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Rice varieties Tadukan (indica), Nanjing 11(indica), Nipponbare (japonica) and Arborio (javanica) were tested to find out the content and accumulation pattern of Si in the hull and brown rice during the grain filling periodand the changes in the weight or the contents of N, P, K, Ca and Mg both in the hull and brown rice. The largest increment in the hull weight during heading to maturity was observed for Arborio. The content of Si in the hull and brown rice increased gradually until 30 days after heading. At maturity, the amount of Si in the brown rice was one twentieth of the hull, irrespective of the cultivars. During the GFP, the increment of Si content was highest in Arborio among the cultivars, and the increase of Si content in the hull of was more remarkable than that of Si concentration. Furthermore, Si concentration in the hull of Tadukan was comparable to Arborio, despite the low Si content. These results suggested that the high amount of Si in the hull of Arborio was accomplished by the high number of silica cells on the large grain surface rather than the increased deposition of Si in each silica cell. Both the content and concentration of N and P in the hull decreased until maturity and twas negatively related to the accumulation of Si in the hull. In brown rice, the content of these elements increased with time although the changes in concentrations were slight andmost pronounced in Arborio. Therefore, it was supposed that the heavy accumulation of Si in the hull was the cause of enhanced accumulation of other elements in the brown rice. In addition, observation of Si distribution on the abaxial surface of lemma by electron-probe X-ray microanalysis revealed heavy deposition of Si on the dentate protuberances of the hull, which was supposed to be one of the reasons for different hull weight among the cultivars.Bangladesh Agron. J. 2016 19(2): 125-137

ウコンおよびハルウコンの根茎におけるクルクミンの蓄積経過を調査した．ウコンにおいてクルクミン含有率は種イモで最も高く，次に2次分岐根茎，1次分岐根茎，主根茎，3次分岐根茎であり，地上部および根にはほとんど含まれていなかった．ウコンおよびハルウコンを5月に植付けると，種イモの乾物重は7月にかけて減少し，1次分岐根茎重は9月から11月にかけて急激に増加した．特にハルウコンでは9月から10月の生育中期に，ウコンでは生育中期（2006年）または10月から11月の生育後期（2007年）に根茎生長が最も盛んであった．ウコンにおいて種イモのクルクミン含有率は乾物重の減少に伴い増加し，1次分岐根茎より高濃度となった．1次分岐根茎のクルクミン含有率は9月から10月の根茎形成直後に増加したが，10月から11月の根茎肥大期にほとんど増加しないかやや減少した．一方，ハルウコンのクルクミン含有率は種イモにおいて5月から11月まで緩やかに増加したが，1次分岐根茎において9月から10月の根茎形成直後に有意に減少した．このようなクルクミン含有率の減少の結果，成熟期のクルクミン含有量（含有率×乾物重）はウコンに比べハルウコンで有意に低くなった．株当たりのクルクミン含有量は根茎収量の増加に伴い増加し，クルクミン含有量の増加のためには根茎収量の増加が重要であることが示唆された．貯蔵期間中のクルクミン含有率はウコンおよびハルウコンともほとんど変化しなかった．

To examine the possibility of breeding high-yielding cultivars with high nitrogen use efficiency for dry matter accumulation (NUEd) and to provide simple criteria for the selecting and breeding high-yielding cultivars with high NUEd as well as useful information for the mapping of quantitative trait loci (QTL) controlling NUEd, we cultured recombinant inbred lines (RILs) of rice hydroponically in 2000 and 2001. RILs with a higher grain yield tended to show greater total dry matter accumulation (TDMA) and higher harvest index (HI), while increasing TDMA resulted in a decrease in HI. The contribution ratio of the TDMA to grain yield (2000 : 67.3%, 2001 : 68.2%) was higher than that of HI in both 2000 and 2001. Even at the same high-yielding level, there was a significant difference in the TDMA and HI values. In both years, the contribution ratios of NUEd and total nitrogen absorption (NTA) to TDMA were about 62.0 and 38.0%, respectively. The contribution ratio of the NUEd to grain yield was higher than those of the NTA and HI in both 2000 (41.6%) and 2001 (42.9%). These results suggested that the high-yielding rice plants generally displayed high TDMA and HI values. Further increase in rice grain yield should be based on the further increase in TDMA than in HI, and to increase TDMA leading to a high grain yield, the emphasis also should be put on improving NUEd in RILs.

