Bringing Agroforestry Technology to Farmers in the Philippines: Identifying Constraints to the Success of Extension Activities Using Systems Modelling

This paper presents a systems modelling approach to evaluating the success of an agroforestry extension program in Leyte, the Philippines. During the program, variables which are intrinsic to farmers’ socio-economic and farming systems were found to have influenced the uptake and acceptance of extension advice. Evaluation of the program therefore depended on identifying the variables and their interdependencies and assessing their relative influence on program outputs. For this purpose, a systems approach which encourages breaking systems into component variables, but also acknowledges the context of problems, assisted construction of models. Using both empirical data collected during program activities and input from stakeholders, Bayesian Belief Network software was used to predict critical success factors for four aspects of the overall extension system, namely recruitment, use of written extension materials, farmers’ self-efficacy and retention of participating farmers throughout the program. A key predicted constraint to program recruitment is farmers’ perception of harvest security and while this variable can be partly addressed through dissemination of information on harvesting legislation, title security cannot. Differing levels of farmers’ education result in differences in predicted reading ability, comprehension of extension literature and possible misconstrual of information. The variable most critical to the development of farmers’ self-efficacy is extended on-farm technical assistance and support.     

Effects of stem girdling on cone yield and endogenous phytohormones and metabolites in developing long shoots of Douglas-fir (Pseudotsuga menziesii)

Stem-girdling treatments were applied in early spring to stimulate cone formation in two genotypes of interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco). After girdling treatments, male cone yield increased significantly in the next growing season. The increase was 14-fold in genotype 9137. In genotype 9550, more than 8,700 male cones were induced from each tree whereas no male cones were found in controls. Female cone yield was zero in controls and low for girdled trees in both genotypes. Multiple phytohormone-related compounds, including gibberellins (GAs), cytokinins, indole-3-acetic acid (IAA), abscisic acid (ABA) and their selected metabolites, were analyzed in developing long shoots after girdling treatments by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC?CESI?CMS/MS) in multiple reaction monitoring mode. Concentrations of GA₄ were slightly higher at week 2 following girdling treatment, whereas at week 8 lower GA₄ concentrations were found in girdled samples. Stem girdling did not affect concentrations of IAA and major cytokinins, such as zeatin riboside and isopentenyl adenosine. Concentrations of ABA differed two-fold between the genotypes. Although girdling treatment did not cause differences in ABA concentrations, it generally resulted in higher concentrations of ABA glucose ester. Concentration increase of 7??-hydroxy ABA by girdling was only found in genotype 9550 at week 8. Girdling caused little change in concentrations of phaseic acid in both genotypes.     

Chlorpyrifos degradation in soil at termiticidal application rates

Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] is an organophosphorus insecticide applied to soil to control pests both in agricultural and in urban developments. Typical agricultural soil applications (0.56 to 5.6 kg ha^?1) result in initial soil surface residues of 0.3 to 32 μg g^?1. In contrast, termiticidal soil barrier treatments, a common urban use pattern, often result in initial soil residues of 1000 μg g^?1 or greater. The purpose of the present investigation was to understand better the degradation of chlorpyrifos in soil at termiticidal application rates and factors affecting its behaviour. Therefore, studies with [¹⁴C]chlorpyrifos were conducted under a variety of conditions in the laboratory. Initially, the degradation of chlorpyrifos at 1000 μg g^?1 initial concentration was examined in five different soils from termite-infested regions (Arizona, Florida, Hawaii, Texas) under standard conditions (25°C, field moisture capacity, darkness). Degradation half-lives in these soils ranged from 175 to 1576 days. The major metabolite formed in chlorpyrifos-treated soils was 3,5,6-trichloro-2-pyrid-inol, which represented up to 61% of applied radiocarbon after 13 months of incubation. Minor quantities of [¹⁴C]carbon dioxide (< 5%) and soil-bound residues (? 12%) were also present at that time. Subsequently, a factorial experiment examining chlorpyrifos degradation as affected by initial concentration (10, 100, 1000 μg g^?1), soil moisture (field moisture capacity, 1.5 MPa, air dry), and temperature 15, 25, 35°C) was conducted in the two soils which had displayed the most (Texas) and least (Florida) rapid rates of degradation. Chlorpyrifos degradation was significantly retarded at the 1000 μg g^?1 rate as compared to the 10 μg g^?1 rate. Temperature also had a dramatic effect on degradation rate, which approximately doubled with each 10°C increase in temperature. Results suggest that the extended (3–24 + years) termiticidal efficacy of chlorpyrifos observed in the field may be due both to the high initial concentrations employed (termite LC ₅₀ = 0.2– 2 μg g^?1) and the extended persistence which results from employment of these rates. The study also highlights the importance of investigating the behaviour of a pesticide under the diversity of agricultural and urban use scenarios in which it is employed.     

