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51.
The expansion of permanent trickle irrigation systems in Sao Paulo (Brazil) citrus has changed the focus of irrigation scheduling from determining irrigation timing to quantifying irrigation amounts. The water requirements of citrus orchards are difficult to estimate, since they are influenced by heterogeneous factors such as age, planting density and irrigation system. In this study, we estimated the water requirements of young ‘Tahiti’ lime orchards, considering the independent contributions from soil evaporation and crop transpiration by splitting the crop coefficient (Kc = ETc/ETo) into two separate coefficients; Ke, a soil evaporation coefficient and Kcb, a crop transpiration coefficient. Hence, the water requirement in young ‘Tahiti’ lime (ETy) is ETy = (Ke + Kcb) · ETo, where ETo is the reference crop evapotranspiration. Mature tree water requirement (ETm) is ETm = Kcb · ETo, assuming no soil water evaporation. Two lysimeters were used; one was 1.6 m in diameter and 0.7 m deep, and the other was 2.7 m in diameter and 0.8-m deep. The first one was used to calculate evaporation and the second one was used for transpiration. ETo was estimated by the Penman–Monteith method (FAO-56). The measurements were conducted during a period between August 2002 and April 2005 in Piracicaba, Sao Paulo state, Brazil. The lysimeters were installed at the center of a 1.0-ha plot planted with ‘Tahiti’ lime trees grafted on ‘Swingle’ citrumelo rootstock. The trees were 1-year old at planting, spaced 7 × 4 m, and were irrigated by a drip irrigation system. During the study period, Kc varied between 0.6 and 1.22, and Kcb varied between 0.4 and 1.0. The results suggested that for young lime trees, the volume of water per tree calculated by Ke + Kcb is about 80% higher than the volume calculated using Kc. For mature trees, the volume of water per tree calculated using just Kcb can be 10% less than using Kc. The independent influence of soil evaporation and transpiration is important to better understand the water consumption of young lime trees during growth compared to mature lime trees.  相似文献   
52.
Resistance to fumigants has been frequently reported in insect pests of stored products and is one of the obstacles in controlling these pests. The authors studied phosphine resistance and its physiological basis in adult insects of 12 populations of Tribolium castaneum (Herbst) (Tenebrionidae), ten populations of Rhyzopertha dominica (F.) (Bostrichidae) and eight populations of Oryzaephilus surinamensis L. (Silvanidae) from Brazil, and the possible existence of fitness costs associated with phosphine resistance in the absence of this fumigant. The bioassays for the detection of phosphine resistance followed the FAO standard method. The production of carbon dioxide and the instantaneous rate of population increase (r(i)) of each population of each species were correlated with their resistance ratios at the LC(50). The resistance ratio at LC(50) in T. castaneum ranged from 1.0- to 186.2-fold, in R. dominica from 2.0- to 71.0-fold and in O. surinamensis from 1.9- to 32.2-fold. Ten populations of T. castaneum, nine populations of R. dominica and seven populations of O. surinamensis were resistant to phosphine. In all three species there was significant association (P < 0.05) between respiration rate and phosphine resistance. The populations with lower carbon dioxide production showed a higher resistance ratio, suggesting that the lower respiration rate is the physiological basis of phosphine resistance by reducing the fumigant uptake in the resistant insects. Conversely, populations with higher r(i) showed lower resistance ratios, which could indicate a lower rate of reproduction of the resistant populations compared with susceptible populations. Thus, management strategies based on the interruption of phosphine fumigation may result in reestablishment of susceptibility, and shows good potential for more effective management of phosphine-resistant populations.  相似文献   
53.
