Selected Rice Varieties Research Articles

Combining Ability Analysis for Quality Traits in Selected Rice Varieties (Oryza sativa L.)

Fifteen hybrid combinations developed by crossing five lines and three testers were assessed for milling and physio-chemical qualities to evaluate the combining ability of the parents using a line x tester design. This investigation provided information about the general combining ability (GCA) of parents and the specific combining ability (SCA) effects of crosses from eight popular inbred varieties. C70 was considered the best general combiner for the head rice recovery trait, while the crosses involving C70 with DH18 and CR203, 13/2 with TBR225 and Xi23, and OM6976 with TBR45 showed significant positive specific combining ability (SCA) effects. Xi23 and OM6976 among the lines showed significant general combining ability (GCA) effects indicating them to be good general combiners for obtaining hybrids with desirable (low or intermediate) properties of amylose content. The variances due to SCA were of greater magnitude than GCA for all the traits, revealing the preponderance of non-additive gene action for all the studied attributes. In all the studied quality traits, the narrow sense heritabilities were ordered as follows: head rice recovery > amylose content > gel consistency > alkali digestion > hulling percentage > milling percentage. The narrow sense heritabilities in these traits were quite low, ranging from 8.11% to 14.4%. Among the eight parents, C70, Xi23, and TBR225 were the most ideal for high-quality line breeding.

Morpho-molecular characterization of fungi associated with seeds of hybrid rice varieties in bangladesh

Rice, as the dominant crop in Bangladesh, is vulnerable to various fungal pathogens. Many of these pathogens infect the seeds, which can later transmit diseases and serve as an efficient means for spreading seed-borne pathogens over long distances. In this study, seven hybrid rice varieties, specifically BRRI Hybrid Dhan 101 through BRRI Hybrid Dhan 107, were collected from the Bangladesh Rice Research Institute (BRRI) to detect and identify seed-borne fungi using both morphological and molecular techniques. Fourteen fungal species were isolated from the selected rice varieties using “Tissue planting method” and “Blotter method”, of which 4 fungal isolates were identified by molecular techniques. Molecular characterization of the isolates was conducted based on the sequence information of internal transcribed spacer (ITS) regions. The sequences obtained using the ITS1 and ITS4 primers were compared with those in the NCBI GenBank using BLAST analysis. Hybrid rice is comparatively more advantageous than inbreed rice because of its high yield, shorter plant life, and higher assimilation translocation. Therefore, it is crucial to identify and manage the pathogenic fungi associated with the seeds to ensure good seed quality, which can contribute to improving the economy of Bangladesh. Bangladesh J. Bot. 53(3): 511-518, 2024 (September)

Exogenous metabolite application is a potential strategy for expanding the use of direct rice seeding with the aim of reducing seeding costs

Rice is a staple food for over half of the global population, necessitates efficient and cost-effective production methods to ensure food security. However, direct seeding of rice often encounters challenges due to adverse environmental conditions, resulting in increased seeding costs. In this study, we analyzed the germination and physiological data of sixty-six rice varieties under cold and submergence conditions. Our results demonstrate that selecting rice varieties with superior germination capacity in these adverse conditions can improve germination rates by 39.43%. Transcriptomic and metabolomic analyses of two contrasting varieties revealed potential regulatory mechanisms involving hormonal pathways and the glycerophospholipid metabolism pathway. Furthermore, we found that the exogenous application of specific metabolites provides a cost-effective seed enhancement strategy for varieties with poor germination capacity. These findings suggest that combining suitable variety selection with seed enhancement treatments can significantly reduce seeding costs in rice production. This research offers valuable insights for developing resilient rice varieties and cost-effective seeding strategies, potentially contributing to improved rice cultivation practices and enhanced global food security.

