岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-874243-452023序iiiiENNo potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551142025Effects of dark respiration on dry matter production of various crop species110ENKuniyukiSaitohGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityTomohiroMurakamiGraduate School of Natural Science and Technology, Okayama UniversityYumiNakamuraSchool of Agriculture, Okayama UniversityMisaNishiboriSchool of Agriculture, Okayama UniversityYukiTakagoshiGraduate School of Natural Science and Technology, Okayama UniversityYoshihikoHiraiGraduate School of Environmental, Life, Natural Science and Technology, Okayama University Eleven crops were cultivated: maize, sunflower, soybean, groundnuts, sesame, kenaf, barley, wheat, rice, potato, and sweet potato. The crop growth rate (CGR) and specific dark-respiration rate (Rs) were measured, and growth efficiency GE =CGR/(CGR+R) (R, respiratory loss) was calculated. In each crop, whole-plant Rs reached a maximum in the earlier stages of growth, declined rapidly until the early reproductive growth, and remained almost constant during the ripening period. The Rs of leaves was higher than that of stems during the reproductive growth period, except for maize and potato. The Rs of storage organs was highest in the earlier stages, followed by a rapid decline to similar or lower values than those of leaves and stems during the ripening period. The GE in whole plant was higher than 60% in wheat, maize, barley, sunflower, rice, kenaf, sesame, but lower in soybean, sweet potato and groundnuts, and lowest in potato, which was affected by the higher respiratory loss. The GE in whole plant during the reproductive growth period was significantly lower, which we attributed to increased maintenance costs due to the increase of non-assimilative organs, and decrease in the dry weight of vegetative organs. A positive correlation was observed between the carbohydrate content of storage organs and GE, indicating that a crop with higher carbohydrate content in storage organs tended to have a higher GE. Crops with higher protein and crude fat content in storage organs tended to have lower GE. The GE over the growing season was low for kenaf, a fiber crop which contains high molecular weight compounds such as lignin and cellulose, and lower for sesame, groundnuts, and soybean, which contain high oil and protein and have high respiration costs for the synthesis of storage materials, suggesting that these higher respiration costs are related to lower dry matter production and hence lower yields.No potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742422020序iiENNo potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551132024異なる施肥条件下における水稲品種の窒素利用効率 ―日本晴とタカナリの比較―3339ENKuniyukiSaitohThe Graduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityYusukeDannoThe Graduate School of Natural Science and Technology, Okayama UniversityThe rice cultivar Nipponbare and the high-yielding cultivar Takanari were cultivated in field trials for three years from 2003, and in pot trials (1/2,000a) for two years from 2004. In the field trials, the following three levels of fertilizer were applied：“0N” without fertilizer, “1N” with the standard amount(8kgN 10a–1), and “2N” with twice the standard amount (16kgN 10a–1). In the pot trial, three levels of fertilizer were applied：“0N” without fertilizer, “1.5N” with 1.5times the standard amount (1.5gN pot–1), and “3N” with three times the standard amount (3gN pot–1). In the field trials, yields were higher in Takanari (538 to 843g m–2) than in Nihonbare (423 to 577g m–2), and the increase in yield with fertilizer application was also larger in Takanari. This was related to the larger sink capacity of Takanari and the smaller decrease in the percentage of filled grain with larger sink capacity. The dry matter weight and nitrogen uptake at the panicle initiation stage were higher in the plots with higher fertilizer application, but the differences between the cultivars were small. Dry matter