Experimental studies on sulfur dioxide injuries in higher plants

Photosynthesis is reversibly inhibited by exposing plants to SO₂. The formation of α-hydroxy sulfonate in the exposed plants is suggested as one of the effects, because this compound inhibits glycolic oxidase which is necessary in the glycolic acid pathway. The suppression of the glycolic acid path should affect various aspects of metabolism in plants, particularly the reduction of the biosynthesis of glycine and serine. In this paper, the biosynthesis of these amino acids in plants exposed to SO₂ was investigated to estimate the significance of the formation of α-hydroxy sulfonate in the plants. The results show that photosynthetic formation of serine was reduced in the exposed plants, and that α-hydroxy sulfonate was formed.     

Effect of horizontal advection induced by intrusion of the Kuroshio water on plankton biomass in the spring fishing period of shirasu on the Pacific coast of Japan

ABSTRACT:   This study explored the fundamental process that controls interannual change in plankton biomass on the Pacific coast of Japan, focusing on the spring period of shirasu fishery. A 1-D model of primary production revealed that the strength of horizontal advection induced by warm water intrusion from the Kuroshio into the Pacific coast is the most critical for plankton biomass compared with other factors such as diffusion and production. This conclusion was also confirmed by a sensitivity analysis of the model.     

The effect of ornithine and citrulline on tile utilization of arginine in rice callus tissue

There are many reports on the effect of arginine on the growth of cultivated tissues or organs. Arginine usually enhances the growth of tissues and organs (1-9).     

Amino acid composition of rice callus tissue grown with different kinds of nitrogen sources

There have been several papers dealing with the difference in chemical composition between callus tissue and normal parent tissue. WEINSTEIN, TULECKE, NICKELL, and LAURENCOT (1–3) revealed, in a series of papers, that the contents of amino acids, sugars, and nucleic acids often differed strikingly between callus and normal tissue of Agave toumeyana Trel. (1), Ginkgo biloba, L. (2), and PAUL's scarlet rose (3). STEWARD, THOMPSON, and POLLARD (4) also reported that the content of some amino acids of rapidly growing and randomly proliferating tissue is outstandingly different from that of normal tissue.     

Allantoin production and its utilization in relation to nodule formation in soybeans

A remarkable accumulation and utilization of allantoin are observed in soybean plant bearing modules (Glycine max variety A62-1). To study ita physiological role, changes in activities and distribution of the enzymes concerning the purine catabolism (i.e., xanthine oxidase, uricase, allantoinase and allantoicase) were measured during development.

Uricase activity was found in the radicles in the early stage of seedling development, and no difference of the enzyme activity was detected between the radicles of the nodulating variety (A62-) and non-nodulating variety (A62-2). On maturation the activity disappeared rapidly in radicles and appeared in leaves, pods and nodules. The activity in nodules was much higher than that in the leaves and the pods throughout the culture period.

Xanthine oxidase activity was found in the radicles and nodules.

Allantoinase activity was present in all regions of both varieties, and the specific activity in the nodules Was 2-10 times that in other regions.

Allantoicase activity was detected in the leaves, but not in the nodules.

The distribution of these enzymes suggested that allantoin is formed in the nodules and utilized mainly in the leaves after translocation.

Changes in the allantoin concentration and in the activities of uricase and allantoicase were studied in non-nodulating soybean (A62-2) grown in a culture solution containing various nitrogenous compounds. The allantoin concentration in the leaves increased as the plants were cultured in the solution containing 100 ppm of nitrate-N, urea-N or allantoin-N, whereas no uricase activity in the root was detected. The specific activity of uricase decreased in the process of plant development in all cultures. Allantoicase activity increased in the roots and leaves when the plants were cultured in this solution containing 100 ppm of urea-N or allantoin-N, indicating that allantoin is utilized easily in the soybean plants.

Intracellular localization of uricase in the nodules was studied by the method of linear sucrose density gradient centrifugation. The uricase activity was associated with the bacteroids, density 1.25.

The uricase activity peak was coincident with the peak of fonnic dehydrogenase activity (bacteria type), and not with peaks of catalase activity, cytochrome oxidase activity and absorbance at 280 nm. This evidence together with the observation by electron microscopy suggested that at uricase is associated with bacteroids.     

