Brown Rice Yield Research Articles

Effects of alkaline and bioorganic amendments on cadmium, lead, zinc, and nutrient accumulation in brown rice and grain yield in acidic paddy fields contaminated with a mixture of heavy metals.

Paddy soils and rice (Oryza sativa L.) contaminated by mixed heavy metals have given rise to great concern. Field experiments were conducted over two cultivation seasons to study the effects of steel slag (SS), fly ash (FA), limestone (LS), bioorganic fertilizer (BF), and the combination of SS and BF (SSBF) on rice grain yield, Cd, Pb, and Zn and nutrient accumulation in brown rice, bioavailability of Cd, Pb, and Zn in soil as well as soil properties (pH and catalase), at two acidic paddy fields contaminated with mixed heavy metals (Cd, Pb, and Zn). Compared to the controls, SS, LS, and SSBF at both low and high additions significantly elevated soil pH over both cultivation seasons. The high treatments of SS and SSBF markedly increased grain yields, the accumulation of P and Ca in brown rice and soil catalase activities in the first cultivation season. The most striking result was from SS application (4.0tha-1) that consistently and significantly reduced the soil bioavailability of Cd, Pb, and Zn by 38.5-91.2% and the concentrations of Cd and Pb in brown rice by 20.9-50.9% in the two soils over both cultivation seasons. LS addition (4.0tha-1) also markedly reduced the bioavailable Cd, Pb, and Zn in soil and the Cd concentrations in brown rice. BF remobilized soil Cd and Pb leading to more accumulation of these metals in brown rice. The results showed that steel slag was most effective in the remediation of acidic paddy soils contaminated with mixed heavy metals.

English

Field experiment on deep placement of fertilizers was carried out using precision hill-drilling machine with the objective of determining super rice growth and photosynthesis characteristics, as well as grain quality in South China. With ‘no fertilizer’ as control, the four fertilizer combinations were 100 kg N ha, 100 kg N ha + 60 kg SiO2 ha, 125 kg N ha, and 125 kg N ha + 60 kg SiO2 ha. Super rice special fertilizer comprised 12.5% N, 6.0% P2O5, 10.0% K2O and 15% organic matter. The super rice varieties were Yuejingsimiao 2 (inbred) and Peizataifeng (hybrid) common in South China. The design was splitplot with three replications. Plant height, LAI, SPAD and net photosynthetic rate (NPR) were affected by both variety and fertilizer. Application of 100 kg N ha gave highest GS activity at booting 125 kg N ha resulted in a favorable GS activity from booting to full-heading. SPS activity at booting was highest with 125 kg N ha + 60 kg SiO2 ha. Application of 100 kg N ha + 60 kg SiO2 ha to Peizataifeng showed higher GS and SPS activity at booting, and gave the highest head rice rate. While milled rice yield was not, brown rice yield, head rice recovery, rice with chalkiness, and chalky ratio were affected by variety and fertilizer. Treatments were significantly different from each other in polished grain protein and amylose content. Yuejinsimiao 2 fertilized with 125 kg N ha + 60 kg SiO2 ha recorded the highest protein content and non-fertilized Peizataifeng the least. While Peizataifeng fertilized with 125 kg N ha accumulated the highest amount of amylose, Yuejinsimiao 2 fertilized with 100 kg ha + 60 kg SiO2 ha had the least. In hybrid Peizataifeng, grain amylose was lower with the silicon-added fertilizers. In inbred Yuejinsimiao 2, grain protein was least when no fertilizer was applied and it increased with addition of silicon and increase in N% of fertilizer. We concluded that deep application of rice special fertilizer can improve growth and photosynthesis characteristics, as well as the quality of super hybrid rice. © 2016 Friends Science Publishers

Mutu Fisik, Mutu Giling dan Mutu Fungsional Beras Varietas Lokal Kalimantan Barat