Mitigating cold stress in rice: a study of genotype performance and sowing time

Rice (Oryza sativa L.) is an essential food for half of the global population and is vital in maintaining global food security. Climate change, increasing population and recent incident of COVID pandemic has generated financial burden and threaten the global food security. Due to theses factors rice cultivation also has to face significant challenges. frequent weather changes pose a considerable challenge to agricultural planning, which was previously relaying on consistent seasonal variations. In this context, rice cultivation is particularly sensitive to cold, where its development and productivity inhibited by low temperatures (< 18 °C). Developing rice varietes with low temprature tolerence and good yield potential is one of the major goals of current breeding efforts of plant scientists. For this purpose, short duration and early rice varieties are most favorable to avoid cold stress and yield more in less number of days. this study was designed to investigate the effect of low temperatures on different rice varieties. the study was designed to identify low temprature tolerent genotypes with early and regular cultivation. For this, thirty-four genotypes were evaluated in two gorwing seasons (2018–2019) with four different sowing times. Statistically sowing time showed significant interaction between all yield contributing parameters. The data indicate that exposure to low temperatures during the reproductive phase prolongs the maturation period of the crop, also length of the panicle and the fertility of the spikelets drops, resulting in a significant decrease in the production of sensitive varieties. Some varieties are more sensitive to cold stress compared to others. In the Egyptian context, Giza176, Sakha104, and Sakha107 are recommended for early cultivation, while the genotypes Giza 179, Sakha101, Sakha104, and GZ 9730-1-1-1-1 are indicated for the normal cultivation period. The Sakha104 variety is particularly notable, as it is recommended for both purposes. In addition, the data obtained in this study provide valuable information for selecting rice varieties suitable for double cropping in the North Delta of Egypt. This study also contributes to the existing literature, providing insights into the resilience of rice cultivation in the face of climate change.

Morphological and molecular identification of fungi isolated from selected brri rice varieties

A total of 19 fungal species were isolated from the seeds of selected rice varieties (BRRI dhan 90 to BRRI dhan 99) following Tissue planting method and Blotter method. The isolated fungi were Aspergillus niger, A. ochraceus, A. oryzae, A. tamarii, A. terreus, Chaetomium globosum, Cladosporium oxysporum, Colletotrichum gloeosporioides, Corynespora cassiicola, Curvularia lunata, Curvularia soli, Daldinia eschscholtzii, Fusarium solani, Penicillium oxalicum,Penicillium sclerotiorum, Pestalotiopsis guepinii, Pyricularia oryzae and Rhizopus stolonifer. Fourteen fungi were selected for molecular identification. Out of the 19 fungal isolates, 14 were confirmed up to species level through ITS sequence based molecular analysis. Among the isolated fungi Pnicillium sclerotiorum and Curvularia soli are the new record for Bangladesh. Association of Daldinia eschscholtzii with rice seeds is also recorded first time from world. Bangladesh J. Plant Taxon. 31(1): 73-82, 2024 (June)

Investigatory study on the qualities of locally grown Rice brands sold in main markets of Abeokuta, South-Western Nigeria

Qualities of some selected rice varieties sold in the main markets of Abeokuta, the capital of Ogun State where rice is mostly grown and consumed in the south-western part of Nigeria was investigated. Rice (Aroso, Mokwa, Royal niger, Orlam and Ofada rice) were evaluated for their physical, chemical properties and sensory qualities using established laboratory procedures. The average width of the rice ranged from “0.261 to 0.268 mm”, “0.260 to 0.265 mm, “0.260 to 0.262 mm”, “0.269 to 0.270 mm”, and 0.271 to 0.275 mm” respectively. The rice average lengths ranged between “0.346 to 0.350 mm”, “0.365 to 0.368 mm”, “0.356 to 0.359 mm”, “0.357 to 0.357 mm” and “0.365 to 0.379 mm” respectively. The physical appearance of the rice investigated ranged from good to very good except for mokwa and orlam rice which shows fair colours. Chemical properties of the rice samples ranged from 10.21 to 11.97%, 0.83 to 2.62, 1.89 to 2.16%, 0.24 to 0.37%, 5.50 to 7.56%, 77.89 to 79.60%, 59.90 to 65.17%, 12.15 to 14.61% and 85.39 to 87.85% for moisture, total ash, fat, crude fibre, crude protein, carbohydrate, starch, amylose and amylopectin contents respectively. The cooking properties ranged from 2 to 7.5, 230 to 250% and 5.49 to 5.64 in length and 0.689 to 1.337mm for volume expansion ratio, water uptake and elongation ratio respectively. This study revealed that Aroso and Orlam rice were of excellent in physical, chemical, sensory qualities and are both recommended for consumption. This research finding serves as a basis of choice for consumers and it also reveals the areas for improvement in terms of qualities of the local rice investigated.

