Modelling species and spacing effects on root zone water dynamics using Hydrus-2D in an Amazonian agroforestry system

Modelling the root zone water dynamics in a tree crop agroforestry system is a useful approach to understanding small-scale effects in tree crop systems and may be helpful for optimizing tree spacing in agroforestry system planning. The agroforestry system in this study consists of the species Theobroma grandiflorum (Willd ex Spreng) Schum (Cupuaçu), Bactris gasipaes H.B.K. (peach palm) and the cover crop Pueraria phaseoloides (Roxb.) Benth (Pueraria). The soiltype is an oxisol. Calibration was conducted for each of the three species separately. Calibration results show good conformity between simulated and measured data. Simulated scenarios examine the influence of different spacing between trees on root water uptake, evaporation and drainage. Mean interception and crop factors of the whole flow region vary with spacing or are held constant to examine below-ground effects only. Also a fictitious scenario of an older agroforestry system with deeper roots is calculated. In order to overcome restrictions of the computer program Hydrus-2D, correction factors in the root zone were introduced and a calculation scheme for root water uptake of a flow subregion was developped. Below-ground effects of spacing between trees are not or almost not present, but the depth of the tree roots has a significant influence on root water uptake, evaporation and drainage. When mean interception and crop factor vary, drainage increases and root water uptake decreases slightly with spacing. The modelling approach has been found promising for optimizing agroforestry systems although it can only be seen as a first beginning. In an agroforestry systems under drier conditions differences in results will probably be larger.     

Bioavailability of zinc glycinate in comparison with zinc sulphate in the presence of dietary phytate in an animal model with Zn labelled rats

The objective of this study was to quantify the bioavailability of zinc (Zn) from sulphate and glycinate as representatives of inorganic and organic zinc sources. The semi-synthetic basal diet contained 2 microg/g of native Zn and was fortified with pure sodium-phytate (8 g/kg) in order to simulate conditions of common cereal-based meals. The basal diet was supplemented with either 53 microg/g of Zn from sulphate (control) or 10 microg/g of Zn from either sulphate (ZnSulphate) or glycinate (ZnGly). Twenty-four (65)Zn-labelled, growing rats weighing 133 g were allotted to the three diets (eight animals per treatment) and were kept pair-fed to ZnSulphate for 15 days. Zn contents in blood plasma, femur and whole body, as well as, plasma alkaline phosphatase activities were reduced compared with control indicating a zinc deficiency in ZnSulphate and ZnGly treatment. This allowed their differentiation in zinc bioavailability. True absorption of dietary Zn was significantly higher in ZnGly than in ZnSulphate (51% vs. 44%) while losses of endogenous faecal Zn and urinary Zn were not affected to a quantitatively relevant extent (mean: 17% and 2% of intake). This resulted in a +30% significantly improved Zn retention for ZnGly (33% vs. 25%) and a lower severity on Zn deficiency symptoms compared with ZnSulphate. Metabolic utilization accounted for 95% of absorbed dietary Zn for both Zn sources. Overall, the bioavailability of zinc glycinate was significantly superior by 16% to zinc sulphate (49% vs. 42%), mainly because of a higher absorptive potential at presence of a strong anti-nutritive component (phytate) in the diet.     

Rates of foliar penetration of chelated Fe(III): role of light, stomata, species, and leaf age

