Production and water use in lettuces under variable water supply   总被引：3，自引：0，他引：3  

M. Gallardo  L. E. Jackson  K. Schulbach  R. L. Snyder  R. B. Thompson  L. J. Wyland 《Irrigation Science》1996,16(3):125-137

The effects of a variable water supply on the water use, growth and yield of two crisphead and one romaine (i.e., Cos) lettuce cultivar were examined in a field experiment using a line source sprinkler system that produced a range of water regimes that occur in growers fields. Four locations at increasing distances from the main line were monitored through the season (i.e., from thinning to harvest, 28–63 days after planting (DAP)). These locations at the end of the season corresponded to: (1) rewatering to field capacity (FC); (2) watering with a volume 13% below that required in the field capacity treatment (0.87*FC); (3) 30% below FC (0.70*FC); and (4) 55% below FC (0.45*FC). A linear production function for dry matter accumulation and fresh weight vs. crop evapotranspiration (ET_c) was determined for lettuce during this period, giving a water use efficiency for dry matter of 1.86 g m^–2 mm^–1 and for fresh weight of 48 g m^–2 mm^–1 . For lettuce irrigated to field capacity, ET_c between thinning and harvest was 146 mm; maximum crop coefficients of 0.81–1.02 were obtained at maturity (55–63 DAP). For the three irrigation treatments receiving the largest water application, ET_c was higher in the Cos culivar than in the two crisphead lettuce cultivars which had similar ET_c. Plant fresh weight was more sensitive than dry weight to reduction in water supply. In the FC treatment, root length density and soil water extraction were greatest in the top 0–45 cm, and decreased rapidly below 45 cm depth. Soil water extraction by roots increased at lower depths when irrigation was reduced. Instantaneous rates of leaf photosynthesis and leaf water potential showed no response to the irrigation treatments in this study, despite differences in biomass production. Evaporation was determined to be the major component of ET_c for 45 of the 63 days of the growing season. The large loss of water by evaporation during mid-season and the apparent insensitivity of lettuce to the volume of irrigation during this period may provide an opportunity for reducing irrigation applications.  相似文献   

Strecker degradation of phenylalanine initiated by 2,4-decadienal or methyl 13-oxooctadeca-9,11-dienoate in model systems     

Zamora R  Gallardo E  Hidalgo FJ 《Journal of agricultural and food chemistry》2007,55(4):1308-1314

The reaction of 2,4-decadienal and methyl 13-oxooctadeca-9,11-dienoate with phenylalanine was studied to determine if alkadienals and ketodienes are able to produce the Strecker-type degradation of amino acids to the corresponding Strecker aldehydes. When reactions were carried out at 180 degrees C, both carbonyl compounds degraded phenylalanine to phenylacetaldehyde, among other compounds. The yield of the phenylacetaldehyde produced depended on the reaction pH and increased linearly with both the amount of the lipid and the reaction time. The yield of this conversion was approximately 8% when starting from decadienal and approximately 6% when starting from methyl 13-oxooctadeca-9,11-dienoate, and the reaction rate was lower for the ketone than for the aldehyde. Simultaneous to these reactions, the lipid was converted into pyrrole, pyridine, or aldehyde derivatives as a result of several competitive reactions. In particular, 9-14% of the decadienal was converted into hexanal under the assayed conditions. All these reactions are suggested to be produced as a consequence of the oxidation of the alkadienal or the ketodiene to the corresponding epoxyalkenal or unsaturated epoxyketone, which were identified in the reaction mixtures by GC-MS. All these results suggest that alkadienals and ketodienes, which are quantitatively important secondary lipid oxidation products, can degrade amino acids to their corresponding Strecker aldehydes. Therefore, under appropriate conditions, these products are not final products of the lipid oxidation and can participate in carbonyl-amine reactions analogously to other lipid oxidation products with two oxygenated functions.  相似文献   

Replacement of live food with a microbound diet in feeding Litopenaeus setiferus (Burkenroad) larvae     

P P Gallardo  R Pedroza-Islas  T García-Galano  C Pascual  C Rosal  A  Sánchez  G Gaxiola 《Aquaculture Research》2002,33(9):681-691

