Comparing apparent electrical conductivity measurements on a paddy field under flooded and drained conditions

Every growing season, paddy fields are kept both flooded and drained for a significant period of time. As a consequence, these soils develop distinct physico-chemical characteristics. For practical reasons, these soils are mostly sampled under dry conditions, but the question arises how representative the results are for the wet growing conditions. Therefore, the apparent electrical conductivity (EC_a) of a 1.4 ha alluvial paddy field located in the Brahmaputra floodplain of Bangladesh was measured in both dry and wet conditions by a sensing system using the electromagnetic induction sensor EM38, which does not require physical contact with the soil, and compared both surveys. Due to the smooth water surface under wet conditions which ensured increased stability of the sensing platform, the results of the survey showed considerably reduced micro-scale variability of EC_a. Furthermore, the wet survey results more reliably furnished soil-related information mainly due to the absence of soil moisture dynamics. The differences between EC_a under wet and dry conditions were attributed to differences in soil texture, mainly the sand content variation having considerable effect on soil moisture differences when flooded following drainage. Accordingly, the largest differences between EC_a under wet and dry conditions were found in those parts of the field with a large sand content. Hence, the conclusion was that an EC_a survey on flooded fields has an added value to precision soil management.     

Strategies and priorities in field collections for ex situ conservation: the case of the Israel Plant Gene Bank

The ex situ collection of the Israel Plant Gene Bank (IGB) aims to encompass the rich local flora and its genetic diversity with an emphasis on crop wild relatives. However, to properly establish a core collection, collection efforts must be prioritized and strategized. We previously classified local plant genetic resources into four priority groups that assisted in strategizing the collection activities. The following years of intensive collection activity yielded over 4200 banked accessions. However, these do not necessarily represent the distribution range of the target species for collection (TSC) and consequently, their genetic diversity. To best cover the latter, the collecting area was divided into botanical districts and the magnitude of the collection was determined according to prioritization group, e.g., a wild relative of an agricultural crop with a vast distribution range should be represented by a larger number of banked accessions than one with a smaller range. Continuous evaluation of specific needs shapes the collection scheme of the IGB to maximize collection efforts, better represent the presumed genetic diversity of TSC, and establish its core collection.     

The performance of community organisers in promotion of community forestry in Leyte Province,Philippines

A study was conducted to assess the role and effectiveness of community organisers in supporting the development of people’s organisations in achieving community-based forest management objectives in Leyte Province Philippines. Community organisers were found to be effective in forming people’s organisations (POs), motivating people to participate in voluntary activities organised by POs and encouraging cohesiveness among PO members. Community organisers manage to raise the level of environmental awareness and knowledge of members of people’s organisations, develop leadership interest and skills, create various livelihood opportunities and provide direction and facilitate the establishment of large tree plantations. However, the short duration of community organisers’ contracts (typically two years) is insufficient to establish mature and cohesive POs prepared to assume management on their own, including the management of tree plantations. Further, lack of training and funding support, low wages, delayed payment of salaries and limited time to work with people’s organisations, as well as the pressure to produce tangible outputs such the establishment of large tree plantations, prevents them from placing greater emphasis on the development and empowerment of the people.     

Farmers perception of pesticide use and genetic erosion of landraces of tetraploid wheat (<Emphasis Type="Italic">Triticum</Emphasis> spp.) in Ethiopia

Perception of farmers’ about the use of pesticides and genetic erosion of tetraploid wheat landraces of Ethiopia was assessed through focus group discussions with farmers, on-farm observations, personal interviews with farmers, by using structured questionnaires of temporal and spatial methods. A total of 1496 farmers from seven provinces in the country were interviewed. Farmers’ knowledge about pesticide increases suggests that they are not happy on using chemicals because of their negative impact on farm land. About 75 % of the farmers believe that, although the use of pesticides may increase the production of wheat, it has a negative impact on (human) health and environment. Women showed a higher concern for pesticides’ harmfulness than men. Farmers’ valuation of genetic erosion was estimated as reduced importance of landraces, as shown by a the lower proportion of landraces either grown or sold on the market. The four most important factors cited for loss of landraces were reduction in land area per capita, displacement by released/modern varieties of hexaploid wheat and teff, reduced benefit from landraces, and displacement by other crops and chat. Genetic erosion of 100 % was observed for Triticum dicoccon in the provinces of Gojam and Gonder and for T. polonicum in Tigray and Gojam. Overall, genetic erosion in the country was 32.0, 35.3, 55.9, 84.4 and 84.4 % for T. durum Desf., T. turgidum L., T. aethiopicum Jakubz., T. polonicum L. and T. dicoccon Schrank, respectively.     