weight and nitrogen uptake at harvest time were higher in Takanari, and nitrogen use efficiency and sink production efficiency were also higher in Takanari, but the differences in nitrogen use efficiency between cultivars became smaller with increasing fertilizer application. The nitrogen use efficiency for dry matter production also decreased with increasing fertilizer application, and was higher in 2005 in Takanari. The leaf photosynthetic rate of Takanari was higher than that of Nipponbare in the pot experiment. The difference in leaf photosynthetic rate was related to the nitrogen use efficiency (photosynthetic rate / leaf nitrogen content), and the difference in leaf nitrogen content between cultivars was small. The nitrogen use efficiency for dry matter was highest in the “0N” and decreased with increasing fertilizer application, and was higher in Takanari than in Nipponbare. This was presumably related to the higher nitrogen use efficiency of photosynthesis. It was found that fertilizer application decreased nitrogen use efficiency and sink production efficiency, but yield increased with increasing sink capacity, and that differences in nitrogen use efficiency among cultivars were related to the amount of nitrogen absorbed up to the panicle initiation stage and sink production efficiency. In order to improve the efficiency of fertilizer application, it is desirable to increase nitrogen absorption, which is expressed as multiplying the number of days to panicle initiation and the rate of nitrogen absorption, and to select cultivars with higher sink production efficiency.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551132024Analytical studies on high-yielding characteristics of US soybean cv. ‘UA4805’ in comparison with Japanese cv. ‘Akimaro’2532ENSultanzada MohammadMaroufGraduate School of Environmental and Life ScienceYuHasegawaSchool of AgricultureRyutaManabeSchool of AgricultureKuniyukiSaitohGraduate School of Environmental and Life ScienceField experiments were conducted in 2020 and 2021 at the Field Science Center of Okayama Univ. (34°41’ N, 133°55’ E). Two Soybean cultivars ‘UA4805’ and ‘Akimaro’ were sown with two planting densities, 12.5plants m−2 (sparse, 80×10cm) and 25plants m−2 (dense, 80×5cm)on May 25 (early), June 29 (normal), and Aug. 3 (late) in 2020, and 80 and 30cm row-width, and 12.5 and 25 plant m−2 in 2021 on June 23. Seed yield was higher in ‘UA4805’ than in ‘Akimaro’ in 2020 and 2021. The later the sowing time, the higher the seeds/stem ratio. Both cultivars showed higher dry matter in dense planting. Dry matter was higher in ‘Akimaro’, while seed yield was lower than ‘UA4805’. In contrast, ‘UA4805’ showed lower dry matter with higher seed yield. The numbers of nodes, pods, and seeds were higher in ‘UA4805’ resulting in the higher seed yield. Lodging score is larger in ‘Akimaro’ especially in dense planting. The seeds/stem ratio is much higher in ‘UA4805’ than ‘Akimaro’ across 2 densities, 3 sowing times and 2 row width. Pods setting ratio was nearly two times higher in ‘UA4805’ compared to ‘Akimaro’. The greater seed yield of ‘UA4805’ compared to ‘Akimaro’ was due to the higher pod setting ratio, seeds/stem ratio, and lower lodging score, nevertheless the dry matter was larger in ‘Akimaro’. If late sowing is applied, higher planting density is recommended for better seed yield. Narrow row is an effective way to improve seed yield in soybean.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551132024水稲における窒素利用効率の品種間差異1724ENKuniyukiSaitohThe Graduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityYoshifumiIwameThe Graduate School of Natural Science and Technology, Okayama UniversityMasahikoMaekawaInstitute of Plant Science and Resources （IPSR）, Okayama UniversityKazuyoshiTakedaInstitute of Plant Science and Resources（IPSR）, Okayama UniversityWe investigated the effects of fertilizer-free and fertilizer-applied cultivation on growth, yield and nitrogen (N) utilization of rice cultivars in our Kurashiki paddy fields (Institute of Plant