Using a Chinese large-panicle-type high-yielding indica rice cultivar, Yangdao 4 (YD), pot experiments were carried out to determine the effects of the removal of the lower nodal primary tillers on the growth and yield-related characteristics in comparison with a Japanese cultivar, Hinohikari (HH), with almost the same growth duration. The plants with all tillers remaining (Cont), those with tillers from the 5th and higher nodes (T5) and those with tillers from the 8th and higher nodes (T8) were prepared by removing the other tillers and grown in early, normal and late cropping seasons, sowing in late April, May and June, respectively. The lowest nodal primary tillers in each group emerged earlier and the number of days from sowing to flag leaf expansion and to full heading stage was reduced in the late cropping season, especially in HH. The maximum number of stems and number of panicles were larger in HH than in YD, and tended to be higher in the order of Cont > T5 > T8 plants. The average panicle weight per stem was higher in YD than in HH and higher in the order T8 > T5 > Cont. Panicle weight per hill was higher in YD than in HH in each cropping season and higher in early cropping season in both cultivars. Panicle weight decreased with delayed tiller emergence in YD, but not in HH. Panicle weight was more closely related to straw weight in YD than in HH. Therefore, the promotion of vegetative growth by early sowing and development of lower nodal tillers is more effective for attaining a high yield in YD than in HH.

A Chinese high-yielding large-panicle indica cultivar Yangdao 4 (YD) was examined for the response of yielding ability, sink size and percentage of filled grains (PFG), to the cultivation practice in comparison with a Japanese cultivar Hinohikari (HH) that had almost the same growth duration in 2005 and 2006. Treatments included planting density and number of seedlings hill-1, and supplement application of fertilizer to deep layer (SAFDL). Results revealed that the average sink size of YD was 17−28% larger than that of HH due to the larger number of spikelets panicle-1 and heavier grain weight. A significantly larger sink size was attained by the high density planting and SAFDL treatments in both cultivars, but not by changing the seedling number hill-1. The sink size of YD responded more significantly to the cultivation practices than that of HH. The average PFG in YD was about 10% higher than that in HH in both years. The PFG in both cultivars decreased with increasing sink size, but the decreasing rate in YD was 1/3 of that in HH and its yearly fluctuation was also less in YD than in HH. Consequently, the yield of YD increased with increasing sink size in contrast to HH. The average brown-rice yield of YD (640−653 g m-2) was 41−51% higher than that of HH (418−454 g m-2). In comparison with HH, the stable PFG in YD at increased sink size could be attributed to the increase of carbohydrate accumulation in the panicle (W+ T ), larger amount of NSC in the LS + C and higher NSC/sink size.

To examine the possibility of breeding higher-yielding cultivars with a high nitrogen use efficiency (NUE) and to provide simple criteria for the selection and breeding of high-yielding cultivars with a high NUE and useful information for the mapping of quantitative trait loci (QTL) controlling NUE, recombinant inbred lines (RILs) of rice were subjected to hydroponic culture in 2000 and 2001. Grain yield and yield components, total nitrogen absorption (NTA), pre-heading and post-heading nitrogen absorption (pre-NA and post-NA, respectively), and nitrogen use efficiency for grain yield (NUEg) were analyzed. Transgressive segregations for grain yield and yield components, NTA and NUEg were observed. RILs with a high grain yield tended to show a larger number of panicles m−2 and of spikelets per panicle, and a higher filled grain percentage than RILs with a low grain yield. Increasing NTA and NUEg resulted in increases in the number of spikelets m−2 and grain yield, while increasing NTA resulted in ...

