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The purpose of this study is to identify the different effects exerted by planting density and nitrogen fertilization on high-salinity reclaimed paddy fields (RPF) and general paddy fields (GPFs), and to find the amount of fertilization and the planting density suitable for the growth of forage rice in each paddy field. Nitrogen fertilization with high-salt and low-salt soils, an untreated control plot, treatment with 200 kg/ha, 300 kg/ha, and 400 kg/ha, and planting densities of 30 cm × 10 cm and 30 cm × 16 cm, growth, and feed values were investigated. In both experimental locations, there was no significant change in the soil due to N treatment, but in the case of RPF, electrical conductivity (EC) decreased significantly from more than 5 dS/m to up to 2.87 dS/m during the yellow ripe stage due to the influence of floods and concentrated precipitation in the fields. In all soils, as both the amount of N treatment and the planting density increased, there was a proportional relationship in which the number of tillers and the dry weight also increased, with the occurrence of lodging also being increased. The dry weight, as expected, was 1.5 times higher at a planting distance of 10 cm, rather than 16 cm. In addition, in both locations, the N treatment led to an increase in the dry weight, but when N treatment reached 400 kg/ha (2.0), the dry weight decreased instead. Moreover, although there was no clear difference in feed value according to N treatment, in RPF, the neutral detergent fiber (NDF) was higher than 60%, the relative feed value (RFV) was less than 98, and the total digestible nutrient (TDN) was also low, confirming that the quality of rice was higher in GPF. [ABSTRACT FROM AUTHOR]

The purpose of this study is to identify the different effects exerted by planting density and nitrogen fertilization on high-salinity reclaimed paddy fields (RPF) and general paddy fields (GPFs), and to find the amount of fertilization and the planting density suitable for the growth of forage rice in each paddy field. Nitrogen fertilization with high-salt and low-salt soils, an untreated control plot, treatment with 200 kg/ha, 300 kg/ha, and 400 kg/ha, and planting densities of 30 cm × 10 cm and 30 cm × 16 cm, growth, and feed values were investigated. In both experimental locations, there was no significant change in the soil due to N treatment, but in the case of RPF, electrical conductivity (EC) decreased significantly from more than 5 dS/m to up to 2.87 dS/m during the yellow ripe stage due to the influence of floods and concentrated precipitation in the fields. In all soils, as both the amount of N treatment and the planting density increased, there was a proportional relationship in which the number of tillers and the dry weight also increased, with the occurrence of lodging also being increased. The dry weight, as expected, was 1.5 times higher at a planting distance of 10 cm, rather than 16 cm. In addition, in both locations, the N treatment led to an increase in the dry weight, but when N treatment reached 400 kg/ha (2.0), the dry weight decreased instead. Moreover, although there was no clear difference in feed value according to N treatment, in RPF, the neutral detergent fiber (NDF) was higher than 60%, the relative feed value (RFV) was less than 98, and the total digestible nutrient (TDN) was also low, confirming that the quality of rice was higher in GPF.

Tachisuzuka, a rice cultivar for whole-crop silage, is characterized by a small panicle and high sugar content in the stem. Our previous study suggests that the high sugar content in the stem of Tachisuzuka is due to a factor other than the small panicle. To characterize sugar metabolism in the stem of Tachisuzuka, here we compared carbohydrate content, enzyme activity, and the expression of genes involved in sugar metabolism in the stem between Tachisuzuka and its parental variety, Kusanohoshi. Thinning the panicles of Kusanohoshi increased the starch content in the leaf sheath and internode but did not increase the sucrose content in the leaf sheath to the same level as that of Tachisuzuka. This suggests that Tachisuzuka has high potential to accumulate sucrose in its leaf sheath. Comparison of enzyme activity showed that the hexokinase activities in the leaf sheath tended to be higher in Tachisuzuka than Kusanohoshi or panicle-thinned Kusanohoshi, suggesting that glucokinase or fructokinase affects sugar accumulation in the stem of Tachisuzuka. Comparative transcriptome analysis revealed the differences in expression levels of carbohydrate-related genes between Tachisuzuka and Kusanohoshi. In particular, the expression levels of ISA2, which encodes starch-debranching enzyme, and TMT2, which encodes tonoplast monosaccharide transporter – both of which maybe involved in sugar accumulation in grass stems – were higher in Tachisuzuka than Kusanohoshi. Thus, these enzymes and transporters may contribute to the high sugar content in the stem of Tachisuzuka.