Soil aggregate characteristics and stability of soil carbon stocks in a <Emphasis Type="Italic">Pinus tabulaeformis</Emphasis> plantation

Pinus tabulaeformis has been widely planted in order to conserve soil and water and improve the ecological environment in China. This study aimed to unravel how soil aggregates and soil carbon (C) stock stability of a P. tabulaeformis plantation change after 60 years of natural development and was performed in Vitex negundo var. heterophylla and Ziziphus jujuba var. spinosa shrub (shrub), a P. tabulaeformis forest (pine), and a coniferous broadleaf P. tabulaeformis mixed forest (pine-oak). Afforestation increased the stability of soil aggregates in the 0–10 cm soil layer but resulted in a decrease in the 10–20 cm soil layer. However, the presence of deciduous broadleaf species in the pine plantation improved the stability of soil aggregates. The total soil C stock was increased by afforestation, especially in the pine-oak forest, where it reached a significant level. The mineral soil C stock in the shrub stand was higher than that in pine and lower than that in pine-oak forests, but the C fractions had a different change. Afforestation increased the C fraction of macroaggregates in the 0–10 cm soil layer but decreased it in the 10–20 cm soil layer. This result suggested that afforestation could improve soil C stabilization in deeper soil. However, the pine-oak forest had a higher C fraction of macroaggregates than the pine forest in the 10–20 cm soil layer, indicating that soil C stabilization of the P. tabulaeformis plantation decreased when deciduous broadleaf species were present and thus formed the coniferous broadleaf mixed forest.     

Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

Low-input farming is an alternative production system that provides a great opportunity to disentangle the natural mechanisms regulating crop pests, since neither pests nor their natural enemies are disrupted by pesticides. Here, we use a key apple pest in Europe, the apple blossom weevil (Anthonomus pomorum), as a model case to unravel the factors driving pest infestation and its biological control in a low-input context, namely the cider apple orchards of NW Spain. We applied a holistic approach based on the complete life cycle of the pest and combined large-scale observation (23 orchards) with small-scale experimental assessment. Weevil attack (0.4–37.4% of flowers) increased with the proportion on apple trees in the immediate orchard neighbourhood and with semi-natural woody habitat in the surrounding landscape and decreased with tree distance to orchard edge and apple bloom level. Thus, the prevalence of the pest depended on the availability of the various resources required for foraging, egg-lying and overwintering. Three types of natural enemies supplied complementary pest control by preying on weevils at different stages in their life cycle: seven parasitoid species attacked immature weevils (6.4–81.5%), while the additive effects of birds and crawling arthropods were evident in terms of the removal of adult weevils (31–44%). We conclude that the effective biological control of A. pomorum can be achieved in low-input systems to maintain the pest at non-harmful levels, through combined management of the pest, its habitat and its natural enemies.     

Evidence for natural resistance towards trifloxystrobin in <Emphasis Type="Italic">Fusarium graminearum</Emphasis>

A collection of 55 Fusarium graminearum (Gibberella zeae) strains isolated between 1969 and 2009 in Belgium, Canada, Germany, Italy, Luxembourg, or the USA belonging to the three known chemotypes (3-acetylated deoxynivalenol, 15-acetylated deoxynivalenol and nivalenol) were screened for their sensitivity towards the fungicide trifloxystrobin using a liquid culture assay. None of the isolates was completely inhibited by trifloxystrobin concentrations up to 3 mM. For comparison, prothioconazole completely inhibited fungal growth of a standard isolate at concentrations as low as 0.007 mM. The maximum level of inhibition, which could be obtained by trifloxystrobin, ranged from 14 to 65% among the strains tested and was not significantly affected by the country of origin or by the chemotype. The absence of significant differences in resistance levels between the countries of origin and chemotypes as well as the fact that strains isolated before the market introduction of strobilurins in 1996 also showed a high level of resistance is evidence that this is largely a case of natural resistance and not primarily related to strobilurin use in agriculture.     