Physicochemical properties, eating and cooking quality and genetic variability: a comparative analysis in selected rice varieties of South India

The physicochemical characteristics and digestibility properties of rice are greatly influenced by its genetic variability. In this study, we attempt to understand the overall quality of five traditional and popularly consumed rice varieties of Kerala. The major traits affecting the eating and cooking quality of rice such as amylose content (AC), gel consistency (GC) and gelatinization temperature (GT) were determined and correlated with the expression of the starch-synthesis-related genes (SSRGs). The Wx is a major SSRG, which modulates the amylose content and the eating as well as cooking qualities of rice. The rice varieties including, Jaya, Matta and Rakthashali were found to have intermediate amylose content (Wxa allele) while Kuruva and Pokkali were found to have high Amylose Content (Wxa allele). The glycemic index (GI) of all varieties was found to be in the range of 51.0–58.6. Among the screened rice varieties, Pokkali was found to have the lowest glycemic index and digestibility with appreciable eating and cooking qualities. Pokkali rice, with its low GI (51.0), could be a recommended variety for diabetes management. Furthermore, the rice eating and cooking qualities, and plant breeding techniques coordinated by the expression of the starch synthesis-related gene (Wx), could be a novel approach to improve the valuable germplasm.Graphical

Control of iron stress in water-saturated tidal land using ameliorant and its impact on rice productivity

Fe stress is a problem in swamp lands that reduces the growth and yield of rice. Providing various types of ameliorants and selecting rice varieties are considered an effort to obtain high rice productivity in tidal land. The research aimed to study the effect of various ameliorants on rice growth and production, and to obtain high productivity of tolerant variety to iron stress at different locations of tidal land. The research was conducted in Karya Bakti Village (1°10'34.8" S and 104°09’31.1” E), Rantau Rasau, East Tanjung Jabung, Jambi. This study adopted a split-plot design with different types and doses of ameliorant as the main plots and several rice varieties as the subplots with three replications. The results showed that the application of ameliorant rice husk ash, coconut husk ash, empty bunch oil palm compost, and goat manure stimulated vegetative and generative growth. Meanwhile, the Inpari 16 Pasundan variety was proven to have better growth and higher production as described through plant height, fresh weight of shoots and roots, dry weight of shoots and roots, root length, number of productive tillers, number of grains per panicle, 1,000 grain weight, and harvested dry grain. The highest rice production was in the Inpari 16 Pasundan variety, 9.3 tons ha-1 (low-Fe) and 7.6 tons ha-1 (high-Fe). The combination of rice husk ash (0.25 tons ha-1) + coconut husk ash (0.25 tons ha-1) + empty bunch oil palm compost (0.75 tons ha-1) + goat manure (0.75 tons ha-1) was the best combination to increase rice productivity. Inpari 16 Pasundan is considered a tolerant variety on tidal land with high-Fe stress. The interaction between ameliorants and varieties was significant on plant height at ages 2 and 4 weeks after planting at low-Fe, number of productive tillers at high-Fe, root length at low-Fe and high-Fe, 1,000-grain weight, and number of grains per panicle at low-Fe, and harvested dry grain at low-Fe and high-Fe.&#x0D; Keywords: B-type tidal fields, Fe stress cultivation, organic ameliorant, tolerant rice variety, water-saturated cultivation

