The cultivation technique required for producing premium-flavor rice is reviewed. The soil preparations, such as the deep tillage and the dosage of organic matter are important for maintaining optimum water and nutrition uptake during the growing season. Good seedlings must be transplanted under optimal conditions to avoid ripening damage by high temperature, and low nodal position and nodal order tillers must be secured to obtain low-protein rice. Furthermore, excessive tillering should be avoided through deep flooding irrigation and mid-season drainage, because tillers at a high nodal position and high nodal order tillers generally produce high-protein rice. Top dressing based on nutrition diagnosis should be conducted to appropriately control the spikelet numbers, and after the heading stage, irrigation management (flow irrigation and intermittent irrigation) should be conducted to counter high temperatures and maintain root function. After harvesting at the appropriate time, it is important to dry the rice quickly at a low temperature setting. For further agronomic approach to produce premium-flavor rice, it is important to analyze the following factors: geographic and climatic conditions of the district that produce premium-flavor rice and cultivation technique of progressive farmers in that district.
A field experiment was conducted in the paddy field in which cool water (about 11ºC) was continuously irrigated, to determine the most low-temperature-sensitive stage of submerged direct-seeded paddy rice seedlings. Cool water treatments were given from just after seeding (JAS), full emergence stage (FES), and second leaf appearing stage (SLA), for 7 and 14 days. Seeds were sown in plastic nursery boxes used for seedling raising. Each treatment was carried out by moving the nursery boxes from the normal field to the cooling field at the starting stage. Average water temperature in each cooling treatment was below 12ºC. Percentage of seedling establishment was lowest in FES, followed by SLA. Leaf age just before and after the cooling was also examined to find the factors that decrease establishment percentage in each treatment. The decrease in seedling establishment in JAS mainly resulted from the decrease in emergence percentage, but that in FES and SLA mainly resulted from the failure of first leaf elongation, and also from the failure to survive after the first leaf elongation in SLA. These results indicate that the stage of seedlings most sensitive to low temperature is just before the first leaf elongation, in other words, the elongation stage of coleoptile.
The growth of ratoon sugarcane on dark-red soil in Miyako island in Okinawa, Japan was promoted by application of bagasse charcoal and bagasse together with phosphorus dissolving bacteria strain-22 identified as Bacillus thuringiensis. Strain-22 was thought to survive in the pores of bagasse charcoal using both bagasse and molasses as organic carbon sources while generating organic acids. The pF-water curve of carbide, showed that the bagasse charcoal retained more water than woody charcoal. The results of this study implied that phosphorus dissolving bacteria such as strain-22 can facilitate solubilizing of accumulated phosphorus in the soil when it is used in conjunction with organic carbon sources such as bagasse and molasses. This resulted in an increase in absorption of phosphorus and nutrient uptake in sugarcane in ratooning cultivation.
A laboratory experiment was conducted to examine the effect of draining just after seeding compared with flooded condition on emergence and seedling establishment of rice with several treatments, such as temperature (21/13ºC and 18/10ºC of day/night) and soil reduction (reduced soil by adding rice straw and normal). Methylene blue was used to examine the soil reduction. The soil and the vicinity of the seeds in draining treatments maintained an oxidative condition during the experiment even in reduced soil, while soil reduction proceeded in flooded treatments. The emergence percentage was lowered in flooded treatment, especially under the combination of lower temperature and reduced soil. Establishment percentage was lowered in reduced soil, but it was significantly higher in draining than in flooded treatments. The period from emergence to first leaf elongation was 2-3 days in draining treatment, while over 7 days in flooded treatments. This quick elongation of first leaf was considered to be important for stable establishment. Also in the field experiment, draining treatment for 12-13 days just after seeding until confirmation of emergence and root elongation showed better establishment and seedling growth, and resulted in higher grain yield compared with the flooded treatment. The difference in daily mean soil temperature at one cm under the soil surface between draining and flooded treatments was negligible. These results indicate that draining management is effective for high and stable establishment of seedlings even in Hokkaido.
The growth and yield components of the second crop (ratoon crop) are affected by the growth of the first crop. The first crop growth was modified by the deep-flood irrigation (DF: 20 days of 15 cm flooding), reduced fertilizer (RF: reduced by 50%), and without treatment (Control). The number of tillers in the second crop was larger in DF and RF than in the Control. The number of days to heading was in the order of DF<RF<Control in the second crop. This suggests that growth control of the first crop advanced the heading time of the second crop. In the second crop, the grain weight per hill and the number of the tillers were negatively correlated with the grain/straw-ratio in the first crop. A heavy grain weight per hill and large number of ratoons were obtained in the plots where the grain/straw-ratio was small, i.e., DF and RF. From these results, it is concluded that the growth, heading and yield components of the second crop were influenced by the crop growth and grain/straw-ratio in the first crop. These observations demonstrated the possibility of attaining a well-balanced high yield in rice ratoon double cropping.