The physical of paddy and milled rice qualities, physicochemical properties and the functional properties of milled rice were analyzed to study the grain characteristics of four local paddy varieties derived from West Kalimantan. The study was conducted at Post Harvest Grain Quality Laboratory, Indonesian Center for Rice Research in 2013. Method used for physical and milling quality properties followed IRRI method. Functional characteristic was analyzed using LC-MS. The observations were done in six replications. The data was analyzed for the correlation among characters. Significant correlation between characters was further analysed for regression equation. The shapes of grains of local rice varieties were slim to medium. There was correlation between paddy moisture content and head rice percentage, between damaged grain and paddy density, between yield of brown rice and yield of milled rice, and percentage of head rice, between percentage of head rice and yield of milled rice, and between empty grain and broken grain. The functional character relationship showed that Cyanidin 3 Glucosidase (C3G) content of brown rice influenced the C3G content of milled rice. “Sanik” red rice, “Beliah” purple rice and “Balik” black rice may be useful to be used as parent for crossing in the breeding program for functional rice varieties, due to their good quality of milled rice and their high content of C3G. The C3G is considered as anticancer, antioxidant, anti coronaria heart disease and it improves fat profiles in the blood. Therefore, colored rice is recommended to be consumed in a form of brown rice or milled rice with 80% degree milling to retain the C3G content which is beneficial for the human health.

Effect of soaking temperature on commingled rice properties

Parboiling involves soaking, steaming, and drying, and soaking is important in achieving desired parboiled rice properties. This study investigated the effects of soaking temperature and commingling on rice properties prior to steaming. Rough rice of four cultivars (Taggart, CL151, XL753, and CL XL745) and their combinations at 1:1 wt ratio were soaked at 65, 70 or 75 °C for 3 h, and dried. Both soaking temperature and difference in onset gelatinization temperature (To) of individual cultivars in commingled rice affected milling and physicochemical properties. The head brown rice yield was greater when the soaking temperature was below but close to the To for individual rice cultivars, but became difficult to predict for commingled rice. Commingled rice consisting of high To rice cultivars required higher soaking temperatures to reduce chalkiness during soaking. The color attributes of commingled rice was predominately affected by the cultivar that exhibited the most change. The gelatinization properties were governed by the low-To cultivar, whereas the pasting properties were more influenced by the high-To cultivar for the commingled rice. Therefore, using commingled rice with a wide range of gelatinization temperature as a feedstock may lead to inconsistent quality of parboiled rice.

Development of Early Maturing Rice Lines with Genes Conferring Resistance to Bacterial Blight and Rice Stripe Virus for Enhancing the Adaptability in Plain Area

This study was conducted to develop the early maturing rice lines with genes conferring resistance to bacterial blight and rice stripe virus to enhance the adaptability in plain area. Unkwang carrying Xa3 was used as a recurrent parent and SR30075 carrying Xa4+xa5+Xa21+Stvb-i was used as a donor parent. RL1(Resistant Line, BC1F7), RL2, RL3, RL4, and RL5(BC2F6) were bred through bio-assay of K3a race inoculation and phenotypic selection of agronomic traits. The presence of introduced genes was confirmed by testing the resistance levels against bacterial blight and rice stripe virus and then double-checked by using DNA marker. RL1 has all target genes, Xa3+xa5+Xa21+Stvb-i. RL2, RL3, and RL5 have Xa3+Xa21+Stvb-i whereas RL4 has only Xa21. Rice lines carrying Stvb-i showed resistance reaction to rice stripe virus. The combinations of bacterial blight resistant genes(Xa3+xa5+Xa21 and Xa3+Xa21) were found to be promising, as the rice lines carrying these genes enhanced a strong resistant reaction against 16 bacterial blight isolates. Also, the inoculation of K3a race did not alter the brown rice yield, ripened grain ratio and kernel quality of brown rice compared to control. Although RL1 containing all the target resistance genes showed excellent resistance performance, it is not suitable to cultivate in plain area due to instability to lodging, 80% yield level than Unkwang, and low grain quality. RL5 backcrossed twice with Unkwang was found to be a promising line due to its effective resistance gene combination, Xa3+Xa21+Stvb-i and good agronomic traits such as stability to lodging, higher yield and quality compared to Unkwang.

