Well-drained Paddy Fields Research Articles

乾田直播水稲の発芽、苗立ちに及ぼす植物生育調節剤(TNZ、ALA)の効果

乾田直播水稲の発芽、苗立ちに及ぼす植物生育調節剤(TNZ、ALA)の効果

Distinction between Poorly and Well-Drained Paddy Fields in Chiba Prefecture Using Landsat TM Data

Distinction between Poorly and Well-Drained Paddy Fields in Chiba Prefecture Using Landsat TM Data

The Optimum Seeding Time on Direct Sowing Culture of Rice in Well-drained Paddy Field in Fukushima Prefecture

The Optimum Seeding Time on Direct Sowing Culture of Rice in Well-drained Paddy Field in Fukushima Prefecture

Adaptability of Leading Rice Varieties to Direct Sowing Culture of Rice in Well-drained Paddy Field in Fukushima Prefecture

Adaptability of Leading Rice Varieties to Direct Sowing Culture of Rice in Well-drained Paddy Field in Fukushima Prefecture

Emergence of Barnyardgrass in Direct Sowing Culture of Paddy Rice on Well-Drained Paddy Field

Emergence of Barnyardgrass in Direct Sowing Culture of Paddy Rice on Well-Drained Paddy Field

The Effects of Soil Acidity upon Growth in Direct Sowing Culture of Paddy Rice on Well-drained Paddy Field

The Effects of Soil Acidity upon Growth in Direct Sowing Culture of Paddy Rice on Well-drained Paddy Field

Farm Land Cosolidation at Direct Seeding Culture of Paddy Rice on Well-drained Paddy Field

Farm Land Cosolidation at Direct Seeding Culture of Paddy Rice on Well-drained Paddy Field

Analysis of Physiological and Ecological Characteristics of Rice Cultivated with Direct Seeding on Dry Paddy Field.

To understand the growth habit of rice plants under direct seedling cultivation on well-drained paddy fields, physiological and ecological characteristics were compared among directly seeded and transplanted rice cultivar Whasungbyeo. Photosynthesis and respiration were lower in direct seeding cultivation (DSC) than in mechanical transplanting cultivation (MTC). Chlorophyll content and root activity were lower in DSC than in MTC from the tillering to heading stages, while they were higher 15 days after heading in DSC. The stomatal resistance of the upper leaves was higher in DSC than in MTC from the tillering to heading stages, however, it was higher in MTC than in DSC 15days after heading. The specific leaf area was higher in MTC than in DSC from the tillering stage to 15 days before heading, and was lower in MTC from the heading stage to 15 days after heading. The length of leaf blade and internode were longer in DSC than in MTC except the flag leaf and first internode. Partial dry weight was high in the upper part in MTC and lower part in DSC. CGR, RGR, NAF and LAI were higher in DSC than in MTC from the tillering to heading stages. The number of spikelets, yield and ripened grain ratio were higher in DSC than in MTC, while the number of panicles was higher in MTC.

Direct Sowing Culture of Paddy Rice on Well-drained Paddy Field of a Large Lot and It's Prospects(Courses of Developments in Low-cost Cultivation Techniques Represented by Direct Sowing of Paddy Rice and "Nyuu-byou" Transplanting)

Direct Sowing Culture of Paddy Rice on Well-drained Paddy Field of a Large Lot and It's Prospects(Courses of Developments in Low-cost Cultivation Techniques Represented by Direct Sowing of Paddy Rice and "Nyuu-byou" Transplanting)

水田転換畑および畑地で栽培されたムギ類からの主要な褐色雪腐病菌の検出

Pythium iwayamai, P. okanoganense and P. paddicum, the main causal organisms of Pythium snow rot, were isolated from rotted leaves of wheat and barley grown in 122 paddy fields and 7 upland fields between 1982 and 1986. P. paddium was the dominant pathogen in ill-drained paddy fields in the previous season. From well-drained paddy fields, all three pathogens were isolated independently or simultaneously. On the other hand, P. iwayamai was the dominant pathogen in upland fields. The results indicate that distribution of the pathogens may vary with the degree of drainage in the fields.

Relationships between canopy structure and yield in rice plants. III. Direct sowing culture of lowland rice at five population density levels having two nitrogen levels on a well-drained paddy field.

