A lot of research work regarding irrigation scheduling in rice has been carried out at global level with the objective of increasing irrigation water productivity (IWP) and sustaining grain yield. Under natural conditions rain disturb the planned irrigation treatments. One way to overcome this problem is to use rain shelters which is a costly affair, crop growth simulation models offer a good scope to conduct such studies by excluding the effect of rain. Very limited studies are available where FAO's AquaCrop model has been used to develop irrigation schedule for crops. Therefore, a study was conducted using FAO AquaCrop model to develop irrigation schedule for rice having higher IWP. The model was calibrated and validated using the experimental data of field experiments conducting during 2009 and 2010, respectively. The model underestimated the above ground dry biomass at 30 days after transplanting (DAT) in the range of 21.60 to 24.85 %. At the time of harvest the model overestimated the above ground dry biomass within the range 11.58 to 14.34 %. At harvest the values of normalized root mean square error (15.54%) suggested a good fit for the above ground dry biomass and an excellent agreement (3.34%) between observed and model predicted grain yield. The model suggested to irrigate rice transplanted in puddled loamy sand soil on every 5 th day to get higher IWP coupled with statistically similar grain yield as obtained with daily irrigation schedule.
The field experiment was conducted at Students’ Research Farm, Department of Agronomy, Punjab Agricultural University, Ludhiana during spring 2010. The crop was sown on January 29, 2010 and harvested on May 14, 2010. The soil was loamy sand with 0.3 and 15 bar values of 33.20 and 9.59 cm respectively, in a soil profile of 0-150 cm depth. The soil was moderately alkaline in reaction, low in organic carbon and available N, medium in available P and K. The field experiment comprised 15 treatment combinations <italic>viz</italic>., five main plot treatments [Planting methods including flat sowing (Flat), sowing at the top of ridge laid down in East-West direction (TR), sowing on the southern slope of ridge laid down in East-West direction (SR), sowing at the centre of raised bed laid down in East-West direction (CB) and sowing on the southern slope of raised bed laid down in East-West direction (SB)] and three sub plot treatments (Irrigation at IW/CPE ratio 0.8, 1.0 and 1.2). The experiment was laid out in split plot design with four replications. The seed yield recorded with SR and SB methods was 21.6 q/ha and 21.3 q/ha, respectively, which were statistically at par with each other, but significantly higher than the seed yield observed under TR, CB and Flat methods. Among irrigation schedules, IW/CPE ratio of 1.2 produced maximum seed yield which was statistically at par with IW/CPE ratio of 1.0 and significantly higher than IW/CPE ratio of 0.8.
Management practices need to be developed for successful cultivation of good quality aerobic basmati rice. Field experiments were conducted at Ludhiana, India during the summer seasons of 2011 and 2012 to ascertain the optimum irrigation schedule and dose and timings of nitrogen application to direct seeded basmati rice cultivar Pusa Basmati 1121. Three irrigation schedules (irrigations at 30, 50 and 70 mm CPE), three nitrogen levels (40, 60 and 80 kg N ha -1 ) and two modules of nitrogen splits (3 splits, i.e. application at 3, 6 and 9 weeks after sowing and 4 splits, i.e. application at 0, 3, 6 and 9 weeks after sowing) were tested in randomized block design with four replications on a loamy sand soil. The maximum grain yield, protein content, brown, milled and head rice recovery were obtained with irrigations at 30 mm CPE and these were significantly better than 50 and 70 mm CPE irrigation schedules. Among nitrogen levels, the significant increase in grain yield as well as quality parameters, viz. protein content, brown, milled and head rice recovery was recorded only up to a nitrogen dose of 60 kg ha -1 . In Indian Punjab, good quality direct seeded basmati rice can be produced by following the irrigation schedule of 30 mm CPE and with the application of 60 kg N ha -1 applied in 3 splits (3, 6 and 9 weeks after sowing).
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