The effects of sd1-d, sd1-r and sd1-c at the sd1 locus, d18-k (kotaketamanishiki dwarf) and d12 (yukara dwarf) on the chilling tolerance at the seedling stage were examined. We used isogenic lines regarding the dwarfing genes/alleles, together with their parental varieties ‘Fujiminori’, ‘Shiokari’, ‘Tamanishiki’, ‘Calrose’, Taichung 65, Norin-PL8 and Norin-PL11. Chilling treatments at 2oC for three, four and five days were conducted at the 1- and 2-leaf stages. The chilling tolerances of the lines were evaluated by survival percentages after the treatments. The d12 lowered the chilling tolerance. The sd1-d and sd1-c lowered the chilling tolerance on the less tolerant genetic backgrounds of ‘Fujiminori’ and ‘Shiokari’, whereas this effect did not appear on the more tolerant genetic backgrounds of Taichung 65 and ‘Calrose’. The d18-k enhanced the chilling tolerance on the less tolerant genetic backgrounds of ‘Shiokari’ and ‘Tamanishiki’, whereas the effect did not appear on the more tolerant genetic backgrounds of Norin-PL8 and Norin-PL11. Consequently, d18-k could be utilized to develop varieties adaptable to areas readily damaged by unseasonably low temperatures at all of the susceptible growth stages of rice, because d18-k is known to enhance the cool tolerances at both the booting and flowering stages also.

The effects of adding deep seawater to a nutrient solution in hydroponics using organic substrates on the plant growth and fruit yield and quality of tomatoes pinched above the 4th truss were investigated. Deep seawater was added to the nutrient solution at concentrations of 20%, 10%, 2%, and 0%(control). With the addition of deep seawater at 2%, plant growth was almost the same as that of the control,but was depressed at 10 and 20%. The marketable fruit yield with 2% deep seawater addition was 65% of the control, while those of 10 and 20% additions were 36 and 38%, respectively. The reduction of marketable fruit yields by the addition of deep seawater was attributed to a decrease in fruit weight and number as well as an increase in defective fruit. However, the soluble solid content and titratable acidity of the fruit increased with the addition of deep seawater. The results indicated that the tomato fruit quality might be improved with the addition of deep seawater to a nutrient solution.

The plant type in high-yielding cultivars (HYC) bred in recent years has tended to change from a higher number of panicles with smaller stems and panicles (panicle number type) to a lower number of panicles with larger stems and panicles (panicle weight type or superpanicle weight type) with a concomitant increase of the contribution ratio of the spikelet number per panicle to the number of spikelets per square meter. Therefore, field experiments were conducted by using twenty-two rice cultivars with different plant types belonging to both japonica and indica ecospecies to analyze cultivar differences in the number of differentiated spikelets per panicle (NDS) and the percentage of degenerated spikelets (PDGS) which determines the number of spikelets per panicle, in relation to the amount of dry matter produced and nitrogen (N) absorbed until and / or during the panicle formation stage. The NDS, number of degenerated spikelets (NDGS) and surviving spike lets per panicle (NSS) were significantly h...

Guava anthracnose was found more prevalent during the main season (April-September) than in off-season (November- February). Pestalotiopsis psidii, Colletotrichum gloeosporioides and Botryodiplodia theobromae were established as causal organisms of guava anthracnose. On potato dextrose agar medium, the growth of P. psidii was observed to be too slow as against the very quick growth of B. theobromae. All the pathogens grew well at 28 and 30 degree centigrade except only the P. psidii at 30 degree centigrade. No varieties were found resistant against all three pathogens tested but local variety I, II and IV proved resistant only against Pestalotiopsis psidii both in vitro and in situ. The Pear shaped fruits had less susceptibility than elliptical round fruits. Local varieties were less susceptible than commercial ones. In inoculated condition, variety kanchannagar showed less susceptibility in comparison with the variety sarupkati and kazipayara. Immature fruits of local variety showed decline in ascorbic acid content when diseased.

イネ科植物 (9種) およびカヤツリグサ科シュロガヤツリを用い, 水上栽培において優れた物質生産および水質浄化作用を示す植物種の養分吸収特性を明らかにし, 自然水域での水上栽培における適種の選抜指標を得ようとした. 結果は以下の通りである. 1) 根の基部に緩効性肥料を施した場合, 乾物生産量はいずれの種においても増加したが, チッソ (N) およびリン (P) の浄化量 (植物による吸収と肥料からの溶出の収支) については増加する種と減少する種があった. このことは施肥条件下でNおよびPの吸収量に顕著な種間差が存在したことによるものであり, 施肥反応性の高い種を選抜することが重要であった. 2) NおよびPの吸収に及ぼす水中のpHおよび栄養塩濃度の影響をイネとシュロガヤツリで比較したところ, イネのNおよびP吸収量は高pH下で低下したが, シュロガヤツリのNおよびP吸収量はpHの影響を受けず栄養塩濃度に伴い増加した. このようにpHの影響は種間で明瞭に異なった. 藻類の増殖によって極度にpHが上昇した水域では, 高pH耐性種を選択する必要性が示された.

