Abstract:
The study was conducted at the Rice Research and Development Centre, Bombuwala, to evaluate
the effects of varying nitrogen fertilizer rates on the grain quality of rice. Three nitrogen levels (0,
50 and 100 kg N/ha) were applied to seven rice varieties (Bw 372, Bw 367, Bw 363, Bg 359, Bw
312, Bg 300 and Bw 272-6b) using a split plot design with three replicates. Physical, biochemical,
nutritional and functional quality attributes of rice grains were assessed in response to nitrogen
application. Results showed that the interaction between rice variety and nitrogen level
significantly influenced grain quality traits. Increased nitrogen rates improved several grain
quality attributes, including brown rice percentage, thousand seed weight, hardness, protein
content, phenol content, flavonoid content and gelatinization temperature. However, iron (Fe)
content decreased with higher nitrogen application while ash content remained unchanged.
Among the rice varieties, Bg 300 exhibited the highest brown rice percentage (81.80 ± 0.37 %)
and thousand seed weight (26.923 ± 1.43g) at all nitrogen levels tested. Variety Bw 272-6b” was
identified as the most protein-rich variety across all the treatments, with 9.613±0.02 %. Bw 312
demonstrated the highest hardness (64.433 ± 1.78N), while Bw 372 and Bw 363 consistently
showed high gelatinization temperatures (fscore value = 1). BW 312 also recordedthe highest
phenol content (160.266±13.71mg Gallic Acid Equivalent/100g). Notably, Bg 300 had the highest
total flavonoid content (132.566 mg Quercetin Equivalent/100 g extract) at 100 kg N/ha, while
Bg 367 showed the highest antioxidant content (69.166 Trolox mM/g) under no nitrogen
application. In conclusion, applying nitrogen fertilizer, particularly at 100 kg N/ha, significantly
enhances several physical and biochemical traits, although it may reduce iron content. The
findings support the use of appropriate nitrogen levels to optimize rice grain quality depending
on the variety and desired quality attributes.
