The objective of this study was to evaluate the influence of the spacing of lettuce rows on the production of a lettuce-rocket intercropping system over two growing seasons (11 August to 25 September 2011 and 12 January to 24 February 2012) in Jaboticabal, São Paulo, Brazil. We evaluated 11 treatments in each season: lettuce-rocket intercrops with five row spacings for the lettuce (0.20, 0.25, 0.30, 0.35 and 0.40 m) and the rocket planted midway between the lettuce rows, sole crops of lettuce at the same five row spacings and a sole crop of rocket. Fresh and dry masses of the lettuce and rocket and number of lettuce leaves per plant were highest with a lettuce row spacing of 0.40 m, but the productivities of the lettuce and rocket were higher with a lettuce row spacing of 0.20 m. The productivities and fresh and dry weights of the lettuce and rocket and the number of lettuce leaves per plant were highest in the sole crops, but the fresh and dry weights of the rocket were higher with intercropping. The land equivalent ratios were >1.0 in both seasons in all intercrops and were highest for the densest crop (1.41). Intercropping was therefore 41% more efficient than sole cropping for the production of lettuce and rocket.

The adequate ratio in the supply of nitrogen (N) and potassium (K) for each phenological growth stage of melon is fundamental for its growth and development with the maximization of the dry mass partition between the vegetative and reproductive parts. The objective of this study was to evaluate the influence of N and K concentrations in two phenological growth stages (vegetative and reproductive stage) of melon and obtain the best N:K ratio for each one. In the first stage, four concentrations of N (8, 11, 14 and 17 mmol L-1) and two concentrations of K (4 and 5 mmol L-1) were evaluated in a randomized block design in a 4 × 2 factorial scheme with five replicates. In the second stage, in a 2 × 2 factorial scheme, the combinations of the two concentrations of N that generated the best characteristics in the previous stage and two concentrations of K (4.5 and 9.0 mmol L-1) were evaluated. The increase of the N concentration in the vegetative stage promoted the increase of the N, P and S content of leaves and the reduction of K, Ca and Mg. Moreover, it increased the number of leaves, the height of the plant (vertically tutored) and the leaf area. Therefore, 17:5 mmol L-1 was considered as the best N:K ratio for the vegetative stage. In the second stage, there was no effect of N and K concentrations on leaf area, yield and fruit quality. So, 14:4.5 mmol L-1 was considered as the best N:K ratio for the reproductive stage.

No abstract

In intensive vegetable production systems, it is natural to increase nutrient contents in the soil due to the frequent fertiliser applications, especially phosphorus (P). There are few studies on the response of vegetables to phosphate fertilisation under such conditions. In this context, the objective of this study was to evaluate the agronomic performance of rocket as a function of phosphorus fertilisation in a P-rich Rhodic Eutrudox soil. Five P doses (0, 50, 100, 200, and 300 kg ha-1 P2O5) were evaluated in a randomised complete block design with four replicates. Maximum soil P content and shoot P content at harvest were obtained at a dose of 300 kg ha-1 P2O5. Rocket responded negatively to P fertilisation. The increase of P doses promoted the decrease of height and yield of the crop.

The objective of this research work was to quantify both the development of potato plants of the 'Asterix' cultivar and the accumulation of nutrients by the plants. The experiment was carried out at Perdizes, state of Minas Gerais, Brazil, in a randomized complete block design with seven treatments (sampling moments) and three replications. The spatial arrangement of the plants in the field was of 0.80 m between rows and 0.35 m between plants in the row. Plant samples were taken 30, 42, 54, 66, 78, 90, and 114 days after planting (DAP) for the determinations of plant dry matter and accumulated nutrients. The potato plant was slow to grow up to 42 DAP and the highest rate of dry matter accumulation was observed between 51 and 90 DAP. Plant cycle was of 97 days and total productivity of 44 t ha -1 . Total macro nutrients accumulated by the plants up to 90 DAP were of 369.3, 184.0, 42.7, 18.0, 16.2, and 13.8 kg ha -1 of K, N, Ca, P, Mg, and S, respectively. The micronutrients Fe, Mn, Zn, B, and Cu were found to have reached values of 1,225, 525, 439, 164, and 96 g ha -1 , respectively.