Eco-Plants LaboratoryThe growth of adventitous roots (nodal root) of rice plants is closely related to the leaf development. The new root began to emerge from the node synchronously with the development of new leaf of the three upper nodes. The newly developing nodal root receives a large amount of nitrogen (N) from the shoot during its growth stage of protein accumulation. Around 50% of N accumulated in young nodal root derives from the shoot even when the root absorbs medium N. A large part of the shoot N translocated to young root involves amino-N compounds exported from mature leaves produced by protein degradation. The shoot N exported from leaves may contain considerable reduced N originating from xylem to phloem N transfer in leaf minor veins. The N exported from mature leaves move in the phloem together with photo-assimilated carbon (C) in the leaf. The C:N ratio of translocates delivered to the root determined with double isotope labeling technique indicates that the old nodal root receives assimilates rich in N than C as compared with the new one, although the N requirement of the old root due to protein synthesis is low. This suggests that excess N moving down to the old root in the phloem would be transferred to the xylem then circulating upward to the shoot. This N circulation system may play a significant role in root growth of rice plants in terms of continuous supply of organic N from shoots to the developing root.

View full abstract

The alleles AS2-2 and SUT1-2 at OsAGPS2 and OsSUT1, respectively, were suggested to improve grain filling in extra-heavy panicle type rice. To confirm the suitability of these alleles, this study sought to generate novel genotypes showing much higher number of spikelets per panicle (SP/P) and examined their degree of grain filling. These genotypes were generated by recurrent selection for higher SP/P from F₂ to F₅ populations derived from a cross between two extra-heavy panicle type rice, Milyang 23 and Nanjing 11. Because both parents contain AS2-2 and SUT1-2, all progenies derived from this cross should have a AS2-2 SUT1-2 genotype. From the change in selection efficiency with successive generations, dominance effects were prevalent in most of panicle traits, including SP/P. Selected lines for SP/P in F₆ generation exhibited much higher SP/P than the parents and non-selected lines, which reached >300 SP/P in the best line. These selected lines also showed higher proportions of well-filled grains (specific gravity >1.15) than cultivars with AS2-1 SUT1-1 genotype, indicating clearly that the alleles for good grain filling, AS2-2 and SUT1-2, should sufficiently improve grain filling even with the greatly enlarged sink capacity of rice panicle. The necessity for improvement in source strength etc. was also suggested to improve grain filling with further increased numbers of SP/P.

View full abstract

Proanthocyanidin (PA), contained in the seed coat of black soybeans, has positive effects on human health. There were wide genetic variations in the PA content in the black soybean seed coat. In this study, chromosomal regions associated with the PA content were determined using the segregating population developed from a cross between a low PA variety, 'Tambaguro', and a high PA variety, 'Peking'. The PA content was not related to flowering time or seed size. Single marker analysis with 150 polymorphic SSR (Single Sequence Repeat) markers revealed that Satt 592, located on Chromosome 10, was detected in both years of the experiment, while other markers were detected only in one year. These results indicate that a primary QTL (Quantitative Trait Locus) was located close to Satt 592 and that it was stable against environmental conditions.

View full abstract

A rice cultivar suitable for sake brewing, "Kyonokagayaki," was developed from a cross between Shu6602 and Yamagata90 in collaboration between Kyoto prefecture and the National Agricultural Research Center. Culm length of Kyonokagayaki is slightly shorter, and heading and maturing occur 3 days earlier than those of Nipponbare. The productivity of Kyonokagayaki is 10% higher than that of Nipponbare. Lodging resistance of Kyonokagayaki is classified as high, viviparity is somewhat high, and levels of resistance to leaf and panicle blasts are moderate and somewhat low, respectively. The 1000 grain weight of brown rice is about 1g heavier than that of Nipponbare. Kyonokagayaki is thus superior to Matsuribare for sake brewing. In performance tests at farmers' fields in Kyoto 2011, Kyonokagayaki was considered to need more panicles than Nipponbare to show its high productivity.

View full abstract

In both the conventional cultivation system and the narrow-row seeding system for the cultivation of azuki bean (Tanba-dainagon), we investigated the effects on yield and bean quality of early sowing compared with the conventional method. In the conventional cultivation system, seed quality declined because of lodging and/or vining in the plot sown on June 17, although the yield increased compared with that upon cultivation with a conventional sowing time. At the plot sown on July 1, in the rainy season, early growth became unstable and yield decreased. On the other hand, the decrease in the effect on yield of early sowing upon partial plowing cultivation was smaller than that upon shallow plowing cultivation in the narrow-row seeding system. At the plot sown in the middle of June, pruning leaf treatment for reduction of luxuriant growth was effective at avoiding lodging and/or vining, and the number of legumes increased as a consequence.

