Higher yield and economic benefits are achieved in the macadamia crop by irrigation and intercropping with coffee

The main difficulty in expanding macadamia (Macadamia integrifolia Maiden &Betche) cultivation is the high payback period, which is caused by low yields and the long juvenile period. The use of technologies such as intercropping and irrigation has been suggested as a solution for this problem. For seven years, an experiment was conducted in the sao Paulo State, Brazil, to evaluate the growth and yield of a macadamia crop and to analyze the profitability and payback period of the investment represented by these technologies. Treatments consisted of two cropping systems (macadamia monocropping and macadamia-Arabica coffee (Coffea arabica L.) intercropping) and two water regimes (without (rainfed) or with drip irrigation) and were replicated ten times. Drip irrigation and intercropping with coffee provided the greatest growth and an earlier production of macadamia. Compared with that of rainfed macadamia monocropping, the kernel yields were 51, 176, and 251% higher in the rainfed macadamiacoffee intercropping, irrigated macadamia monocropping, and irrigated macadamia-coffee intercropping treatments, respectively. Irrigation also increased the yield of coffee intercropped with macadamia; thus, the income from this cropping system was more increased. Irrigation and intercropping with coffee reduced the payback period of the macadamia crop investment. The highest profitability was achieved using both irrigation and the intercropping of macadamia with Arabica coffee. (C) 2015 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Root morphology and phosphorus uptake by potato cultivars grown under deficient and sufficient phosphorus supply

Information regarding the characteristics that affect P-uptake capacity may assist in the selection of more adapted potato (Solanum tuberosum L.) cultivars and more adequate fertilization management for each cultivar. This study evaluated the P-uptake capacity of potato cultivars (Agata, Asterix, Atlantic, Markies, and Mondial) grown under P-deficient (2 mg L-1) or P-sufficient (31 mg L-1) conditions in nutrient solution and related it to physiological parameters of uptake and morphological root characteristics. When the plants were 24 days old, they were subjected to a P-uptake kinetics study. The length and surface area of roots and the uptake kinetic parameters (I-max, K-m, and C-min) varied among potato cultivars. Phosphorus-deficient potato plants had an approximately 60% smaller root surface area and an increase of 86% in the I-max and net P influx compared with the plants in P-sufficient conditions. However, these modifications in P uptake kinetics can do not influence P acquisition in the soil environment due to very limited P diffusion. The amount of P accumulated by plants grown under P-deficient conditions was directly related to the root length and surface area; a greater root surface, as demonstrated by the Asterix cultivar, is the most important factor for achieving a greater P-uptake capacity. Under P-sufficient conditions, potato cultivars such as Markies and Mondial showed a balance between morphological root characteristics (medium/large length and surface area) and physiological parameters (medium/high I-max values and net P influx) and had a greater P-uptake capacity. However, under field conditions, the responses to P deficiency may be different due to the very limited diffusion of P in the soil and because plants can use additional mechanisms to improve their P uptake from the soil. (C) 2014 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Upland rice yield enhanced by early nitrogen fertilization on previous palisade grass

High grain yields of upland rice (Oryza sativa L.) can be achieved in no-tillage systems. However, managing nitrogen (N) fertilization for rice in succession to forage grasses is a challenge because forage residues change N cycling and increase microbial immobilization of N, thereby reducing N availability to the subsequent cash crop. In the present study, two field experiments were conducted to determine if applying all or part of the N fertilizer on preceding palisade grass (Urochloa brizantha) and ruzigrass (Urochloa ruziziensis) or their desiccated residues immediately before rice seeding can supply N to the subsequent rice crop. Forage biomass yield (8–16 Mg ha− 1), N accumulation, and N supply to the subsequent upland rice were highest when all of the N fertilizer was applied on forage grasses at 50, 40 or 35 days before rice seeding (DBS), as opposed to the conventional split application at rice seeding and at tillering. On average, the grain yield of upland rice was 54% higher in succession to palisade grass compared with ruzigrass. The grain yield of rice was higher when N was applied to palisade grass at 35 DBS and ruzigrass at 50 DBS, reaching 5.0 Mg ha− 1 and 3.7 Mg ha− 1, respectively. However, applying N to ruzigrass was less effective for increasing upland rice yields since the yields did not differ from the treatments with the conventional split application. Adjusting the time of N application to forage grasses to increase the grain yields of subsequent upland rice is a sustainable alternative that can promote the economic viability of upland rice production