Effect of Time of Harvest and Nitrogen Level on Yield and Grain Breakage in Transplanted Rice¹

Abstract

An application of up to 120 kg/ha of nitrogen fertilizer in the dry season improved the milling quality of the chalky varieties ‘IR8,’ ‘IR5,’ and ‘Sigadis’ but not that of the nonchalky variety ‘C4‐63.’ An application of up to 60 kg/ha of nitrogen increased the protein content of brown rice of the four varieties but increased the head rice yield of only Sigadis, the most chalky of the four varieties; the head rice yield of the other three varieties remained unchanged. Irrespective of variety and nitrogen level, the optimum time of harvest of transplanted rice for obtaining maximum grain and head rice yields and highest germination percentage was between 28 and 34 days after heading in the dry season, and between 32 and 38 days in the wet season. These heading periods correspond to moisture contents of between 22 and 19% and between 21 and 18%, respectively. Lodging increased grain yield losses in both seasons, with the losses being greater when harvested late; therefore, lodging‐susceptible varieties should be harvested earlier than lodging‐resistant varieties. Nitrogen fertilization in the dry season delayed by 2 to 4 days the optimum time of harvest of the improved varieties IR8, IR5 and C4‐63.

Importance and Effect of Nitrogen on Crop Quality and Health

“…Early work with improved rice varieties conducted in the 1960s and 1970s demonstrated that grain protein could be significantly increased by ensuring adequate nitrogen fertilizer application up to panicle initiation stage (Nangju and De Datta, 1970;De Datta et al, 1972). Subsequent field research has found that improved fertilizer nitrogen use efficiency to achieve both high yields and high grain quality requires careful attention to the rate and timing of nitrogen fertilizer applications such that the total available nitrogen supply from soil and fertilizer is congruent with crop nitrogen demand.…”

Predictive model for grain cracking in terms of rice plant and panicle morphology derived from multivariate analysis

“…Certain physiological and chemical factors involved in the maturity, grain hardness and cracking have also been recorded (Nagato and Kono 1963;Nangju and De Datta 1976;Bhashyam et al 1985;Srinivas et a1 1985). Although the varietal and genetic bases of grain cracking (Srinivas et al 1977;Kunze and Prasad 1978) and of plant and panicle characters in relation to yield (Mallik et a1 1988a b; Bashar et a1 1991, Anon 1991) have been independently studied, it has not been possible to assign a discrete phenotype to the unique cracking character to show its relation with plant and panicle morphology.…”

Review of Rice Quality under Various Growth and Storage Conditions and its Evaluation using Spectroscopic Technology

“…The current hypothesis is that yield is related to the nitrogen-supplying capacity of the soil, which in turn determines the grain protein content (Perez et al, 1996). The application of nitrogen fertilizer at different stages, from panicle initiation to flowering and the grain-filling stages, significantly increases the seed-storage protein content (Nangju and De Datta, 1970;Taira et al, 1970;Nagarajah et al, 1975). It also improves protein content-related traits such as the growth rate of milled and head rice (Wopereis-Pura et al, 2002;Leesawatwong et al, 2005), and translucency (Perez et al, 1990).…”