Search

BackgroundGarcinia subelliptica(Fukugi in Japanese) is an evergreen tropical tree, first identified in Batanes, the Philippines, which has been planted as a homestead windbreak and in coastal forests extensively on the Ryukyu Archipelago, Japan. This article focuses on the traditional uses and cultural values of Fukugi trees and provides ethnobotanical information for the conservation scheme of this important tree species.MethodsA combination of ecological and ethnobotanical approaches was applied in this study. Extensive field surveys were conducted to collect dimensions of relatively large trees, and in-depth interviews with the village leaders and knowledgeable persons were conducted to collect ethnobotanical data.ResultsFukugi trees have been primarily planted as homestead or farmland windbreaks. Timber was harvested during difficult times, for example, after WWII, and used for recreational purposes for children or farmers. The fruits were also eaten on some remote islands. Old-growth Fukugi trees are widely found in sacred sites, within cities, and as symbolic trees. The older generations respect Fukugi trees; however, the cultural significance valued by older generation seems to be lacking in the younger generation. We argue that Fukugi is a cultural keystone species in Okinawa, which underpins Ryukyu culture and has transformed islands into a pleasant land, a unique place, and shared identity for the community.ConclusionsFukugi windbreaks provide significant ecosystem services, such as biodiversity in the forest, reducing soil erosion, and spiritual and cultural values. A combination of biophysical environment, as well as tradition and custom, has played an essential role in tree species selection for windbreaks. The positive impacts that anthropogenic activities have had on the sustainability of woody species, namely, the active utilization of tree species, may have enabled the species to sustain. Strategies for protecting old-growth Fukugi trees, in addition to restoration of damaged trees, are needed to improve the sustainable management of Fukugi trees in Okinawa.

The phytotoxic effects of two allelochemicals (trans-cinnamic acid and syringaldehyde) at different concentrations (1000, 100, 10, and 1 µM) on seed germination, seedling growth, and physiological and biochemical changes of Echinochloa crus-galli L. were tested by comparison to a commercial herbicide ‘Nominee’ (that is, 100 g/L bispyribac-sodium). trans-Cinnamic acid and the herbicide inhibited seed germination completely at 100 µM, whereas for syringaldehyde, complete inhibition required 1000 µM. However, with 100 µM syringaldehyde, the seed germination of the test species was 53% of the control. Allelochemicals and the herbicide delayed seed germination and significantly affected the speed of germination index (S), speed of cumulative germination index (AS), and coefficient of germination rate (CRG). The roots were more affected when nutrients were not added to the growth bioassay. In general, with the increasing concentration of allelochemicals from 100 to 1000 µM, the inhibitory effects increased. Via microscopy analysis, we found leaf blade wilting and necrosis at concentrations above 100 µM in allelochemical-treated plants. Roots of E. crus-galli treated with 1000 µM allelochemicals had black points on root nodes but had no root hairs. The anatomy of roots treated with allelochemicals (1000 µM) showed contraction or reduction of root pith cells as well as fewer and larger vacuoles compared to the control. The allelochemicals also showed remarkable effects on seedling growth, SPAD index, chlorophyll content, and free proline content in a pot culture bioassay, indicating that trans-cinnamic acid and syringaldehyde are potent inhibitors of E. crus-galli growth and can be developed as herbicides for future weed management strategies.

A series of experiments was conducted in the laboratory and greenhouse of the Subtropical Field Science Center, University of the Ryukyus, Japan, from April to October 2015 to assess the allelopathic potential of 50 indigenous Bangladeshi rice varieties by using the donor–receiver bioassay, equal compartment agar method (ECAM), plant residue extract method and pot culture method. Lettuce (Lactuca sativa L.), cress (Lepidium sativum L.), radish (Raphanus sativus L.), barnyard grass (Echinochloa crus-galli L. Beauv.) and jungle rice (Echinochloa colona L.) were used as the test plants. The highest inhibition effect was given by Boterswar, while the stimulating effect was given by Kartikbalam and Panbira in the donor–receiver bioassay and ECAM tests. Boterswar, Goria, Biron and Kartiksail were selected as the highest allelopathic-potential varieties by the donor–receiver bioassay and ECAM. In the methanol extract test, Boterswar gave the strongest inhibitory effect on both barnyard grass and jungle rice, while Kartiksail gave the highest inhibitory effect on the jungle rice shoot. The growth parameters and total dry matter of barnyard grass in the greenhouse pot experiment were significantly reduced as a result of the application of aqueous extracts of the selected rice varieties, which was similar to the results of the laboratory experiments. The varieties of Boterswar, Goria, Biron and Kartiksail were selected as the most allelopathic among the 50 indigenous Bangladeshi rice varieties. These rice varieties could be used for the isolation and identification of allelochemicals and to further develop new varieties that are tolerant to weeds.