Cultivars with different spikelet weight were compared with the ripening characteristics of primary and secondary spikelets at different positions in panicle and discussed the relation of the ripening process and dry matter production. The objectives were to know the variations of grain filling process of both primary and secondary spikelets among different grain size cultivars. Second, to find out the main ripening period (MRP, the accumulation period from 15.9-84.1% of the maximum grain weight) with the rate of grain filling and which factor between these two are important for the determination of final grain weight. The MRP of different grain size cultivars groups varied from 14-21 (small), 15-21 (medium), and 16-21 d (large) . The dry weight accumulation rate of a spikelet (DWAR-S) during MRP ranged 0.404-0.720, 0.624-0.981 and 0.703-1.297 mg/spikelet/d in small, medium and large grain cultivars, respectively. Among all cultivars MRP of primary and secondary branch spikelets were 13-16 and 14-23 d where DWAR-S were 0.672-1.544 and 0.334-0.939 mg/spikelet/d, respectively. The larger spikelet weight was accompanied with the faster rate of accumulation and a slower rate enhances the MRP. The relations between DWAR-S during MRP and a final spikelet dry weight showed significant positive correlation (r=0.834***) but no significant correlation was observed between the days of MRP and the final spikelet dry weight (FSDW) . Further, the temperature and radiation showed insignificant relationship with DWAR-S during MRP and for the same temperature the DWAR-S varied much among the cultivars which indicated that the FSDW was controlled mainly genetically with a partial impact of environment. It could be concluded that the large grain cultivars gained the higher spikelet weight at a faster rate of accumulation and not to the long period of accumulation.

Norin-PL11 (PL11) is a highly cool-tolerant line which contains genes for cool tolerance introduced from ‘Padi Labou Alumbis’, a landrace of Borneo. We investigated whether the dwarfing gene d18-k (kotaketamanishiki dwarf) exerts its pleiotropic effect of enhancing the cool tolerance at the booting stage under the genetic background of PL11, using the d18-k isogenic line of the recurrent parent PL11 (D11). During the booting stage, two cool-air treatments at 12°C for five days with and without deep water of 15 cm depth (DW and CA treatments, respectively) were conducted in growth chambers illuminated at about 600 μmol PAR m−2 s−1. Besides spikelet fertility, the ratio (%) of the fertilized-spikelet number of each treated panicle to the varietal mean of fertilized-spikelet number per panicle in the control, viz. FS-T/C was adopted in order to estimate the extent of cool damage including the factor of spikelet degeneration. The CA treatment induced notable spikelet degeneration in PL11, but not in D11. The parameter L5, which is the average of the lowest five FS-T/C values (or spikelet fertilities) on five consecutive days in each line, was used for evaluating the cool tolerances of the lines. In the CA treatment, D11 had a higher L5 in FS-T/C than PL11, indicating that D11 is more cool-tolerant than PL11. D11 showed a significantly higher L5 of FS-T/C in the DW treatment than in the CA treatment, but PL11 showed no significant difference of L5 between the CA and DW treatments. Similar results were obtained for spikelet fertility. In D11, almost the whole panicle at the most susceptible stage was under the surface of the deep water. On the other hand, the whole panicle was above the water surface at that stage in PL11. Consequently, D11 almost eluded the damage from the severe cool-air treatment when combined with the deep water. D11 exceeded PL11 not only in ripened pollen grain number per anther in the control but also in an indicator of pollen fertility after the CA treatment, owing to the effects of d18-k. It is concluded that d18-k may be useful for developing super-highly cool-tolerant cultivars for cool-weather areas.

