Resumo

VIDAL-MARTINEZ, J. Luis et al. Potassium nutrition of broccoli (Brassica olearacea) with conventional management and fertigation in a vertisol in greenhouse. Agrociencia [online]. 2006, vol.40, n.1, pp.1-11. ISSN 2521-9766.

Most agricultural soils in México are rich in potassium because they are located in arid or volcanic zones, and volcanic ash is rich in this nutrient. These soils do not require potassium fertilization in field crops; however, it is a usual practice in the more demanding crops. Information on fertilization of horticultural crops is insufficient, especially fertigation. Therefore, the objective of this study was to obtain information to generate recommendations for fertilizing broccoli with potassium under fertigation. The experiment was conducted in Montecillo, State of México in a greenhouse with the cultivar Heritage in a Vertisol from Celaya, Guanajuato, from March to July, 2003. The experimental design was randomized complete blocks with eight treatments: two crop management systems (conventional and fertigation) and four levels of K(K0=0,K1=70, K2=140 and K3=210 mg Kkg−1 soil; 9kg soil per pot). Each treatment was replicated 12 times. The results were analyzed statistically as a 2×4 factorial with two replications for each of the four samplings taken during the development of the crop and four replications at harvest. The response variables were yield, biomass weight (fresh and dry), K concentration in the plant, and dynamics of water-soluble, exchangeable and nonexchangeable K in the soil. The mean yields of broccoli under fertigation were 33.5% higher than conventional management. The extractions of K by the crop under fertigation were 83.8% higher than those under conventional management. K2 treatment significantly increased the yield of broccoli but only under conventional management. There was greater absorption of K under fertigation because of a more adequate supply of water, which helped to economize water and fertilizer.

Palavras-chave : Brassica oleracea var. nutrient extraction; fertilization.

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