scholarly journals 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.

1985 ◽  
Vol 54 (1) ◽  
pp. 22-31
Author(s):  
Hideo TSUCHlYA ◽  
Osamu KINOSHITA
Keyword(s):  
Population Density ◽  
Paddy Field ◽  
Canopy Structure ◽  
Lowland Rice ◽  
Rice Plants ◽  
Nitrogen Levels ◽  
Direct Sowing

Population dynamics of Meloidogyne graminicola and Hirschmanniella oryzae in a double rice-cropping sequence in the lowlands of Myanmar

Nematology ◽  
2013 ◽  
Vol 15 (7) ◽  
pp. 795-807 ◽  
Author(s):  
Pa Pa Win ◽  
Pyone Pyone Kyi ◽  
Zin Thu Zar Maung ◽  
Dirk De Waele
Keyword(s):  
Population Density ◽  
Growing Season ◽  
Lowland Rice ◽  
Population Densities ◽  
Rice Varieties ◽  
Meloidogyne Graminicola ◽  
Rice Plants ◽  
Double Rice ◽  
Heading Stage ◽  
Rice Growing Season

The rice root-knot nematode, Meloidogyne graminicola, and the rice root nematode, Hirschmanniella oryzae, are considered potentially important nematode pathogens in lowland rice. A study was undertaken from December 2009 until December 2010 in the Ayeyarwady River Delta, the major lowland rice-producing area of Myanmar, to monitor the population dynamics of M. graminicola and H. oryzae in a naturally infested field. Root samples of the two rice varieties Yatanartoe and Taungpyan that are commonly cultivated in double rice-cropping sequences in Myanmar and represent irrigated and rainfed lowland rice varieties, respectively, were obtained for nematode analysis. During the summer-irrigated rice-growing season the root population density of second-stage juveniles (J2) of M. graminicola showed two distinct peaks – at the maximum tillering stage of the rice plants in January and at the heading stage of the rice plants in March 2010. With the onset of the monsoon rains, the J2 population densities in the roots of ratoon rice plants gradually decreased in May. During the rainfed monsoon rice-growing season, very low population densities of M. graminicola J2 were detected in the roots of rice plants, while the root population density of H. oryzae juveniles and adults showed two distinct peaks – at the maximum tillering stage of the rice plants in August and at the heading stage of the rice plants in October 2010. With the onset of the dry season, population density of H. oryzae in the roots reached the lowest density at harvest in November. Root galling caused by M. graminicola followed the same trend as the J2 population densities throughout the irrigated season. No root galls were observed during the monsoon season. Our results can be used for practical purposes aimed at a better management of both M. graminicola and H. oryzae.

Effect of topsoil removal and selective countermeasures on radiocesium accumulation in rice plants in Fukushima paddy field

2017 ◽  
Vol 603-604 ◽  
pp. 49-56 ◽  
Author(s):  
Baolu Yang ◽  
Yuichi Onda ◽  
Yoshihiro Ohmori ◽  
Hitoshi Sekimoto ◽  
Toru Fujiwara ◽  
...  
Keyword(s):  
Paddy Field ◽  
Rice Plants ◽  
Topsoil Removal

Rice (Oryza sativa L.) germplasm with better seedling emergence under direct sowing in flooded paddy field

2018 ◽  
Vol 16 (4) ◽  
pp. 352-358 ◽  
Author(s):  
Junichi Kashiwagi ◽  
Koji Hamada ◽  
Yutaka Jitsuyama
Keyword(s):  
Paddy Field ◽  
Oryza Sativa L ◽  
Seedling Emergence ◽  
Screening Method ◽  
Paddy Fields ◽  
Rice Germplasm ◽  
Geographical Regions ◽  
Wide Range ◽  
Cultivation Practice ◽  
Direct Sowing

AbstractDirect sowing of rice in a flooded paddy field is a beneficial cultivation practice for water use and labour efficiency, compared to the transplanted cultivation. However, a drastic reduction in seedling emergence under flooded paddy fields is a serious constraint especially when the seeds fell at deeper soil layers. Suitable rice germplasm for the direct sowing in flooded paddy fields could ensure the success of this cultivation practice. Instead of laborious field-based screening systems, a pot-based screening method was adopted for simplicity and efficient evaluation of seedling emergence of a subset of world rice germplasm (n = 75) at different sowing depths. As a result, two rice genotypes, ‘Vary Futsi’ (landrace from Madagascar, non-glutinous, subspecies Indica) and ‘Dahonggu’ (landrace from China, non-glutinous, subspecies Indica), with consistently better seedling emergence were identified from a wide range of rice germplasm. These genotypes could serve as excellent parents for the breeding program in developing new rice cultivars with the improved seedling emergence in flooded paddy fields. There were no significant differences in the seedling emergence rate in flooded paddy conditions among the groups from various agro-geographical regions.

Mineral nitrogen in soils undergoing irrigated rice-upland crop rotations

1980 ◽  
Vol 20 (107) ◽  
pp. 731 ◽  
Author(s):  
IR Willett ◽  
ML Higgins
Keyword(s):  
Ammonium Nitrogen ◽  
Early Growth ◽  
Mineral Nitrogen ◽  
Lowland Rice ◽  
Rice Crop ◽  
Growth Stages ◽  
Poor Growth ◽  
Nitrogen Levels ◽  
Crop Uptake ◽  
Upland Crop

Surface soil (0-150 mm) mineral nitrogen levels were monitored in field plots undergoing rice-wheat-wheat and rice-fallow rotations to study the effects of rice growing on the mineral nitrogen content of soils for subsequent crops. Ammonium nitrogen accumulated in the soils during the first 3 weeks of flooding of the rice crop, reaching 54 mg N kg-1 in a grey clay, and 23 mg N kg-1 in a transitional red-brown earth. Thereafter, ammonium nitrogen decreased so that at the time of drainage the soils contained between 2 and 6 mg N kg-1. Nitrate levels during the flooding period fluctuated between 1 and 7 mg N kg-1. In each subsequent fallowing period, nitrate levels increased so that there was approximately 20 mg N kg-1 as nitrate present during the early growth stages of the post-rice crops. However, at the harvests of each post-rice crop, nitrate nitrogen levels had decreased to between 1 and 7 mg N kg-'. Fluctuations in nitrate levels were interpreted in terms of gains from mineralization and nitrification and losses by crop uptake, although leaching and denitrification during periods of heavy rainfall or irrigations could not be assessed. Ammonium levels in the post-rice period increased in the months of October and November when fallowed, but other fluctuations showed no consistent trends. Nitrite levels were low (< 0.6 mg N kg-1) throughout the experiments. Total mineral nitrogen levels during the early growth stages of the crops grown after the rice corresponded to between 31 and 95 kg N ha-1 in the surface 0-150 mm of soil. It was concluded that in the rotations studied, lowland rice cropping did not lead to depletion of mineral nitrogen to such an extent that it could be implicated as a factor in the poor growth of upland crops grown in rotation with lowland rice.

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