Cultivation of forage rice for whole‐crop silage has been increasing in Japan and will be important in Asia. In this study, effects of cultural practices on growth and yield of a forage rice cultivar "Tsukisuzuka" having short panicle 1 allele were analysed quantitatively using linear mixed model. The contribution of basal dressing to dry yield per 1 g/m2 nitrogen fertilizer was larger than that of topdressing. In addition, topdressing 30 and 20 days before heading was considered to have the disadvantage of increasing risk of lodging and panicle weight respectively. Effects of weather elements on growth of forage rice were also speculated. In tested fields, high solar radiation at seedling and tillering stage was considered important for the high yield. As the number of continuous cropping cycles increased, growth of forage rice got worse. And application of compost improved growth of forage rice. Elemental analysis of soil and plants revealed that this continuous cropping obstacle was likely to attributed to deficiency of potassium. In addition, potassium deficiency increased panicle weight of a forage rice cultivar having short panicle 1 allele. Therefore, control of potassium nutrition will be useful for both sustaining productivity (sufficient application of potassium) and seed production (restriction of potassium). These findings will be useful for improvement of cultivation method of forage rice. [ABSTRACT FROM AUTHOR]

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Two consecutive pilot-scale experiments were conducted to investigate the potential reuse of treated municipal wastewater (TWW) as an irrigation source for cultivating forage rice (Oryza sativa L., cv. Bekoaoba) through examining our newly developed continuous irrigation systems, namely surface and subirrigation. Although only P-fertilizer was applied in 2016 and no fertilizer was supplemented in the 2017 season, the obtained yields were comparable to that recorded from normal paddy fields (7.3 t ha−1). The yields of the subirrigation plots (9.1 and 7.5 t ha−1) were significantly higher than those of the surface irrigation plots (7.5 and 7.1 t ha−1) in 2016 and 2017, respectively. There was no significant difference in the protein content of brown rice between the two fields, and this content (11.6–13%) was significantly higher than that (8.8%) recorded in normal paddy fields. This indicates our harvested rice was more favorable for animal husbandry since it can reduce the use of costly protein feed such as imported soymeal. Accumulation of heavy metals was not found in either paddy soil or brown rice after the two experiments. An effective N removal efficiency of the examined irrigation systems along with the reduced usage of chemical fertilizers could contribute to a substantial decrease in nutrients discharged from the wastewater treatment plants into surface water bodies. This study conveys the high feasibility of continuous irrigation with TWW to achieve high production and good nutritional quality of rice for animal feeding, which could promote an effective reuse of TWW in forage rice cultivation and enhance the self-sufficient feed ratio for sustainable dairy farming in Japan. [ABSTRACT FROM AUTHOR]

Sugar content in rice (Oryza sativa L.) stem is an agronomically important trait for rice used in straw silage or whole-crop silage. However, the mechanisms underlying sugar accumulation in rice stems remain unclear, mainly due to the time-consuming method for measuring sugar content. Here, we established a simple method for squeezing stem juice from rice plants, similar to that used during breeding selection in sugarcane or sorghum. The Brix value of the stem juice, which can easily be measured using a portable refractometer, significantly correlated with the soluble sugar contents in the stem juice and tended to correlate with those in stem tissues. This indicates that the Brix value of the stem juice can be used for estimating the sugar content in rice stems. This simple estimation method will be a useful tool for high-throughput analysis of sugar content in rice stems during mutant screening, QTL analysis, and breeding selection.

The grain yield of two high-yielding rice varieties, Kita-aoba and Tachijobu, was examined in a field experiment by using swine compost at a rate of 0, 1 and 2 kg m–2 and chemical fertilizer at a rate of 5.25, 7.35, and 10.5 g N m–2 in 2010, and 5.25 and 10.5 g N m–2 in 2011 (Exp. 1). The grain yield of Tachijobu was also evaluated by applying compost at a rate of 0 or 2 kg m–2 and chemical fertilizer at a rate of 5.25, 10.5, and 15.75 g N m–2 from 2011 to 2013 (Exp. 2). Tachijobu had a lower grain yield than Kita-aoba under the same fertilizer management in Exp. 1 due to its lower sink production efficiency, but it showed the highest grain yield of 1085 g m–2 at the highest fertilizer level in Exp. 2. A significant interaction between compost application and nitrogen fertilizer level was observed in grain yield and nitrogen uptake in Tachijobu in Exp. 2, and the nitrogen uptake in Tachijobu reached its maximum at around 15 g m–2 at maturity. In addition, the apparent nitrogen use efficiency of compost (NUEcompost) was higher at a lower nitrogen fertilizer level. From the nitrogen uptake and NUEcompost at each fertilizer level, the optimum rates of compost and fertilizer were discussed. The compost also increased the concentration of protein in Tachijobu (significantly in 2013).

Experiments were conducted to evaluate the nitrogen (N) balance in forage rice cultivation using animal manure in 1/2,000a Wagner pots in a greenhouse. The cattle manure and poultry manure were applied at 3 levels of N (0, 14, 28 g available N m–2) without additional chemical fertilizer application. The pots were designed to simulate the fluid percolation in the paddy field. The results indicated increasing levels of N input improved plant height, tiller number, SPAD value and biomass (straw, grain and root) production, however, N leaching from soil (Andosols) due to percolating water also increased. The planting of rice plants proved to reduce 30% of the N leaching loss. N use efficiency, the ratio of N uptake by plant per unit N application, decreased in higher N application. The N uptake by the above-ground parts occupied about 66% of the whole plants.

