Lipophilic extractives from the cortex and pith of elephant grass ( Pennisetum purpureum Schumach.) stems

The composition of lipophilic extractives in the cortex and pith of elephant grass ( Pennisetum purpureum Schumach.) stems was thoroughly studied by gas chromatography-mass spectrometry. The predominant compounds were fatty acids followed by sterols (in free and conjugated forms as esters and glycosides). Other steroid compounds, as steroid hydrocarbons and ketones, were also present. Additionally, important amounts of mono-, di-, and triglycerides were identified. Other aliphatic series such as n-alkanes, n-fatty alcohols, and n-alkyl ferulates, together with tocopherols and a series of high molecular weight esters, were also found, although in minor amounts. The analyses also revealed the presence of a β-diketone (12,14-tritriacontanedione), which was particularly abundant in the cortex. Finally, two lignans, matairesinol and syringaresinol, were also detected. In general terms, the abundances of the different classes of compounds were higher in the pith, except for the series of n-fatty alcohols, n-alkyl ferulates, β-diketones, and lignans, which were more prominent in the cortex.     

The role of synthetic pesticides in the intensification of highland agriculture in Thailand

The objective of this study is to quantify the relationship between synthetic pesticide use and agricultural intensification in the northern highlands of Thailand. We surveyed the crop management decisions of 295 farmers across 12 villages, and assessed the level of pesticide use in terms of monetary value, the active ingredients used, and using the Environmental Impact Quotient method. The results show that 77% of the farmers relied solely on synthetic pesticides for their pest management activities. The average farmer used 13.3 kg of active ingredients per hectare of agricultural land, but the variation was large. The highest levels of pesticide use were observed with the cultivation of cut flowers and greenhouse vegetables, while greater land use intensity was associated with increased usage of synthetic pesticides and a greater potential environmental impact. We found that those farmers following public certification of Good Agricultural Practices (Q-GAP), were neither able to reduce pesticide use nor its environmental impact. The findings suggest that to limit the environmental impact caused by the use of synthetic pesticides, greater priority must be given to developing and promoting non-synthetic methods of pest control together with gradually restricting the supply of highly hazardous pesticides.     

The contribution of international vegetable breeding to private seed companies in India

Crop breeding research by international agricultural research centers usually serves public sector crop breeding, but does it still have a role when research and development have shifted to the private sector? This paper explores this question for vegetables in India using data from 27 private companies and 9 public organizations. We focus on tomato (Solanum lycopersicum L.) and chili pepper (Capsicum annuum L.)—two of India’s most important vegetables, and the role of international germplasm received from the World Vegetable Center. Results show that as the role of the private sector in vegetable breeding increased, and with it the share of hybrids in the market, the role of international agricultural research shifted from the provision of ready-made varieties to the provision of specific resistance traits. Still, international germplasm continued to be used in varietal development with 11.6 t (14 % of the total market) of hybrid tomato seed and 15.0 t (13 %) of hybrid chili pepper seed sold in 2014 containing international germplasm in its pedigree. We estimate that over half a million farmers use such seed. We conclude that for tomato and chili pepper, international breeding needs to focus on pre-breeding research, capacity strengthening of smaller seed companies, and the delivery of open-pollinated varieties for marginal environments.     

Chemical composition of lipids in brewer's spent grain: A promising source of valuable phytochemicals

Brewer's spent grain (BSG) is an important by-product from the brewing process produced in high amounts worldwide. BSG is rich in carbohydrates, lignin, proteins and lipids. In this work, the chemical composition of the lipids in BSG was studied in detail by gas chromatography and mass spectrometry. The predominant lipids were triglycerides (67% of total extract), followed by a series of free fatty acids (18%). Lower amounts of monoglycerides (1.6%) and diglycerides (7.7%) were also identified among the lipids in BSG, together with minor amounts of other aliphatic series such as n-alkanes and alkylresorcinols. Steroid compounds (steroid hydrocarbons, steroid ketones, free sterols, sterol esters and sterol glycosides) were also found in important amounts in BSG (ca. 5%), with free and conjugated sterols being the most abundant steroids. BSG can thus be regarded as a valuable source of phytochemicals of interest for the pharmaceutical, cosmetic, food or other industries.     

Structural characterization of the lignin in the cortex and pith of elephant grass (Pennisetum purpureum) stems

The structure of the lignin in the cortex and pith of elephant grass (Pennisetum purpureum) stems was studied both in situ and in isolated milled "wood" lignins by several analytical methods. The presence of p-coumarate and ferulate in the cortex and pith, as well as in their isolated lignins, was revealed by pyrolysis in the presence of tetramethylammonium hydroxide, and by 2D NMR, and indicated that ferulate acylates the carbohydrates while p-coumarate acylates the lignin polymer. 2D NMR showed a predominance of alkyl aryl ether (β-O-4') linkages (82% of total interunit linkages), with low amounts of "condensed" substructures, such as resinols (β-β'), phenylcoumarans (β-5'), and spirodienones (β-1'). Moreover, the NMR also indicated that these lignins are extensively acylated at the γ-carbon of the side chain. DFRC analyses confirmed that p-coumarate groups acylate the γ-OHs of these lignins, and predominantly on syringyl units.     

Can public GAP standards reduce agricultural pesticide use? The case of fruit and vegetable farming in northern Thailand

In response to the chronic overuse and misuse of pesticides in agriculture, governments in Southeast Asia have sought to improve food safety by introducing public standards of good agricultural practices (GAP). Using quantitative farm-level data from an intensive horticultural production system in northern Thailand, we test if fruit and vegetable producers who follow the public GAP standard use fewer and less hazardous pesticides than producers who do not adhere to the standard. The results show that this is not the case. By drawing on qualitative data from expert interviews and an action research project with local litchi (“lychee”) producers we explain the underlying reasons for the absence of significant differences. The qualitative evidence points at poor implementation of farm auditing related to a program expansion that was too rapid, at a lack of understanding among farmers about the logic of the control points in the standard, and at a lack of alternatives given to farmers to manage their pest problems. We argue that by focusing on the testing of farm produce for pesticide residues, the public GAP program is paying too much attention to the consequences rather than the root cause of the pesticide problem; it needs to balance this by making a greater effort to change on-farm practices.     

