Genotype × environment interaction amongst spring barley lines grown at sites in the northern and southern hemispheres

Summary Measurements and scores for juvenile plant habit, time to ear emergence, plant height, leaf diseases and 1000 kernel weight were recorded on 123 lines of spring barley grown at Palmerston North, (40°S) New Zealand, and at Cambridge, (52°N) England. The material was grown at both sites from F₄ to F₇.For juvenile habit, time to ear emergence, plant height and 1000 kernel weight highly significant correlations were found between sites and seasons though few accounted for more than 50 per cent of the variation. There was no evidence of closer correlation between seasons within sites than between sites and seasons, and it was concluded that selection at either site should be equally effective.Analysis of yield performance over sites and seasons within sites revealed large effects due to genotypes and seasons within sites but small effect due to sites. Large interactions were found between genotypes and sites but the genotypes × seasons within sites effect was relatively small; better agreement was found in relative yields between seasons within sites than between sites, so that yield performance in one country was a poor indication of potential performance in the other country.The implications of these results for the use of a selection nursery in New Zealand are discussed.     

The effects of cis-trans ABA on embryo germination and seed dormancy in wheat

Pre-harvest sprouting of wheat grain can cause economic losses especially in cultivars with low levels of seed dormancy. The aim of this study was to determine genotype differences in embryo sensitivity to germination in response to exogenous (+/–) cis-trans ABA treatments at different concentrations. Six white and four red seed-colored bread wheat genotypes that differed in dormancy were grown in a field near Swift Current, Saskatchewan in 2000 as a randomized complete block design with four replicates. The seed samples from this experiment were germinated in a controlled environment at 20 °C without light. The exogenous ABA treatments were 0 μM – whole seed (control), 0 μM-embryos, 25 μM – embryos and 50 μM – embryos. The ABA experiment was a factorial design with four randomized complete blocks with four ABA treatments in all combinations with the ten genotypes. A weighted (by day) germination index (WGI) was calculated for each genotype in each ABA treatment. Genotypes differed in response to ABA. The genotypes, ABA concentration and genotype by ABA concentration interaction effects were significant (p ≤ 0.05). Excised embryos showed significantly decreased dormancy in most of the experimental genotypes. The addition of exogenous ABA enhanced embryo dormancy of most genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Geographical ‘handicaps’ and small states: Some implications for the Pacific from a global perspective

Abstract: Research on the economic performance of small states has concentrated on the implications of small size and thin local markets. An interesting feature of many of the world's smallest states, of which the Pacific region has many, is that they face additional challenges than just small size. Many are remote from global markets for their products. In addition, a large number are also islands, many of which are also mountainous. Many of the smaller states are not just islands, but are also archipelagos. Hence in addition to small size, many of the world's small states also exhibit four other characteristics that may affect their economic performance: insularity, remoteness, being archipelagos and being highly mountainous entities. This paper examines the nature of the challenges posed by these four characteristics and seeks to produce empirical evidence of how difficult it has been to overcome these challenges. The paper draws on empirical evidence for 126 very small global states, dependent territories and highly autonomous regions. The paper then turns to the position of the Pacific small states and dependent territories.     

Impact of land-use changes and sedimentation on the Muhammad Nur Reservoir, South Kalimantan, Indonesia

The Muhammad Nur Reservoir (MNR) is a major multipurpose reservoir located on the Riam Kanan River in the Indonesian Province of South Kalimantan. The MNR has a high sediment trap efficiency and there is concern that accelerated erosion in the catchment, resulting from inappropriate land use, poses a significant threat to the storage capacity and effective life span of the reservoir. Furthermore, on-going deforestation of large parts of the catchment may have changed the inflow pattern to the reservoir. This paper uses data from fieldwork and published information from different sources to examine the extent of erosion and sedimentation in the catchment and the sediment delivery to the reservoir. Water level variations in the reservoir over a 22-year period are examined for changes that might indicate an alteration of the hydrologic balance in the catchment.     

Field Evaluation of Selected Soil Erosion Models for Catchment Management in Indonesia

Three models, viz., areal non-point source watershed environment response simulation (ANSWERS), universal soil loss equation (USLE) and adapted universal soil loss equation (AUSLE) are evaluated for their performance under the field conditions of the Riam Kanan catchment in South Kalimantan province of Indonesia. While ANSWERS is evaluated for its accuracy to predict both runoff and soil loss, USLE and AUSLE are evaluated for soil loss only. The study was carried out in the context of sedimentation concerns for the Muhammad Nur Reservoir—an important source of drinking and irrigation water supply for the catchment. The models are evaluated using field data collected under four different land uses and during 2 years of field experiments. The land uses considered are cropland with minimum tillage, cropland with conventional tillage, grassland and areas reforested with rubber trees. The ANSWERS model in general has a tendency to overpredict runoff values. The ANSWERS model also was relatively better for predicting soil loss followed by the AUSLE and USLE models. Overall, the ANSWERS model proved superior for predicting soil loss in the Riam Kanan catchment. However, given that the AUSLE model produced sufficiently reliable results and is relatively easy to use, the AUSLE model would also appear to be a useful tool for predicting soil erosion in the catchment.     

Specific tropism of HIV-1 for microglial cells in primary human brain cultures

Human immunodeficiency virus (HIV) frequently causes neurological dysfunction and is abundantly expressed in the central nervous system (CNS) of acquired immunodeficiency syndrome (AIDS) patients with HIV encephalitis or myelopathy. The virus is found mostly in cells of the monocyte-macrophage lineage within the CNS, but the possibility of infection of other glial cells has been raised. Therefore, the effects of different HIV-1 and HIV-2 strains were studied in primary cultures of adult human brain containing microglial cells, the resident CNS macrophages, and astrocytes. These cultures could be productively infected with macrophage-adapted HIV-1 isolates but not with T lymphocyte-adapted HIV-1 isolates or two HIV-2 isolates. As determined with a triple-label procedure, primary astrocytes did not express HIV gag antigens and remained normal throughout the 3-week course of infection. In contrast, virus replicated in neighboring microglial cells, often leading to their cell fusion and death. The death of microglial cells, which normally serve immune functions in the CNS, may be a key factor in the pathogenesis of AIDS encephalitis or myelopathy.     

Cytokinin from soluble RNA of Escherichia coli: 6-(3-methyl-2-butenylamino)-2-methylthio-9-beta-D-ribofuranosylpurine

We have isolated a compound responsible for the cytokinin activity of soluble RNA from Escherichia coli. The structure, indicated as 6-(3-methyl-2-butenylamino)-2-methylthio-9-beta-D-ribofuranosylpurine, C(16)H(23)N(5)0(4)S, on the basis of low-and high-reso!ution mass spectrometry, was established by unequivocal synthesis. The mass spectra, chromatographic behavior, and ultraviolet spectra of the compounds from natural and synthetic sources were identical.