The purpose of this study is to identify the different effects exerted by planting density and nitrogen fertilization on high-salinity reclaimed paddy fields (RPF) and general paddy fields (GPFs), and to find the amount of fertilization and the planting density suitable for the growth of forage rice in each paddy field. Nitrogen fertilization with high-salt and low-salt soils, an untreated control plot, treatment with 200 kg/ha, 300 kg/ha, and 400 kg/ha, and planting densities of 30 cm × 10 cm and 30 cm × 16 cm, growth, and feed values were investigated. In both experimental locations, there was no significant change in the soil due to N treatment, but in the case of RPF, electrical conductivity (EC) decreased significantly from more than 5 dS/m to up to 2.87 dS/m during the yellow ripe stage due to the influence of floods and concentrated precipitation in the fields. In all soils, as both the amount of N treatment and the planting density increased, there was a proportional relationship in which the number of tillers and the dry weight also increased, with the occurrence of lodging also being increased. The dry weight, as expected, was 1.5 times higher at a planting distance of 10 cm, rather than 16 cm. In addition, in both locations, the N treatment led to an increase in the dry weight, but when N treatment reached 400 kg/ha (2.0), the dry weight decreased instead. Moreover, although there was no clear difference in feed value according to N treatment, in RPF, the neutral detergent fiber (NDF) was higher than 60%, the relative feed value (RFV) was less than 98, and the total digestible nutrient (TDN) was also low, confirming that the quality of rice was higher in GPF., Competing Interests: The authors declare no conflict of interest.

Tachisuzuka, a rice cultivar for whole-crop silage, is characterized by a small panicle and high sugar content in the stem. Our previous study suggests that the high sugar content in the stem of Tachisuzuka is due to a factor other than the small panicle. To characterize sugar metabolism in the stem of Tachisuzuka, here we compared carbohydrate content, enzyme activity, and the expression of genes involved in sugar metabolism in the stem between Tachisuzuka and its parental variety, Kusanohoshi. Thinning the panicles of Kusanohoshi increased the starch content in the leaf sheath and internode but did not increase the sucrose content in the leaf sheath to the same level as that of Tachisuzuka. This suggests that Tachisuzuka has high potential to accumulate sucrose in its leaf sheath. Comparison of enzyme activity showed that the hexokinase activities in the leaf sheath tended to be higher in Tachisuzuka than Kusanohoshi or panicle-thinned Kusanohoshi, suggesting that glucokinase or fructokinase affects sugar accumulation in the stem of Tachisuzuka. Comparative transcriptome analysis revealed the differences in expression levels of carbohydrate-related genes between Tachisuzuka and Kusanohoshi. In particular, the expression levels of ISA2, which encodes starch-debranching enzyme, and TMT2, which encodes tonoplast monosaccharide transporter - both of which maybe involved in sugar accumulation in grass stems - were higher in Tachisuzuka than Kusanohoshi. Thus, these enzymes and transporters may contribute to the high sugar content in the stem of Tachisuzuka. [ABSTRACT FROM AUTHOR]

To determine methane (CH4) emission differences between edible and forage rice cultivars, we conducted a pot experiment in Yamagata, Japan to grow edible rice Haenuki, and forage rice Fukuhibiki (for feed rice) and Tachisuzuka (for whole-crop silage (WCS) rice) under similar soil and meteorological conditions. The total amounts of N, P, and K fertilizers applied for Fukuhibiki and Tachisuzuka were 1.7, 1.3, and 1.3 times, respectively, higher than those of Haenuki. CH4fluxes, and rice plant night respirations were measured once weekly or fortnightly. As per the results, for the whole growth period, shoot height, maximum and productive tiller numbers, and plant biomass were significantly different among the three rice varieties. The rice growth period for Haenuki and Fukuhibiki was 107 days after transplanting (DAT), while that for Tachisuzuka was 135 DAT. The highest peak of CH4flux occurred around the heading stage for the three varieties. Consistently significant (P < 0.05) or obvious (P < 0.1) positive correlations between CH4flux and night respiration among the varieties were observed from 9 weeks after rice transplanting to harvest, indicating that much of the CH4flux was from newly produced root exudates and plant debris through plant photosynthesis. The cumulated CH4emissions during the same growth period, 106 DAT, from Haenuki, Fukuhibiki, and Tachisuzuka were 55.36, 77.46, and 78.40 g C m−2, respectively. Additionally, Tachisuzuka emitted 25.11 g C m−2more CH4between 106–134 DAT. The final cumulated CH4emissions from Fukuhibiki and Tachisuzuka were 39.9% and 87.0% higher than that from Haenuki, respectively, throughout their growth period. [ABSTRACT FROM PUBLISHER]

We investigated the effects of changes in the density of rice skipper Parnara guttata guttata Bremer et Grey larvae in paddy fields on the damage caused during the cultivation of forage rice for whole-crop silage. Young instar larvae were released in mesh cages on late-transplanted rice plants. The larvae were reared in the cages until the pupal stage. After removal of the insects, rice plants at the yellow ripening stage were harvested and dried, and the number of panicles and dry weight of panicles and straw were measured. The total digestible nutrients content of the rice plants was also estimated. Dry matter weight decreased with increasing larval density on the rice plants, whereas total digestible nutrients content did not decrease significantly. Thus, P. guttata guttata may cause quantitative damage to forage rice, but the qualitative damage it causes is relatively small. [ABSTRACT FROM AUTHOR]