A study on the relationships between canopy architecture and yield of rice sown directly requires experimentation with population density of different magnitude and basal nitrogen levels. A lowland rice cultivar, Yamabiko, was sown directly in a square design at five population density levels (1600, 400, 100, 25 and 6.25 plant/m2 at seedling stage) having two nitrogen levels as basal dressing (0 kg-N/10a : 0-N plot and 10 kg-N/10a : 10-N plot) on a well-drained paddy field in 1972. Each plot was replicated three times. Plants were grown on available soil moisture for one month. Thereafter, field was flooded with irrigation water which was kept stagnant in the field till dowgh-ripe stage. The leaf stratified structure of each plot was evaluated on the basis of F1 and F2 scores obtained by the multivariate analysis method as described in part I14). The relationship between the leaf stratified structure and yield was analysed and the results were compared with those of a rice community of transplanting culture reported in two previous papers14, 15) in order to find the characteristics of the structure of this rice community sown directly. The results are as follows : 1. The relationship between F1 or F2 score and the leaf stratified structure and the seasonal trend of leaf stratified structure were virtually the same as those of two previous papers (Tables 1 and 2 ; Figs. 1, 2 and 3). 2. The yield (winnowed paddy) was maximum at 400 plant/m2 density level both in 0-N and 10-N plots and the yield of 10-N plot was about 19% higher than that of 0-N plot (Table 3). 3. The leaf stratified structure and top dry weight appeared to be independent of each other. 4. Positive correlation between yield and top dry weight at each growth stage was found in 0-N and 10-N plots. The correlation was higher at later stage of plant growth, and it was always higher in 0-N plot than in 10-N plot (Table 4). 5. The correlation between yield and F1 or F2 score was high and positive at the young panicle formation stage only in 0-N plot and at all stages except active-tillering in 10-N plot (Table 5). This trend was similar to that reported in part I, presumably due to the similarity of the weather between these experiments. 6. The relative strength of correlation between yield and F1 or F2 score compared with correlation between yield and top dry weight (see part II15)) was greater in the communities with larger leaf area index (LAI), which include 10-N plot or later stage of plant growth. By contrast, in the communities with smaller LAI, the relative strength was small. The smaller the LAI was, the higher was the change of this relative value (Figs. 4 and 5). 7. The comparison of the leaf stratified structure of a rice community sown directly with that of a transplanted community15) shows that the former structure had a tendency to have a high leaf weight percentage (see part I for the definition) in the lower stratum at the active-tillering stage and in the upper stratum after the young panicle formation stage (Fig. 6). The results of No. 1, 3, 5 and 6 are the same as those of two previous papers14, 15). It is therefore suggested that the relationship between the leaf stratified structure and yield of rice is little influenced by the differences in cultural methods as well as the yearly variations in the environmental conditions. It was observed that F1 and F2 factors maintained their individual characteristics in the three experiments. Thus, it is concluded that the statistical method used in the series of this study is very useful for analysing canopy architecture of rice community and for investigating the yielding ability of rice from the viewpoint of canopy architecture.

The Fate of Applied Nitrogen and Mineralized Soil Nitrogen on Immobilization, Denitrification and Absorption by Rice Plants as Well as Biological Nitrogen Fixation in Ill-Drained and Well-Drained Paddy Fields

The Fate of Applied Nitrogen and Mineralized Soil Nitrogen on Immobilization, Denitrification and Absorption by Rice Plants as Well as Biological Nitrogen Fixation in Ill-Drained and Well-Drained Paddy Fields

Prevention of Lodging of Rice Plants under Direct Sowing Culture on Well-Drained Paddy Field : II. Transition of the characters related to lodging resistance after the heading

Prevention of Lodging of Rice Plants under Direct Sowing Culture on Well-Drained Paddy Field : II. Transition of the characters related to lodging resistance after the heading

Prevention of Lodging of Rice Plants under Direct Sowing Culture on Well-Drained Paddy Field : I. Varietal differences in lodging resistance under dense sowing

The lodging resistance as affected by dense sowing and the interrelationships of the traits related to the lodging resistance were examined in rice varieties under direct sowing culture on well-drained paddy field. The results obtained were summarized as follows: 1. Under sparse sowing condition (22.2 hills/m2), the severer lodgings were observed in longer culmed varieties. However, under dense sowing condition (200 hills/m2), the chief reason for lodging was the decrease in breaking strength of stem, and the additional one was the elongation of the basal internodes in long-culmed varieties. 2. The elongation of culm by dense sowing was attributed to the lengthening of lower internodes (N3∼N5). In some long-culmed varieties, the breaking internode came to one internode lower than usual by means of the elongation of the lower internode, and this resulted in the decrease of living leaf sheaths wrapped on the culm, which increased the stem strength. 3. By the research on the relationship between breaking strength and other characteristics, the following facts were made clear. (1) The decrease of breaking strength of the stem by dense sowing was related both to that of the culm and to that of the leaf sheath. Of the two, the latter gave larger influence than the former. There could be observed high positive correlation between breaking strength of stem (culm with leaf sheath) and that of leaf sheath. (2) The contribution rate of leaf sheath to breaking strength of stem amounted high, in some varieties attaining as much as 50-60%. This contribution value was shown larger in short-culmed varieties than in long-culmed varieties and greater in lodging resistant varieties than in lodging susceptible ones. Dense sowing made this rate decrease by diminishing the number of living leaf sheath wrapped on the basal internode. (3) Long diameter/short diameter ratio of culm was increased by dense sowing, and there could be observed negative correlation between this ratio and the breaking strength of the culm. Similar results were recognized also in the leaf sheath. (4) Starch grains were noticed in the culm of lodging resistant varieties, however, the effect of dense sowing on starch amount could not be made clear. 4. By multiple regression analysis, high multiple coefficients of correlation were shown between lodging resistance and four characters (plant height, fresh weight, breaking strength and length of lower internode). Also, high ones were observed between breaking strength of culm (also leaf sheath) and three characters (cross-sectional area, long diameter/short diameter ratio and amount of starch in culm), however, these multiple coefficients of correlation became low in long-culmed varieties under sparse sowing condition. 5. The results may be concluded as follows. One of the most effective method to hold lodging resistance larger is to increase both the living number of leaf sheath on the basal internode and the duration period of it, and the other is to inhibit the elongation of the basal internode, especially in long-culmed varieties.