PHYSICAL PROPERTIES AND CORRELATION BETWEEN NIRS SPECTRUM OF 'KHAO DAWK MALI 105' PADDY RICE

Thailand is one of the main rice exporters in the world. The Thai rice cultivar known ‘Khao Dawk Mali 105’, also known internationally as Jasmine rice. The quality of Jasmine rice is important and must be determined prior to distribution or export. The non-destructive methods that assure accurate results are the alternative to time consuming conventional methods. One alternative method, and the most widely used, is near infrared spectroscopy (NIRS). This study focused on the use of paddy rice spectrum to develop models for prediction of physical properties of brown rice. Entire paddy rice samples were scanned with a near infrared spectrophotometer. Reflectance spectra from 1400-2400 nm were recorded, the spectra were then subjected to spectral analysis and model developed by using JMP software version 10. A partial least squares (PLS) model was developed and provided R2 values ranging from 0.39 to 0.79. The preceding analysis suggested that it was possible to develop simple models by PLS from the NIRS spectra for predicting physical properties of brown rice excepted for head rice yield of brown rice (HRYB). It was obvious that whiteness of brown rice (WB), translucency of brown rice (TB) and hardness of brown rice (HB) could be predicted and were found adequate for rough screening aiming at the approximate predictions.

Enhancement of γ-aminobutyric acid in germinated paddy by soaking in combination with anaerobic and fluidized bed heat treatment

Enhancement of γ-aminobutyric acid (GABA) in germinated grain could be induced via environmental stresses. Soaking in combination with anaerobic treatment (SA) as well as soaking in combination with anaerobic and heat treatment (SAH) are proposed in this work to increase the GABA content in germinated paddy; the results were compared with that obtained via a conventional germination (soaking) method (CS). The quality of germinated rice prepared from paddy (GP) by CS, SA and SAH after shade drying and fluidized bed drying in terms of the GABA content, number of fissured kernels and textural property was also investigated. The results showed that the GP prepared via SAH had the highest GABA content. The GABA contents in GP prepared by CS, SA and SAH increased 15, 25 and 29 times as compared to that of the un-germinated brown rice, respectively. However, SAH resulted in the higher number of fissured kernels as compared with CS and SA. After fluidized bed drying at 150°C, the GABA content in GP did not decrease, but the number of fissured kernels of the fluidized bed dried samples was higher than that of the shade-dried samples. However, the head brown rice yield of the fluidized bed dried samples was higher than that of the shade-dried samples. Hardness and stickiness of the fluidized bed dried samples prepared by the three germination methods were not significantly different; exception held nevertheless for the hardness value of the complete kernels obtained via CS.

Effect of 2-Azahypoxanthine (AHX) Produced by the Fairy-Ring-Forming Fungus on the Growth and the Grain Yield of Rice

To examine the effect of 2-azahypoxanthine (AHX) on rice plant (Oryza sativa L. cv. Nipponbare) growth, we carried out pot and field experiments. AHX was applied at 50 μM for two weeks at four growth stages (transplanting, tillering, panicle formation and ripening stages) in the pot experiment, and 1 mM AHX at three stages [at rising of seedling in nursery boxes (seedling treatment), transplanting and panicle formation stages] in the field experiment. Both pot and field experiments showed a tendency toward increased panicle number (PN), culm length (CL) and plant dry weights with AHX treatments. Brown rice yields were also improved by AHX treatments, especially when applying at stages of tillering and panicle formation and seedling and transplanting during pot and field experiments, respectively. In the latter, yield increased drastically up to 18.7, 15.8, 9.6 and 5.8% of control. However, panicle length and 1000-grain weight were not affected by AHX application. These results suggested that AHX increased the brown rice yield through its effects on PN and/or CL.