Soil types and fertilizer regimes were evaluated on growth, yield, and quality of Amaranthus tricolor lines, IB (India Bengal), TW (Taiwan), BB (Bangladesh B), and BC (Bangladesh C) in developing management practices in Okinawa. Growth and yield of all amaranth lines were higher in gray soil (pH 8.4) than in dark red soil (pH 6.6) and red soil (pH 5.4). The combined NPK fertilizer resulted in highest growth parameters and yield of amaranths in all soils. Nitrogen fertilizer alone did not affect growth parameters and yield of amaranths in dark red and red soils. Growth parameters and yield increased similarly with the 30, 40, and 50 g m−2 of NPK fertilizer in BB line, and with the 20, 30, 40, and 50 g m−2 in BC line. Agronomic efficiency of NPK fertilizer at 50 g m−2 was not prominent on the amaranths, compared to the fertilizer at 40 g m−2. Amaranth lines had higher Na in dark red and red soils, while K and Mg in gray soil, Ca in gray and red soils, and Fe in dark red soil. The NPK fertilizer resulted in higher Na, Ca, Mg, and P in BB line in glasshouse. These minerals in BB line were not clearly affected, but in BC line were lower with NPK fertilizer at 20–50 g m−2 in field. These studies indicate that gray soil is best for amaranth cultivation and combined NPK fertilizer at 20–40 g m−2 is effective in gray soil in Okinawa for higher yield and minerals of amaranth.

In vitro dry matter digestibility (IVDMD) is one of the most important traits for grass quality improvement. Analysis of IVDMD in laboratory with a large number of breeding populations is very laborious. The objectives of this study were to evaluate IVDMD of brachiariagrass germplasm as material in breeding program, and also to determine the appropriate selection criteria for high digestibility. IVDMD (pepsin-cellulase method), morphology traits and water content of 17 genotypes of Brachiaria spp. (B. brizantha, B. decumbens, B. ruziziensis and Brachiaria hybrid) were evaluated at two harvesting times, winter and early summer seasons. The correlations among traits were determined, and their heritability were also estimated. IVDMD ranged from 48.9 to 59.0% in winter, and 42.9 to 54.4% in early summer. Among morphological traits, leaf-stem index (ratio of leaf width/stem diameter) showed the highest correlation with whole plant IVDMD (r = 0.74) followed by leaf-shape ratio (leaf width/leaf length; r = 0.72), and leaf water content also highly correlated with whole plant IVDMD (r = 0.79). The broad sense heritability of IVDMD and the related traits of two harvests combination were high with the range of 0.75–0.93. The results demonstrate that leaf-stem index, leaf-shape ratio and water content could be the useful selection criteria for the breeding of brachiariagrass for high digestibility.

To investigate the effect of nitrogen fertilization on the quality of tropical grass silage, guinea grass grown with 3 types of nitrogen fertilizers, namely, urea, ammonium sulfate, and compound fertilizer 804, at 2 fertilization levels, 0.5 and 2.5 kg (0.5 N and 2.5 N, respectively), was subjected to silage fermentation. Silage fertilized with 0.5 N showed butyrate-dominant fermentation, irrespective of the type of fertilizer used. On the other hand, fermentation of silage fertilized with 2.5 N was significantly affected by the type of fertilizer used; fertilization with ammonium sulfate and compound fertilizer 804 resulted in silage that contained a large amount of butyrate and no lactate; this silage was considered to be of a significantly low quality as compared with silage fertilized with 0.5 N. Among silage fertilized with 2.5 N, the desirable butyrate-free fermentation was found only in urea-fertilized silage, which had the best quality. Grass material fertilized with a high level of urea accumulated a relatively high concentration of nitrate nitrogen (0.22% dry matter). Our results presented here suggest that nitrogen fertilizer management could affect the quality of tropical grass silage and that a relatively high concentration of nitrate in silage may promote butyrate-free fermentation even in tropical grass silage.