Science and Resources, Okayama Univ.), which have been cultivated without fertilizer since 1970, and also in our Okayama paddy fields, which are conventionally cultivated. In 2001, the cultivars Nipponbare (NIP) and Nourin 18 (N18) were cultivated in the Kurashiki fields, with a “0N plot” (no fertilizer application), a “1N plot” (standard fertilizer application), and a “2N plot” (double fertilizer application). In 2002, five cultivars were grown without fertilizer in the Kurashiki fields, and 51cultivars were tested in 0N and 1N plots in the Okayama fields. Yield (2001) in the Kurashiki fields was higher in the 0N plot for N18 (379g m–2), which had a higher number of spikelets per m2, than NIP (300 g m–2), while in the 1N and 2N plots it was higher for NIP, which had a higher percentage of ripening, and N18 had high yield potential even without fertilizer application, but low fertilizer tolerance. The differences in yield were related to N-uptake (NU), and the differences in N use efficiency (NUE, yield/NU) between cultivars were small. The pot experiment showed that the yield of 0N plot was higher for N18 than NIP grown in Kurashiki soil because of the higher number of spikelets per hill, and the yield in the Okayama soil was higher than that in the Kurashiki soil. Long-term non-fertilized soils are of poor soil fertility, which also decreases the NUE, and the NUE of N18 is higher than that of NIP under isolated conditions. The difference in yields is closely related to sink capacity (SC). In 2002, yields in the Kurashiki fields were highest in Takanari (TAK, 494g m–2) and lowest in NIP (350g m–2), and differences in yields were closely related to SC. NUE was highest in TAK (68.6) and lowest in Akebono (48.1). TAK had high NUE and high sink production efficiency (SPE, SC/NU), while N18 had low NUE but high SC due to higher NU, ensuring high yield even under unfertilized cultivation. Yields in the 0N and 1N plots cultivated in 2002 varied between 244–631g m–2 and 199–769g m–2, respectively. A close positive correlation was observed between yield and SC, and between NU and SC, suggesting that the SC through NU is involved in determining yield. A positive correlation was also observed between NUE and yield. It was found that yield increased with an increase in NUE, and that NUE decreased although yield increased with fertilizer application. Through selection of cultivars with high SPE, it is expected that it will be possible to breed low-input, high-yielding cultivars with high NUE in the future.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551092020Effect of System of Rice Intensification（SRI）on growth and yield performance in Nam Dong district, Thua Thien Hue province, Vietnam1320ENNguyen Quang CoUniversity of Agriculture and Forestry, Hue UniverNguyen Thi Thanh HienInstitute of Resources and Environment, Hue UniversityKuniyukiSaitohGraduate School of Environmental and Life Science, Okayama University The field study was conducted in Nam Dong district, Thua Thien Hue province, Vietnam during May 2019 to observe the effects of SRI method on the rice yield and eradicate the factor affecting the yield. The study was carried out to evaluate the agronomic characteristics of rice, fresh and dry matter production, soil characteristics with a focus group discussion regarding cultivation by SRI and non-SRI methods. The soil analyses using standard measurements showed quite similar soil fertility in both SRI and non-SRI methods, while rice plants showed good agronomic performances and fresh and dry matter production in SRI method. At harvesting time, the yield and yield potentials of rice were greater in SRI than that in non-SRI methods. Focus group discussion found some factors that limited SRI development in Nam Dong district.