Selenium addition alters mercury uptake, bioavailability in the rhizosphere and root anatomy of rice (Oryza sativa).

Mercury (Hg) is an extremely toxic pollutant, especially in the form of methylmercury (MeHg), whereas selenium (Se) is an essential trace element in the human diet. This study aimed to ascertain whether addition of Se can produce rice with enriched Se and lowered Hg content when growing in Hg-contaminated paddy fields and, if so, to determine the possible mechanisms behind these effects. Two cultivars of rice (Oryza sativa, japonica and indica) were grown in either hydroponic solutions or soil rhizobags with different Se and Hg treatments. Concentrations of total Hg, MeHg and Se were determined in the roots, shoots and brown rice, together with Hg uptake kinetics and Hg bioavailability in the soil. Root anatonmy was also studied. The high Se treatment (5 μg g(-1)) significantly increased brown rice yield by 48 % and total Se content by 2·8-fold, and decreased total Hg and MeHg by 47 and 55 %, respectively, compared with the control treatments. The high Se treatment also markedly reduced 'water-soluble' Hg and MeHg concentrations in the rhizosphere soil, decreased the uptake capacity of Hg by roots and enhanced the development of apoplastic barriers in the root endodermis. Addition of Se to Hg-contaminated soil can help produce brown rice that is simultaneously enriched in Se and contains less total Hg and MeHg. The lowered accumulation of total Hg and MeHg appears to be the result of reduced bioavailability of Hg and production of MeHg in the rhizosphere, suppression of uptake of Hg into the root cells and an enhancement of the development of apoplastic barriers in the endodermis of the roots.

Effect of elevated carbon dioxide and nitrogen management on rice milling qualities

Elevated atmospheric carbon dioxide (CO2) concentration has a potential impact on the growth and yield of rice (Oryza sativa L.), but little is known on grain milling quality. A field experiment in open-top chamber (OTC) was conducted to assess the effect of elevated CO2 under varying N management on brown rice, milled rice and head rice yield. The experiment was conducted during wet season (June–November) of the year 2011 and 2012 at Kharagpur, India, using a long-duration, high-yielding cultivar ‘Swarna Sub1,’ which was grown in open field and in OTCs of ambient and elevated CO2 environment (25 % higher than ambient) with five different N management levels. The elevated CO2 reduced the brown rice, milled rice and head rice percentage by 1.2, 1.4 and 14 %, respectively, as compared to ambient environment in OTC. Due to elevated CO2, the reduction in processed yields were 9 and 4 % in brown/milled rice and 21 and 15 % in head rice under sole application of chemical fertilizer and integration of chemical and organic sources, respectively. The decrease in rice milling quality was associated with increasing canopy temperature (+0.8 °C) during grain-filling stage under elevated CO2 environment. The elevated CO2 has a substantial adverse impact on grain milling quality, and to some extent, this can be compensated through proper N management.

Predictive models for yield and protein content of brown rice using support vector machine

Rice production in Japan is facing problems of yield and quality instability owing to recent climate changes, aging of farmers, and a decrease in the farmer population. Thus, it is becoming important to develop an improved rice production technology that utilizes collected data about rice production rather than relying on the conventional technology that is based on the experience and knowledge of individual farmers. We developed predictive models for yield and protein content of brown rice that can provide useful knowledge to support farmer’s management decision-making, utilizing data sets from 47 paddy fields where rice was produced under various environments and management styles. Support vector machines (SVMs) were applied to build the predictive models based on explanatory variables representing the growth and nutrition conditions after the heading stage and the meteorological environment after the late spikelet initiation stage. The models achieved quantitative accuracy that was within approximately 1tha−1 in yield for 85.1% of the total data sets and within 0.8% in protein content for 76.6% of the total data sets, respectively. Further, patterns of explanatory variables classified in three classes of yield and protein content, which were visualized by the predictive models, were reasonable in terms of knowledge of crop science. We found that the predictive models using SVMs had the potential to describe a relation between yield or protein content and multiple explanatory variables that reflected diverse rice production in actual fields, and could provide useful knowledge for decision-making of topdressing and basal fertilization.

