Bulk density by Proctor test as a function of texture for agricultural soils in Maputo province of Mozambique

Soil degradation processes may be of various kinds, including soil compaction. The present study was carried out with the objective of assessing the sensitivity of agricultural or recently abandoned soils in Maputo province of Mozambique to compaction. The assessment is based on the maximum of bulk density attained using the Proctor test (MBD).

In this study the soil texture is expressed by silt plus clay (S + C) or clay (C). The relations between the soil texture and MBD, and between soil texture and critical water content (CWC—soil water at which MBD is attained) were determined. Selected soils range from 10 to 74% of S + C and 9 to 60% of C.

The results suggest there is a relationship between the considered parameters, being that between S + C and MBD or CWC, the best. For MBD the relationship is represented by two quadratic equations with the boundary in between these being a S + C value of 25% and C value of 20%.

Based on the obtained results, one can conclude that the selected parameters may be a useful basis for estimation of the sensitivity to compaction of the Maputo province's soils. It is recommended that similar studies be carried out for soils under forest land and for soil of other provinces to establish the national physical degradation hazard as a function of soil parameters determined routinely and at low cost. The suggested parameters are texture and soil organic matter (SOM).     

Effect of cutting height and frequency on Leucaena leucocephala forage and wood production

Abstract

Leucaena leucocephala is a fast‐growing tree that can provide both high quality forage and firewood. The objective of this trial was to determine the optimum height and frequency of cutting for both wood and forage production. Cutting heights at 0.3 m, 0.6 m and 1.0 m were superimposed on 3‐month and 6‐month cutting frequencies on mature rows of L. leucocephala for three years. Effects of year or its interaction with the other factors were not significant (P≥0.10). There was an increase (P=0.07) in wood production but not forage production (P≥0.10) with the longer interval. Cutting height had an effect on forage (P<0.001) production, with 5.47 t ha^?1 a^?1 for the 0.3‐m height, 7.62 t ha^?1 a^?1 for the 0.7‐m height, and 8.71 t ha^?1 a^?1 for the 1.0‐m height. Cutting height also had an effect on wood production (P<0.001), with 7.22 t hd^?1 a^?1 for the 0.3‐m height, 9.33 t ha^?1 a^?1 for the 0.7‐mheight, and 11.55 t hd^?1 a^?1 for the 1.0‐m height. In this experiment, the six‐month interval produced more wood than the three‐month interval, but there were no differences in quantity of forage dry matter in L. leucocephala; there were advantages in both wood and forage production with the taller trunk base.     

High diversity,expanding populations and purifying selection in phytoplasmas causing coconut lethal yellowing in Mozambique

In this study, the putative phytoplasma species causing coconut lethal yellowing disease in Mozambique and Tanzania were characterized. The 16S rRNA and secA genes were sequenced. Phylogenetic analysis revealed that Mozambican coconut phytoplasmas belong to three different types: ‘Candidatus Phytoplasma palmicola’ 16SrXXII‐A, a second strain that was previously isolated in Tanzania and Kenya (16SrIV‐C), and a third strain that was different from all known lethal yellowing phytoplasma species. The third strain potentially represents a novel species and is closely related to pine phytoplasma. Co‐infection with ‘Ca. Phytoplasma pini’‐related and ‘Ca. Phytoplasma palmicola’ 16SrXXII‐A strains was observed. Furthermore, sequence variation in ‘Ca. Phytoplasma palmicola’ at the population level was consistent with purifying selection and population expansion.     

Morphological and molecular characterization of Glossidium pedatum Looss, 1899 and Orientocreadium batrachoides Tubangui, 1931 from sharptooth catfish,Clarias gariepinus (Burchell, 1822)

The superfamily Plagiorchioidea has a considerable number of genera and species with great uncertainty of their phylogenetic position. The objectives of the current study were to specifically describe the morphology and determine for the first time the phylogenetic position of Glossidium pedatum and Orientocreadium batrachoides. Examination of G. pedatum using conventional light and scanning microscopy techniques revealed undescribed features related to the digestive system, the presence of papillae-like lateral lappets, and terminal lobes covered with backwardly directed spines. Orientocreadium batrachoides revealed a pharynx that is four lobed anteriorly. Both the large (28S) and small (18S) subunits of the ribosomal genome, analysed through Bayesian inference and maximum likelihood, were used to genetically characterise these species. Phylogenies indicate that G. pedatum does not fit well into any known family within the Plagiorchioidea, as currently indicated in various systematic structures based on morphology. However, G. pedatum was closely related to Haematoloechidae according to analyses of 18S and 28S rDNA. Based on 28S rDNA, O. batrachoides formed a well-supported clade with Orientocreadium pseudobagri within the family Orientocreadiidae. In turn, Orientocreadiidae is closely related to Leptophallidae. The current study provides essential information that could be helpful to assign the family for Glossidium in future studies. Characterisation of life-cycle stages may be necessary to fully elucidate the systematic position of G. pedatum.     