Unfertilized crop cultivation system (unfertilized cultivation) is believed to reduce the yield markedly. However, some rice farmers using unfertilized cultivation attain high yields, which are comparable with those obtained in conventional farming. In the present study, we surveyed 16 rice farmers employing unfertilized cultivation in Aomori, Iwate, Miyagi, and Niigata prefectures. Our objective was to identify factors contributing to yield variation. During 2011-2013, the mean annual rice yield obtained by these farmers was 300 kg per 10a; however, some farmers consistently achieved annual yields of 420-480 kg per 10a. The yield was highly correlated with the grain number per m2, especially with the panicle number (r=0.92***). In addition, the panicle number showed a strong correlation with the average air temperature from transplanting to 43 days before heading (r=0.66**). We conducted a rice growth experiment in pots using unfertilized paddy soil and transplanting at four different days. The tillering rate was highly correlated with the average air temperature during the growing period (r=0.92***). The results of path analysis based on multiple linear regression revealed that the effects of air temperature on the tillering rate were derived from a direct effect on rice growth (57%) and from increased nitrogen mineralization in the soil (43%). Our findings indicate that ensuring an adequate accumulated temperature during the early vegetative growth period is crucial in unfertilized rice cultivation in northern Japan.
The effects of compost fertilization and pesticide application on the grain yield of an early maturing rice variety were examined for 15 years in the paddy field of Shizuoka University. Husk manure was applied without a pesticide (weeds were removed with a weeder and by hand) in the HMP-F plot from 1996 to 2010. Cattle manure was applied without a pesticide in the CMP-F plot from 1996 to 2010. Both chemical fertilizer and pesticide were applied in the CFP plot from 1996 to 2010. Neither fertilizer nor pesticide was applied in the NFP plot from 1998 to 2010. The rice grain yield during the first five years was 437, 430, 523 and 329 g m-2 respectively in the HMP-F, CMP-F, CFP and NFP plots. The effect of long-term manuring became apparent in CMP-F after the fifth year, and in HMP-F after the seventh year. It was confirmed that the eating quality value measured with a rice analyzer for eating quality tended to be high in the organic cultivation with husk manure or cattle manure compared with the conventional cultivation with a chemical fertilizer. It was clear that the total amount of nitrogen in paddy soil in the organic cultivation is larger than in conventional cultivation with a chemical fertilizer.
The optimal date of submergence after draining just after seeding of calcium peroxide (CAL)-coated seeds was estimated by two methods. The first was an accumulated effective temperature (AET) method, in which accumulated temperature was obtained by subtracting the basal temperature from the daily maximum-minimum average air temperature during the period from the day after seeding to the submergence. The coefficient of variation of AET was the smallest when the basal temperature was 6ºC. The AET at the optimal date was 85.9ºC. The second was a developmental index (DVI) method, which was given by integrating the developmental rate (DVR). The DVR was defined as follows, DVR=1/(1+exp(-A(T-Th)))/G, where T was the daily mean air temperature, and A, Th and G were the parameters. The optimal values of the parameters, A=0.1908, Th=16.06, and G=4.118, were estimated by the Simplex method. The root mean square error of the difference between the measured and estimated dates was 1.4 days by the AET method, and 1.2 days by the DVI method. Using these two methods, the establishment percentage without CAL coating was tested. It was 52.2% in standard draining and was significantly lower than that with CAL (70.9%) in standard draining. However, it increased to 60.9% when the draining period was prolonged for about three days. The optimal date of submergence without CAL coating was estimated to be the day when AET was 105ºC and when DVI exceeded 1.3.
We investigated the changes in dry weights and nitrogen contents of plant organs during the grain filling period in naked barley cultivar “Toyonokaze.” Three treatments with different amounts of nitrogen fertilizer at the spike formation stage (SFS) were given in 2012/2013 and 2013/2014. Changes in dry weight and nitrogen content of each productive stem were similar in all the treatments in both seasons. Total dry weight increased from full heading time (FHT) to four weeks after FHT in both seasons. Grain weight increased from two weeks after FHT to maturity in 2012/2013, and did from two weeks to five weeks after FHT in 2013/2014. The amount of nitrogen in the total above-ground part increased from four weeks after FHT to maturity in 2012/2013, while it did not increase during the grain filling period in 2013/2014. That in the grain increased throughout the grain filling period in 2012/2013, but not from five weeks after FHT to maturity. The nitrogen in grain might come not only from vegetative organs by remobilization, but also from absorption from soil during the grain filling period. Thus, how the grain accumulated nitrogen during the later grain filling period varied with the experimental season.