Microbound feeds have been well accepted by shrimps and farmers in many penaeid shrimp hatcheries. The present study focused on an adequate level of replacement of Artemia nauplii and microalgae by a microbound diet for rearing Litopenaeus setiferus (Burkenroad) larvae. A microbound diet (MBD) consisting of fishmeal, squid meal, shrimp meal, yeast meal and soybean meal was used. The first experiment was designed to obtain the optimum level of MBD to complete the live feeding schedule, from Protozoea (PZ_III) to Mysis (M_III). The experimental levels of the microbound diet tested were 2, 4, 6 and 8 mg MBD L^?1 day^?1. The next step was to determine the Artemia nauplii replacement level from PZ_I to M_III by MBD. These experiments were carried out either in the presence (Experiment 2) or in the absence of algae (Experiment 3). Four replacement levels were tested: 0% (4 mg MBD L^?1 day^?1: 1 Artemia nauplii mL^?1), 40% (5.5 mg MBD L^?1 day^?1: 0.6 Artemia nauplii), 60% (6.5 mg MBD L^?1 day^?1: 0.4 Artemia nauplii) and 100% (8 mg MBD L^?1 day^?1: 0 Artemia nauplii). In all experiments growth, survival, development, quality index (QI) and performance index (PI), were used to determine the optimum concentration of microbound diet. Results showed that 6 mg MBD L^?1 day^?1 can be recommended as a complement to live food for L. setiferus larvae from PZ_III to M_III. In the presence of algae, maximum growth and survival may be obtained in 40–60% (5.5–6.5 mg MBD L^?1 day^?1) of Artemia nauplii replacement levels. In the absence of algae, the Artemia nauplii replacement resulted in slower development, less salinity resistance, lower growth and lower survival than was obtained in larvae fed with algae.  相似文献   

The diving behaviour of little penguins in Western Australia predisposes them to risk of injury by watercraft     

Belinda Cannell  Yan Ropert‐Coudert  Ben Radford  Akiko Kato 《水产资源保护:海洋与淡水生态系统》2020,30(3):461-474

1. The most western little penguin colony globally, and the most northern in Western Australia (WA) is found on Penguin Island, WA. The penguins use coastal bays that are also used extensively by recreational watercraft. These penguins have been found to either dive predominantly to shallow depths of 1–5 m or to depths >8 m. It is thus hypothesized that (a) both the shallow and deeper diving penguins can potentially be disturbed or injured by these watercraft but that the risk will differ between the two diving strategies, and (b) that risk of injury for both is greater during the summer and autumn, when people are more likely to use watercraft.
2. This was tested by attaching data loggers to little penguins during chick rearing and by investigating necropsy records. Diving activity was studied for the very shallow and relatively deeper diving penguins separately, and we considered the penguins were vulnerable to interactions with watercraft when they were within the top 2 m of the water column or at the surface.
3. Shallow‐diving penguins executed >1,200 dives per day, 64% of dives occurred within the top 2 m, and they were vulnerable for approximately two‐thirds of their time at sea. The deeper diving penguins executed fewer dives. Almost half of dives were to ≥10 m, yet they were vulnerable for almost one‐third of their time at sea. Their post‐dive recovery was also longer. Thus, the risk of interaction from watercraft differs depending on the diving behaviour.
4. This study highlights the potential impact to little penguins throughout Australia and New Zealand.

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Triploid induction in Penaeus japonicus (Bate) with 6-dimethylaminopurine     

Belinda J Norris  Frank E Coman  Melony J Sellars  & Nigel P Preston 《Aquaculture Research》2005,36(2):202-206

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Osmoregulation in juvenile Siberian sturgeon (Acipenser baerii)     

A. Rodríguez  M.A. Gallardo  E. Gisbert  S. Santilari  A. Ibarz  J. Sánchez  F. Castelló-Orvay 《Fish physiology and biochemistry》2002,26(4):345-354

The osmoregulation capabilities of juvenile Siberian sturgeon exposed to three experimental osmolalities (22, 250 and 387 mOsmol kg⁻¹) were studied over a 45-day period. Growth performance, haematological parameters, ion concentrations, gill and spiral valve Na⁺-K⁺-ATPase activities, as well as gill and spiral valve histology, were measured. At the end of the period, the plasma osmolality of fish kept in 250 and 387 mOsmol kg⁻¹ was higher than that of fish kept in 22 mOsmol kg⁻¹. Similar trends were observed in electrolyte concentrations. Spiral valve and gill Na⁺-K⁺-ATPase activity varied with exposure time and environmental salinity. Shortly after being transferred to hyperosmotic media, spiral valve Na⁺-K⁺-ATPase activity fell, while gill Na⁺-K⁺-ATPase activity remained constant. At the end of the experiment, gill Na⁺-K⁺-ATPase activities in fish kept in isosmotic and hyperosmotic media had increased in comparison to those of the control fish. Moreover, spiral valve Na⁺-K⁺-ATPase activities recovered and were similar to those recorded in fish kept in hyposmotic environments. Although some of the morpho-physiological mechanisms were operational in juvenile Siberian sturgeon in their adaptation to hyperosmotic media, fish cannot be considered hyperosmotic regulators as they were unable to maintain their plasma osmolality and electrolyte equilibrium in salinities higher than 250 mOsmol kg⁻¹. This suggests that the culture of juvenile Siberian sturgeon in brackish environments is unlikely to be successful. However, our data indicate that in natural environments, juvenile Siberian sturgeon in migratory populations (Ob and Lena Rivers) would be able to migrate successfully into estuarine brackish grounds with a salinity of up to 9%. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Phosphatase activity, microbial phosphorus, and fine root growth in forest soils in the Sierra de Gata, western central Spain     