Effect of Varying Irrigation Regimes and Cultivars on Growth, Yield, Water Use Efficiency and Economics of Rice (Oryza sativa) under Aerobic Condition

The present study was undertaken for standardization of irrigation interval and performances of medium duration selected rice varieties under the aerobic conditions in the westen Odisha. The field experiment was conducted at the Regional Research Technology and Transfer Station (RRTTS), Chiplima, Sambalpur, Odisha, during the summer season of 2019 and 2020 to see the performance of medium-duration rice varieties with varying irrigation regimes under aerobic conditions. The experiment was laid out in split plot design with three replications and consisted of four irrigation regimes (I1 = Irrigation at IW/CPE = 1.0, I2 = Irrigation at IW/CPE = 1.5, I3 = Irrigation at IW/CPE = 2.0, and I4 = Irrigation at IW/CPE = 2.5) in main plot treatments and four varieties (V1 = Naveen, V2 = MTU-1010, V3= CR Dhan-201 and V4 = CR Dhan-204 in subplot treatments. The result of the pooled mean of both years showed that growth and yield attributes significantly affect in regards to different irrigation regimes and cultivars. The maximum plant height (69.0 cm) and filled grains per panicle (80.98) leaf area index (LAI ) at 75DAS (3.940, dry matter accumulation of the shoot at 90 DAS ( 927 g m-2), number of effective panicles m-2 (287) and test weight (22.27 g) was maximum at irrigation regime IW/CPE = 2.5. In contrast, it was at par with the irrigation regime at IW/CPE = 2.0. The maximum plant height(67.1cm), filled grains per panicle (74.47), leaf area index (LAI ) at 75DAS (3.52), dry matter accumulation of the shoot at 90 DAS (901 g m-2 ), and a number of effective panicles m-2 (286) were recorded with CR Dhan 201 which was significantly higher as compared to other cultivars. The result of the pooled mean of both years showed that the highest grain yield was recorded at IW/CPE = 2.5, i.e., 4.07 t/ha, which was at par with IW/CPE = 2.0 (3.90 t/ha) and significantly superior to rest of other irrigation regimes. But in the case of cultivars, the highest grain yield was obtained with variety CR-Dhan 201 (3.54 t/ha), which was at par with variety Naveen (3.30t/ha) and significantly superior to the rest of other cultivars. The highest mean FWUE of 40.71kg/ ha-cm was observed with irrigation at IW/CPE 1.5, which was at par with other irrigation regimes except IW/CPE 2.5, whereas the highest B: C ratio (1.74) was observed with irrigation at IW,/CPE 2.0 which was at par with IW/CPE 2.5 (1.73) and significantly superior to other irrigation regimes. But in the case of cultivars, the highest mean FWUE of 41.60kg/ ha-cm and B: C ratio (1.62) was observed with variety CR Dhan 201 and significantly superior to the rest of the other cultivars. Hence, a variety like CR Dhan 201 needs to be irrigated at IW/CPE 2.0 to produce economically optimum yield and field water use efficiency on sandy loam soils of the western region of Odisha under aerobic conditions.

Two halogenated flame retardants and cadmium in the soil-rice system: sorption, root uptake, and translocation.

The migration and transformation of Tetrabromobisphenol A (TBBPA), DechloranePlus (DP), and cadmium in soil-rice system was investigated, and the influence on the quality of two varieties of rice was studied. The degradation half-lives of TBBPA, BBPAs, syn-DP, and anti-DP were 23.18 ~ 26.36days, 30.14 ~ 36.10days, 72.96-81.55days, and 169.06-198.04days in the soil. TBBPA was gradually degraded to tri-BBPA, di-BBPA, mono-BBPA, and bisphenol A by the debromination. TBBPA and its bromide metabolites could be bioaccumulated in different tissues of rice; mono-BBPA and bisphenol A was easy to accumulate in the stems, and bisphenol A was easy to bioaccumulate in the grain. Comparing with single and compound pollution, there was no significant difference in bioaccumulation factors of two rice species. The grain of NO7 had stronger bioaccumulation ability to mono-BBPA and BPA than NO1, and there is no significant difference in TBBPA. Residual level of DP in the rice: roots > stems > grain; there was no significant difference in bioaccumulation of two varieties of rice. Cadmium was easily bioaccumulated in the roots of rice and translocated to the rice stems and grains. NO7 rice had stronger bioaccumulation and transport capacity than NO1. The effects of the three pollutants on the quality of two varieties of rice varied significantly; cadmium had the greatest effect on the iodine blue value (BV) and amylase activity of the grain. This study proved that selecting rice varieties with low bioaccumulation to polluters can effectively reduce the risk of the food chain harming human health.

