Respuesta del cultivo de pepino en sustrato a la relación N:K en términos de bioproductividad y eficiencia

Résumé

The effect of the N:K ratio (expressed in mmol L-1) in the supplied nutrient solution on the N and K uptake and bioproductivity of cucumber (Cucumis sativus) crop cv. Borja grown in perlite in a greenhouse has been evaluated. The modification of the N:K ratio was performed when the crop had already reached a vegetative development with a LAI of 3.5, coinciding with the initiation of the harvest. Therefore, until 52 days after sowing, the N:K ratio in the supplied nutrient solution was 15:8 and from there until the end of the crop cycle four different ratios were established: 14:8, 10:8, 7:8 and 10:6. Statistically significant differences were obtained both in fruit yield as well as in total fresh and dry matter production. The 10:8 and 7:8 N:K ratios provided a higher fruit production than the 14:8 and 10:6 ratios. As the N and K supply decreased the use efficiency of these nutrients increased in terms of fruit production. The 10:8 N:K ratio contributed to a higher total dry and fresh matter production. The N absorption concentration (mmol of N absorbed per L of water consumed) was not affected when the N supply decreased from 14 to 10 mmol L-1 and was lower when supply decreased to 7 mmol L-1. The K absorption concentration (mmol L-1) decreased as the supply decreased from 8 to 6 mmol L-1. These results indicate that the N reduction in the generative stage of the crop favours the fruit production. On the other hand, the reduction in the supply of K negatively affects the fruit production. The 7:8 N:K ration proved to be the most efficient in terms of N use and could be a good strategy contributing to a reduction in the use of N and its loss by lixiviation.