Effect of grape seed and skin supplement on milk yield and composition of dairy ewes

In the present study, we investigated the effect of grape seed and skin supplement (GSSS), on lactating dairy ewes’ production. Ten dairy pregnant ewes from northern Tunisia were allocated to two groups: control diet (C) and supplemented with 20 % (w/w) GSSS. The experiment lasted for 8 weeks and took place after 2 months of lambing. During the experiment, daily milk yield and milk composition were determined. Supplementation of the diet with GSSS increased milk production (P?<?0.001), calcium (P?<?0.01), free iron (P?<?0.01) and urea content (P?<?0.001) but had no effect on milk fat nor protein. From these data, it is concluded that the inclusion of GSSS in sheep diets increased significantly ewes’ milk yield.     

Biodegradation of carbofuran by <Emphasis Type="Italic">Pichia anomala</Emphasis> strain HQ-C-01 and its application for bioremediation of contaminated soils

A novel yeast named HQ-C-01 was isolated from activated sludge and identified as Pichia anomala based on the morphology and 18S rDNA sequence analysis. The HQ-C-01 strain degraded 95.2% of carbofuran when the insecticide was used as the only C source and added at 50 mg/L in a mineral salts medium within 48 h. The optimal concentration, temperature, and pH of medium for degradation of carbofuran were 50 mg/L, 30°C, and pH 7.5, respectively. Strain HQ-C-01 could also effectively degrade other carbamate insecticides including carbaryl, indoxacarb, and fenobucarb, and the degradation rates were 99%, 85%, and 67%, respectively. Gas chromatography–mass spectrometry analysis showed that the strain metabolized carbofuran to produce benzofuranol as the intermediate metabolite, which was further degraded. Degradation of carbofuran added at 50 mg/kg of soil was higher in yeast-inoculated soil than in the control. These results indicated that strain HQ-C-01 may potentially be used in bioremediation of carbofuran-contaminated soil.     

The potential of hyperspectral images and partial least square regression for predicting total carbon,total nitrogen and their isotope composition in forest litterfall samples

Purpose

The main objective of this study was to examine the potential of using hyperspectral image analysis for prediction of total carbon (TC), total nitrogen (TN) and their isotope composition (δ¹³C and δ¹⁵N) in forest leaf litterfall samples.

Materials and methods

Hyperspectral images were captured from ground litterfall samples of a natural forest in the spectral range of 400–1700 nm. A partial least-square regression model (PLSR) was used to correlate the relative reflectance spectra with TC, TN, δ¹³C and δ¹⁵N in the litterfall samples. The most important wavelengths were selected using β coefficient, and the final models were developed using the most important wavelengths. The models were, then, tested using an external validation set.

Results and discussion

The results showed that the data of TC and δ¹³C could not be fitted to the PLSR model, possibly due to small variations observed in the TC and δ¹³C data. The model, however, was fitted well to TN and δ¹⁵N. The cross-validation R² _cv of the models for TN and δ¹⁵N were 0.74 and 0.67 with the RMSE_cv of 0.53% and 1.07‰, respectively. The external validation R² _ex of the prediction was 0.64 and 0.67, and the RMSE_ex was 0.53% and 1.19 ‰, for TN and δ¹⁵N, respectively. The ratio of performance to deviation (RPD) of the predictions was 1.48 and 1.53, respectively, for TN and δ¹⁵N, showing that the models were reliable for the prediction of TN and δ¹⁵N in new forest leaf litterfall samples.

Conclusions

The PLSR model was not successful in predicting TC and δ¹³C in forest leaf litterfall samples using hyperspectral data. The predictions of TN and δ¹⁵N values in the external litterfall samples were reliable, and PLSR can be used for future prediction.