Nitrogen Fertilizer Affects Growth,Yield, and N Recovery in Cassava (Manihot esculenta L. Crantz)

Cassava is a very important tuber crop in Asia. As fertilizer application, especially nitrogen (N), is important to sustain yields, the impact of different rates of N fertilizer and their time of application on growth, yield, and N-recovery efficiency was evaluated over two major seasons in Asia. Applying N at planting increased leaf area index (LAI), especially at greater rates. Split application of 90 kg N at planting and 45 days later induced growth of more tubers, resulting in good yields, when compared to single or three split applications at 45 and 90 days after planting. Split application on two occasions also developed the greatest N-recovery efficiency by both shoots and roots. The correlations between N efficiency and yield parameters were significant and negative (P = 0.05). The importance of two split applications of moderate rates of fertilizer to cassava is presented.     

A viewpoint to apply water pricing to the Asian humid tropics

The OECD has introduced a water pricing mechanism and listed eight categories gleaned from experience in OECD countries. However, in the Asian humid tropics, it is too early to apply water pricing because there is seldom a concept of water right, or practical organization of water management. In almost all irrigation projects in Japan, area charge has been applied, and collected fees have recovered entire operation and maintenance costs. Although effective volumetric charge is employed in several regions in Japan, most farmers pay area-based annual charges at several times of the year via Land Improvement Districts. In the Asian humid tropics, it is important to facilitate the establishment of sound management organizations of irrigation water before introducing a strict water pricing mechanism to levy the charge.     

Distribution of free oxides along soil profiles in time series of dry rice fields in polder lands of Kojima-basin

The distributions of free oxides along profiles of some dry rice fields were set forth in the previous reports²,³,⁴,⁶⁾, In this paper, the distribution of free oxides in dry rice field⁵⁾ in polder lands of Kojima-Basin, Okayama pref. is reported. Localities, years elapsed since the planting of rice began in each field and the characteristic of soil profiles are given in Table 1. All the fields are dry rice fields except Soil A, and carry barley or wheat in winter season. Parent materials are similar in all horizons of all soils and rich in fine particles. Fine sands (0.2-0.02 mm) are mainly composed of quartz somewhat accompanied with feldspars, mica, augite and amphibolite. Clays (< 0.002 mm) are mainly composed of halloysite accompanied with a small proportion of montmorillonite. The structure develops well in all the soils.     

Amino acid metabolism in plant leaf

¹⁴C-labelled sodium bicarbonate and ¹⁵N-labelled ammonium sulfate were simultaneously vacuum-infiltrated into detached sunflower leaves, and the incorporation of ¹⁴C and ¹⁵N into free amino acids was chased during 60-min period in the light and in the dark.

In the light, the ue specific activity of aspartic acid, alanine, serine and glycine rapidly increased for 5 min and thereafter decreased. On the other hand, that of gultamic acid continued to increase slowly during the entire 60-min period. In the dark, aspartic acid most actively incorporated ¹⁴C. The difference of changes in ¹⁴C specific activity between glutamic acid and other amino acids was also observed in the dark as in the light. These results suggest that the carbon skeleton of glutamic acid is synthesized from aspartic acid, alanine, serine and glycine.

¹⁵N content of glutamine was the highest of all amino acids investigated in the light, and it was followed by glutamic acid. alanine, aspartic acid, serine and glycine, in this order. In the dark, ¹⁵N content of glutamic acid fell remarkably and was lower than that of alanine up to 5 min. From these ¹⁵N tracer experiments, it is suggested that the incorporation of ammonium into glutamic acid is strictly dependent on light and that alanine incorporates ammonium by the direct amination besides the transamination from glutamic acid.     

An index for evaluating the flood-prevention function of paddies

Urbanization is expanding in and around small to medium-sized cities as well as in large cities, and the expansion includes low-lying areas where the flood risk is high. Flood risk in small watersheds has been evaluated using precise mathematical models. However, these models cannot be applied to larger basins due to the complexity of data collection and analysis. As a result, quantitative evaluations of flood risk at macro scales and the flood-prevention function of paddies around urban areas have not been made. This paper proposes a method and an index that can be used to evaluate the flood-prevention function of paddies on a regional scale. In addition, the use of this system for basin-wide management is illustrated by an example for the Kinu and Kokai rivers, which are tributaries of the Tone River of Japan. The applicability of the approach is evaluated using data from a major flood that occurred in the study area.     

How widespread is Parthenium hysterophorus and its biological control agent Zygogramma bicolorata in South Asia?