Adaptability of Rice Varieties for Late Culture of Direct Seeding on Well-drained Paddy Field

Adaptability of Rice Varieties for Late Culture of Direct Seeding on Well-drained Paddy Field

Studies of the Effect of Root-cutting Treatment on Growth and Yield in Direct Sowing Culture of Paddy Rice : II. Changes in the physiological characteristics induced by root-cutting treatment and its relationship to growth behavior

In order to make clear thc mode of the occurrence of favorable effect of root-cutting treatment on the growth behavior of direct sown rice plants, several pot experiments were carried out from the view point of stress physiology. Result of the experiments and conclusion on causes of the occurrence of beneficial effect of root-cutting treatment as obtained from the first and second reports are summarized as follows: 1. Root-cutting treatment on the plants grown by direct sowing culture in well-drained paddy field brought about decreases in stomatal aperture, transpiration, and consequently, water stress on the plant due to lack of water balance, which is seen in the decrease of water content in the leaf and wilting of leaves. The investigation revealed that ethylene production increased in the plant body due to the water stress. 2. Root-cutting inhibited the production of cytokinin in the roots and checked its translocation to the plants grown above the ground surface, resulting in the decrease of chlorophyll content and increase of ethylene production in the leaf. Further investigation revealed that increase of ethylene production by the root-cutting treatment can be prevented by treating the leaves with kinetin solution. 3. The increase in ethylene production by root-cutting is due to water stress and inhibition of cytokinin translocation. It also lowers chlorophyll content in the leaf. However, as new roots emerged seven to ten days after the root-cutting treatment, absorption of nitrogen by roots increased along with reactivated cytokinin translocation. In consequence, chlorophyll content regained its level and after that it became higher than that in the control, and number of fresh leaves increased until later growing stages. 4. After the root-cutting treatment, physiological activity of thc roots, namely, oxidizing ability of α-Naphtylamine, was greatly enhanced due to the emergence of thick new roots and branched roots from the old remaining roots, which had also been accelerated by the treatment. This root activity lasted until the later growth stages. 5. The present experiment also suggested that thc increase of breaking strength which enhanced lodging resistance, observed in the previous report was presumably caused by the increase in ethylene produced in the plant until the later growth stages. 6. It was found that in the treated plants, physiological activity of the upper leaves to adapt themselves to drought condition was enhanced at the maturing stage; this was observed in the decrease of water content in upper leaves and of transpiration rate per unit leaf area, increase of diffusion pressure deficit (D P D) in the leaf blade, and of osmotic pressure in the cell, and decline of water potential in the leaf blade and panicle. The above-mentioned morphological, physiological and ecological changes in the rice plant induced by root-cutting treatment are reflections of water stress and of the changes of plant hormonal behaviour due to the treatment, which resulted in better ripening and increased yield of the rice plants.

水田の物質収支に関する研究(第3報) : 霞ヶ浦流域の乾田における窒素およびリンの収支と排出について

水田の物質収支に関する研究(第3報) : 霞ヶ浦流域の乾田における窒素およびリンの収支と排出について

Root System Formation in Rice Plants in Ill-drained and Well-drained Paddy Field Conditions

Root System Formation in Rice Plants in Ill-drained and Well-drained Paddy Field Conditions

Physiological and Ecological Studies on Barnyard Grass (Echinocloa crus-galli Beauv. var. oryzicola Ohwi) : IV. On the death of seeds in the process of dormancy awakening

We have discovered that some of the seeds lost their viability in the process of dormancy awakening. Following facts were found concerning this phenomenon. Dead seeds were found after one month from the beginning of dormancy awakening (either primary or secondary) in the storage within the soil under upland condition (70 to 80 per cent. soil moisture content of field capacity) at low temperature below 10°C (especially 10°C). Dead seeds did not differ from fresh seeds in the morphological appearance of the embryo at earlier time, but its dehydrogenase activity was missing. However, occurrence of dead seeds in the soil varied acording to the temperature and moisture content of the soil. In the storage under any moisture content of the soil at germination temperature and under submerged or air-dry condition at low temperature, dead seeds were not found. In well-drained paddy fields (submerged condition in rice season, upland condition after rice season), numbers of viable seeds decreased very rapidly during from winter to early spring. In poor-drained paddy fields (submerged condition in the whole year), numbers of viable seeds decreased very slowly because the seeds hardly died in the process of dormancy awakenig in winter. Accordingly, it was well established that longevity of seeds of barnyard grass are longer in poor-drained paddy fields than in well-drained paddy fields.

Effect of Harrowing upon the Behavior of Nitrogen in Well-Drained Paddy Field with Gravel Layer

Effect of Harrowing upon the Behavior of Nitrogen in Well-Drained Paddy Field with Gravel Layer