Effect of Drying on Physical Qualities and Sensory Evaluation of Herbal Germinated Brown Rice by Hot Air: Turmeric and Roselle

The object of this project was to study the effect of drying temperature on physical quality and sensory evaluation of germinated brown rice soaking with tumeric and roselle. The drying was run under the conditions of drying temperatures of 80-100°C and air velocity of 7.3 m/s. Initial moisture content of brown rice samples was of 54-55% dry-basis and was dried until the final moisture content reached to 20-25% dry-basis. After drying, the rice was tempered and then was ventilated by ambient air until its moisture content reached to 14-15% dry-basis. The experiment showed that highest drying rate is incident at 100°C. For physical qualities analysis, the results showed that the drying air temperature does not affect to head rice yield, fissured kernels, chalky grain and color (L*, a*, b* CIE-lab unit) of herbal germinated brown rice. In addition, herbal germinated brown rice drying can maintain low percentage of chalky grain compared to commercial brown rice. The soaking solution was not affect to drying rate. Finally, the sensory evaluation showed that the herbal germinated brown rice dried with all drying conditions was acceptable taste (>5).

Changes of Anthocyanidin Content and Brown Rice Yield in Three Pigmented Rice Varieties Among Different Transplanting and Harvesting Times

Anthocyanin pigments from three pigmented rice varieties, Hongjinju, Sintoheugmi and Josaengheugchal pigmented by black color, were quantified to evaluate effects of transplanting and harvesting time during seed development. Hongjinju, a rice variety of grains pigmented by red color, contains only two kinds of anthocyanins, delphinidin and cyanidin. Meanwhile, delphinidin, cyanidin, and pelargonidin were identified in Sintoheugmi and Josaengheugchal. Anthocyanidin contents in pigmented rice variety Hongjinju under different planting times were decreased with prolonged harvesting times. The Sintoheukmi showed that cyanidin content was the highest among analyzed pigments during seed development. Two anthocyanins (cyanidin and pelargonidin) in Josaengheugchal recorded highest contents at 20 days after heading in three transplanting times. Cyanidin content was also slightly increased with prolonged transplanting time. Total anthocyanidin contents in Hongjinju were always lower than that of Sintoheukmi and Josaengheukchal. In two rice varieties, Sintoheugmi and Josaengheugchal, <TEX>$a^*$</TEX> values were commonly slightly decreased by late transplanting and harvesting times. Changes of <TEX>$a^*$</TEX> and <TEX>$b^*$</TEX> values in waxy rice varieties, Sintoheugmi and Josaengheugchal varied more than those in Hongjinju. In Josaengheugchal, early harvesting before maturity showed lower brown rice yield and late harvesting in the each transplanting times resulted in highest brown rice yield.

Rice cultivar responses to elevated CO2 at two free-air CO2 enrichment (FACE) sites in Japan.

There is some evidence that rice cultivars respond differently to elevated CO2 concentrations ([CO2]), but [CO2]×cultivar interaction has never been tested under open-field conditions across different sites. Here, we report on trials conducted at free-air CO2 enrichment (FACE) facilities at two sites in Japan, Shizukuishi (2007 and 2008) and Tsukuba (2010). The average growing-season air temperature was more than 5°C warmer at Tsukuba than at Shizukuishi. For four cultivars tested at both sites, the [CO2]×cultivar interaction was significant for brown rice yield, but there was no significant interaction with site-year. Higher-yielding cultivars with a large sink size showed a greater [CO2] response. The Tsukuba FACE experiment, which included eight cultivars, revealed a wider range of yield enhancement (3-36%) than the multi-site experiment. All of the tested yield components contributed to this enhancement, but there was a highly significant [CO2]×cultivar interaction for percentage of ripened spikelets. These results suggest that a large sink is a prerequisite for higher productivity under elevated [CO2], but that improving carbon allocation by increasing grain setting may also be a practical way of increasing the yield response to elevated [CO2].