An application of digital imagery analysis to understand the effect of N application on light interception,radiation use efficiency,and grain yield of maize under various agro-environments in Northern Mozambique

Light-based analysis is a fundamental approach to quantify the effects of factors determining crop growth in a given environment. The objectives of this study are to confirm the applicability of a digital imagery technique to extract green leaf areas for estimating light interception (LI) of maize canopy and to understand the effect of fertilizer application on the LI and radiation use efficiency (RUE) of maize under various agro-environments in Northern Mozambique. A locally recommended variety, Matuba, was grown in a single season with three different N application rates (0, 30, and 80 kgN ha^?1) at one hot/dry low-elevation site, two hot/humid mid-elevation sites, and one cool/humid high-elevation site. Repeated measurements with quantum sensors revealed that the digital imagery is applicable to estimate the LI of maize except for leaf-senescing period close to maturity. The N application demonstrated profitable yield increases with agronomic nitrogen use efficiencies (kg grain yield per kg N input) of 20.6–35.3 kg kg^?1 except for the low-elevation site with severe drought stress. In the mid-elevation sites, the yield increases were mostly explained by the improvement of RUE while the effect on LI was small because the vegetative growth was naturally vigorous under high temperatures irrespective of N inputs. At the high-elevation site, the N application improved its stagnant initial canopy development and increased both RUE and LI. The simple and inexpensive imagery technique should be useful to identify physiological basis of maize responses to fertilizer application and its interaction with regional environment even under poorly equipped regions in the tropics.     

莫桑比克渔业发展现状、存在问题和建议

莫桑比克渔业起步较晚,但凭借其得天独厚的自然条件和地理位置,渔业发展潜力巨大。在淡水渔业研究中心开展30多年的国际培训工作和即将开展的国际合作项目调研的基础上,整理了莫桑比克学员国家渔业发展报告和相关文献资源,就莫桑比克国内水产养殖业、捕捞业、水产品加工业和水产品贸易等方面进行全面的介绍,以期为业界了解莫桑比克渔业发展现状提供参考。     

Studies on very-low volume (VLV) water-based sprays for the control of cotton pests

We evaluated, water-based very-low volume (VLV) sprays of various pyrethroids at different dosage levels, comparing these with ultra-low volume (ULV) sprays for the control of cotton pests in the Nampula province of Mozambique. The results showed that karate (lambda-cyhalothrin) 2.5% SG at a dosage level of 15 g a.i./ha applied as VLV gave a significantly higher yield than karate 0.8% ULV (28 g a.i./ha). Also, karate 3.75% WG (12 and 15 g a.i./ha) gave a similar yield to that of karate 0.8% ULV (28 g a.i./ha). Karate 5% EC (15 and 20 g a.i./ha) gave a yield similar to Karate 0.8% ULV (28 g a.i./ha). Baythroid (cyfluthrin) 5% EC at 15, 22.5 and 30 g a.i./ha gave a yield similar to baythroid 1.2% ULV (36 g a.i./ha). Bulldock (beta-cyfluthrin) 12.5% SC at dosage levels of 6, 9 and 12 g a.i./ha gave a similar yield to that using baythroid 1.2% ULV (36 g a.i./ha). In all four trials, water-based VLV sprays gave a yield of cotton and degree of pest-control similar to those obtained with the ULV formulations at comparatively lower dosage levels. Integrated with other pest management practices, these could play an important role in the cost effective management of insect pests of cotton on small-scale farms in many countries.     

Cassava brown streak disease in northern Mozambique

Cassava brown streak disease (CBSD) of cassava ( Manihot esculenta ) caused by cassava brown streak virus (CBSV) has been known in Tanzania since the 1930s, but has not been recorded previously in Mozambique. A virus disease survey of cassava was undertaken, therefore, in 1999 in Zambezia and Nampula Provinces, which are the main areas of production in Mozambique. During the survey, CBSD was identified for the first time in these areas of Mozambique. Disease incidences in some fields in coastal areas reached 80-100% and many of the main cassava cultivars were affected. Cassava is the staple crop for most of the rural population in northern Mozambique where food security is threatened by these high incidences of CBSD.     

中莫两国大学生英语学习策略使用情况比较

中莫(莫桑比克)两国大学生在学习英语中使用学习策略存在着明显差异:在记忆策略的使用上,中国学生的使用频率明显高于莫桑比克的学生;而在社会策略的使用上,莫桑比克学生使用的频率却远高于中国学生。     

A simple agro-ecological zonation for fertilizer recommendations in Mozambique

Abstract. A practical and simple agro-ecological zonation of Mozambique is presented to facilitate the identification of production conditions and to serve as a basis for agricultural recommendations. The zonation is based on: FAO Major Soil Groupings, altitude and mean annual rainfall. The rationale of the zonation is evaluated by correlating these criteria with other climatic variables and the maize growth cycle. The effectiveness of the zonation was tested with maize yield data from fertilizer trials.
The results show that FAO Major Soil Groupings explain a significant part of the total variation in N and organic C contents, Olsen P, exchangeable K, pH and CEC. Altitude relates significantly with temperature, maize growth cycle, radiation and rainfall reliability. Mean annual rainfall relates significantly with rainfall reliability and radiation. Grouping the maize fertilizer trials according to the zonation criteria explained 39% of the variation in unfertilized yields and yield responses to NPK fertilization, and 51% of the variation in fertilized (NPK) yields.
The agro-ecological zonation on the basis of soil, altitude and mean annual rainfall proved to be a sound and practical way to identify land areas sufficiently homogeneous to be served by the same fertilizer recommendation.