The effects of relative light intensity (RLI) on the growth, yield and curcumin content of turmeric (Curcuma longa L.) were examined in Okinawa, Japan. The plants were shaded with white nets with different mesh sizes for maintaining respective RLI. Five RLI, 100 (without shading), 82, 79, 73 and 59% in 2004−2005 and four RLI, 100, 68, 52 and 48% in 2005−2006 were evaluated. In the first experiment, plant height increased markedly, but the number of leaves and tillers, and SPAD value increased slightly in the plants grown at 59−82% RLI compared with control (without shading). Turmeric shoot biomass and yield increased significantly at 59−82% RLI and they were highest at 73% RLI in the first experiment. Curcumin content of turmeric increased markedly at 59−73% RLI as compared with the control in the first experiment. Similar results in plant growth, shoot biomass, yield and curcumin content were obtained in the second experiment, but the effects of RLIs were smaller than in the first experiment because of late planting. This study indicates that turmeric is a partial shade-tolerant plant that could be cultivated at around 59−73% RLI for higher yield and curcumin content in Okinawa. However, the degree of RLI required for better turmeric cultivation may vary with the place, year and irradiance level.

A field experiment was conducted in Okinawa, Japan from 2005 to 2007 to evaluate the effect of purple nutsedge and other weeds on turmeric growth and yield and determine the effective weed-control period to minimize crop interference. Treatments consisted of all weeds removed at 70, 115, and 160 d sequentially after planting (DAP), all weeds except purple nutsedge removed at these three dates, plus weedy and weed-free controls. Purple nutsedge density increased until 115 DAP when grown alone with turmeric and thereafter decreased markedly, whereas it increased only until 70 DAP when grown with other weeds. Weed reinfestation in turmeric that was sequentially weeded was high until 115 DAP, but thereafter was negligible. In the weedy control, the weed infestation was severe until 160 DAP. Plant height and leaf and tiller number per plant of turmeric increased rapidly from 70 to 160 DAP. Season-long weed infestation significantly reduced shoot biomass and rhizome yield of turmeric, but both were similarly hi...

(2007). Effects of Application of N, P And K Alone Or In Combination on Growth, Yield And Curcumin Content of Turmeric(Curcuma Longa L.) Plant Production Science: Vol. 10, No. 1, pp. 151-154.

The effects of planting pattern and planting distance on the growth and yield of turmeric (Curcuma longa L.) were examined in Okinawa Prefecture situated in southern Japan. The dry weights of shoot and rhizome (yield) of turmeric planted in a triangular pattern were heavier than those planted in a quadrate pattern. A 30-cm-triangular planting resulted in the heaviest shoot and rhizome yield among the planting patterns examined. Dry weight of shoot per unit land area (m^2) was significantly heavier when planted at a 20- and 30-cm spacing than when planted with a larger spacing, whereas the highest yield was obtained when planted at a 30-cm spacing followed by 20- and 40-cm spacing. When turmeric was planted at a 20-cm spacing, rhizome could not expand properly, which ultimately resulted in the smaller rhizome compared with that planted with a larger spacing. The highest turmeric yield coupled with the lowest weed biomass was obtained on the two-row ridge in a 75-100cm width compared with a one-or two-row ridge in a larger or smaller width. This study indicates that for reducing weed interference and obtaining higher yield, turmeric should be planted in a 30-cm-triangular pattern on two-row ridge in a 75-100cm width., 論文