Rates of foliar penetration of Fe(III) chelates of imidodisuccinic acid (IDHA), ligninsulfonic acid (Natrel), and citric acid (ammonium ferric citrate) were studied at 20 degrees C using a leaf disk method. After drying of the donor droplets, the humidity over the donor residues was maintained at 100% because Fe(III) chelates deliquesce only when humidity is higher than 90%. The wetting agent Glucopon 215 CSUP was added at a concentration of 0.2 g L(-1) to all donor solutions. With fully expanded stomatous broad bean leaves, penetration of Fe-IDHA followed first-order kinetics and rate constants of penetration were higher in light (0.073 h(-1)) than in the dark (0.042 h(-1)). Permeability of broad been leaves to CaCl2 was about 8 times higher than to Fe-IDHA. Doubling the Fe-IDHA concentration in the donor from 2.5 to 5 mmol L(-1) decreased rate constants of Fe-IDHA penetration by a factor of 2.2. Adding the silicon surfactant Break Thru S240 at 10 g L(-1) to the donor induced infiltration of open stomata and about 80% of the applied Fe-IDHA penetrated during droplet drying, while with Glucopon 215 CSUP stomatal infiltration was not observed. With broad bean leaves, penetration of Natrel and ammonium ferric citrate also followed first-order kinetics and rate constants were also higher in light than in the dark. Adaxial astomatous surfaces of fully expanded pear, apple, and grapevine leaves were practically impermeable to Fe-IDHA while stomatous abaxial leaf surfaces were permeable, but rate constants of penetration decreased with time and differed greatly among species. Astomatous surfaces of young unfurling grapevine and peach leaves were permeable to Fe-IDHA, but permeability of stomatous surfaces was much higher. The effect of light on permeability of stomatous leaf surfaces is attributed to the presence of aqueous pores in cuticles over guard cells, and it is suggested that permeability of these pores increases as stomata open. Consequences of these results for foliar applications of Fe chelates are discussed.     

IgA and secretory component (SC) in the third eyelid of domestic animals: a comparative study

Objective The third eyelid of domestic animals is important for the production and distribution of tears, in removing ocular debris and in protection of the globe, and has significant immunologic functions. Although it is known that tears contain antibodies of the immunoglobulin A (IgA) isotype which are produced mainly by plasma cells of the lacrimal gland, very little is known about the antibody repertoires in the third eyelid of domestic animals. To assess whether IgA is derived from local synthesis, we analyzed the location of IgA‐producing cells and the cellular distribution of secretory component (SC) in the third eyelid of domestic animals in a comparative study. Animal studied A total of 83 third eyelids of dogs, cats, pigs, cows, sheep, goats and horses were investigated in the course of this study. Procedures Third eyelids were obtained immediately after death, cut length‐wise, fixed overnight and processed for immunohistochemical detection of IgA and SC by the ABC technique. Results The results show that IgA‐producing plasma cells are densely populated in subepithelial spaces of the surface epithelium as well as in the nictitating gland in a species‐specific manner. In contrast, the SC could be demonstrated exclusively in glandular acinar and ductal epithelial cells and in different cell types of the surface epithelium, preferentially located on the bulbar side of the nictitating membrane. Conclusion It is suggested that most of the SC is locally produced by resident plasma cells and subsequently transferred through the surface epithelium and glandular duct cells by transcytosis. This indicates that the third eyelid is an important member of the secretory immune system in domestic animals.     

Schorffungizide—Ihr Einfluss auf die Penetration von Kalziumchlorid in Äpfel

To examine the effect of fungicides against apple scab on the penetration of CaCl₂ in apples, experiments were conducted in a growth chamber using segments of Golden Delicious apples 89 days after full bloom in 2003. ⁴⁵CaCl₂ (5 g l^?1) and mixtures of the ⁴⁵CaCl₂ solution with the fungicides Baycor, Discus, Benomyl, Malvin, and Omnex at concentrations recommended for commercial practice were applied to the fruit segments. The penetration experiments were conducted with and without adding the alkylpolyglycoside Plantacare 1200 UP (0.2 g l^?1) as wetting agent in the ⁴⁵CaCl₂ solution and each mixture of fungicide + ⁴⁵CaCl₂ solution. The results show that a suitable wetting agent is necessary to obtain high rates of CaCl₂ penetration. While only 1.2% of the applied dose penetrated the fruit surface in the CaCl₂ control without the wetting agent, 17.9% penetration was found in fruit segments after 24-h incubation when the wetting agent was added. The mixtures of CaCl₂ solution with Baycor and Discus but without additional wetting agent resulted in penetration rates of 1.1% and 1.3% respectively of the applied dose within 24 h, and the mixtures with Malvin and Omnex resulted in 3.5% and 5.6% penetration within 24 h. Adding the wetting agent Plantacare 1200 UP to the CaCl₂-fungicide mixtures revealed penetration between 12.5% and 15.5% of the applied dose within 24 h. Thus, adding a wetting agent increased the CaCl₂ penetration by factors of 3 to 14. This promoting effect was not observed when it was added to the CaCl₂-Benomyl mixture. Adding the wetting agent to the applied CaCl₂ solution and the CaCl₂-fungicide mixtures lowered surface tension of all solutions below 30 mN m^?1. The importance of low surface tension is discussed with regard to calcium penetration via hydrophilic pores in the cuticle and to infiltration of lenticels by the fungicide-CaCl₂ solutions.     