Increased use of N fertilizer may substantially increase of nitrate nitrogen (NO3-N) leaching, which potentially pollutes groundwater. Leaching behaviour of nitrogen (N) was observed in the paddy field of forage rice cultivation. Two kinds of animal manure, cattle manure (CM) and poultry manure (PM) at 5 levels of N application (0, 70, 140, 210, 280 kg N ha-1) as the organic N sources, and without any chemical fertilizers. “Tachisuzuka” forage rice variety was conducted in the experimental plot. Porous ceramic cups were installed in triplicate of each treatment at 45 cm depth to collect the percolation water samples during the cultivation rice periods. The concentration of total N, NH4-N, NO2-N and NO3-N of water (surface and percolation) and soil sample solution were analysed using a Hach DR/2800 spectrophotometer. Result showed that NO3-N leaching was higher than NH4-N in the percolation water during the cultivation of forage rice periods. The highest NO3-N leaching was found in 280 kg N ha-1 (6.3 mg L-1), that it was indicated on the polluted levels. The highest of biomass production was in N280 (16.22 t ha-1) and nearly similar result in N140, N210 and N280. It was concluded that the best application of N-fertilizer in 140 kg N ha-1 because it greatly enhanced N-fertilizer efficiency, and decreased steadily of NO3-N concentration leaching in the environment of the groundwater.

The effects of planting time (early or normal), nitrogen (N) application rate (150 or 225 kg N ha-1), and N application method (early, even, and late application of extra N) on total digestible nutrient (TDN) concentration and yield of forage rice (Oryza sativa L.) in southwestern Japan were examined. For optimal forage rice production, it is important to maximize nutritional level in leaves and stems rather than panicles because the hull restricts cattle’s ability to digest rice grain. In particular, it is important to maximize the TDN in leaf sheath plus stems (stems) which are the major part of the crop rather than leaf blades (leaves). Stem TDN yield was higher with early planting (340 g m-2) than with normal planting (217 g m-2) irrespective of N application rate or method. The high stem TDN yield with early planting resulted from both the high DM yield and the high TDN and organic cellular content (OCC) concentration. Stem TDN yield was not affected by the N application rate. With both early and normal plantings, stem TDN yield was higher with early N application (374 and 226 g m-2, respectively) than with late N application (305 and 208 g m-2, respectively). With early planting, the high stem TDN yield with method 1 resulted from both the high DM yield and the high TDN and OCC concentration. Thus, to obtain high stem TDN concentration and yield of forage rice, early planting and early N application are recommended.

We examined the effects of cutting height and trampling over stubbles of the first crop on dry matter yield in twice harvesting of forage rice Oryza sativa L., Tachiaoba and Taporuri. Dry matter yield of the second crop, after the first harvest at the full-heading stage, increased with increasing cutting height. However, the dry matter yield of the first crop decreased with increasing cutting height. Overall, total dry matter yield did not vary with the cutting height. Dry matter yield and its components of the second crop were not greatly affected by the trampling treatment. At cutting heights of 15 and 5 cm from the base, the number of tillers developed from unelongated nodes was increased by the trampling treatment. Thus, although the number of tillers developed from the elongated nodes was decreased after the trampling treatment, the decrease is compensated for by the increased number of tillers from unelongated nodes.

We examined the effects of planting time on the dry matter (DM) yield of the forage rice cultivar Tachiaoba in southwestern Japan. DM yield was much higher with early planting than with normal planting. Dry weight (DW) per tiller was much higher with early planting than with normal planting. Thus, early planting is effective to obtain high DM yield. DM yield was closely related to the DW increase from transplanting to the full-heading stage (DW increase before heading) and DW per tiller. These results suggest that early planting leads to an increase in DW at the full-heading stage through an increase in DW per tiller and gives a high DM yield at the yellow-ripe stage. We also examined the effects of nitrogen (N) application rate and method on DM yield at the yellow-ripe stage. DM yield was higher with application of 22.5 g N m-2 than with 15.0 g N m-2. Although DW per tiller was slightly lower with application of 22.5 g N m-2 than with 15.0 g N m-2, the number of tillers per square meter was much higher with application of 22.5 g N m-2 than with 15.0 g N m-2. DM yield was the highest with N application method 1 that was applied more N early, followed by methods 2 that was applied more N evenly over time and 3 that was applied more N later. The number of tillers per square meter was much higher with method 1 than with method 2 or 3. Thus, application of 22.5 g N m-2 by method 1 is effective to obtain high DM yield. With both early and normal plantings, DM yield was closely related to the DW increase before heading and the number of tillers per square meter. These results suggest that application of 22.5 g N m-2 by method 1 lead to an increase in DW at the full-heading stage through an increase in the number of tillers per square meter resulting in a high DM yield at the yellow-ripe stage.