Optimization of drying process for PB1121 variety of paddy

Rough rice is typically harvested at moisture contents ranging from 20% to 24%, and subsequently dried to approximately 12% for safe long-term storage and milling. Harvesting paddy at high moisture content normally results in high yields and less damage and prevents field losses due to dropping and shattering. Drying of grains creates moisture and temperature gradient within the kernel resulting in the development of tensile stresses at the surface and compressive stress at the interior of the rice kernel. These stresses may result in kernel fissuring and subsequent breakage during milling. Thus, drying is considered to be one of the most critical operations in post-harvest processing of paddy which has great influence on milling yield. Basmati rice possesses unique cooking, eating and digestive qualities. India accounts for more than 70% of the world basmati rice production. Among basmati, PB1121 is widely grown in India and contributes a major share of rice exports from the country. Therefore drying of PB1121 was carried out with the objective to optimize the drying variables for minimum drying time and maximum head yield. Drying was carried out in 2-passes using a cross-flow dryer. The drying experiment in thin layer was conducted as per a central composite rotatable design in response surface methodology with 3 factors (drying air temperature, tempering time and moisture reduction in first drying pass) at 5 levels. The variables chosen for the experiment were drying air temperature (40–70 °C), tempering time (60–240 min) and moisture reduction percentage (3–10%) in the first pass of drying. Optimization of drying variables was done through the use of a desirability function by combining all responses into one measurement. The desirability functions were minimum drying time, maximum brown rice yield and head rice yield. Total drying time ranged from 35 to 132 min in two stages of drying, while in continuous drying it varied from 41 to 204 min. Head rice yield ranged from 39.77 to 71.56%. Optimum conditions for drying of paddy grains were found to be temperature of 58.3 °C, 7.13% moisture reduction and 148 min tempering time. At optimized conditions, total drying time and head rice yield were calculated at 53.1 min and 54.53%, respectively.

The impact of elevated tropospheric ozone on grain quality of hybrid rice: A free-air gas concentration enrichment (FACE) experiment

Rising tropospheric ozone concentration is currently the most important air pollutant which suppresses plant growth and thus results in yield loss of agronomic crops. However little is known about ozone effects on grain quality of crops. Using a free-air gas concentration enrichment (FACE) facility for ozone fumigation in paddy rice (Oryza Sativa L.), a Chinese hybrid indica cultivar Shanyou 63 was exposed to either ambient or elevated ozone concentration (ca 23.5% above ambient) for two consecutive growth seasons from 2007 to 2008. Harvested grain samples were subjected to various quality tests. In both seasons, the brown, milled and head rice yield all reduced by elevated ozone concentration, with this reduction being greater in 2008 (17–22%) than in 2007 (8–19%). Ozone elevation caused small but significant decrease in brown rice percentage, but greatly increased head rice percentage by 8.8%. Chalky grain percentage increased (5.8%) due to ozone elevation, while chalkiness area and chalkiness degree remaining unchanged. Although the amylose concentration of rice grains was marginally reduced, starch pasting properties demonstrated that grains in elevated ozone concentration had lower breakdown (7.7%) and higher setback value (25.2%) and gelatinization temperature (0.9°C) than those grown in ambient conditions. Nutrition evaluation indicated that ozone exposure tended to increase the concentrations of protein and all mineral elements analyzed (i.e., K, Mg, Ca, Fe, Zn, Mn and Cu), but the contents of protein and mineral elements in harvested grains were unchanged or reduced. For most traits of grain quality, the year effect was significant, however, its interaction with ozone was not detected. Our results suggested that long-term exposure to ozone-enriched atmospheres projected in the coming a few decades not only caused serious reductions in yield, but also tended to produce the deleterious effects upon grain quality of hybrid Shanyou 63 in terms of appearance and eating/cooking quality.