The coffee berry borer, Hypothenemus hampei (Ferrari), is an important devastating coffee pest worldwide. Both trypsin and chymotrypsin enzyme activities from H. hampei larval midgut can be inactivated by proteinaceous enzyme-inhibitors. A serine proteinase inhibitor belonging to the Bowman-Birk class was purified from a wild accession of Phaseolus coccineus L. seeds. The inhibitor (PcBBI1) is a cysteine-rich protein that is heat-stable at alkaline pH. MALDI-TOF/MS analysis showed that PcBBI1 occurs in seeds as a monomer (8689 Da) or dimer (17,378 Da). Using in vitro inhibition assays, it was found that PcBBI1 has a high inhibitory activity against H. hampei trypsin-like enzymes, bovine pancreatic chymotrypsin, and trypsin. According to this, PcBBI1 could be a promising tool to make genetically modified coffee with resistance to coffee berry borer.  相似文献   
54.
Agroforestry Systems - The use of native trees in agroecosystems is a promising way to increase litter deposition and nutrient cycling and foster the recovery of degraded areas, especially in...  相似文献   
55.
New Forests - Monitoring and assessment reveal important information about restoration areas and can also be useful for understanding ecological processes such as succession and species-area...  相似文献   
56.
Agroforestry Systems - Inland waters such as streams that receive carbon from terrestrial landscapes usually have a net heterotrophic metabolism and emit significant amounts of CO2 to the...  相似文献   
57.
Precision Agriculture - Defining the ideal soybean stand is essential for obtaining maximum grain yield. As a hypothesis of the work, it was questioned whether it is possible to vary seeding...  相似文献   
58.

The development and intensification of Nile tilapia farming systems has happened together with ever increased use of antibiotics and therapeutants. Research on the use of probiotics has come along as alternative to routine use of antibiotics in fish diets. The manipulation of the gut microbiota through dietary probiotic inclusion targeting improved growth rate and disease resistance has been investigated in many farmed fish species. However, mechanisms underlying modulation of fish immune response remains unclear. This review summarizes and discuss recent findings in the role of probiotics on the immunity of Nile tilapia Oreochromis niloticus addressing available information regarding immunological parameters such as phagocytic activity, lysozyme, respiratory burst activity, antioxidant enzymes, complement system as well as immune-related gene expression, in the aim to foster research efforts on effective strategies for the successful use of probiotics in the tilapia farming industry.

  相似文献   
59.
This study evaluated the effect of short-term baths with the essential oils (EOs) of Lippia sidoides, Ocimum gratissimum and Zingiber officinale on the survival, haematological, biochemical and histopathological parameters of native fish tambaqui (Colossoma macropomum), challenged with Aeromonas hydrophila. After challenge, the fish infected with A. hydrophila received therapeutic baths of 60 min, for five consecutive days. Treatments were as follows: challenged and not treated; challenged and treated with 10 mg L?1 of gentamicin; challenged and treated with EO of L. sidoides (2.5 and 5.0 mg L?1); challenged and treated with EO of O. gratissimum (5.0 and 10.0 mg L?1); challenged and treated with Z. officinale EO (5.0 and 10.0 mg L?1). The highest survival rates were 89.5% (fish treated with 5.0 mg L?1 of O. gratissimum EO) and 75.0% (fish treated with 5.0 mg L?1 of L. sidoides EO). Reductions in the haematocrit percentage, haemoglobin and erythrocyte number were observed in fish treated with L. sidoides and Z. officinale EOs compared with control fish. Mild to moderate damage to the liver tissue of fish after challenge and EO treatments were observed. It is suggested that baths containing O. gratissimum and L. sidoides EOs consist in a viable treatment to increase survival rates of C. macropomum infected with A. hydrophila.  相似文献   
60.
This trial was performed to study the use of the mushroom Agaricus brasiliensis as an alternative additive to antimicrobial growth promoters in broiler chicken diets and to assess the quality of the broiler chicken breast meat of birds that are fed diets containing this fungus. Thus, 595 1-day-old chicks were reared in reused poultry litter without anticoccidial and antimicrobial additives. The results showed that a concentration of 1.6 g mushrooms/kg diet was ideal for these birds because it provided better bird performance. When the birds’ immune system organs were analyzed, it was found that the addition of both mushrooms influenced the immune system organs of these broiler chickens. Adding A. brasiliensis to broiler chicken diets did not compromise breast meat quality.  相似文献   
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