The effects of potato pulp and feeding level of supplements on digestibility, in situ forage degradation and ruminal fermentation in beef steers

Six ruminally cannulated Wagyu (Japanese Black) steers (average initial bodyweight (BW) 387 ± 29 kg) were used in a split‐plot design experiment, comprising a 3 × 3 Latin square design (whole plot) and a randomized block design (subplot). The whole plot treatments were three different feeding levels of supplemental diet, fed at 0.2, 0.4 and 0.6% of BW, on a dry matter (DM) basis. Subplot treatments were two different supplemental diets: a potato pulp silage‐based diet (PPS) and a grain‐based diet (GRAIN). Chopped, medium‐quality cool‐season grass hay (predominately Timothy, Phleum pratense L) was fed daily at 0.7% BW (on a DM basis) as the basal diet. Each period consisted of 21 d, which included 11 d of adaptation to the diets and 10 d of the collection period. Chromium oxide was used as an indigestible marker. In situ forage degradation was measured using the nylon bag technique. The dry matter intake increased (linear; P < 0.01) as the feeding level increased and was not affected by the diet. Digestibility was not affected by any treatments. The GRAIN diet tended to decrease the rate of in situ forage degradation as the feeding level increased, but this trend was not found in the steers fed the PPS diet. Steers fed the GRAIN diet had a lower (P < 0.1) ruminal pH compared with steers fed the PPS diet. Ruminal pH was not significantly affected by feeding level; however, it was numerically higher for steers supplemented at 0.2% per BW than that for the steers supplemented above 0.4% per BW due probably to the higher starch intake. The total volatile fatty acids concentration numerically increased as the feeding level increased and was not affected by the diet. Increasing the feeding level decreased (linear, P < 0.01) the proportion of acetate. Neither diet nor the feeding level had any effects on the proportion of ruminal propionate. The results suggested that, for steers fed the PPS diet, there are not adverse effects on forage digestion in the rumen that occur as the feeding level is increased.     

Isolation of <Emphasis Type="Italic">Penicillium hirsutum</Emphasis> from spoiled,packaged asparagus spears in Japan

During storage studies on asparagus spears packed in plastic film and held at 15°C, a Penicillium fungus was associated with subsequent spoilage. On the basis of colony characteristics, the isolate was identified as Penicillium hirsutum Diercks. This report is the first of Penicillium hirsutum causing spoilage of asparagus spears in Japan. Inoculation tests showed that among all the Penicillium species tested in this study only the identified fungus was able to infect asparagus spears.     

An effective approach to sustainable small-scale irrigation developments in Sub-Saharan Africa

Countries in Sub-Saharan Africa (SSA) that depend on foreign aid once political independence is gained, continue to be affected by changing aid modalities led by aid communities. It has been claimed that previous irrigation programs in SSA have not improved agricultural production as expected, and that the budget for implementation of further irrigation development has then been decreased. As a result, small-scale operations, which are part of participatory integrated rural development (PIRD), have become mainstream in the implementation of irrigation development in SSA. A small-scale irrigation development (SSID) was considered capable of attracting initial investment, required shorter construction periods, was comparatively easy to design, farmers were able to maintain the system themselves, and it had a lesser environmental impact. In general, to achieve a sustainable irrigation scheme, three systems must be established: a “water utilization system”; an “operation and maintenance (O&M) system”; and a “succession system”. This paper discusses SSID in SSA with regard to a number of important factors, i.e., environmental, economic, and social factors, all of which impact on the sustainability of SSID. The progress of low-input, effective, and sustainable irrigation development (LESID) and the impact of changing aid modalities is followed in three countries, Ghana, Malawi, and Tanzania. In addition, the future effective implementation of SSID by way of LESID in other SSA countries is discussed. A self-supported SSID (as employed in Malawi) is currently considered the most appropriate LESID for least developed countries (LDCs) in SSA.     

Experimental studies on SO2 injuries in higher plants III: Inhibitory effect of suite ion on 14 CO 2 fixation

Photosynthesis decreases reversibly in plants exposed to SO₂. Photosynthesis recovers when the exposure to SO₂ is discontinued. Inactivation of a photosynthetic enzyme, ribulose-1,5-diphosphate carboxylase, by sulfonation of its SH groups was investigated as a cause of the reversible reduction of photosynthesis. The relationship between the sulfite ion concentration in the reaction mixture and ¹⁴CO₂ fixation catalized by the enzyme which was prepared from alfalfa leaves was explored by using radioactive NaHCO₃. About 50% and 85% inhibitions of ¹⁴CO₂ fixation were observed at 3 × 10^?3 M and 3 × 10^?2 M concentration of sulfite ion in the reaction mixture, respectively. The accumulation of 3 × 10^?4 M sulfite ion on the reaction site of the enzyme involved in the plants which were exposed to SO₂ could considerably reduce the CO₂ assimilation of the plant.