Parthenium hysterophorus is a weed of global significance causing severe economic, environmental, human and animal health problems in Asia, Africa, Australia and the Pacific. In South Asia, P. hysterophorus occurs in India, Pakistan, Sri Lanka, Bangladesh and Nepal. A host-specific leaf-feeding beetle Zygogramma bicolorata from México was introduced into India in 1984, as a biological control agent for P. hysterophorus . In this study, a GIS-based distribution map of P. hysterophorus and its biological control agent Z. bicolorata in South Asia based on meta-analysis is presented. The map highlights the limited published information on P. hysterophorus incidence in many of the states and territories in India, as well as in neighbouring Bangladesh, Bhutan, Nepal and Pakistan. Incidence of Z. bicolorata was recorded as three distinct clusters, covering many states in India. In Pakistan, Z. bicolorata was recorded in the Punjab region bordering India. A CLIMEX model based on the current distribution of Z. bicolorata in India suggests that the geographic range of this agent in India and Pakistan can extend to other P. hysterophorus -infested areas in the region. The CLIMEX model also suggests that all of Bangladesh and Sri Lanka, and parts of Nepal are climatically suitable for Z. bicolorata.     

利用Asia 1型口蹄疫病毒VP1蛋白的单克隆抗体建立单抗竞争ELISA方法(英文)

Using the purified VP1 protein of Asia 1 type foot-and-mouth disease virus as the antigen, the purified monoclonal antibody was labeled by the sodium periodate method and the monoclonal antibody competitive ELISA was established in this study. Ten positive porcine foot-and-mouth disease serums and more than two hundreds negative serum were tested, and the results were the same as the background of samples. The sensitivity test and replicate test indicated that this method was stable and sensitive, which was suitable for monitoring Asia 1 type porcine foot-and-mouth disease virus antibody.     

Ludwigia hyssopifolia emergence and growth as affected by light, burial depth and water management

Experiments were conducted to evaluate the effects of light, seed burial depth, and flooding on germination, emergence and growth of Ludwigia hyssopifolia. Germination was strongly stimulated by light, suggesting that seeds of this species are positively photoblastic. Seeds sown on the soil surface gave the greatest percentage of seedling emergence in plastic trays, and no seedlings emerged from seeds buried in soil at depths of ≥1 cm. Intermittent or shallow flooding suppressed emergence and growth of L. hyssopifolia. Flooding to a depth of 2 cm for 4 days out of 7 days reduced seedling emergence by more than 71% and seedling dry matter by 97% compared to where the soil had not been flooded. Flooding up to a depth of 10 cm however, when delayed to 21 days after sowing, did not significantly suppress growth of this species. This study illustrates the role of seed burial by tillage and flooding as two important tools for the management of L. hyssopifolia.     

Farmers' perceptions of soil erosion and its consequences in India's semiarid tropics

This paper investigates farmers' perceptions of soil erosion and how it affects crop yields, land values, and private conservation investments in India's semiarid tropics. It is based on three types of data: (1) a survey of farmers in three study villages; (2) a plot survey by a professional soil surveyor in the same villages; and (3) experimental and simulated data from nearby research stations with similar conditions. Farmers' perceptions of erosion are compared to the surveyor's using kappa, a statistical measure of interrater agreement. Perceived erosion–yield relationships are estimated econometrically and compared to experimental and simulated data. Effects on land values and conservation investments are estimated econometrically. Findings suggest that farmers are keenly aware of rill erosion but less aware of sheet erosion; kappa values ranging from 0 to 0·28 suggest low agreement with the soil surveyor. They anticipate annual yield losses of 5·8–11 per cent due to rill erosion; these figures are reasonably consistent with those from nearby research stations. They anticipate yield increases of 3·8–14·5 per cent due to installation of soil conservation bunds, largely because they can harvest soil from up the slope and capture organic matter. Perceived erosion has some effect on land values and soil conservation investments, but other factors such as irrigation and soil type have a much greater effect. These findings suggest that promoting soil conservation requires capitalizing on farmers' interest in short‐term gains, such as from water and nutrient management. Copyright © 2005 John Wiley & Sons, Ltd.     

新疆与中亚国家林果业和畜牧业合作潜力分析

新疆与中亚国家在林果园艺业和畜牧业上均拥有自身优势,双方合作潜力很大,合作前景广阔。在研究新疆与中亚各国林果业和畜牧业发展现状及优势的基础上,分析了双方的合作潜力。