Global socioeconomic developments create strong incentives for farmers to shift from transplanted to direct-seeded rice (DSR) as a means of intensification and economization(1). Rice production must increase to ensure food security(2) and the bulk of this increase will have to be achieved through intensification of cultivation, because expansion of cultivated areas is reaching sustainable limits(3). Anaerobic germination tolerance, which enables uniform germination and seedling establishment under submergence(4), is a key trait for the development of tropical DSR varieties(5,6). Here, we identify a trehalose-6-phosphate phosphatase gene, OsTPP7, as the genetic determinant in qAG-9-2, a major quantitative trait locus (QTL) for anaerobic germination tolerance(7). OsTPP7 is involved in trehalose-6-phosphate (T6P) metabolism, central to an energy sensor that determines anabolism or catabolism depending on local sucrose availability(8,9). OsTPP7 activity may increase sink strength in proliferating heterotrophic tissues by indicating low sugar availability through increased T6P turnover, thus enhancing starch mobilization to drive growth kinetics of the germinating embryo and elongating coleoptile, which consequently enhances anaerobic germination tolerance.

Amylose content is a parameter that correlates with the cooking behavior of rice. It is measured at the earliest possible stages of rice improvement programs to enable breeders to build the foundations of appropriate grain quality during cultivar development. Amylose is usually quantified by absorbance of the amylose-iodine complex. The International Network for Quality Rice (INQR) conducted a survey to determine ways that amylose is measured, reproducibility between laboratories, and sources of variation. Each laboratory measured the amylose content of a set of 17 cultivars of rice. The study shows that five different versions of the iodine

The holistic understanding derived from integrating grain quality and sensory research outcomes in breeding high-quality rice in the light of post-genomics resources has been synthesized. Acceptance of new rice genotypes by producers and consumers hinges not only on their potential for higher yield but recent emphasis has also been on premium-value genotypes that have the ability to satisfy consumer preferences for grain quality. This review article provides insights into how to link grain quality attributes and sensory perception to support breeding superior rice varieties. Recent advances in quality profiling and omics technologies have provided efficient approaches to identify the key genes and biochemical markers involved in rice quality traits. Emphasis has been given to the upcoming area of holistic understanding of grain quality and attributes derived from sensory evaluation to leverage integrative gene discovery strategies that enable breeding programs to efficiently tap the huge genetic diversity in rice for novel genes that enhance rice food quality.

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Soil phenols have been implicated as inhibitors of soil N cycling within many agroecosystems, including irrigated lowland rice (Oryza sativa L.). To quantify the effects of crop management on temporal patterns of phenol accumulation in lowland rice soils, we measured phenol concentrations in two humic fractions at two crop growth stages in each growing season during a 4‐yr field study at the International Rice Research Institute (Philippines). Samples were collected from two double‐crop rotations (continuous rice and rice–maize [Zea mays L.]) with two N fertilizer rates (0 and nonlimiting), and with either aerobic or anaerobic decomposition of incorporated crop residues. Phenols were determined by tetramethylammonium hydroxide thermochemolysis. Compared with the other field treatments, anaerobic decomposition of crop residues with continuous rice and nonlimiting rates of N fertilizer promoted a gradual increase in the relative enrichment of phenols in the mobile humic acid fraction during the 4 yr. The level of enrichment varied among phenol compounds, developing the fastest and becoming most pronounced with the smaller molecules of molecular weight 168 or less. Anaerobic decomposition had less effect on phenol enrichment for continuous rice cropping without N fertilizer. No phenol enrichment was found with anaerobic decomposition of rice residues in the rice–maize rotation. Our results are consistent with previous findings of inhibited mineralization of humic N with anaerobic decomposition, continuous rice, and nonlimiting rates of N fertilizer. Rotation of maize with rice or other techniques to ensure aerobic decomposition of crop residues may help mitigate or prevent phenol accumulation.