquinho' pepper as an agricultural alternative for regions with restricted supply of fresh water and availability of brackish water, such as the semi-arid, a NFT hydroponic culture of this crop was experimentally conducted for 120 days after transplanting (DAT). A nutrient solution prepared in local water (electrical conductivity of water - CEa 0.34 dS m-1) and other six brackish waters artificially produced with the addition of NaCl with CEa: 1.50; 2.50; 3.50; 4.50; 5.50 and 6.50 dS m-1, composing seven treatments repeated six times in randomized blocks. Fruits and vegetative part of the plant were evaluated about: presence of visual symptoms, water consumption and use efficiency, vegetative growth, fruit yield and quality, sensorial analysis, salinity tolerance, precocity and technical viability of cultivation. From 8 to 14 DAT, the plants under salinity progressively showed chlorosis and foliar necrosis, which was attenuated by acclimatization when the productive phase was reached. Afterwards, these symptoms were restricted to older leaves appearing also foliar abscission and flower abortion. The salinity provided a beneficial effect on the fruits as to the appearance of cracks in the cuticle, which only manifested in the control treatments (CEa 0,34 dS m-1) and of lower salinity ECa 1,50 dS m-1. There was recovery of the growth and yield with the acclimatization of the plants to the salinity. It is recommended to consider maximum consumption of water by crop around 5.9 L per plant per day. The efficiency of water use was 11 kg m-3 to CEa 3.38 dS m-1, with an exponential reduction as a function of the salinity. Fruit length and width decreased with increasing salinity, but maintained a proportion between these measurements and wall thickness. The size of the 'Biquinho' pepper fruits obtained in saline conditions in the NFT system would be acceptable until an electrical conductivity of 2.50 dS m-1, based on the demand of the industry and suppliers of the preserved intact fruit segment. Salinity reduced the precocity of 'Biquinho' pepper production. Threshold salinity of the 'Biquinho' pepper plant was 5.22 dS m-1 in a nutrient solution, corresponding to the potential relative productivity, based on the plateau response model. The total yield of ‘Biquinho’ pepper plant cultivated in NFT hydroponics, without salinity restriction, was 2.92 kg per plant, corresponding to 46.9 t ha-1, considering an area of 0.62 m2 per plant. It was technically feasible to produce 'Biquinho' pepper plant in NFT hydroponics, with PVC pipes of 0.075 m diameter, but it is recommend testing larger diameter tubes.