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551062017Effect of shading on dry-matter production, yield and grain appearance quality of Vietnamese rice cultivars （Oryza sativa L.） in the paddy field1320ENTran LocThuyaGraduate School of Environmental and life Science, Okayama UniversityKuniyukiSaitohGraduate School of Environmental and Life Science, Okayama UniversityLight intensity is one of the most important environmental factors to determine the growth and yield of rice. However, little information is known about the response of indica cultivars, especially Vietnamese cultivars to shading conditions. In this study, a field experiment was conducted in 2015 to determine the response of Vietnamese cultivars to shading condition during the grain filling period. Fourteen Vietnamese cultivars were covered by black cloth (50% shading treatment) after the heading stage in the field conditions. Grain yield of fourteen Vietnamese cultivars in shading condition fell to about 32.2–65.0% of the natural light condition. The most sensitive cultivars to shading are ‘Jasmine 85’ and ‘OM2395’, of which the grain yield decreased to 65.0 and 59.8% of natural light condition, respectively. The shaded yield decreased corresponding to the reduction in crop growth rate (CGR) and yield components, especially in the percentage of filled grain due to the increase in spikelet sterility. Shading increased the percentage of immature grains in all cultivars. Shading induced an increase in the percentage of chalky and green grains, which was largest in ‘OM2517’ and ‘OM5451’, respectively. Clearly, shading depressed both grain yield and the appearance quality of brown rice in Vietnamese cultivars, similarly reported in previous studies with Japanese cultivars.No potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742382016鉄コーティング種子を用いた湛水直播栽培における 飼料用水稲品種の適応性916ENKuniyukiSaitohNo potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742372015序iiENNo potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742362014序iiENNo potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551042015Effects of different types of fertilizers and methods on dry matter production, yield and nitrogen use efficiency of rice cultivars under field conditions1321ENRyoYabeNguyen Quang CoTrinh Thi SenKuniyukiSaitoh To examine the effects of different types of fertilizers and application methods on dry matter production, yield, nitrogen accumulation and use efficiency in rice cultivars, we used two rice cultivars (Nipponbare and Takanari) and five fertilizer methods, i.e. Control (0N), Conventional method, Deep fertilizer
method, Standard fertilizer method and High fertilizer method in 2009. Dry matter production
was more markedly increased with nitrogen fertilizer application than in control, and it was higher with deep fertilizer application in Takanari and standard fertilizer application in Nipponbare, respectively. The differences in dry matter production resulted from CGR and mean LAI in rice cultivars. Greater dry matter production was accompanied with the nitrogen accumulation at harvesting. Rice cultivars accumulated the largest amount of nitrogen at deep fertilizer application. Higher fertilizer application increased the number of panicle and total spikelets m–2. The higher grain yield in Takanari
resulted from the larger sink capacity. The grain yield of rice cultivars tended to be higher with deep fertilizer application due to the increase in sink capacity. Both deep fertilizer application and basal application of slow-release fertilizer increased the recovery efficiency and partial factor productivity of applied N, however, using slow-release fertilizer is recommended in terms of labor saving and lower
cost.No potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742352013鉄コーティング種子を活用した乾田直播栽培法の開発917ENNo potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742352013序iiENNo potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742342012序iiENNo potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama2186-77551012012水稲玄米の外観品質と米飯の食味に及ぼす高温・遮光処理の影響2532ENYuukiIshizukiKuniyukiSaitohWe examined the appearance quality and palatability of milled rice for each grain-thickness group. The rice cultivars, Nipponbare and Hinohikari, were cultivated at the paddy field of Field Science Center, Okayama University in 2009. For high-temperature treatment, both sides of the transparent chamber were opened when the temperature exceeded 36 degrees C, and closed when lower than 25 degrees C, and 50% shading treatment with black cloth was applied during the grain-filling period. After harvesting, the grains of brown rice were sorted according to thickness using a rice grader, and classified