Livestock wastewater disposal onto rice paddy fields is a cost- and labor-effective way to treat wastewater and cultivate rice crops. We evaluated the influence of nitrogen loading rates on nitrogen assimilation by rice plants and on nitrogen losses (leaching and NO emission) in forage rice fields receiving liquid cattle waste (LCW). Four forage rice fields were subjected to nitrogen loads of 107, 258, 522, and 786 kg N ha (N100, N250, N500, and N750, respectively) using basal fertilizer (chemical fertilizer) (50 kg N ha) and three LCW topdressings (each 57-284 kg N ha). Nitrogen assimilated by rice plants increased over time. However, after the third topdressing, the nitrogen content of the biomass did not increase in any treatment. Harvested aboveground biomass contained 93, 60, 33, and 31 % of applied nitrogen in N100, N250, N500, and N750, respectively. The NH concentration in the pore water at a depth of 20 cm was less than 1 mg N L in N100, N250, and N500 throughout the cultivation period, while the NH concentration in N750 increased to 3 mg N L after the third topdressing. Cumulative NO emissions ranged from −0.042 to 2.39 kg N ha; the highest value was observed in N750, followed by N500. In N750, NO emitted during the final drainage accounted for 80 % of cumulative NO emissions. This study suggested that 100-258 kg N ha is a recommended nitrogen loading rate for nitrogen recovery by rice plants without negative environmental impacts such as groundwater pollution and NO emission. [ABSTRACT FROM AUTHOR]

Proper floodwater management during the cultivation period of paddy rice is essential for regulating the trade-off between methane and nitrous oxide emissions, as well as for saving irrigation water resource and maintaining crop productivity. To elucidate the effects of water saving irrigation (WS) and rice variety on different agro-environmental parameters such as CH and NO emissions, global warming potential (GWP), greenhouse gases intensity (GHGI), carbon efficiency ratio, water use efficiency (WUE), rice growth and yield, a field experiment was conducted with two factors of split-plot design consisting of (1) main factor; WS (WS in which irrigation was withdrawn at soil Eh < −150 mV and kept 0-1 cm floodwater afterward) and continuous flooding (CF), and (2) sub-factor; a forage rice variety Leaf Star (LS) and a normal rice variety Kinuhikari (KN). Results showed that WS irrigation significantly ( P < 0.05) mitigated CH emission by 65 % and $$ {\text{GWP}}_{{{\text{CH}}_{ 4} + {\text{N}}_{ 2} {\text{O}}}} $$ by 60 %, and enhanced WUE significantly ( P < 0.01) by 180 % from that of CF. Carbon use efficiency of the grain and aboveground biomass carbon increased by 2.4 and 2.5 times, respectively, and GHGI was reduced by 3.1 times in WS. No significant differences were observed in the plant height, tiller number, rice biomass, N uptake and C accumulation between water treatments but the rice varieties: LS showed significantly ( P < 0.05) higher values in these parameters than KN. This study highlighted that the WS is an effective measure for mitigating GWP, saving water while sustaining crop productivity. [ABSTRACT FROM AUTHOR]

Dry-thermophilic anaerobic co-digestion (DTAD) can be used to treat forage rice straw and pig manure and generate biogas as an energy source. Solid residue produced from DTAD process can be used as a fertilizer in forage rice fields, while addition of the residue could increase methane (CH) and nitrous oxide (NO) emissions from the soil. We evaluated the effects of adding DTAD residue and water management on CH and NO emissions from a forage rice field. Three treatments were evaluated: (a) 100 kg N · ha chemical fertilizer and continuous flooding (CC); (b) residue addition (300 kg N · ha DTAD residue) with continuous flooding (RC); and (c) residue addition with intermittent irrigation (RI). RC and RI showed higher CH fluxes than CC throughout the growing period. After a midsummer drainage, RI showed higher soil Eh values and lower CH fluxes (mean, 7.6 mg C · m · h) than those in RC (mean, 18.6 mg C · m · h). Abundance of mcrA gene copy number was not different between RC and RI, suggesting CH flux was reduced by suppression of methanogenic activity by intermittent irrigation. Cumulative CH emissions during the cultivation period were 105, 509, and 306 kg C · ha in CC, RC, and RI, respectively. NO fluxes were within detection limits in all treatments. Our results, to our knowledge, are the first to show greenhouse gas emission from forage rice fields supplemented with DTAD residue and of the effectiveness of water management in CH mitigation. [ABSTRACT FROM AUTHOR]

Although the forage rice ( Oryza sativa L.) cultivar 'Ruriaoba' has very high dry matter ( DM) yield, it readily lodges after heading because of its high plant height. As a result, seed production and conventional cultivation of 'Ruriaoba' are very difficult. To improve this situation, we examined the effects of cultivar ('Ruriaoba' or 'Tachiaoba') and row spacing (30 [30-30-30-30] cm, 45 [30-30-30-45] cm, or 60 [30-30-30-60] cm) on the yield and nutritive value of forage rice. The lodging score of 'Tachiaoba' did not differ among row spacings but that of 'Ruriaoba' decreased with increasing row spacing. 'Ruriaoba' had lower grain yield than 'Tachiaoba'. Among its components, 'Ruriaoba' had fewer spikelets per m2, fewer spikelets per panicle and lower 1000-grain weight than 'Tachiaoba'. 'Ruriaoba' had fewer grains per m2 than 'Tachiaoba'. Grain yield and its components did not differ among row spacings, nor did the number of grains per m2. Thus, 'Ruriaoba' planted at 60-cm row spacing may not decrease the grain yield and number of grains without lodging. This type of low-density planting of 'Ruriaoba' may be useful for seed production. At heading and yellow ripe stages, 'Ruriaoba' had higher DM yield than 'Tachiaoba' because 'Ruriaoba' had higher number of panicles than 'Tachiaoba'. Furthermore, 'Ruriaoba' had higher total digestible nutrients ( TDN) yield than 'Tachiaoba'. At heading, DM yield decreased with increasing row spacing because the number of panicles decreased with increasing row spacing. Total digestible nutrients yield was lower at 45- and 60-cm row spacings than at 30-cm row spacing. However, at heading and yellow ripe, 'Ruriaoba' planted at 60-cm row spacing had DM and TDN yields similar to those of 'Tachiaoba' planted at 30-cm row spacing. Such low-density planting of 'Ruriaoba' may be an option for forage rice production. [ABSTRACT FROM AUTHOR]

