RESUMEN
This study assessed the optimal nitrogen (N) fertilizer rate and planting density for the well-adapted upland rice cultivar NERICA_4 on the Fogera Plain. The primary objective was to evaluate the effects of varied planting densities and N-fertilizer rates on upland rice yield and other agronomic parameters. A two-year field study (2020 and 2021) was conducted at the Fogera Rice Research Field Station, testing nine plant densities (75, 87, and 98; 72, 82, and 91; 70, 79, and 89 plants per m2 and two N rates (115 and 138 kg N ha-1). The Crop Simulation Model Crop Environment Resource Synthesis (CSM-CERES-Rice) within the Decision Support System for Agrotechnology Transfer (DSSAT) framework was calibrated and validated using site-specific weather, soil, crop, and agronomic management data from the experiment. Results on the subsequent RMSE, RMSEn, and d index values during the calibration phase were 0.074 t ha-1, 1.82 %, and 0.86 of grain yield; 0.307 t ha-1, 3.36 %, and 0.87 of by-product yield; 0.489 t ha-1, 3.74 %, and 0.79 of top dry biomass yield; and 0.28, 8.24 %, and 0.63 of leaf area index values, respectively. Whereas results on the corresponding RMSE, RMSEn, and d index values during the evaluation phase were: 0.58 t ha-1, 1.33 %, and 0.90 of grain yield; 0.69 t ha-1, 0.58 %, and 0.99 of by-product yield; 0.678 t ha-1, 4.36 %, and 0.67 of top dry biomass yield; and 0.75, 13.92 %, and 0.74 of leaf area index, respectively. The findings of the long-term simulation showed that a 23 % increase in grain yield was achieved with 138 kg N ha-1 and 87 plants per m2 of planting density, as compared to 115 kg N ha-1 and 75 plants per m2 of plant density. The recommended optimum plant density and N fertilizer rate were 138 kg N ha-1 with PD2 of plant density for upland rice production in the Fogera Plain.
RESUMEN
Study was conducted during the main cropping season of 2016 in Fogera and Libo Kemkem District, South Gondar, Ethiopia to evaluate agro-morphological and physiochemical studies of upland rice (Oryza sativa L.) varieties for variability and their association with yield and their quality. A total of ten up land rice varieties namely NERICA13, NERICA12, NERICA4, SUPERICA1, HIDASE, ADET, ANDASA, TANA, KOKIT and GETACHEW laid down in a randomized complete block design with three replications were used. The study revealed significance (P < 0.05) difference in ago-morphological parameters like plant height, number of spike lets, biomass yield, straw yield, grain yield and harvest index in Fogera district, and productive tillers, number of spike lets, grain yield and harvest index in Libo Kemkem District. At Fogera district the highest yield were recorded in NERICA13 (4738 kg/ha), GETACHEW (4614 kg/ha), NERICA4 (4092 kg/ha), NERICA12 (4020 kg/ha) and Adet (3557.4 kg/ha) varieties, and NERICA12 (4583 kg/ha), NERICA13 (4013 kg/ha) NERICA4 (4002 kg/ha) and Adet (3380 kg/ha) varieties at Libo Kemkem districts. Five varieties (NERICA (4, 12 and 13), GETACHEW and ADET) at both locations had been tested for physicochemical analysis. The result showed that such rice varieties grain have a cooking grain length of 7.39 mm (ADET), 7.68 mm (NERICA4), 7.65 mm (NERICA12), 7.88 mm (NERICA13) and 6.76 mm (GETACHEW); cooking grain width of 2.61 mm (ADET), 2.64 mm (NERICA4), 2.70 mm (NERICA12), 2.79 mm (NERICA13) and 2.91 mm (GETACHEW); Grain thickness of 1.91 mm (ADET), 2.73 mm (NERICA4), 2.69 mm (NERICA12), 2.72 mm (NERICA13) and 2.23 mm (GETACHEW. and grain length/width (L/w) ratio 2.67 mm (ADET), 1.85 (NERICA4) 1.80 (NERICA12), 1.92 (NERICA13) and 2.09 (GETACHEW) were revealed and determination of grain shapes. Broken density was obtained 85.74mg/cm3 (ADET), 83.47mg/mm3 (NERICA4), 84.38mg/mm3 (NERICA12), 87.5mg/mm3 (NERICA13) and 73mg/mm3 (GETACHEW). Also investigations showed that upland rice grains contained 11.63-14.27% moisture; 1-1.24%, ash; 2.90-3.62% fiber and 8.07-10.35% protein. Gelatinization Temperatures ranged from 58.33 to 72.67% and grain contents of carbohydrates 73.57-75.65% were shown and significantly affected among their five upland rice grains varieties. Among the treatments of upland rice varieties were gained 35.79% of grain yield advantageous over all treatments at both locations. The results revealed in relatively morphologically and physicochemical properties of the three types of upland rice varieties NERICA (4, 12 and 13) were recommended to maximizing grain yielding for rice producing farmers.