Productivity and nutrient concentration in spineless cactus under different fertilizations and plant densities

摘要

The objective was to evaluate the productivity and nutrient concentration in spineless cactus ‘Miúda’ ( Nopalea cochenillifera Salm Dyck) under levels of nitrogen (N) fertilization (0, 150, 450 and 600 kg N ha -1 year -1 ), P fertilization (0 and 150 kg P 2 O 5 ha -1 year -1 ), plant densities (5,000 and 40,000 plants ha -1 ) in two sites (Caruaru and S?o Bento do Una). The productivity was greater in plots with 40,000 plants ha -1 , regardless of the site, with average of 16.8 and 7.2 t DM ha -1 two years -1 , for 40,000 and 5,000 plants ha -1 , respectively. In plots with 5,000 plants ha -1 , nitrogen fertilization did not affect productivity, however, there was a linear increase in plots with 40,000 ha -1 plants. The plant N concentration increased with nitrogen fertilization and ranged from 7.3 to 9.9 g kg -1 . The plant phosphorus (P) concentration was influenced by the interaction between all the factors evaluated and reduced until estimated fertilization of 322 kg N ha -1 in plots with 40,000 plants ha -1 and 150 kg P ha -1 and only in S?o Bento do Una, with P concentration of 1.19 g kg -1 . Nitrogen fertilization increased N concentration in cladodes and productivity when using high plant density. The increase in planting density increases productivity and reduces the concentration of most nutrients, except sulphur (S).