Continuous Submergence Research Articles

Influence of continuous submergence on pH, exchange acidity and pH-dependent acidity in rice soils

Two acid lateritic rice soils were submerged under laboratory conditions. During 90-day submergence, (a) pH values of submerged soils gradually increased to stabilized values in the neutral range, (b) exchange acidity increased and pH-dependent acidity decreased to fairly stabilized values.

Alternate wetting and drying irrigation for rice cultivation

A field experiment was conducted at the Bangladesh Agricultural University (BAU) to find out possible effects of alternate wetting and drying irrigation (AWDI) on the yield, water use and water use efficiency (WUE) of Boro rice. The experimental layout was furnitured using split-plot design (SPD) with two modern varieties (MV) of rice viz. BRRIdhan 28 and BRRIdhan 29, which received four irrigation treatments randomly and was replicated thrice. The treatments ranged from continuous submergence (T1) of the field to a number of delayed irrigations (T2, T3 and T4) denoting application of 5 cm irrigation water when water level in the perforated PVC pipe fell 10, 20 and 30 cm below ground level (G.L.), respectively. The study revealed that treatment T1 attributed by the highest total water use (122.2 cm) and the lowest WUE (58.53 kg/ha/cm) produced the highest grain yield (6.86 t/ha). Treatment T2, on the contrary, gave the second highest yield (6.58 t/ha) and consequently the second highest WUE (69.48 kg/ha/cm) indicating quite a large water saving (15 cm) compared to treatment T1. The yields in treatments T3 (6.27 t/ha) and T4 (5.86 t/ha) were significantly lower at 1% level of significance compared to that of treatment T1. No significant effect was found either for the treatment or for the varieties on the number of effective and total tillers hill-1 nor did they affect 1000 grain weight. Reduced plant height, no. of effective tillers hill-1, grain yield, straw yield, biological yield and harvest index were found with the increasing water stress. Key words: Alternate wetting and drying irrigation; Boro rice; Yield; Water use efficiency DOI: 10.3329/jbau.v6i2.4841 J. Bangladesh Agril. Univ. 6(2): 409-414, 2008

Effect of Continuous Submergence Versus Alternate Flooding and Drying on Growth, Yield, and Nitrogen uptake of Rice1

AbstractA comparison was made of rice (Oryza saliva) grown under continuously submerged conditions and under alternately dry and flooded conditions in several greenhouse and field experiments. With nitrogen‐deficient soils, alternately dry and submerged conditions caused an appreciable decrease in growth, yield, and nitrogen uptake. With soils high in available nitrogen as a result of being in permanent pasture for several years, drying and reflooding resulted in a yield increase. Drying and reflooding apparently resulted in a loss of soil nitrogen which was detrimental in the nitrogen‐deficient soils and beneficial in the soils that had been in pasture.

Phosphorus Supplying Capacity of Lowland Rice Soils

AbstractIn a greenhouse experiment with rice (Oryza sativa L.) on four lowland soils, Milfor 6(2), an indica variety from the Philippines, was used to test the relative utilization of soil and fertilizer P (P32‐labelled superphosphate) at various N rates. Added P remaining in solution in six soils was also determined using Ca (H2P32O4)2 at various equilibration times.From 8 to 27% of the total P in the plant was derived from applied P, the amount presumably depending on the availability of soil P under continuous submergence. In general the amount derived was not affected by different levels of N fertilization. The results indicate that, by using the ‘A’ value concept, the rice plant itself gives an indication of the P supplying capacity of some flooded rice soils. Results also show that within 4 days of equilibration the added P remaining in solution was lowest in acid latosolic soils containing kaolin type minerals, moderately high in soils containing mainly montmorillonite, and essentially unaltered in calcareous soil.

On the Fossa Magna disturbance of the Uetsu region and the orogenic movement of the Ou backbone range

By the Median groove running northsouth, the Ou region may be divided into two parts: the U-Etsu region, and the Ou backbone range. The former contains the Gan-Etsu Paleozoic mountain land whose northward extension comprises the Akita region which was ever torn and depressed by the pulling force of the Fossa Magna. In the Miocene times the continuous submergence of the floor of the sea and the oil bearing deep sea deposits of the Akita region might be quite due to the pulling of the Echigo Mountain Range which wes dragged by the Kwanto Range of the Fossa Magna. But the latter comprises the Paleozoic Abukuma and part of the Kitakami range, of which the former was subjected to the dynamic activity of the Futaba fault running northsouth. In this movement the detached blocks cut by the fault havesunkrapidly within the earth, drawing the transgression sea water but at the same time spouting the Andesite lava. It formed a geosyncline which was filled in the next phase by the abundant gushing mass of Green Tuff. Since then the backbone range has kept on upheaving and the Akita region submergence. Both the Futaba fault and the Fossa Magna disturbance may have come from the same origin and be regarded as the manifestation of the Circum-Pacific orogenic energy at that time.