We examined three types of ensiling container and two storage periods with respect to the fermentation quality of rice grain silage, and our findings confirmed that a method previously identified as optimal for silage production at the laboratory scale was also appropriate for farm-scale production. Crushed rice grain was adjusted to 30% moisture content, inoculated with lactic acid bacteria and ensiled in plastic pouches (200 g), plastic drums (15 kg) and flexible containers (100 kg). Samples of silage from the surface layer in the flexible containers had the pH value >5 and fungal growth was observed, but all internal samples had low pH (<4). Extending storage in the drums from 60 to 365 days reduced the lactic acid content of the internal samples, but pH remained at an acceptable level of <4.2. Overall, the production method outlined is appropriate at the farm scale. [ABSTRACT FROM AUTHOR]

Fertilizing livestock waste for forage rice production can remove nitrogen and reduce the need for chemical fertilizers. Furthermore, rice straw can be used for biogas production. Here, the growth characteristics of different forage rice varieties in Japanese paddy fields fertilized with liquid cattle waste were investigated. Six experimental plots were established in a paddy field planted with three varieties of forage rice developed for livestock feed. Methane production potential assays were then conducted to investigate the anaerobic digestion characteristics of the stems and leaves of these three varieties. The total methane production potential of the Leafstar variety was higher than that of other varieties, while its lag phase was significantly shorter. Co-digestion of ethanol fermentation residue with Leafstar straw revealed that the NH4+-N concentration decreased as the C/N ratio increased. Additionally, the methane production potential of the mixed substrate was higher than that of ethanol fermentation residue or forage rice straw applied alone. Hence, Leafstar forage rice is a promising variety for establishment of agricultural resource recycling systems in which higher straw biomass can be achieved by applying liquid cattle waste and more biogas can be produced due to the potential for increased methane production. [ABSTRACT FROM AUTHOR]

Abstract: To evaluate global warming potential (GWP) on livestock waste treatment and biomass production in rice field, methane (CH4) and nitrous oxide (N2O) fluxes from forage rice fields planted with 4 different cultivars (Oryza sativa L. cv. Hamasari, Leafstar, Kusahonami and Takanari) were measured. Each of the cultivars were subjected either to basal fertilization alone (control plots) (84kgNha−1), or to basal fertilization plus topdressing with liquid cattle waste or LCW (treatment plots) (567kgNha−1). Liquid cattle waste application to the rice field resulted in peak CH4 fluxes ranging from 22.0 to 32.1mgm−1 h−1 during flooded conditions and large N2O fluxes ranging from 526 to 8591μgm−1 h−1 after midsummer drainage and final drainage. The GWP of the control plots was between 1358 and 3872kgCO2eqha−1, while the treatment plots ranged between 4503 and 8426kgCO2eqha−1 and more than 60% of the GWP was from the N2O emission in treatment plots. In both the control and treatment plots, the lowest GWPs per ton of above-ground biomass were found to be from the Leafstar cultivar, which had a higher aboveground biomass than other cultivars; 117kgCO2eqt−1 from the control and 257kgCO2eqt−1 from the treatment plots. Thus, both forage production and suitable disposal of the LCW may be able to be achieved concomitantly with lower levels of GWP by cultivation of Leafstar in our field. [Copyright &y& Elsevier]

Abstract: We examined the effects of cultivar (Taporuri, Mohretsu, Tachiaoba, and Hinohikari) on estimated total digestible nutrient (TDN) yield of forage rice in double harvesting. The total estimated whole-plant TDN yield (i.e., of the first crop plus second crop) of Taporuri was the highest in double harvesting. In the first crop, the estimated whole-plant TDN yield of Taporuri was the highest. In the second crop, the estimated whole-plant TDN yield of Taporuri was almost the same as those of Mohretsu and Tachiaoba but higher than that of Hinohikari. We also examined the effects of cultivation method (double harvesting or single harvesting) on estimated TDN yield of forage rice. In Taporuri and Mohretsu, the total estimated whole-plant TDN yield was similar in double harvesting and single harvesting. However, in Tachiaoba and Hinohikari, it was lower in double harvesting than in single harvesting. It is important to maximize the amount of nutrition in leaf and stem rather than panicle because the grain is not digested well by cattle. In the double harvesting, the total estimated leaf blade (leaf) TDN yield of Taporuri was higher than that of Hinohikari and almost the same as those of Tachiaoba and Mohretsu. The total estimated leaf sheath plus stem (stem) TDN yield of Taporuri was the highest. In comparison of the total TDN yield of double harvesting with that of single harvesting, the total estimated leaf and stem TDN yields were higher in double harvesting than in single harvesting in all cultivars except for Hinohikari. Thus, double harvesting of Taporuri is an effective way of reducing the overall loss of nutrition from the crop. [Copyright &y& Elsevier]

