Nitrogen-potassium ratios in fertirrigation for protected cultivation of tomato in Red Ferralitic soil

The objective of the present work was to evaluate the effect of nutrient solutions in fertirrigation, with different nitrogen–potassium ratios, on yield and quality of tomato fruits (hybrid Hazera 3019) in Red Ferralitic soil (Oxisol). The trial was performed at Instituto de Investigaciones Hortícolas Liliana Dimitrova (La Habana, Cuba). Four nutrient solutions were studied, which were different in their NO3-+NH4+/K+ ratios in terms of meq L-1 (N/K), keeping a K+/Ca2++Mg2+ ratio of 0,75 in every variant. The resulting treatments (T1, 1:0.45; T2, 1:0.60 or production test control, T3, 1:0.75 and T4, 1:0.90) were distributed in a completely randomized design with four replicates. The N/K ratio variation in the nutrient solution influenced the yield, external quality and postharvest life of tomato fruits, without affecting the bromatologic quality. The best combination of yield structure and fruit quality was obtained with the 1:0.75 N/K ratio, which had superior yield in extra, first and extra plus first commercial qualities, as well as fruits with higher firmness and larger endocarp thickness, lesser abnormal fruit percentage and lower postharvest losses.El objetivo del presente trabajo fue evaluar el efecto de soluciones nutritivas en el fertirriego, con diferentes relaciones entre el nitrógeno y el potasio, en la productividad y calidad de los frutos del tomate (híbrido Hazera 3019), en suelo Ferralítico Rojo. La experiencia se desarrolló en el Instituto de Investigaciones Hortícolas Liliana Dimitrova (La Habana, Cuba). Se estudiaron cuatro soluciones nutritivas, que se diferenciaron en su relación NO3-+NH4+/K+ en términos de meq L-1 (N/K), con una relación K+/Ca2++Mg2+ en todas las variantes de 0,75. Los tratamientos resultantes (T1, 1:0,45; T2, 1:0,60 o testigo de producción, T3, 1:0,75 y T4, 1:0,90) fueron distribuidos en un diseño completamente aleatorizado con cuatro réplicas. La variación de la relación N/K en la solución nutritiva influyó en el rendimiento, la calidad externa y la vida en anaquel de los frutos de tomate, sin afectar la calidad bromatológica. La mejor combinación entre estructura del rendimiento y calidad de los frutos se obtiene con la relación N/K 1:0,75, al presentar rendimientos superiores en las categorías de calidad comercial extra, primera y extra más primera, así como frutos con mayor firmeza y grosor del endocarpio, menor porcentaje de frutos fuera de norma y valores inferiores de pérdidas postcosecha.The objective of the present work was to evaluate the effect of nutrient solutions in fertirrigation, with different nitrogen–potassium ratios, on yield and quality of tomato fruits (hybrid Hazera 3019) in Red Ferralitic soil (Oxisol). The trial was performed at Instituto de Investigaciones Hortícolas Liliana Dimitrova (La Habana, Cuba). Four nutrient solutions were studied, which were different in their NO3-+NH4+/K+ ratios in terms of meq L-1 (N/K), keeping a K+/Ca2++Mg2+ ratio of 0,75 in every variant. The resulting treatments (T1, 1:0.45; T2, 1:0.60 or production test control, T3, 1:0.75 and T4, 1:0.90) were distributed in a completely randomized design with four replicates. The N/K ratio variation in the nutrient solution influenced the yield, external quality and postharvest life of tomato fruits, without affecting the bromatologic quality. The best combination of yield structure and fruit quality was obtained with the 1:0.75 N/K ratio, which had superior yield in extra, first and extra plus first commercial qualities, as well as fruits with higher firmness and larger endocarp thickness, lesser abnormal fruit percentage and lower postharvest losses