Knut Schneider  Maria-Belen Turrion  Pauline F. Grierson  Juan F. Gallardo 《Biology and Fertility of Soils》2001,34(3):151-155

Acid phosphatase activity (APA), labile P fractions and fine root growth were studied in an oak (Quercus pyrenaica Willd.) forest in the Sierra de Gata, in western central Spain. Soils in the region are acid and rich in organic matter, with low levels of extractable inorganic P but with a high proportion of organic P. In such soils, the activity of phosphatase enzymes is likely to be important for the control of P mineralization and P cycling and, consequently, can affect the availability of P for plant uptake. The biomass of fine roots was about 25-fold that of leaf litter, demonstrating a high allocation of C resources to the root system in order to compensate for a low availability of soil nutrients. The study compared plots fertilized with triple superphosphate (100 kg P ha^-1) to control (unfertilized) plots. Fertilizer application had no significant effect on APA and fine root density; however, there were significant differences in available and microbial P. Spatial and seasonal variations in the APA were related to plant root density and biotic demand. Seasonal differences in the APA may also be the consequence of changes in the amount of hydrolysable organic substrates at different times of the year.  相似文献   

Purkinje cell degeneration (pcd) phenotypes caused by mutations in the axotomy-induced gene, Nna1     

Fernandez-Gonzalez A  La Spada AR  Treadaway J  Higdon JC  Harris BS  Sidman RL  Morgan JI  Zuo J 《Science (New York, N.Y.)》2002,295(5561):1904-1906

The classical recessive mouse mutant, Purkinje cell degeneration (pcd), exhibits adult-onset degeneration of cerebellar Purkinje neurons, retinal photoreceptors, olfactory bulb mitral neurons, and selected thalamic neurons, and has defective spermatogenesis. Here we identify Nna1 as the gene mutated in the original pcd and two additional pcd alleles (pcd2J and pcd3J). Nna1 encodes a putative nuclear protein containing a zinc carboxypeptidase domain initially identified by its induction in spinal motor neurons during axonal regeneration. The present study suggests an unexpected molecular link between neuronal degeneration and regeneration, and its results have potential implications for neurodegenerative diseases and male infertility.  相似文献   

Erratum to: Measurement and estimation of plastic greenhouse reference evapotranspiration in a Mediterranean climate     

M. D. Fern��ndez  S. Bonachela  F. Orgaz  R. B. Thompson  J. C. L��pez  M. R. Granados  M. Gallardo  E. Fereres 《Irrigation Science》2011,29(1):91-92

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Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response     

Liu PT  Stenger S  Li H  Wenzel L  Tan BH  Krutzik SR  Ochoa MT  Schauber J  Wu K  Meinken C  Kamen DL  Wagner M  Bals R  Steinmeyer A  Zügel U  Gallo RL  Eisenberg D  Hewison M  Hollis BW  Adams JS  Bloom BR  Modlin RL 《Science (New York, N.Y.)》2006,311(5768):1770-1773

In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria, which in murine, but not human, monocytes and macrophages is mediated principally by nitric oxide. We report here that TLR activation of human macrophages up-regulated expression of the vitamin D receptor and the vitamin D-1-hydroxylase genes, leading to induction of the antimicrobial peptide cathelicidin and killing of intracellular Mycobacterium tuberculosis. We also observed that sera from African-American individuals, known to have increased susceptibility to tuberculosis, had low 25-hydroxyvitamin D and were inefficient in supporting cathelicidin messenger RNA induction. These data support a link between TLRs and vitamin D-mediated innate immunity and suggest that differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection.  相似文献