into eight grain thickness groups, less than 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, and over 2.2mm. The appearance quality of grains was measured, and milled grains were cooked, and the palatability and physical properties were measured. The brown rice yield in high-temperature plots was 10-21% less than control due to the decrease in the ripening percentage and 1000-grains weight. Yield in the shading plot dropped to 16-24% less than control mainly due to the decrease in the ripening percentage. The percentage occupation of grains with 1.8-1.9mm thickness was higher in Hinohikari than Nipponbare. In high-temperature plots, thickness of 1.8-2.0mm decreased and thickness of higher than 2.0mm increased in both cultivars. The shading treatment increased thickness of lower than 1.9mm markedly. It was
cleared that the shading decreased grain thickening growth and grains was distributed more among thinner groups, and high-temperature promoted the grain thickening growth despite the decrease in 1000-grains weight. In both cultivars, the lower the grain thickness group, the lower the percentage of perfect grain due to the increase in the percentage of chalky grain. The palatability value of milled rice
was greater in Hinohikari than Nipponbare. The lower the grain thickness group, the lower the palatability value and stickiness, and those tendencies were remarkable in Nipponbare than Hinohikari. The shading and high-temperature treatments decreased the palatability value and the stickiness, especially in Nipponbare. The palatability value decreased with lower the grain thickness group due to an increase in the percentage occupation of chalky grains.No potential conflict of interest relevant to this article was reported.岡山大学農学部附属農場Acta Medica Okayama0910-8742191996水稲における無代掻き作韓直播栽培浜に関する研究 第3報 緩効性肥料の利用による全量基肥施肥16ENNo potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742312009「岡大ライス」の候補品種の選定912ENKuniyukiSaitou現在，水田部門では毎年平均45～50トン前後の米を収穫している。以前はその全量をJAに出荷していたが，平成16年からJAへの出荷を止めて，「岡大ライス」と称して生協食堂の米飯用と学内で販売を行ってきた。平成20年度の実績では生協に約37トン，宮下酒造（｢おお岡大｣用）に６トン，残り９トンを一般販売や学内販売している。現在，生協の食堂では‘ヒノヒカリ’と‘アケボノ’をブレンドして使用しているが，それよりも単一品種で安価で美味しい品種はないものかと探していた。九州沖縄農業研究センターで育成された‘あきまさり’(6))は，‘ヒノヒカリ’と同等の食味で収量性も約10％高いことが報告されている。また，‘にこまる’(5))は‘ヒノヒカリ’に比べ高温条件においても白未熟粒の発生が少なく(4))，収量性も優ることが報告されている。そこで，岡山大学フィールド科学センターの主力品種である‘ヒノヒカリ’，‘アケボノ’に‘あきまさり’，‘にこまる’を加えて，2005年と2006年に岡山農場の水田で試験栽培を行い，収量性および食味官能試験を行った。さらに，2007年に八浜農場で小面積の栽培を行い，センター職員および生協職員の協力を得て食味官能試験を行った結果について報告する。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-0254 9712008気温上昇が水稲品種の玄米外観品質，食味におよぼす影響3339ENIzumiOh-eYasukoKobayashiKuniyukiSaitohToshiroKurodaThe effects of high temperatures on grain quality and palatability of cooked rice of four rice cultivars were examined in a temperature gradient chamber (TGC). Experimental plots going from TG1 (near the air intake side) to TG3 (near the air exhaust side) along the temperature gradient in TGC, corresponding to low and high temperature, and an open field plot (outside of TGC) were arranged. The mean and maximum air-temperatures in TG3 were 3.6℃ and 7.2℃ higher, respectively, than those in TG1. Brown rice yield per m2 in the outside was the highest, and those in the TGC plots were lower than outside in all cultivars. This yield decline was due to the decrease in the percentage of ripened spikelets. The
increase in the percentage of sterile spikelets due to high temperatures in Nikomaru and Akimasari was larger than that in Hinohikari and Akebono. The yield difference among TGC plots was not significant. High temperature increased the white berry grains and white back grains in Hinohikari and Akebono, respectively. The overall eating quality (＋3 to －3) in the outside was in the order of Nikomaru (0.56)