A study was conducted to determine nitrogen budget and ammonia volatilization in Japanese paddy fields supplemented with liquid cattle waste (LCW). A series of four, 2 × 10 m experimental plots was established in a paddy field with silty clay soil planted with forage rice ( Oryza sativa L.). In addition to 195 kg N ha−1 of chemical or compost-based basal fertilizer, LCW was applied as an additional fertilizer at total nitrogen rates of 0, 255, 255, and 405 kg N ha−1 to the four plots C195, T450-1, T450-2, and T600, respectively. The mass balance showed that after application of LCW, 32–39% of total input nitrogen was assimilated into aboveground parts of rice plants, 11–15% leached downward, 2.5–4.0% was lost via ammonia volatilization, 1.6–5.1% was retained in roots or was adsorbed onto soil, and approximately 30–40% was lost via denitrification. Compared to animal waste slurries applied to unsaturated soils, nitrogen loss via ammonia volatilization was relatively lower, probably due to the dilution effect of floodwater. Nitrogen loss via denitrification was markedly higher in areas where LCW was applied compared to areas without LCW application. On the other hand, nitrogen leaching downwards represented a substantial loss and may be an environmental concern. However, after LCW application only, the ammonium ion was detected, at a maximum nitrogen concentration of 11.4 mg L−1. In this system, therefore, nitrogen has a different fate to that in animal waste slurries applied to unsaturated soil. In that situation, the major nitrogen form in leaching water is nitrate nitrogen, which moves readily into groundwater. [ABSTRACT FROM AUTHOR]

Abstract: A pilot-scale surface-flow wetland planted with a new rice variety (Oryza sativa ’Kusahonami’) developed for livestock feed was constructed for treating nutrient-polluted river water. To calculate the balance between nitrogen removal and rice plant uptake of nitrogen, nitrogen removal from river water and nitrogen interactions among plants, soil water, and soil were investigated for this constructed wetland over two growing seasons in 2004 and 2005. The constructed wetland removed 33% of the total nitrogen entering with the river water. Rice plants were found to constitute the major nitrogen storage, with plant uptake being the major removal mechanism. The total inorganic nitrogen concentration in the rhizosphere changed seasonally because of plant uptake. Most nitrogen taken up by rice plants was contained in the aboveground biomass, with the mean amount being 34.0gNm−2. However, the nitrogen balance calculation suggested that rice plants uptake some nitrogen from soil, decreasing the available nitrogen in the soil of the lined impermeable wetland. [Copyright &y& Elsevier]

Abstract: We examined the effects of planting time and cultivar on dry matter yield of forage rice in southwestern Japan. The cultivar Tachiaoba produced a 81.1% higher dry weight per tiller but a 40.5% fewer tillers per square meter than Hinohikari, thus producing a 9.0% higher dry matter yield. Nishiaoba produced almost the same dry matter yield as Hinohikari. Early transplanted plants produced a 14.9% higher dry matter yield and a 21.1% higher dry weight per tiller than normally transplanted plants. Early transplanted Tachiaoba produced the highest dry matter yield in the experiment. We also examined the effects of planting time and cultivar on estimated total digestible nutrient (TDN) content. The estimated TDN content in panicles was 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blades. Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to total dry weight than Hinohikari, respectively, had a 2.0% lower estimated TDN content in the whole plant than Hinohikari in 1 of the 2 years. However, early transplanted plants, which had a 5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 0.6% higher estimated TDN content in the whole plant than normally transplanted plants. Early transplanted plants had a 4.7% higher estimated TDN content in leaf sheath plus stem than normally transplanted plants. These results suggest that early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants because of the higher estimated TDN content in leaf sheath plus stem. Tachiaoba produced a 9.1% higher estimated TDN yield than Nishiaoba and a 7.7% higher than Hinohikari. Early transplanted plants produced a 16.1% higher estimated TDN yield than normally transplanted plants. Early transplanted Tachiaoba produced the highest estimated TDN yield in this experiment. Therefore, it is effective to plant Tachiaoba early to obtain high dry matter and estimated TDN yields. [Copyright &y& Elsevier]