Turmeric (Curcuma longa L) plant species produces different sizes of daughter rhizomes (R) and mother rhizomes (MR), which are the only propagules (seed) for its cultivation. Here, we evaluated the effects of seed rhizome size on growth and yield of turmeric. Daughter rhizomes of 5-50 g (R-5g∿R-50g) and mother rhizomes of 48-52g (MR) were tested. The heavier the R up to 40g, the better the plant growth, and the plants from the R-30g, R-40g, R-50g and MR grew similarly well. The seed rhizomes with a greater diameter developed vigorous seedlings. The plants grown from R-30g, R-40g and R-50g had a similar plant height, tiller number and leaf number, which were significantly higher than those from lighter R. The plants from R-30g, R-40g and R-50g had a significantly larger shoot biomass and higher yield than those from smaller R in both the greenhouse and field experiments. R-50g was easily broken at the time of planting, and had secondary and tertiary daughter rhizomes, which developed thinner plants and resulted in a lower yield. The shoot biomass and yield were highest in the plants grown directly from MR, and lower in the plants grown from daughter rhizomes attached to MR. This study indicates that the turmeric seed rhizome should be 30-40g with a larger diameter, and seed mother rhizome should be free from daughter rhizomes., 論文

A glasshouse study was conducted to evaluate the effects of different rates (0, 50, 100, 200 and 400 kg ha−1) of nitrogen (N) fertilizer application on the growth, biomass production and N-uptake efficiency of torpedograss. The growth responses of torpedograss to the N application were significant throughout the observation periods. Torpedograss grown for 60 days obtained the highest total biomass of 23.0 g plant−1 with an application of 200 kg ha−1 N, followed by 20.4 g plant−1 with an application of 100 kg ha−1 N; when it was grown for 90 days a significantly higher biomass of 102.3–106.0 g plant−1 was obtained with the 200–400 kg ha−1 N than the biomass (68.0 g plant−1) obtained with the fertilizer applied at a lower rate. When the torpedograss was grown for 130 days the highest biomass was 230.0 g plant−1 with the 400 kg ha−1 N application, followed by a biomass of 150.0 g plant−1 with the 200 kg ha−1 N application, but the above-ground shoot in all treatments was over mature for animal food. The ratio of the above-ground shoot to the underground part increased with the increase in N application up to 400 kg ha−1 during the 90 days after planting (DAP), but the above-ground shoot biomass was the same with the 200 and 400 kg ha−1 N. The agronomic efficiency of the N application decreased to 5–38 with the increase in N application to 400 kg ha−1, which was less than half the agronomic efficiency with the 200 kg ha−1 N. The agronomic efficiency of N was very low (5–22) during the 60 DAP, which indicated that the N application would not be economically viable in this period for torpedograss as a pasture, and short-duration plants could be cultivated in torpedograss-infested fields to minimize weed-crop competition. The nitrogen concentration (%) in the torpedograss increased with the increase in N application, but N-uptake efficiency was the opposite and the value was very low with the 400 kg ha−1 N. The above results lead us to conclude that the N application rate of 200 kg ha−1 is the most effective for torpedograss growth.

Two field experiments each conducted during a 1 year period at the Agricultural Experiment Farm, University of the Ryukyus, Japan evaluated the interval needed between sequential applications of asulam (3 kg ai ha−1) for successful control of torpedograss (Panicum repens L.). Regrowth of torpedograss from rhizomes was lowest when asulam was applied at 40-day intervals. Application at intervals of 70 days or longer completely controlled above-ground shoots but not regrowth from rhizomes. Above-ground biomass of torpedograss regrowth was 7- and 49-fold higher when asulam was applied at 70 and 100 day intervals, respectively, compared with 40-day intervals. Asulam applied three times at 40-day intervals starting 40 days after land preparation provided almost total torpedograss control 1 year after the initial application.