＞Akimasari (0.50)＞Hinohikari (0.00)＞Akebono (－0.06). The overall eating quality in TG3 was lower
than outside, especially in the quality of appearance. However, the decreasing degrees of appearance quality in Nikomaru and Akimasari were smaller than those in Hinohikari and Akebono. The protein content of milled rice in TG3 (6.0−7.8%) was higher than that in the outside (8.6−10.4%) in all cultivars. The increase in protein content by higher temperature was in the order of Akebono (4.4%)＞Hinohikari (1.9%)＝Akimasari (1.9%)＝Nikomaru (0.8%). In terms of grain quality, the cultivation of new cultivars, Nikomaru and Akimasari are recommended when air temperature exceeds normal years. However, yield reductions in Nikomaru and Akimasari caused by high temperatures were larger than those in the conventional cultivars, Hinohikari and Akebono.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02548811999Effect of Moisture Storess on the Growth and Yield of Determinate and Indeterminate Types of Soybean8794ENTariqMahmoodKuniyukiSaitohToshiroKurodaThe effect of moisture stress on determinate(Enrei)and indeterminate(Touzan69)types of soybean was studied under vinyl house field conditions.Moisture stress seriously reduced the growth,yield components of both soybean types,but the quantitative effects were seen more in Touzan 69 than in Enrei.Although water stress reduced the floral buds and pod setting ratio in both types the differences were not sighification.The contribution to the number of per plant and seed yield on low and high order racemes was unaffected in Touzan 69,while in Enrei,the contribution to these parameters increased on high order racemes and decreased on low order racemes.In Enrei the contribution to
these two parameters on the main stem and branches was not affected by water stress;however,in Touzan 69 the contribution increased 16-18% on the main stem and decreased on the branches.It
was concluded that the contribution to the number of soybean pods per plant at different positions essntially mimicked differences in seed yield.In both soybean types the detrimental effects of water stress on all the yield components resulted in lower total yield.The main difference between both types was that comparatively more reduced growth(less number of nodes/plant)of indeterminate type reduced a greater number of floral buds which also had a synergistic effect on reducing the yield,so ultimately the yield reduced more in indeterminate than in determinate type.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02549312004岡山県における主要水稲品種の食味と理化学的特性5157ENEmaYamamotoYujiMatsueKuniyukiSaitohToshiroKurodaThe palatability and physicochemical properties of cooked rice, in the cultivars Koshihikari, Hinohikari, Asahi and Akebono, which are commonly cultivated in Okayama prefecture were compared with standard cultivar Nipponbare, in the paddy fields of Okayama, Hachihama and Kurashiki Farm of Okayama University. The rate of fertilizer application on those properties in Okayama Farm was also examined. Hinohikari beat the other four cultivars in all tests of palatability. Asahi tested better than Koshihikari, and was harder than Akebono, but in overall eating quality and stikiness it was almost indistinguishable from Koshihikari. The palatability values of cooked rice produced at Kurashiki farm, in which fertilizers were not applied for 25 years, were the highest out of the three locations. It was considered that the protein content of milled rice was lowest in Kurashiki due to the lower nitrogen content of the soil there. In all cultivars the higher the application rate of fertilizer, the lower the values of palatability due to the increase in nitrogen content of the milled rice, but not with amylose content or amylographic characteristics, i.e., maximum viscosity and breakdown values. The textural characteristics, i.e., the ratio of hardness/stichiness and hardness/adhesiveness were negatively correlated with overall eating quality. The results suggested that it is important to create manuals for the production of rice with good eating quality at each location in consideration of the nitrogen content of milled rice and the yield of brown rice.