An incompletely dominant gene Ur1 (Undulate rachis -1) increases spikelet number per panicle owing to increase of secondary branches. This genic effect on spikelet number can increase grain yield in either the Ur1/Ur1 or Ur1/+ genotype by enlarging sink size. We examined whether the yield-increasing effect of Ur1 in the heterozygous genotype can be superimposed upon the high yield ability of a japonica F1 hybrid. Two F1s with and without Ur1 (HU and H+) were produced by the hybridization between ‘Nishihikari’ (common maternal parent, short-culm variety) and the isogenic line of Taichung 65 possessing both Ur1 and sd1 or that carrying sd1 only. In 1999, HU, H+ and ‘Hinohikari’, a leading variety in southern Japan, were grown under three fertilizer levels. ‘Nishihikari’ was included in the experiment only at the middle fertilizer level. In 2000, HU and ‘Hinohikari’ were grown at the twofold (heavy) fertilizer level. H+ had a 21 % higher yield than ‘Nishihikari’, revealing its heterobeltiosis. The yield of H+ was 12 to 15 % higher under the three fertilizer levels than that of the check variety ‘Hinohikari’. H+ had a higher ripened-grain percentage than either ‘Hinohikari’ or ‘Nishihikari’. HU had a 7, 10 and 11 % higher yield, respectively, at the low, middle and high fertilizer levels than H+. Among the four yield components, spikelet number per panicle alone contributed to the higher yield of HU, even though its ripened-grain percentage was lower than that of H+. In yield, both F1s showed positive responses from the middle to high fertilizer levels but little response from the low to middle fertilizer levels. HU showed 22, 25 and 24 % (116, 126 and 137 g/m2) higher yield, respectively, at the low, middle and high fertilizer levels in 1999 than ‘Hinohikari’. HU gained the highest yield, 723 g/m2 at the twofold fertilizer level in 2000 which was 14 % (88 g/m 2) higher than that of ‘Hinohikari’. Thus, the yield-increasing effect of Ur1 was superimposed upon the high yield ability of H+. Consequently, Ur1 could be utilized for developing high yielding F1 varieties in the Ur1/+ genotype.

Sago palms (Metroxylon sagu Rottb.) growing on peat soils were found to grow more slowly and to show a lower production than palms growing on mineral soils. This difference was related to the physical and chemical constraints of peat soils, which include low bulk density, high acidity, and low N, P, K, Ca, Zn, and Cu levels. In coastal lowland peat soils, the distance from the sea has been found to be an important determinant of soil elemental composition. We predicted that a sufficient supply of N at the rosette stage would improve sago palm growth and that the availability of N in soil to which controlled release N fertilizer was applied might be higher than that in soil treated with soluble fertilizer. To investigate the changes in the nutrient composition of peat soils at various distances from the sea and the effect on sago palm growth, we studied sago palm areas in Indonesia and Malaysia. To observe the influence of N on the growth performance, we also conducted a fertilizer experiment on c...

Sago palm (Metroxylon sagu Rottb.), which produces starch in large quantities in its trunk, could become one of the most important nutritious food resources in the near future. Although its root functions are thought to be very important for the enormous shoot growth, the morphological and anatomical studies are limited. This study investigates external and internal structures of sago roots with reference to their functions to distinguish two types of roots in each plant; i.e., large (about 6-11 mm diameter) and small (about 4-6 mm diameter) roots. Large roots were adventitious roots whose primordia were formed just inside the epidermis in the stem, emerged from the trunk surface and grew downward into the soil. Small roots were lateral roots whose primordia were formed on large roots running horizontally or on other small roots, grew not only downward and obliquely in both deep peat and mineral soils, but also right above in deep peat soils. Anatomical observations revealed that both large and small roots had the same internal structures containing epidermis, exodermis, suberized sclerenchyma cells, cortex and stele, with only differences in their sizes or cell numbers. Both roots had characteristic development of schizogenous or lysigenous aerenchyma, but seem to have different functions. Root primordia were formed successively throughout the trunk. Root primordia in the lower trunk had a large diameter, while density of root primordia per unit trunk surface area was high in the upper trunk.

