Cereal Chem. 73(5):556-560 Rice yields of 10 and 6 t/ha can be achieved in the humid tropics dur- improved, but Kett whiteness decreased with late N fertilizer application. ing the dry and wet seasons, respectively. At these high yield levels, late Brown-rice weight was not affected by late N application. In most cases, nitrogen (N) fertilizer application at flowering at the International Rice there was a significant positive correlation between head rice content, Research Institute (IRRI) farm often results in increased rough rice yield milled rice protein, and translucency. Thus, when crop management of IR cultivars and is accompanied by higher milled rice protein and seeks to achieve yields that approach yield potential levels, late N fertilincreased total and head-milled rice contents. The combined effects of N izer application provides an option to improve milling and nutritional application at flowering resulted in a 30-60% increase in head-rice pro- quality of rice grain. tein yield in three field experiments. In general, milled rice translucency A yield decline has occurred in several long-term experiments where continuous irrigated rice is grown in the Philippines (Flinn and De Datta 1984, Cassman et al 1995). In recent studies to identify the cause of decreasing yield trends at the International Rice Research Institute (IRRI) farm, increased nitrogen (N) fertilizer rates including a top-dressing applied at flowering stage was found to increase the yield of IR rices (Cassman et al 1993, 1994). It was hypothesized that the current low yields at the IRRI farm were partly related to a change in the N supplying capacity of soil which results in low N concentration in the leaf canopy during the grain filling period, early senescence of leaves, and low rates of photosynthesis (Kropff et al 1993; Cassman et al 1995). Consistent with this hypothesis, grain protein content also appears to have decreased. For example, mean protein content of milled rice was typically =7% in the 1960's and 1970's at the IRRI farm in plots without applied N (Cagampang et al 1966, Eggum and Juliano 1975, Gomez and De Datta 1975), whereas grain protein from 0-N IRRI field plots (block B4) in the 1991 wet season was only 5.5% for IR72 and 5.0% for IR58109-113-3-3-2 (IRRI, un

Effects of Late Nitrogen Fertilizer Application on Head Rice Yield, Protein Content, and Grain Quality of Rice

The changes in the physicochemical properties of rices which had different amylose contents were studied when the rice was stored at 2°C and 29°C as rough rice, milled rice, defatted milled rice, and as starch. Changes in hardness index, water absorption, stickiness, viscosity, salt-soluble protein, free fatty acids, and carbonyl compounds during storage are discussed.

Changes in Physicochemical Properties of Rice during Storage

Formation of Protein Bodies in the Starchy Endosperm of Rice (Oryza sativa L.): A Re-investigation

Rice grain breakage during milling is a problem in many parts of Asia. It has been suggested that nitrogen (N) fertilizer can improve the milling quality of rice. Therefore, this study investigates effects of N fertilization on grain N concentration, endosperm storage protein distribution, and milling quality of rice. Four Thai extra long grain commercial rice cultivars (KDML105, KLG1, PTT1, and CNT1) were grown at Chiang Mai University in the wet season of 2001 with 0 or 120 kg of N/ha at flowering. Anatomical sections showed that there was more storage protein accumulated in the lateral regions of polished grain of high N concentration than in grain of low N concentration. Percent (%) unbroken rice was positively correlated with relative abundance of storage protein in the lateral region of the endosperm in all cultivars. Applying N increased head rice N concentration in all cultivars, whereas % unbroken rice was increased in KLG1 and CNT1. KDML105 cultivar, on the other hand, already had high ...

/pdf/nitrogen-fertilizer-increases-seed-protein-and-milling-160gw7dve4.pdf

Nitrogen Fertilizer Increases Seed Protein and Milling Quality of Rice

Rice provides a staple source of energy, protein and other nutrients to half of the world population. Over 90 of the rice seeds consists of starch and protein by dry weight. The quantity and property of starch and protein thus play a dominant role in the yield and quality of rice. The amylase content of starch is a determining factor in the eating and cooking quality while the amount and essential amino acids balance of storage proteins affect the nutritional quality of rice. In China, the super-hybrid rice currently under the last phase of development has a 35 yield advantage over the best inbred rice varieties. However, its grain quality needs further improvement. This study reported the expression patterns of 44 genes participating in starch, storage protein, and lysine synthesis in the developing rice grain. Field grown rice cultivar 9311, the paternal line of an elite super-hybrid rice LYP9with its draft genomic sequence released, was used as plant material. Results revealed diverse yet coordinated expression profiles of the genes involved in the three pathways which lead to the final composition and property of starch, protein and lysine that determine the quality of rice, providing useful information for rice quality improvement.

Profiling the expression of genes controlling rice grain quality.

The protein of brown rice became more evenly distributed as protein content increased. Kjeldahl protein content of brown rice provided a better indication of milled rice protein content than histological examination of individual grains because protein content varied among grains. The increase in protein content was mainly due to an increase in the number of protein bodies. Screening 10 493 varieties from the world rice collection for lysine content by dye-binding capacity showed that lysine content of rice protein varied only by at most 0.5 % point at any protein level. A negative correlation between the lysine content of protein and protein content of brown and milled rice was observed only in samples with protein below 10%. As protein content increased water-soluble nitrogen also increased as a percentage of brown rice.

Alicia A. Antonio

Papers

Effects of protein content on the distribution and properties of rice protein

Amylose content and puffed volume of parboiled rice

Molecular weight of starch synthetase from Oryza sativa leaves