Assistance Of Farmers In Utilizing The Consortium Of Endophite Bacteria And Organic Fertilizer As Well Organic Pesticides Based On Local Wisdom To Increase Rice Productivity

The "Sidodadi" farmer group in Demangan village, Sambi sub-district, Boyolali district consists of 15 members, which is a rainfed farmer group. Paddy productivity in rainfed lowland is quite low (2-3 tons/ha) compared to irrigated land (5 tons/ha). The use of a consortium of endophytic bacteria, organic fertilizers and organic pesticides based on local wisdom and the selection of varieties according to their designation can increase rice productivity. Rice farming in this farmer group does not yet have proper management, so assistance is needed. The purpose of this service is to assist in the management of rainfed land so that their income increases.The problems of this farmer group are 1) Aspects of Production and 2) Aspects of management. Production aspects include (a) Technology Utilization Aspect: not having technology to increase rice productivity (b). Aspects of Soil Fertility: rarely use organic fertilizers (c) Aspects of Use of Varieties: rice varieties that are not suitable for allotment of rainfed rice fields. The solution to the problems that arise is to assist farmer group members to use endophytic bacteria consortia, use organic fertilizers and organic pesticides based on local wisdom, use rice varieties that are suitable for sub-optimal rainfed land and farm management training. This activity will be carried out in two places, 1) in the yard of the farmer group members and 2) in the paddy fields in Demangan village, Sambi sub-district, Boyolali Regency from July 2023 to December 2023. The method used is 1) Farm management counseling and assistance, 2) Practice: making a consortium of endophytic bacteria, organic fertilizers and organic pesticides based on local wisdom 3) Cultivating organic rice in rainfed paddy fields, 4). Monitoring and evaluation. The result of this community-based service activity is an increase in the skills of farmers in making endophytic bacteria, making local microorganism (MOL), making solid organic fertilizers, making liquid organic fertilizers and organic pesticides and selecting rice varieties that are suitable for rainfed lowland rice fields and its application in rainfed lowland rice cultivation.

Prevalence of Seed-Borne Fungi Associated With Selected Rice Varieties of Brri

Selected rice varieties such as BR-78, 80, 81, 82, 83, 84, 86, 87, 88 and 89 were used in this experiment to investigate the prevalence of seed-borne fungi. A total of twelve fungi belonging to six genera was isolated from the seeds of selected BRRI (Bangladesh Rice Research Institute) rice varieties by using tissue planting method. They were Alternaria alternata (Fr.) Keissler, Aspergillus flavus Link, A. fumigatus Fresenius, A. niger van Tieghem, A. ochraceous Wilhelm, A. terreus Thom, Curvularia lunaata (Wakker) Boedijn, Curvularia sp. 1, Drechslera oryzae Breda de Haan (Subramanian and Jain), Penicillium sp.1, Penicillium sp. 2 and Rhizopus stolonifera (Ehrenb.) Vuill., Among the isolated fungi A. niger was the most prevalent fungi associated with the seeds of the rice varieties with a mean per cent frequency of 16.93 and the least prevalent fungi was A. ochraceous with a mean per cent frequency of 0.27. Mean per cent frequency of A. niger (16.33) was highest which was followed by A. flavus (7.27), Penicillium sp.1 (5.93), Penicillium sp. 2 (3.27), Drechslera oryzae (2.67) and A. terreus (2.53). Among the identified seed-borne fungi Curvularia lunata and Drechslera oryzae were found as pathogenic and cause seed-borne diseases. J. Biodivers. Conserv. Bioresour. Manag. 2023, 9(1): 61-68

Rice Variety Preferences in Bangladesh – What is the Role of Public Breeders?

