Limited water availability is a major constraint for cultivation of rice (Oryza sativa L.) in the traditional flooded systems, particularly in the semiarid regions of the world. Aerobic rice cultivation provides feasible alternative to traditional rice production in these regions, allowing significant water savings. Field experiments were conducted at the ANGR University Agricultural Research Station, India during 2009–2010 and 2010–2011 to compare crop growth, yield, and water savings under aerobic rice–maize (R–M) and flooded R–M rotation systems. The effect of aerobic rice on the succeeding maize crop was also studied. The total amount of water applied (including rainfall) in the aerobic plots was 967 and 645 mm compared to 1546 and 1181 mm in flooded rice system, during 2009 and 2010, respectively. This resulted in 37 to 45% water savings with the aerobic method. The soil moisture in aerobic treatment was maintained in the –30 to –40 kPa range throughout the crop growth. The aerobic rice system produced significantly lower grain yields in 2009 and 2010, where differences between flooded and aerobic rice were 39 and 15.4%, respectively. The yield differences were attributed to the differences in spikelet number per panicle and grain weight. Significant increase in yields was recorded in both systems with increased N rates up to 120 kg ha−1. Significantly higher yields were obtained in no‐till maize grown subsequent to the aerobic rice than flooded rice, possibly due to residual soil N and improved soil physical conditions.

2016-11-02T23:50:20

The effect of simulated overhead flash flooding for 10 days at an early vegetative stage of rice grown from transplanted seedlings with and without fertilizer N applied to the nursery soil, was studied under intermediate deepwater conditions at Cuttack, India. Application of 100kg fertilizer N per ha to nursery soil at sowing or in splits improved seedling vigor measured as dry weight and N concentration of the plant tissue at transplanting. The crop raised with healthy and vigorous N-fertilized seedlings was more tolerant to ravages of flooding and showed a better stand with more profuse tillering and less mortality. The grain yield of the semi-tall cultivar Suresh was not affected by N applied to the nursery soil under partial submergence of 70 +-2 cm water depth. However, the semi-dwarf cultivar Gayatri planted with N-fertilized seedlings established better in the early stages and produced more panicles and a two-to five-time higher grain yield. The beneficial effect of nursery fertilization was less marked under natural flooding conditions (25-40 cm). Transplanting semi-dwarf rice with healthy and vigorous seedlings obtained by fertilizing nursery seed-bed could therefore, be a very productive low-cost technology for farmers growing rice under conditions of intermediate deepwater and flash floods.

In an intermediate deepwater (15-50 cm) situation, the number of tillers increased with increase of nitrogen fertilizer from 0 to 40 and 80 kg/ha and of seed rate from 100 to 200, 300 and 400 seeds/m 2 . The tiller mortality due to higher water depth was higher under no-N treatment and under higher seed rates. The number of panicles and grain yield increased significantly with increase in N. Similarly, an increase in the seed rate increased the number of panicles and decreased the number of grains per panicle and panicle weight. The grain yields of the different seed rates were similar. The interaction between N levels and seed rates was not significant. INTRODUCTIONIn low-lying, waterlogged areas, maintenance of an optimum plant population density for a desired crop yield is a major problem. Direct-sown rice crop in such a situation is often subjected to water stress, either deficit or excess, at the beginning of the crop growing season, and excess later resulting in suppression of tiller formation, death of tillers and

No abstract