This study was carried out to determine heterosis in different photosynthetic and morphological characters, and to observe photosynthetic ability and dry matter production potentiality of two F1 hybrids of rice grown in pots supplied with N fertilizer in the normal or double dose. Photosynthetic rate in terms of CO2 exchange rate (CER), leaf N concentration, SPAD value, soluble protein content and ribulose-l,5-bisphosphate carboxylase (Rubisco) activity was increased significantly by doubling the dose of fertilizer in most parental cultivars and F1 hybrids, but the rate of increase was higher in F1 hybrids than in their parents. Several morphological parameters were also increased significantly by doubling the dose of fertilizer, but not the percentage of dead leaf blades. The rates of increase of plant height, leaf area and dry matter production were higher in F1 hybrids. In particular, the rates of increase of total dry matter and root weight were very high in one of the F1 hybrids. The percentage of dead leaf blades decreased significantly in plants grown with a high dose of fertilizer as a result of higher leaf N concentration. At a normal fertilizer dose, both F1 hybrids failed to show positive heterosis in most photosynthetic characters. However, positive heterosis was found at a high fertilizer dose. Both F1 hybrids showed positive heterosis over mid-parent in dry matter production per plant at both fertilizer doses. One of the F1 hybrids also showed positive heterosis over the better parent. Heterosis in most photosynthetic and morphological characters was increased by increasing the dose of fertilizer. The sufficient supply by doubling the dose of fertilizer increased the leaf N concentration, chlorophyll content, soluble protein content and Rubisco activity in F1 hybrids, which led to higher positive heterosis in CER. A larger leaf area plus higher CER, especially at a high fertilizer dose, contributed to higher dry matter production in F1 hybrids of rice.

The present study describes the influence of temperature levels and planting time on the sprouting of rhizome-buds and the biomass production of torpedograss (Panicum repens L.) in the Okinawa prefecture, Japan. Torpedograss planted in each month (1994–95) was grown for 210 days. Sprouting of the rhizome-bud of torpedograss was 92–96% at the temperature range of 20–35°C in an incubator, and the sprouting was not observed at the extreme low and high temperature of ≤5 and ≥45°C, respectively. The plant showed 40–72% emergence when grown in pots throughout the year in the ambient temperature range of 17–29°C. The percentage emergence was comparatively higher in March to September, and shoots elongated rapidly in the period from April to October when the temperature range of 22–29°C prevailed. Torpedograss-rhizome sown in the period from January to June obtained significantly higher biomass because higher temperatures prevailed in the following growth period from May to October, as compared with the torpedograss-rhizome sown in the period of July to December. The plant required higher temperatures for proper growth and development during the period of moderate (70–110 days after planting (DAP)) and fast growth phases (110 DAP to the last harvest).

Field and glasshouse experiments were conducted from 1995 through 1996 to evaluate application timing of asulam (methyl sulfanilylcarbamate) for torpedograss (Panicum repens L.) control in relation to plant age in sugarcane. Above-ground shoots of torpedograss were completely controlled with asulam at 2–4 kg active ingredient (a.i.) ha−1 applied 60 or 80 days after planting (DAP) in artificially infested pots. But some newly developed rhizome buds survived after asulam application resulting in 1–25 and 76–100% or more regrowth in 60 and 80 DAP-applied pots, respectively. Whereas the herbicide at 2–4 kg a.i. ha−1 applied within 60 DAP completely controlled above-ground shoots, applied 80 DAP at 2 kg a.i. ha−1 it did not completely control the weed in the artificially infested field. Regrowth levels were 1–25 and 76–100% or more in 60 and 80 DAP-applied plots, respectively. Asulam at 2–3 kg a.i. ha−1 applied 20, 40, 60 or 80 DAP in a naturally infested field completely controlled above-ground shoots and regrowth levels were 76–100 or more, 51–75, 1–25 and 26–50% in these same DAP applied plots, respectively. The herbicide applied at 4 kg a.i. ha−1 caused chlorosis on younger sugarcane leaves (one-leaf stage), but when applied at 2–3 kg a.i. ha−1, no injury symptoms were shown. The herbicide at 2–4 kg a.i. ha−1 applied within 60 DAP resulted in remarkably higher yield and shoot biomass of sugarcane than that applied 80 DAP. This study suggested that asulam at 2–3 kg a.i. ha−1 should be applied 60 days after planting for the maximum control of torpedograss regrowth and better yield of sugarcane. This study also indicated that torpedograss cannot be completely controlled with a single application of asulam in a naturally infested field because of rhizome fragmentation by cross plowing and distribution of rhizomes into different soil layers that require different times to emerge. The shoots emerging after asulam application could not be controlled. Another study is required to determine the interval between sequential applications of asulam for better control of torpedograss in a naturally infested field.