Extensive pilot use of the grain protectant combinations,fenitrothion plus bioresmethrin and pirimiphos-methyl plus bioresmethrin

Each of the combinations, bioresmethrin (1 mg kg^?1) plus pirimiphos-methyl(6 mg kg^?1) or fenitrothion (12 mg kg^?1), was applied in 1976 to grain in 21 commercial storages. Grain condition and protectant residues were regularly monitored. Three storages became infested with Rhizopertha dominica (F.), but all storages remained free of other insect species. In two of the three infested storages, application of protectant was uneven, and the third became infested only after 8 months of storage. Despite some variations in recovered residues between sites, the mean residue levels were accurately described by predictive models. Falls in temperature during storage varied considerably, and were related to factors other than climate and bin size. There was a marked effect by aeration with ambient cold air on both the grain temperature and the rate of loss of residues. Results of collaborative studies on the determination of residues indicate a need for regular check programmes of analysis, and confirm previous conclusions that residues of fenitrothion and pirimiphos-methyl can be accurately and conventionally determined.     

Hydrolysis of precipitated phytate by three distinct families of phytases

While genetically modified plants that secrete histidine acid phosphatases (HAPs), β-propeller phytases (BPPs) and purple acid phosphatases (PAPs) have been shown to assimilate soluble phytate, little is known about whether these plants have the ability to hydrolyze precipitated phytate. In this study, the ability of representative members of these three classes of phytases to hydrolyze metal-phytate salts and to hydrolyze phytate adsorbed to aluminum precipitates was compared. All three phytases were able to hydrolyze Ca²⁺-, Mg²⁺-, and Mn²⁺-phytates, but were unable to hydrolyze Al³⁺-, Fe²⁺-, Fe³⁺-, Cu²⁺-, and Zn²⁺-phytates. When these ions were present, the hydrolysis of Ca²⁺-phytate was prevented. Citrate was more potent than malate and oxalate in solubilizing some of these phytate salts for enzyme hydrolysis. Phytate adsorbed to aluminum precipitates was resistant to all three enzymes, except when organic acids were added (citrate>oxalate>malate). While increasing concentrations of organic acids were inhibitory to enzyme activity (oxalate >citrate>malate), PAP was more resistant to citrate than HAP. As desorption of phytate from a solid surface by organic acids is essential for phytase activity, the genetic engineering of plants that enhances the secretion of both citrate and phytases from the root may be a feasible approach to improving soil phytate assimilation.     

Genetic diversity in cucumber (Cucumis sativus L.): I. A reevaluation of the U.S. germplasm collection