Response of corn, grain sorghum, and sunflower to irrigation in the High Plains of Kansas

Groundwater is being mined in much of the irrigated area of the central and southern High Plains of the USA. Profits and risks inherent in irrigation management depend on the association between crop yield and level of water application. Research was conducted over a 14 year period (1974–1987) to establish the yield vs. water application relationships of corn, grain sorghum, and sunflower. The research was located near Tribune, Kansas, USA on a Ulysses silt loam soil. Plots were level-basins to which water was added individually through gated pipe. Irrigation studies of the three crops were located adjacent to each other. Irrigation treatments were arranged in completely randomized blocks with three replications. As total irrigation amount increased from 100 to 200, 200 to 300, and 300 to 400 mm, sunflower yield increased by 0.53 Mg ha⁻¹, 0.43 Mg ha⁻¹, and 0.37 Mg ha⁻¹, respectively. Corn outyielded grain sorghum at total irrigation amounts of 345 mm and above. Yield increase over continuous dryland was greater in corn than in grain sorghum at total irrigation amounts above 206 mm. Therefore, if grain mass is the consideration, grain sorghum is a better choice than corn at less than 206 mm of irrigation, whereas corn is a better choice than grain sorghum at more than 206 mm of irrigation.     

Effects of additional zinc and phytase on zinc availability in piglets and chicks fed diets containing different amounts of phytates

Two maize based diets containing 2.3 g phytic P and 38 mg Zn/kg (P+) or 1.3 g phytic P and 25 mg Zn/kg (P−) were formulated. A third diet (P+/Phytase) was P+ supplemented with 3-phytase (500 FTU/kg). Each of these three basal diets, supplemented or not with 15 mg Zn/kg, was given during 20 days to weaned piglets and to 1-day-old chicks. Chicks fed the P− diets were removed from the data set because of an abnormally low feed intake.

In piglets, added Zn increased bone (P < 0.05) and plasma Zn (P < 0.01) irrespective of the basal diet (basal diet × Zn, P > 0.05). Supplementing P+ with phytase was more efficient in improving these indicators of Zn status than replacing P+ by P−. In chicks, supplemental Zn improved Zn status in a higher extent when added to P+ than to P+/Phytase (basal diet × Zn, P < 0.05). Phytase increased Zn status in a lesser extent than 15 ppm supplemental Zn. More Zn was soluble in gizzard than in stomach which corresponded to the differences in pH (4.2 vs 5.0). Phytase increased soluble Zn in stomach (P < 0.05) but not in gizzard. These results suggest a higher availability of Zn in chicks than in piglets in the absence of phytase. This may explain the higher efficacy of phytase for improved Zn availability in piglets than in chicks.     

仔猪喜爱甜味饲料

全球饲料业每年用在调味剂上的花费大约为一亿五千万欧元. 用在调味剂上的花费,大约一半是用在幼猪日粮的.幼猪若能在这一关键阶段内增加食欲,就可减轻其断奶后应激综合征,因为断奶后离开母猪、运送去新猪舍、建立新秩位而等都会对仔猪产生应激,尤其可减轻因日粮改变而产生的应激.