Abstract: We examined the effects of time of first harvest, total amount of nitrogen, and nitrogen application method on the total dry matter yield of a twice-harvested rice (Oryza sativa L.) cultivar Taporuri grown in southwestern Japan. The highest total dry matter yield was 27.1tha−1. We examined the effects of two times of first harvest (booting stage versus full heading stage). Plants harvested at the full heading stage produced 50% higher dry matter yield of first crop than those harvested at the booting stage, because the plants had greater weights per tiller than those harvested at the booting stage. Plants harvested at the booting stage produced 37% higher dry matter yield of second crop than those harvested at the full heading stage, because the plants had greater dry weights per tiller than those harvested at the full heading stage. Overall, plants harvested at the full heading stage produced 8% higher total dry matter yield than those harvested at the booting stage. We also examined the effects of two total amounts of nitrogen (300kgNha−1 versus 150kgNha−1) and three nitrogen application methods (method 1: 33.3% applied at transplanting, 66.7% at the maximum tiller number stage, 0.0% at 7 days after the first harvest, and 0.0% at 21 days after the first harvest; method 2: 33.3, 33.3, 16.7, and 16.7%, respectively; method 3: 33.3, 0.0, 33.3%, and 33.3%, respectively). For the first crop, plants that received 300kgNha−1 produced 10% higher dry matter yield than those that received 150kgNha−1 in 2004. Plants that underwent nitrogen application methods 1 and 2 produced 21% and 23% higher dry matter yield of first crop than plants that underwent method 3, respectively. The increase in number of tillers per meter in the 300kgNha−1 treatment and in nitrogen application methods 1 and 2 resulted in the higher dry matter yields of first crop in these treatments. For the second crop, plants that received 300kgNha−1 produced 10% higher dry matter yield of second crop than those that received 150kgNha−1. Plants that underwent nitrogen application methods 2 and 3 produced 57% and 56% higher dry matter yield of second crop than method 1, respectively. The increase in number of tillers per meter in the 300kgNha−1 treatment and in nitrogen application methods 2 and 3 resulted in the higher dry matter yields of second crop in these treatments. Overall, plants that received 300kgNha−1 produced 7% higher dry matter yield than those that received 150kgNha−1 and plants that underwent nitrogen application method 2 produced 21% and 11% higher dry matter yield than those that underwent methods 1 and 3, respectively. Therefore, our findings suggest that to produce the highest total dry matter yield the best time for first harvest is the full heading stage and the best nitrogen management is to provide 300kgNha−1 in accordance with nitrogen application method 2. [Copyright &y& Elsevier]

Ammonia fluxes from application of anaerobically-digested slurry (ADS) and chemical fertilizer (CF) to flooded forage rice ( Oryza sativa L.) in Japan were measured using a dynamic flow-through chamber method in lysimeters. The CF was applied at a rate of 300 N ha−1 (three times) as ammoniacal-N fertilizer, and the ADS was applied to the lysimeters at total rates equivalent to 75, 100 and 150 kg N ha−1, by broadcasting uniformly into the floodwater at three or six times (equal splits) between 17th June and 17th November, 2005. The emission fluxes for the first 2 days after application were very high from ADS, the highest values being 679 compared with a maximum of 156 mg N m−2 d−1 from CF. Most (61–93%) of the ammonia loss occurred during the first 5 days after each application of fertilizer. The total N loss as ammonia from ADS (29.6–51.7%) was much higher than from CF (12.2%). The highest fluxes were observed in August (2005) when air temperature was highest. More ammonia was lost from the ADS applied at the early stages (i.e. root taking, tiller stages) than at later stages (i.e. elongation, fruiting stages) of rice growth. [ABSTRACT FROM AUTHOR]

Abstract: We examined the effect of twice harvesting of forage rice with the first harvest at the full heading stage on total dry matter yield in the cultivars Taporuri, Mohretsu, and Hinohikari and in line Saikaishi 253 in southwestern Japan. Taporuri produced the highest total dry matter yield, with a value 60% higher than that of Hinohikari. The first crop of Taporuri had a longer duration of vegetative growth than those of Mohretsu and Hinohikari, and had the highest dry matter yield because of its greater weight per tiller than Hinohikari and its more tillers per square meter than Saikaishi 253, which had a similar duration of vegetative growth. The second crops of Mohretsu, Taporuri, and Saikaishi 253 had longer vegetative growth and higher dry matter yields than Hinohikari. Dry matter yields of both crops were closely related to the duration of vegetative growth and the weight per tiller, but not to tillers per square meter. These results suggest that cultivars with a long duration of vegetative growth, high weight per tiller, and adequate tillers per square meter can produce high dry matter yield in both crops. There was a significant interaction (P <0.05) in total dry matter yield between cultivar or line and cultivation type. The total dry matter yield of Taporuri in twice harvesting was about 10% higher than that in once harvesting, whereas that of Hinohikari was about 10% lower. The suitability for twice harvesting ([total dry matter yield in twice harvesting]/[total dry matter yield in once harvesting]) was significantly positively correlated (r =0.875) with the increase in dry weight before the full heading stage, but significantly negatively correlated (r =−0.903) with the increase in dry weight between full heading and the yellow ripe stage. Thus, cultivars with a high increase in dry weight before full heading appear to be more suitable for twice harvesting than those with a high increase between full heading and the yellow ripe stage. In addition, our study showed that twice harvesting can prevent lodging in Taporuri, thereby increasing the suitability of this cultivar as a forage rice. Our results suggest that twice harvesting can be performed in southwestern Japan and warmer regions. [Copyright &y& Elsevier]

The article presents a study that attempts to describe a high-performance liquid chromatographic (HPLC) method for determining ustiloxin A, a mycotoxin produced by Ustilaginoidea virens, in whole-crop rice silage in Japan. This HPLC method will also evaluate the degree of false smut ball contamination of the silage. In this research, lyophilized silage samples were ground and extracted with water. It suggests that this method can be used for routine monitoring of the contamination of ustiloxin A in forage rice silage.