This study compared preferred rice varieties by millers and farmers in Bangladesh, hypothesizing that public breeders would focus on public goods like disease resistance, whereas private breeders would focus on profits in the entire chain. Primary data were collected from 99 farmers and 68 millers, who are among the key stakeholders in the rice production system. A four-point rating scale was designed to assess the level of preference for different traits of the selected rice varieties. It was found that farmers who prioritize disease resistance prefer the public over privately bred Aman rice varieties. In general, they prefer rice varieties that are high yielding, have high market value and are of short duration while millers prefer rice verities considering the size and shape, color, and milling performance of the grains. Most significantly, millers prefer privately bred rice varieties if compared to farmers. It can be concluded that public rice breeders should take efforts to also consider the needs of intermediaries in the chain.

Physical Characteristics, Phytochemical Contents and Antioxidant Activity of Ten Organic-Pigmented Rice Varieties from Surin Province

The objective of this study was to investigate the physical characteristics, phytochemical contents, and antioxidant activity of 10 organic-pigmented rice varieties including Tubtim Chumpae, Niaw Daeng, Nieng Guang, Mali Daeng, Hom Nil, Niaw Dam, Riceberry, Mali Gomain Surin, Malinil Surin, and Pa Ga Am Puen (obtained from Tapthai organic villages, Tha-mo, Prasat, Surin province, Thailand in June, 2021). The physical characteristics investigated included grain length, width, shape, and color in both paddy and unpolished rice. The results revealed that the mean length and width of paddy rice grain varieties ranged from 6.58 to 10.85 mm and 2.12 to 3.27 mm, respectively, while the length and width of unpolished rice grain were 5.94 to 7.53 mm and 1.74 to 2.61 mm, respectively. Most organic-pigmented rice varieties had a slender shape except for Nieng Guang and Niaw Dam, which were moderately shaped. There were 5 colors of paddy rice, including straw, purple, purple straw, black and black furrow on straw background and light purple straw while unpolished rice showed red, dark purple, black, purple, and light brown color. The anthocyanin content, total phenolic compounds and antioxidant activity of different rice varieties showed a significant difference in the range of 4.38 to 77.96 mg/100 g DW, 42.94 to 341.19 mg GAE/100 g DW and 2.71 to 34.77 mM TE/100 g DW, respectively. Niaw Dam exhibited the highest anthocyanin concentrations. The highest total phenolic content was found in Mali Daeng and Nieng Guang, resulting in high antioxidant activity. This study suggested that pigmented rice is rich in phytochemicals and antioxidants. Nieng Guang, in particular, could be promoted for cultivation and beneficial use in the food, pharmaceutical, and cosmetic industries. HIGHLIGHTS Surin province is one of the principal regions with diverse indigenous and commercial rice varieties in Thailand The grain shape of eight varieties of rice, including Tubtim Chumpae, Niaw Daeng, Mali Daeng, Hom Nil, Riceberry, Mali Gomain Surin, Malinil Surin and Pa Ga Am Puen were slender while that of Nieng Guang and Niaw Dam varieties were moderate. The physical aspects of rice indicate its quality, market value and have essential role in selecting, handling, storing, and processing of rice Niaw Dam black rice had a high content of anthocyanin while Mali Daeng and Nieng Guang red rice had the highest content of total phenols, resulting in higher antioxidant activity than the other Pa Ga Am Puen brown rice had the lowest anthocyanin content, total phenolic content and antioxidant activity The basic information of this study might be useful for selecting rice varieties for future rice breeding and provide pigmented rice nutrition information especially indigenous pigmented rice which has potential in the food, pharmaceutical and cosmetic industries GRAPHICAL ABSTRACT