In glasshouse experiments,Panicum repensrhizomes with more than two nodes emerged from soil depths of 1 to 20 cm. Emergence from one-node rhizomes was greatly reduced at depths more than 5 cm. In contrast, culm emergence from ginger like rhizomes decreased when burial depth (BD) was greater than 20 to 30 cm.P. repensemerged from deeper soil levels with an increasing number of nodes per cutting. Culms emerged from 36% of total underground regenerative organs. About 75 and 95% of the emerged culms were recorded 30 and 60 d after burial, respectively, and 91% emergence was recorded from 20-cm BD. In field studies, only 9% of nodes produced culms following cross-plowing. About 61 and 67% of the emerged culms were recorded 50 and 60 d after land preparation, respectively. Results indicate that mechanical and chemical control methods could be most effective forP. repenswhen applied approximately 50 d after land preparation. Burying deeper than 30 cm by deep plowing and reducing rhizome length by cross-plowing might effectively reduce emergence ofP. repens.

Torpedograss (Panicum repens L.) is a serious rhizomatous perennial weed in sugarcane (Saccharum offacinarum L.) in Taiwan, Hawaii and Okinawa. Two experiments were conducted to investigate torpedo-grass control and sugarcane injury using 2, 3 and 4kg ai/ha of asulam (methyl sulfanilyl carbamate) based on the time of herbicide application in the early growth stage of sugarcane. The asulam formulations used were SL (soluble concentrate, 37%) and WG (water soluble granule, 80%). Each formulation was applied at 20 days after planting (DAP) in the first experiment, and at 40DAP in the other experiment. Asulam SL and WG at 2 to 4kg ai/ha gave 100% control of torpedograss when applied either at 20 or 40DAP. Asulam applied at 20 and 40DAP required about 28 and 35 days after treatment, respectively to control torpedograss completely. Higher growth, yield and yield parameters of sugarcane were obtained by the 20DAP application of both formulations at 2kg ai/ha than those at higher rates. The formulations at 4kg ai/ha applied at 20DAP had severe injury effects on growth, yield and yield parameters of sugarcane, while 2, 3 and 4kg ai/ha of the formulations applied at 40DAP caused no negative impact on sugarcane growth, yield or yield parameters. Yield of sugarcane was significantly increased by all examined rates of the two asulam formulations applied at 40DAP in comparison with those of untreated weedy crop cultivation. The results of these experiments suggest that both asulam formulations (SL and WG) at 2kg ai/ha would successfully control torpedograss in sugarcane by post emergence application within 20-40 days of planting.

Aims: Utilization of silage in livestock farming is expected to increase in developing countries in the tropical and subtropical parts of the world. The aim of this study was to investigate the influence of nitrogen fertilization on the chemical composition of herbage, ensiling process and silage quality, and to contribute to the improvement of tropical-grass silage preparation. Methods and Results: Guinea grass grown under two different nitrogen-fertilizer application conditions [1·5 kg N a−1 (high-N) and 0·5 kg N a−1 (low-N)] was packed in plastic bags, and its ensiling process was investigated by chemical and microbial-community analyses. Relatively well-preserved silage was obtained from high-N herbage, which accumulated a high nitrate concentration. Denaturing gradient gel electrophoresis analysis revealed that Lactobacillus plantarum dominated throughout the ensiling of high-N herbage and in the early phase of that of low-N herbage. In low-N silages prepared from ammonium sulfate- and urea-fertilized herbage, Lact. plantarum was replaced by clostridia after 40 and 15 days of ensiling, respectively. Conclusions: Nitrate content of herbage is an important factor that influences silage quality, and careful fertilization management can facilitate stable and successful fermentation of tropical-grass silage without any pretreatment. Significance and Impact of the Study: The positive effect of nitrate on the ensiling process of tropical-grass was proved by microbial-community analysis.