Heterosis in the number of differentiated, degenerated, and surviving spikelets in two important Chinese F1 hybrids Shanyou 63 (SY63) and Yayou 2 (YY2) and their parents was observed under solution culture conditions. The results indicated that the number of differentiated, degenerated, and surviving spikelets all showed a very high value for mid-parental (MP) heterosis in the hybrids at both panicle and plant levels. The increase in the number of surviving spikelets primarily depended on that of the number of differentiated spikelets. The percentage of degenerated spikelets showed a positive value for MP and higher-parental (HP) heterosis (increase) in SY63, while it showed a negative value for MP and HP heterosis (decrease) in YY2. Morphologically, the components of the number of surviving spikelets increased in the hybrids, especially the number of surviving secondary rachis branches. Dry matter production at heading showed a high value for MP and HP heterosis. However, the ratio of dry matter...

By applying nitrogen (N) and phosphorus (P) fertilizers at different rates and times to high-yielding rice cultivars, we analyzed the absorption of N at different stages in relation to the formation of the source and sink as well as grain yield. The results showed that, the grain yield increased along with the enlargement of the sink size. N absorption from 30 d before heading (DBH) to heading was more important for enlarging the yield sink than that at other stages. N absorption during this period was even more important for panicle weight type cultivars (line 9004 and Yangdao 4) than that for a panicle number type cultivar (Suweon 258). N absorption before 30 DBH led to a higher increase of the leaf area index (LAI) compared to that afterwards. And faster decrease of LAI after heading was correlated more closely with the LAI at 30 DBH than with the LAI increase from 30 DBH to heading. A larger N absorption from 30 DBH to heading enabled to maintain a higher LAI after heading. Dry matter accumul...

The presence of large panicles enables to reach a sufficient number of surviving spikelets per unit area for further increase of rice yield. However, the response of differentiated and degenerated spikelets to environmental factors in terms of number in cultivars with large panicles has not been elucidated. By applying top-dressing at different rates and frequencies, shading, and day/night temperature treatments in pot experiments, we observed the response of the main stem in two cultivars with large panicles: Yangdao 4 (Chinese indica) and Akenohoshi (Japanese japonica-indica hybrid). The results showed that top-dressing increased the number of differentiated spikelets per panicle and decreased the percentage of degenerated spikelets. Consequently, the number of surviving spikelets per panicle increased. Shading increased the percentage of degenerated spikelets, resulting in the decrease of the number of surviving spikelets per panicle. Higher day/night temperature treatments led to a higher per...

Varietal differences in the number and cross area of large vascular bundles (LVs) at the neck internode were investigated in 18 rice cultivars. There were two kinds of LVs in Chinese japonica (CJ), Japonica-indica hybrid (JI), Tall indica(TI) and Semidwarf indica (SDI) types, i.e. the large (L1) and the small (L2) bundles. The number of L2 varied with the cultivar group. The total number of LVs was in the decreasing order of SDI>TI>JI>CJ>JP (Japonica panicle weight type) >JN (Japonica panicle number type). The ratio of the number of LVs to the number of primary rachis branches (V / R ratio) was nearly 1.0 in JP and JN. However, the V / R ratios in JI, TI and SDI were higher than 1.0 because the number of L2 was added. Total or phloem areas of L1 were larger in T1 and SDI than in JP and JN. The whole area of LVs and phloem areas were in the decreasing order of SDI>TI, JI>CJ>JP>JN because of the difference in the numbers of L2. The whole area of LVs and phloem areas of JP (cv. Koganemasari) and SDI (cv. Gui zhao 2) were increased by the increment of N application at the panicle formation stage. The increment of the area of LVs and the running of L2 at the neck internode are considered to be important indicators jto strengthen the transportation system of assimilates by breeding.

By categorizing the water selected ripened paddy grains into groups with different specific gravity, we observed several characteristics of the paddy grain and brown rice in four cultivars. It was found that the grains of cultivars with heavier grain were intensively distributed in higher specific gravity, whereas those of cultivar with lighter grain were sparsely distributed around lower specific gravity. The coefficient of variation (CV) of the character in brown rice was always higher than that of the respective character in paddy grain. These results suggested that after the size of the hull was determined at flowering, the brown rice still had a wider variation. The brown rice volume was primarily determined by its thickness, and the influences of its length and width varied among cultivars. With the increases of brown rice volume, all characters of the paddy grain volume, the specific gravity of paddy grain, the paddy grain weight, and the brown rice-paddy grain ratio increased. These were found to be consistent in the four cultivars. The hull weight and the paddy grain weight showed positive correlation in two cultivars, but not in the others. It was concluded that the specific gravity closely related with the paddy grain weight, which was mainly determined by its brown rice volume. The brown rice volume was primarily subject to its thickness. The hull's role in regulating the growth of brown rice might be different among cultivars.