Genetic variation within the U.S. cucumber collection (Cucumis sativus var. sativus L. and var. hardwickii (Royle) Alef.) was assessed by examing the variation at 21 polymorphic isozyme loci and comparing the results of this investigation with a similar previous analysis of 14 loci. About 29% (15 of 51) of the enzyme systems examined in an initial survey were polymorphic. Seven loci (Ak-2, Ak-3, Fdp-1, Fdp-2, Mpi-1, Pep-gl and Skdh) which were not previously used to estimate genetic diversity, were assessed. On average, 1.4 loci were polymorphic per enzyme system and 2.2 alleles were present per polymorphic locus. The frequency of polymorphisms was relatively low for Fdp-1(2) (0.01), Mpi-1(1) (0.03), and Skdh(1) (0.02). Principal component and cluster analyses of allelic variation at polymorphic loci separated a diverse array of 757 cucumber accessions from the U.S. National Plant Germplasm Systesm's (NPGS) collection into distinct groups by country (45 nations examined). All accessions of C. s. var. sativus were isozymically distinct from C. s. var. hardwickii, which were themselves dissimilar from each other. Data suggest that C. s. var. hardwickii is not a feral derivative of extant C. s. var. sativus populations. The allelic profile of C. s. var. sativus accessions originating from Burma, Thailand, Indonesia, Hong Kong, Zimbabwe and Ethiopia were distinct from the other accessions examined. Allelic fixation has occurred at Pgd-2 in accessions from Burma, and at Ak-2 in accessions from Zimbabwe and Ethiopia. Some of the countries examined that were in close geographic proximity (e.g., Thailand, Indonesia and Hong Kong) contained accessions with similar isozyme profiles. Accessions are fixed for certain alleles [e.g., Gr(1) (100%), Fdp-1(1) (100%) and Mpi-2(2) (50%) for accessions from Thailand, Indonesia and Hong Kong]. Grouping countries by continent or sub-continent (i.e., North and South American, China, Eastern Europe, Western Europe) and by numbers of accessions examined (i.e., India/Burma, Iran, Japan, Turkey, and remaining accessions) was used to identify accessions with unique allozymic profiles [PIs 209064 (USA), 257486 (China), 188749 (Egypt), 285607 (Poland), 369717 (Yugoslavia), 357844 (Poland), 255936 (Netherlands), 183127 (India), 200818 (Burma), 200815 (Burma), 137836 (Iran), 227013 (Iran), 227235 (Iran), 451976 (Japan), 181752 (Syria), 181874 (Syria), 169383 (Turkey), 171613 (Turkey)].     

Chemical components with health implications in wild and cultivated Mexican common bean seeds (Phaseolus vulgaris L.)

Common bean effects on health have been related to its dietary fiber content and other active compounds. This study assessed the content of flavonoids, coumestrol, phenolic acids, galactooligosaccharides, and phytic acid in wild and cultivated Mexican common bean seeds (raw and cooked) and that of flavonoids, coumestrol, and phenolic acids in germinated bean seeds. The presence of isoflavones in raw bean seeds was not confirmed by the UV spectra. Quercetin, kaempferol, p-coumaric acid, ferulic acid, p-hydroxybenzoic acid, and vanillic acid mean contents were 10.9, 52.3, 10.1, 9.6, 5.4, and 18.2 microg/g, respectively; raffinose, stachyose, verbascose, and phytic acid mean contents were 8.5, 56.3, 5.5, and 11.5 mg/g, respectively, in raw seeds. All compounds were affected by autoclaving, and germination resulted in a de novo synthesis of flavonols, phytoestrogens, and phenolic acids. The impact on health of common bean seed is affected by dietary burden, specific compounds content, and processing. On the other hand, germinated bean seed or beans sprouts may be sources of antioxidants and phytoestrogens.     

Stabilization of oil-in-water emulsions by beta-lactoglobulin-polyethylene glycol conjugates

The disulfide bonds of beta-lactoglobulin (beta-lg) were modified by oxidative sulfitolysis to generate beta-lgSO(3). The native protein (beta-lg) and the modified protein (beta-lgSO(3)) were conjugated to activated polyethylene glycol (PEG) to generate beta-lgPEG and beta-lgSO(3)PEG, respectively. Oil-in-water (o/w) emulsions containing 1% beta-lg or beta-lg conjugates were prepared at pH 2.8, 5.0, and 7.0. Emulsion droplet diameters and zeta potentials were measured. For the same emulsifier, emulsion droplet diameters decreased when emulsion pH increased. Zeta potentials of emulsion droplets increased with pH for beta-lg and beta-lgSO(3). Zeta potentials of beta-lgPEG and beta-lgSO(3)PEG approached zero, suggesting that the protein molecule was covered by PEG chains. Accelerated and 7-day storage stabilities at 21 degrees C of the emulsions were monitored. The emulsifying activity index (EAI) of beta-lgPEG was not significantly different from the EAI of beta-lg. The EAI of beta-lg was enhanced following sulfitolysis of beta-lactoglobulin. The emulsifying activity increased more when the oxidatively modified protein was conjugated to polyethylene glycol. Emulsions made with beta-lgSO(3)PEG were more stable than emulsions made with beta-lg, beta-lgPEG, or beta-lgSO(3) under accelerated stability study and for 7 days at 21 degrees C. The stability of o/w emulsions stabilized with beta-lgSO(3)PEG increased because individual droplets were better protected, against protein bridging or coalescence, by the thick adsorbed protein-PEG layer.