Wheat grown in paddy fields has lower bread-making quality than wheat grown in upland fields because of lower grain protein content. Nitrogen topdressing at flowering increases flour protein content. Here, we investigated the effects of the nitrogen topdressing at flowering on the bread-making quality of wheat grown in a paddy field. Nitrogen topdressing at 8 g m-2 at flowering raised the flour protein content to 13% which is as high as that in wheat grown in the upland field. However, the valorimeter value (VV) on the farinogram, an indicator of bread-making quality, was smaller in wheat grown in a paddy field than that grown in the upland field. The protein content of the flour was as high as 13%, detention time (DT) on the farinogram was shorter, water absorption on the farinogram was larger, and compression of bread was smaller in wheat grown in the paddy field than in wheat grown in the upland field. The bread made from wheat grown in the paddy field was softer than that made from wheat grown in the upland field. The ratio of sodium dodecyl sulfate (SDS)-soluble extractable monometric proteins (EMP) to SDS-insoluble unextractable polymeric proteins (UPP) in the flour was significantly lower in wheat grown in the paddy field than in wheat grown in the upland field. Wheat grown in the paddy field ranked B or C owing to its high ash content and low volume weight even with nitrogen topdressing of 8 g m-2 at flowering. On the other hand, wheat grown in the upland field ranked A in all test groups.
The promotion of domestic sesame requires the development of sesame varieties with a high lignan content, which inevitably necessitates the elucidation of the genetic factors affecting sesamin and sesamolin contents. Therefore, in this experiment, the F1 and F2 plants of seven genetic resources crossed in the half-diallel manner were cultivated in the field, and the sesamin and sesamolin contents of their seeds were analyzed. Based on the Vr /Wr graph, the results fit an additive-dominant model without the influence of epistasis. The additive variance exceeded the dominance variance in both contents—the average degree of dominance was 0.58–0.88. Most of the dominance effects reduced these contents. The narrow sense heritability was 0.859–0.903, which was higher than that estimated from the other traits of sesame. Since no major differences were observed between the F1 and F2 plants in the sesamin and sesamolin contents, and a statistically significant positive correlation was observed between the sesamin and sesamolin contents in each generation, the contents of both sesamin and sesamolin would be controlled by a common polygenic system. The seed parents artificially pollinated with other pollen parents had sesamin and sesamolin contents similar to the self-pollinated seeds. These results clearly showed that selection based on the phenotype in early generations should be effective for breeding higher contents of sesamin and sesamolin.
Experiments were conducted to determine the effects of a bagasse vinegar application to the soil surface on the growth and nutrient uptake in ripening sugarcane when applied to the original soil surface of a field. First, we checked the effect of bagasse vinegar on the dissolution of tricalcium phosphate (Ca3(PO4)2). In the presence of bagasse vinegar tricalcium phosphate was ionized thus producing phosphoric acid. The stem weight and yield of sugarcane at harvest. 100 days after application tended to be increased by applying bagasse vinegar at 1-100-fold higher concentrations. Sugar content of sugarcane was significantly increased by application of bagasse vinegar at a 100-fold higher concentration. Phosphorus and silicic acid contents of squeezing juice of sugar cane were bagasse vinegar and those contents were positively correlated with sugar contents of the juice. The results suggest that the bagasse vinegar applied to the soil surface at the ripening stage of sugarcane improves the cane quality at harvest, 100 days after application through the utilization of phosphoric acid in the soil.
In the Tohoku district of Japan, spinach is cultivated 4 or 5 times from spring to autumn, but production in summer has become increasingly unreliable. The objective of this study was to establish a system of crop rotation to improve summer spinach yield without chemical treatment. Eight rotation systems were tested for the preceding cultivations in spring: immature soybean, immature kidney bean, burdock, carrot, lying fallow, lying fallow (April to mid-May) followed by spinach crop, spinach (April to mid-May) followed by a fallow period, and spinach followed by komatsuna (Brassica rapa L. Perviridis Group) crop. Compared with the two spring spinach cultivations (April to June) as a control, the dry matter yields of the first summer spinach crop were greater in the systems using soybean, kidney bean, burdock, carrot, and lying fallow for the entire spring. The other systems did not have any clear effect. On the other hand, differences in dry matter yield of the second summer spinach crops between the control cultivation and the eight rotation systems were small. These results indicate that a) the yields of the first summer spinach crop could be improved by avoiding spinach cultivation for the entire spring; and b) lying fallow for the half period of spring is not effective on the yield of summer spinach. Spinach cultivation should be avoided in spring to increase theyield of summer spinach.
Field experiments were conducted in 2009 to establish integrated weed control methods for prevention of herbicideresistant water foxtail (Alopecurus aequalis) and Beckmann's grass (Beckmannia syzigachne), which cause serious problems in the wheat and barley fields in northern Kyushu. Partial shallow tilling and sowing (PSTS) combined with glyphosate potassium salt treatment were effective for the control of water foxtail and Beckmann's grass. PSTS without glyphosate potassium salt treatment increased the number of survived water foxtail plants and Beckman's grass to 117～185% and 185%, respectively. It increased fresh weight to 202～321%, and dry weight of Beckmann's grass to 190% of that under the conventional method. Howeve, PSTS combined with glyphosate potassium salt treatment reduced the number of survived water foxtail plants to 25～53% and their fresh weight to 22～24%. It reduced the number of survived Beckmann's grass to 13% and dry weight to 5% of that under the conventional method.