Studies on Water Management in the Ill-drained Paddy Field : VI. Effects of surface drainage on tillering of rice plants.

Though there has been reported by some workers that draining a paddy field generally tended to suppress tillering of the plants on it, the present authors have found many exceptions in the matter by their five years' experiments. The influence differed according to the growth stage. When draining was started at the growth revival stage of the plant after transplanting, it affected the tillers to decrease in number. But when started at the critical stage where the last fructiferous tillers develop, of when started at the floral initiation stage, draining was found more favorable for increase of tillers rather than continuous submergence. Draining decreased the ammonium content in the soil at every stage. It made the soil temperature low in cooler weathers, but high in hotter one. It depressed the nitrogen absorption at the earlier stage, but promoted it at the later stage. Greater importance should be assigned to the soil temperature and the nitrogen absorption than the water content and the ammonium amount in the soil as the factors affecting tillering.

Une serie subbrianconnaise typique; la serie de Piolit (Hautes-Alpes)

Abstract Detailed analysis of the Piolit series in the Piolit massif, Hautes-Alpes, France, a typical Subbrianconnais series, shows that in spite of continuous submergence, an important post- Oxfordian, pre-Tithonian (Jurassic) hiatus is present in the sequence. Berriasian strata identified in the sequence represent the first known occurrence in the intra-Alpine domain. The overlying beds are continuous but telescoped at the Infracretaceous-lower Cretaceous boundary. The late Cretaceous-lower Eocene beds correspond to a fine-grained flysch sediment. The Subbrianconnais Piolit series is distinct from the contiguous Ultradauphinois and Brianconnais zones to the west and east respectively.

Studies on the flooding irrigation of rice. : (II) The effects of continuous submergence on the growth and tillering of rice plants.

In the preceding paper the author reported preliminarily on the effect of continuous submergence upon the growth and structure of rice plants. In the present studies, he intends further to ascertain the influence of continuous submergence on the growth of rice with special reference to its tillering. The plan and the methods of investigation are, therefore similar to those of the previous year. The variety used is Norin-ichigo, an early lowland rice. The submerged plot: The water level of 8 cm high is kept continuously since 2 weeks after seeding till harvest. The no-submerged plot: Soil is always moist enough with no submergence. The tendencies being recognized through the results of both studies are summarized as follows. (1) In Kanto District, the temperature of May (when the rice is seeded) is rather low, hence the submergence of water raises the temperature of earth and water surrounding rice plants, especially at night, because of its high specific heat, and promotes the growth of rice and advances the date of heading several days. But later in June, the temperature rises fairly high, and the submergence is not so effective as in May, but becomes rather infavourable for growth of rice chiefly due to want of aeration. Therefore, the plants seeded and submerged later in June are reduced in growth and the date of heading is not promoted. (2) In the submerged plot, the number of tillers is increased in May seeded Plants and decreased in June seeded ones, and the lowest tillering locus on the main stem is always moved upwards by submergence. (3) The culm and panicle length seems to become less variable by submergence, but the grains per plant or per head may diminish in number, the reason of which is to be studied later. (4) The form of tillering curve in rice may be analogous with that of the autocatalytic one, and each tillering curve of the first, second and third (and rarely forth) orders is its formative stuff.

Effect of Reduced Oxygen Pressure on Rice Germination1

In the 3 years during which this work was conducted in the field rice sown on the surface of the soil, 1/2 inch, and 1 inch deep, then continuously submerged, produced an average of 78.14, 20.00, and 2.66% of seedlings, respectively. No seedlings were obtained from seed sown 1/2, 2, or 2 1/2 inches deep and continuously submerged either in the field or in pots in the greenhouse, except when oxygen was forced into the soil. All seed sown on the surface of the soil either germinated and produced normal seedlings or failed to germinate. Of the seed sown 1/2 inch deep in the field an average of 25.78% produced plumules only. With increased depth of seeding, however, the percentage of seed that produced plumules only decreased and the percentage of seed that failed to germinate increased materially. The results presented indicate that when continuously submerged a 1/2-inch layer of Stockton clay adobe soil materially reduced the oxygen pressure and a layer 1 inch or more in depth reduced the oxygen pressure to a point at which normal germination did not occur. Apparently there was insufficient oxygen under such conditions to initiate growth of the radicle. These results indicate that seeding in the water (surface seeding in these experiments) is the best practice when rice is grown by continuous submergence. The results presented from germination in pots into which oxygen was forced, especially in sand, indicate that a deficiency of oxygen is probably the principal factor causing a lack of normal germination in rice seed sown at various depths and continuously submerged with water. The development of the radicle is initiated by a suitable supply of oxygen. Early seeding of rice is preferable to late seeding because temperatures of the atmosphere and water are lower early in the spring than they are late in the spring, and more oxygen is dissolved in water at low temperatures than at high temperatures. The dissolved oxygen at the lower temperatures results in a larger percentage of seedlings than can be obtained at higher temperatures.