The response of rice grain quality to ozone exposure during growth depends on ozone level and genotype

The effects of ozone exposure during the cropping season on rice grain quality were investigated in chamber experiments employing four ozone treatments (charcoal filtered air, ambient, 2× ambient, and 2.5× ambient concentration) and six genotypes. The concentrations of protein and lipids in brown rice increased significantly in response to ozone, while starch concentration and thousand kernel mass decreased. Other parameters, including the concentrations of iron, zinc, phenolics, stickiness and geometrical traits did not exhibit significant treatment effects. Total brown rice yield, protein yield, and iron yield were negatively affected by ozone. Numerous genotypic differences occurred in the response to ozone, indicating the possibility of optimizing the grain quality in high ozone environments by breeding. It is concluded that although the concentrations of two important macronutrients, proteins and lipids, increased in ozone treated grains, the implications for human nutrition are negative due to losses in total grain, protein and iron yield.

Yield Potential of High-Yield Rice Varieties in the Tohoku Region of Japan

To achieve a super high brown rice yield exceeding 10 t ha -1 in the Tohoku region (relatively cold), a two-year field experiment was conducted. The yield components, morphological traits and dry matter production among the Japonica type high-yield variety “Fukuhibiki,” indica type high-yield variety “Takanari,” large grain type high-yield variety “Bekoaoba” and two conventional Japonica type varieties were compared. Although the traits relating to high yield varied greatly, the three high-yield varieties all showed a large sink size, heavy rice yield at 30 days after heading (30 DAH) and a high harvest index. The effects of nitrogen application and planting density on the morphological traits, dry matter production and yield in the large grain type variety Bekoaoba were investigated. Although high nitrogen application (HN) increased the brown rice yield from 8 to 9.5 t ha -1 , regulation of the timing of topdressing and/or planting density under HN could not increase the brown rice yield beyond 10 t ha -1 . Strategies to achieve a super high-yield rice in the Tohoku region were discussed.

Effects of high temperature and early drainage on leaf CO2 assimilation and grain yield in the rice cultivar Hinohikari

In western Japan, rice grain damage from high temperatures has recently been severe. The adverse effects of high temperature on rice ripening can be accentuated by water management practices. In field experiments carried out under different weather conditions, the early drainage decreased yield, grain weight, and quality in 2008, but early drainage had no effect on brown rice yield in 2009 or 2010. Decreases in grain weight, yield, and the percentage of perfect grain in the dry regime in 2008 compared with the wet regime of the years can be explained by the early drainage during the early grain-filling period. In 2010, the mean daily temperature averaged over the 20 days after heading was 29°C, and the percentage of perfect grains was low. The combination of high temperature and abundant radiation during the grain-filling period may explain the low proportion of perfect grains without a decrease in grain weight in 2010. The effect of drainage was smaller in 2010, when the high temperatures caused rapid senescence and shortened the grain-filling period. Thus, grain filling may have been completed before the water shortage could reduce the availability of CO2 to a critical level.

Bioactive compounds in rice during grain development

The bioactive compounds in two developing rice grains, KFSW (a waxy indica red rice) and TK16 (a non-waxy japonica rice), were investigated. The total phenolics and total flavonoids of two developing rice grains were significantly higher than those in mature seeds. The phenolics extract was further fractionated into three fractions, free, soluble-ester and insoluble-bound; ferulic acid was the most abundant compound in each fraction, in both immature grain and mature seed. α-Tocopherol was the most abundant vitamin E homologue, followed by γ-tocotrienol in KFSW and α-tocotrienol in TK16. High contents of free and soluble-ester ferulic acids, soluble dietary fibre, total tocols and oryzanols were found in the 15th and 18th DAA (days after anthesis) grains, which were suitable for dehulling, with a reasonable brown rice yield. Immature rice grains, containing a remarkable amount of bioactive compounds with a high reducing power, have a great potential for applications in nutraceutical foods.