天津市を中心とする半乾燥地域の野菜栽培畑と穀類畑土壌特性を比較検討した.野菜畑は穀類畑と比較して, 作土層が厚く, 理化学性の改善と熟畑化がみられるが, これらは有機物の施用効果が大きいことが考えられた.野菜畑土壌の有機物, 窒素, リン酸が栽培年数の増加とともに集積傾向がみられた.いずれの圃場も表層土の含有率が高く, 下層ほど低下する傾向がみられたが, 栽培年数の増加に伴い, 可給態リン酸の下層への集積が顕著であった.また, 本地域の野菜畑土壌は, 栽培年数の影響は小さいが, 交換性Ca, Mg, Naが高く, Kは比較的低いことからCa/K, Mg/K当量比が日本の畑土壌と比較して顕著に高く, これら成分のアンバランスが栽培条件によっては生育に影響を及ぼすことも考えられた.野菜畑土壌に生存する微生物は栽培年数が長いほど多く, 細菌は各地点とも比較的安定して生息した.また, 糸状菌は細菌に比べて極めて少なく, 放線菌は糸状菌と同等か, やや上回る程度であった.その結果, いずれも細菌/糸状菌比は高い値を示し, 細菌主導型土壌であることが確認された.土壌の糸状菌生存許容環境を調査した結果, 腐生能や栄養源を質的, 量的に異にする3種の糸状菌の各土壌への住み着きは, 栽培年数と対応がみられ, 表層で高く, 土壌養分の差異に応じて住み着いた.以上の結果, 天津市周辺野菜畑土壌の理化学的環境の改善などにより, 微生物相の改善が促進され, 土壌をより熟畑化させることができると推察された.

A water culture pot experiment was conducted to analyze the effects of N application during the ripening period (RP) on photosynthesis, dry matter production, and its impact on grain ripening and yield in two semidwarf indica type varieties viz. Gui Zhao 2 (GZ) and BR3 (BR) compared with a japonica type variety Koganemasari (KO) under four N rates viz. 0 (N0), 10 (N10), 20 (N20), and 40 (N40) mg L−1. Results showed that N application enabled to maintain a higher leaf area and delay leaf senescence in both indica and japonica type varieties but the decrease in the rate, of leaf area was higher in the former than in the latter and the rate was reduced with increasing N rates. Flag leaf photosynthesis and SPAD values of N treated plants were higher throughout the RP, showing the presence of a significant correlation either for each variety or all the varieties together. Higher photosynthetic rate was supported by higher leaf chlorophyll (SPAD value basis) content, stomatai conductance, and N concent...

A field experiment was carried out to investigate the dry matter production characteristics before and after heading, the partitioning of dry matter to panicles, and some related factors in high yielding semidwarf indica (SDI) and japonica-indica hybrid (JI) varieties in comparison with those of japonica panicle weight (JP) and panicle number (JN) type varieties transplanted in early and late cropping seasons (ET and LT). Leaf area indices (LAIs) of the JI and SDI varieties in both ET and LT were higher at full heading, but decreasing percentages were much more prevalent in these varieties after heading, which resulted in much lower LAIs than those of japonica varieties at maturity. Total top dry weights at full heading of SDI and JI varieties were higher than those of JP and JN varieties in ET and LT, except for Akenohoshi in LT. However, the difference in dry matter increment during the period from full heading to maturity (LIM) among the varieties were not found to be significant. Crop growth rates (CGR) during HN of SDI varieties both in ET and LT were the lowest among thc varietal groups due to the highest decreasing percentage of LAIs and SPAD readings at the later grain filling stage. Panicle dry weights of SDI and JI varieties were about 125∼190gm-2 (20∼31%) and 105∼115gm-2 (18∼20%) higher than those of japonica varieties in ET and LT, respectively. Mean ratios of panicle dry weight to total top dry weight at maturity of the SDI and JI varieties in both ET and LT were about 56%, which were significantly superior to the corresponding mean ratios of JP and JN varieties (i.e., about 47%). These higher mean ratios resulted in panicle weight differences between the high yielding varieties and japonica varieties. The shoot dry matter partitioning percentages to panicles of SDI and JI varieties were more than two times higher in ET, and those of SDI varieties were about four times higher than those of the japonica varieties in LT. The panicle dry weight at full heading (sink capactiy) was found to be closely related to the panicle dry weight at maturity. When the sink capactiy was high, the increment in top dry weights during HM tended to be lower. It was also observed that the partitioning ratios of the accumulated assimilates in shoot to panicles were closely related to the sink capacity.