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-0254 9612007気温上昇が水稲の玄米外観品質, 食味と理化学的特性におよぼす影響1318ENIzumiOh-eYujiMatsueKuniyukiSaitohToshiroKurodaThe effect of high temperatures on grain quality, palatability of cooked rice and physicochemical characteristics of rice was examined in a temperature gradient chamber (TGC). Experimental plots going from TG1 (near the air intake side) and TG4 (near the air exhaust side) along the temperature gradient in TGC, corresponding to low and high temperature, and an open field plot (outside of TGC) were arranged. The mean and maximum air-temperatures in TG4 were 2.8 °C and 5.9 °C higher, respectively,
than those in TG1. Brown rice yield per m2 in outside (572 g) was the highest, and those in TG1 (503 g) and TG4 (180 g) were 12.1 and 68.6ｵ lower than outside, respectively. This yield decline was due to the decrease in the number of panicles and percentage of ripened grains, and an increase in the percentage of sterile spikelets. Most of the immature grain was milky white grains (10.8ﾝ14.6ｵ) and white berry grains (10.7ﾝ43.4ｵ), and other white immature grain accounted for only 0ﾝ2.6ｵ. The grains from the outside plot were separated into perfect grain and milky white grain. The overall eating quality (＋3 to －3) was in the order of perfect grains (0.31) ＞ outside (0.00) ＞ milky white grains (－0.56) ＞ TG1 (－1.0) ＞ TG4 (－1.44). This indicates that the palatability of perfect and milky white grains was
superior to and inferior to that of normal grain, and high temperatures deteriorate the eating quality of cooked rice. In the physicochemical characteristics of rice, the protein content showed a small variation (8.6ﾝ8.9ｵ) between normal, perfect and milky white grains, but that in TG1 (9.9ｵ) and TG4 (9.8ｵ) were higher than that in the outside. Amylose content of each plot was in the same order as the overall eating quality. This showed that amylose content did not affect the palatability because amylose content is normally negatively correlated with overall eating quality. H/-H ratio, a texture characteristic, was smaller in perfect grains than in normal grains, and that in milky white grains was larger than normal grains. This shows that the higher the share of milky white grains, the higher the H/-H ratio. Despite the superior eating quality, H/-H in TG1 was larger than that in TG4. Thus, the effect of H/-H ratio on the palatability of cooked rice grown in TGC was not clear.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02549512006Effects of Rising Temperature on Growth, Yield and Dry-matter Production of Winter Wheat5762ENIzumiOh-eKuniyukiSaitohToshiroKurodaMany studies on the crop response to climate change have been examined for isolated plnts or plants grown in a small-scale popuration. We constructed a Temperature Gradient Chamber(TGC) in a lowland field of Okayama University to clarify the effect of rising temperature on growth, yield and dry-matter production of winter wheat during the whole growth season. The four experimental plots were arranged by the distance from the intake side, TGI(control), TG2, TG3, and TG4. The temperature gradient occurred from TG1 to TG4, the daily ,mean temperature in TG4 increased 2.8℃ more than that of TG1. The dry weight in hight-temperature plots was larger than TG1. The grain yield per M2 was lowest in TG1(218g) and highest in TG2(248g), but gradually decreased with resing temperature in TG3(230g) and TG4(225g). The percentage og spikelet sterility and floret sterillity were not significantly different among the plots. The grain yield tended to decrease with higher the temperature more than 28℃ during the ripening period due to the decrease in dry-matter accumulation in the panicle at the latter ripening period. Clearly, rising temperature increased the wheat grain yield until 28℃ of daily mean temperature during the ripening period, furtuer rise in temperature limited the yild due to the decline in photosynthetic activity.