View full abstract

We investigated the effect of nitrogen topdressing 10 days after heading as fertilization method for increasing the grain protein content of the bread wheat cultivar 'Minaminokaori'. Grain protein content was improved by increasing the amount of topdressing. We were able to achieve 13% grain protein content, which indicated a high aptitude as bread wheat, by 6Nkg/10a fertilization.

View full abstract

We found one line of Perilla herb with good smell, as a local genetic resource that may have been cultivated in the Kinokawa plain since ancient times. In this study, firstly, we revealed the morphological and aromatic characteristic of this line by comparison with that of four varieties of Perilla frutescens. Since the leaves of this plant were dark purplish-red color on both surfaces without crepe-like undulations, and this plant contained a notable amount of perillaldehyde and limonene, it was suggested that this line of perilla was one of the varieties belonging to the medicinal red perilla, P. frutescens var. crispa f. purpurea. Secondly, to grow up this resource as a local special product, we have begun to develop the cultivation method for year round production and open up new uses. Supplemental lighting by blue LEDs to the perilla plants which were grown under the natural daylight dreadfully inhibited the flower formation, and allowed the continuous differentiation of young leaves wealthy in perillaldehyde. This cultivation method is useful to inhibit flower formation during short-day period and to improve the functional component content in this perilla herb.

View full abstract

Leaf dynamics is one of the important characteristics in rice (Oryza sativa L.) because it determines dry matter productivity. Nevertheless, few studies have evaluated the genotypic variation in leaf dynamics. This study conducted one-week-interval nondestructive measurements by using plant canopy analyzer, and parameterized leaf dynamics for a rice diversity research set of germplasm (RDRS) and high yielding varieties. Three year experiment in Kyoto University showed large genotypic variations in 5 indexes of leaf dynamics, which consisted of 4 parameters from the nondestructive measurements (relative growth rate of LAI, the maximum growth rate of light interception, days to 80% coverage and extinction coefficient) and LAI at heading from destructive measurement. The significant differences among genotypic groups were observed in relative growth rate of LAI, the maximum growth rate of light interception, days to 80% coverage. High-yielding varieties released by IRRI had higher values of the maximum growth rate of light interception, suggesting that the varieties have been improved in terms of canopy development. In contrast, since Takanari and Milyang23 didn't have extreme characteristics in leaf dynamics, further improvement may be possible.

View full abstract

Interrelationships among sensory evaluations of hardness and viscosity, physical properties and chemical components were investigated using several black soybean lines and varieties possessing various seed characteristics, and the contribution of these properties to the texture of boiled seeds in black soybean was clarified. The fracture force showed a strong positive correlation with the hardness score (r=0.954). The V2 value in this study, which is the ratio of brittleness strain to brittleness force, showed a strong positive correlation with the viscosity score (r=0.961). These results indicate that these fracture characteristics using a texture analyzer are effective indexes to evaluate the sensory texture of boiled seeds. The increasing ratio of seed length after soaking (SSL) and the water-soluble pectin content (WSP) of boiled seeds were related to hardness and viscosity by sensory evaluations. It is considered that the objective evaluation methods and these quantitative indexes of texture for boiled seeds are effective for evaluation of the quality of local black soybean varieties and research on their utilization.

View full abstract

We investigated the effects of the application of sub-phosphoric acid fertilizer (granulated or dissolved in water) on the growth, yield, yield components and seed qualities of soybean (Tanbaguro), and demonstrated two fertilizer application methods for the purpose of reducing labor time. It was confirmed that root weight, plant weight of the aerial part, number of main stem nodes, number of ripening pods, weight of ripening pods, weight of seed-setting, ratio of seed-setting and ratio of 2L grade seeds were increased by the application of these fertilizers. However, application of these fertilizers did not result in improvement of the apparent quality of seeds. A duration of about 36% was required for ridge application with a backpack auxiliary tool or overall application with a battery-driven spreader on 1,000m² compared with that for the conventional application method. Yield indexes in ridge application with a backpack auxiliary tool and overall application with a battery-driven spreader were 98 and 97, respectively, if the yield index in the conventional application method was set as 100, so yields among the three fertilizer application methods were almost the same. Consequently, it is considered that both ridge application with a backpack auxiliary tool and overall application with a battery-driven spreader are effective methods for larger-scale farmers and community farming organizations that require labor-saving approaches.

View full abstract