Three high-yielding japonica-indica hybrid (JIH) and semidwarf indica (SDI) rice varieties, and ten japonica (J) rice varieties, including different plant types, were cultivated under sparse (30×30 cm) and dense (20×20 cm) conditions to clarify the characteristics for the efficiency of spikelet production and the ripening in these high-yielding rice varieties in comparison with japonica rice varieties. 1) Brown rice yields in JIH and SDI were generally higher than those in J in both planting densities, because the number of spikelets per m2 of JIH and SDI, which mainly depended on the number of spikelets per panicle, especially those on the secondary rachis-branch, were greater than those of J. 2) The number of spikelets per m2 for the same level of leaf area index, top dry weight or top nitrogen content at heading stage was greater in JIH and SDI bearing bigger panicles than in J bearing smaller ones. 3) The number of spikelets per m2 of JIH and SDI, or that of J showed significant negative correlation with the percentage of ripened grains. Although the decline of percentage of ripened grains in each varieties was due to the increase of spikelets on the secondary rachis-branch, the percentage of ripened grans in JIH and SDI was higher than that in J at the same level of the spikelets number. 4) From the results mentioned above, it was suggested the high-yielding character in JIH and SDI was based on the greater spikelets per m2 due to the higher number of spikelets per panicle, and the less decline of percentage of ripened grains at this greater spikelets, in spite of the increase of the spikelets on the secondary rachis-branch, as compared with J.

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Using isolated aleurone particles of rice grains it was found that ADP was easily transformed to ATP. This reaction is likely explained by either a transphosphorylation of a phosphate group from phytic acid to ADP or a mechanism involving adenylate kinase. The optimum temperature and pH for this reaction were 30°C and 7.8 respectively. The apparent Km for ADP was 4.0 × 10−4 m. Cyanide arsenate and azide at 10−3 to 10−2 m had no effect on the ATP formation, indicating that the formation was not due to oxidative phosphorylation.

When aleurone particles isolated from rice grains were incubated with 32P-orthophosphate or 3H-myo-inositol, both radioactivities were incorporated into an acid-stable phosphate ester. As the reaction product, myo-inositol monophosphate was recognized by ion exchange column chromatography. The phosphorylation activity was highest at the bran which corresponded to the aleurone layer. These observations suggest that the phosphorylation site of myo-inositol in the rice grain is the aleurone particles.The phosphorylation of myo-inositol was enhanced by the existence of ATP. The optimum pH and temperature for the phosphorylation were 7.9 and 30°C, respectively.

Electron microprobe X-ray analysis was used to determine the transversal microdistribution of P, K, Mg, Ca, Fe, and Mn, with special attention to the outer layers of rice and wheat grains. P, K, Mg, Fe, and Mn were concentrated in the aleurone layer in each case. In particular, P, Mg, and K were highly concentrated in the subcellular particles of the aleurone layer, and had very similar distribution patterns in the outer layers of the matured grain of rice and wheat. By contrast, Ca was abundant in the pericarp.

Subcellular particles were isolated from the phosphorus-rich portion of rice bran using a differential centrifugation in nonaqueous media. Isolated particles were characterized by high contents of phosphorus and metals and low contents of proteins. Most of the phosphorus was found as phytic acid. Chemical composition and electron microscopic observation confirmed that isolated particles were derived from the aleurone layer and were distinguished from protein bodies.