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02549512006Effects of High Temperature on Flowering and Pod Set in Soybean4955ENMachikoKitanoKuniyukiSaitohToshiroKurodaPlants of soybean(cv.Enrei) were grown in pots(1/5000a) in a viny house. Temperature treatment was conducter for 10 days from the beginning of the flowering period(BFP) in the growth chambers under artificial light controlled at day/night air temperatures of 27/27, 32/27, and 37/27℃, respectively. the pollen viability at 37/27℃(89.4%) was significantly lower than 27/27℃(97.2%). In ouder to identify the sensitive stage to high temperature, the plants were treated for 2 days before BFP in the growth chambers controlled at 27/27 and 40/27 ℃, respectively, and the pollen viability of flowers opening after the treatment was investigates. By the treatment at 40/27℃, the pollen viability of flowers which opened at 4 days after the treatment(82.9%) was significantly lower than 27/27℃(97.3%). This indicates that floral buds at 4 to 5 days before flowering, which coincide with the microsporogenesis stage, are sensitive to high temperature. However, high temperature affected the pod setting ratio a little in both experiments. High temperature treatment was conducted by transferring the plants into the glasshouse under natural light before and after BFP. High temperature treatment at 7-1 days before BFP promoted vegetative growth and increased the pod setting ratio, while reducing the seed size. High temperature treatment at 14-8 days before BFP promoted floral differentiation on the second order racemes with compound leaves and increased the number of the floral buds, so that reduced the pod setting ratio. These results suggest that hight temperature at the microsporogenesis stage reduces pollen viabillity, however, pod setting ratio is affecter by the pollen viabillity.No potential conflict of interest relevant to this article was reported.岡山大学農学部附属農場Acta Medica Okayama0910-8742181995水稲における無代掻き作溝直播栽培法に関する研究 第2報カルパー・倒伏軽減剤の処理が生育収量に及ぼす影響17ENKuniyukiSaitohRyoIshimuraToshiroKuroda本試験はこれまでの直播栽培法の一層の省力化,安定性,多収性および低コスト化を目的として1992年に引き続き無代掻き作溝直播栽培法の実証試験を行った。岡山大学農学部附属農場の水田において品種日本晴を用い,1993年5月18日に乾田状態の水田に溝幅30cmと20cmで作溝を行い,10a当り4.5kgの種子を動力散粒機で播種し,播種後湛水を行った。作溝幅30,20cmそれぞれの区についてカルパーを粉衣した区と無処理区を設けた。また,参考区として慣行移植区を設けた。倒伏防止を目的として出穂前17日に倒伏軽減剤を直播区と移植区の一部に処理した。得られた試験結果の概要は以下のとおりである。(1)湛水後の溝の深さは,溝幅30cm区および20cm区ともに,播種翌日に約1/2となり,湛水直後の溝の崩壊に伴って種子が覆土されることが確認された。(2)出芽・苗立ち率はいずれの区でも高く,特に溝幅30cm区で,さらにカルパー粉衣区で高くなった。また,種子深度は溝幅30cm区が溝幅20cm区より深く,覆土効果は溝幅30cm区で高かった。さらにカルパーを粉衣した区で覆土効果が高くなる傾向があった。(3)穂数は移植区に比べ直播区で,溝幅20cm区に比べ30cm区で多くなったが,カルパー粉衣による影響は小さかった。一穂穎花数は直播区に比べ移植区で多かったが,m2当り穎花数は各区ともに24～28×103の範囲にあった。精玄米収量は溝幅30cm・カルパー粉衣区で582g・m-2と最も高く,移植区よりも多収を示した。(4)9月上旬に接近した台風の影響で各区ともに倒伏がみられたが,倒伏軽減剤の処理により上位節間,葉身長,穂長が短縮し,処理区では全く倒伏が認められなかった。しかし,倒伏軽減剤処理により移植区では増収が認められたが,直播区では収量に及ぼす影響は小さかった。No potential conflict of interest relevant to this article was reported.岡山大学農学部附属農場Acta Medica Okayama0910-8742171995水稲における無代掻き作溝直播栽培法に関する研究 第1報作溝幅・湛水方法による生育収量の相違18ENKuniyukiSaitohRyoIshimuraToshiroKuroda本試験はこれまでの直播栽培法の一層の省力化,安定性,多収性および低コスト化を目的として実証試験を行った。栽培方法は,水稲品種アキヒカリを供試し,10a当たり4.5kgの種子を,無代掻きの作溝区(幅30cm深さ11cm,幅20cm深さ9cm)と無作溝区を設け,湛水後播種した。また,作溝区(幅30cm深さ11cm)に播種後湛水する区と,移植区を設けた。(1)覆土効果は,作溝幅においては20cmより30cmが,また湛水後播種より播種後湛水の方が大きかった。(2)出芽率および苗立ち率は,湛-播30cm区と湛-播20cm区で高く,播-湛30cm区で低かった。(3)草丈は各区ともほぼ同様に推移し,最終的にいずれの直播区も移植区に比ベ10cm以上低くなった。最高分げつ期および出穂期は湛水後播種区で移植区に比べ早まる傾向があった。最高分げつ期茎数は出芽率および苗立ち率と同様な傾向を示した。(4)穂数および精玄米重は出芽率および苗立ち率と同様な傾向を示し,湛-播30cm区＞湛-播無作溝区＞播-湛30cm区の順に高く,精玄米収量は出芽・苗立ちに起因した穂数が著しく影響したと推察された。湛-播30cm区では,移植区に匹敵する精玄米収量が得られた。また直播区と移植区の収量構成要素を比較してみると,移植区では穂数と一穂粒数が高かったのに対し,直播各区では登熟歩合と精玄米千粒重が高かった。(5)以上の結果,湛水後播種を行うことにより,高い苗立ち率が得られ,収量の安定性が確保された。播種後湛水を行った場合,種子深度が大きくなって苗立ち率が低下し,収量は低下した。しかし,覆土効果が高く,出芽・苗立ちの不安定性が克服されれば,倒伏抵抗性の観点からも有効であると考えられた。No potential conflict of interest relevant to this article was reported.