The impact of elevated water nitrite concentration on physiology,growth and feed intake of African catfish Clarias gariepinus (Burchell 1822)

The nitrite threshold concentration in rearing water of African catfish (Clarias gariepinus) was assessed. African catfish with an initial mean (SD) weight of 219.7 (57.8) g were exposed to an increasing range of water nitrite from 6 (Control) to 928 μM nitrite for 28 days. Mean (SD) plasma nitrite concentrations increased from 5.0 (3.6) to 32.5 (12.6) μM at 928 μM ambient nitrite. The increase in nitrite was accompanied by gradual increase in plasma nitrate from 41.6 (28.4) μM to 420.2 (106.4) μM. Haematocrit, haemoglobin, methemoglobin, plasma concentrations of cortisol, glucose, lactate, osmolality, gill morphology and branchial Na⁺/K⁺‐ATPase activity were not affected. Feed intake, final weight, SGR, FCR and mortality were not affected. We advise not to exceed a water nitrite concentration of 43 μM (0.6 mg L^?1 NO₂^?‐N) to prevent the risk of reduced growth and feed intake in African catfish aquaculture.     

The impact of elevated water nitrate concentration on physiology,growth and feed intake of African catfish Clarias gariepinus (Burchell 1822)

The nitrate threshold concentration in rearing water of African catfish (Clarias gariepinus) was assessed. Female African catfish with an initial mean (SD) weight of 154.3 (7.5) g were exposed to 0.4 (Control), 1.5, 4.2, 9.7 and 27.0 mM nitrate for 42 days. Mean (SD) plasma concentrations of nitrate increased from 71 (29) to 6623 (921) μM at the highest ambient nitrate level. Mean (SD) plasma nitrite concentration ranged from 1.2 (0.5) to 7.9 (9.0) μM. Haematocrit, plasma concentrations of non‐esterified fatty acids (NEFA), cortisol, glucose, lactate, osmolality, gill morphology and branchial Na⁺/K⁺‐ATPase activity were not affected. Feed intake and specific growth rate were significantly reduced at the highest nitrate concentration. We advise not to exceed a water nitrate concentration of 10 mM (140 mg L^?1 NO₃‐N) to prevent the risk of reduced growth and feed intake in African catfish aquaculture.     

Morphological characteristics and composition of lipophilic extractives and lignin in Brazilian woods from different eucalypt hybrids

The morphological and chemical characteristics of the woods from several eucalypt hybrids from the Brazilian Genolyptus program were studied. The hybrids selected for this study were Eucalyptus grandis × E. urophylla (IP), E. urophylla × E. urophylla (U1 × U2), E. grandis × [E. urophylla × E. globulus] (G1 × UGL), and [E. dunnii × E. grandis] × E. urophylla (DG × U2). The analyses of the lipophilic extractives indicated a similar composition in all eucalypt hybrids, which were dominated by sitosterol, sitosterol esters and sitosteryl 3β-d-glucopyranoside. These compounds are responsible for pitch deposition during kraft pulping of eucalypt wood. Some quantitative differences were found in the abundances of different lipid classes, the wood from U1 × U2 having the lowest amounts of these pitch-forming compounds. The chemical composition and structure of lignins were characterized by Py-GC/MS and 2D-NMR that confirmed the predominance of syringyl over guaiacyl units and only showed traces of p-hydroxyphenyl units in all the woods, with the highest S/G ratio for G1 × UGL. The 2D-NMR spectra gave additional information about the inter-unit linkages in the lignin polymer. All the lignins showed a predominance of β-O-4′ ether linkages (75-79% of total side-chains), followed by β-β′ resinol-type linkages (9-11%) and lower amounts of β-5′ phenylcoumaran-type, β-1′ spirodienone-type linkages or β-1′ open substructures. The lignin from the hybrid G1 × UGL presented also the highest proportion of β-O-4′ linkages, and therefore, it is foreseen that the wood from this hybrid will be more easily delignifiable than the other selected Brazilian eucalypt hybrids. In complement to these chemical analyses, the morphological characterization of fibers, vessels and fines revealed that hybrid eucalypt clone DG × U2 presented the most interesting properties for the manufacture of paper pulps and biofuels.     

Multi-agent simulation for the targeting of development policies in less-favored areas

Complex combinations of biophysical and socio-economic constraints characterize the less-favored rural areas in developing countries. More so, these constraints are diverse as they vary considerably between households even in the same community. We propose multi-agent systems as a modeling approach well suited for capturing the complexity of constraints as well as the diversity in which they appear at the farm household level. Given that empirical multi-agent models based on mathematical programming share the characteristics of bio-economic farm models plus some additional features, one may interpret bio-economic farm models as a special case of multi-agent models without spatial dimension and direct interaction. Evidently, spatially explicit, connected multi-agent models have higher requirements in terms of development costs, empirical data and validation. Therefore, we see them as a complement, and not a substitute, to existing bio-economic modeling approaches. They might be the preferred model choice when heterogeneity and interactions of agents and environments are significant and, therefore, policy responses cannot be aggregated linearly. We illustrate the strength of empirical multi-agent models with simulation results from Uganda and Chile and indicate how they may assist policymakers in prioritizing and targeting alternative policy interventions especially in less-favored areas.