Characterizing Rice Quality Properties and Comprehensive Taste Quality: A Case Study of Three-years of Regional Varietal Trials in the Mekong Delta

A data set of 140 selected rice varieties from regional registration testing in the Mekong delta with four rice registration groups was studied for quality properties and correlations between each quality parameter and comprehensive taste quality in this paper. Differences in rice quality among the four registration groups and three taste categories were identified. (1) The three maturity groups of A0, A1, and A2 could be divided into fairly good and medium taste categories only whereas the aromatic group could be divided into three taste categories. (2) In the A0, A1, and A2 groups, the amylose content values of the fairly good taste category were lower than those of the medium taste category in the three groups, by 5.91%, 4.38%, and 6.38%, respectively (P &lt;0.05). However, the gel consistency values of the fairly good taste category were higher than those of the medium one, by 25.79mm, 16.53mm, and 26.66mm, respectively. (3) In the aromatic group, the hulling percentage and milling percentage of the good taste category were lower than that of the medium one, respectively. The grain length, length/width ratio, smell, and taste of the high-taste quality category rice were higher than those of the medium taste category rice, however, the amylose content was non-significantly different among the three taste quality categories (P &lt;0.05). (4) The smell and tenderness were found to be highly positively correlated with the comprehensive taste quality, but the amylose content was highly negatively correlated with the comprehensive taste quality in all groups (P &lt;0.01).

Comparative studies of the effect of processing conditions on cooking and sensory properties of selected rice varieties

Cooking and sensory properties of rice varieties are important quality indices that influence market value and consumer acceptability. The objective of this study was to evaluate the effect of processing conditions on cooking and sensory properties of five rice varieties grown in Nigeria. The rice varieties; FARO 44, FARO 52, FARO 60, FARO 61 and NERICA 8, were processed using four processing parameters at varying conditions [soaking temperature (65-75°C), soaking time (10-16 h), steaming time (20 – 30 min) and paddy moisture content (12-16%)] using response surface methodology. The effect of processing conditions on cooking properties (cooking time, water uptake ratio and elongation ratio) was analyzed using standard procedures. Quantitative descriptive analysis and principal component analysis were used to describe eleven sensory characteristics (uniform appearance, black specks, whitish appearance, yellow colour, brown colour, creamy flavour, typical rice odour, sweet taste, sticky texture, grainy texture and hard texture) of the rice varieties. The cooking time, elongation ratio and water uptake ratio ranged from 12.75 to 51.58 min, 0.91 to 1.94 and 2.21 to 4.95, respectively. The cooking properties differed with respect to rice varieties and processing conditions. The shortest cooking time, longest elongation ratio and highest water uptake ratio varied from one variety to another. It was observed that NERICA 8 had the shortest cooking time (12.75 min) at 65ºC soaking temperature, 16 h soaking time, 20 min steaming time and 16% paddy moisture content while FARO 52 had the highest water uptake ratio (4.95) at 65ºC soaking temperature, 16 h soaking time, 20 min steaming time and 16% paddy moisture content. The maximum elongation ratio (1.94) was observed at 65ºC soaking temperature, 16 h soaking time, 30 min steaming time and 12% paddy moisture content in FARO 60. The sensory properties of the rice varieties were generally characterised as having uniform appearance, whitish appearance, sweet taste, creamy flavour and rice odour. The information on the cooking and sensory properties of the rice varieties would assist rice processors and consumers in selecting rice variety of choice. Key words: Cooking properties, Rice varieties, Processing conditions, Sensory properties

Do tillage systems affect the cadmium threshold in farmland soil for environmental quality standard setting?

Tillage systems may change the cadmium (Cd) threshold of farmland soil. However, there have been few studies on this topic. Therefore, this study aimed to explore the influence of tillage systems on Cd threshold. The study conducted 2-year field experiments under different tillage systems (early rice-fallow, early rice-late rice and early rice-vegetable) at three typical Cd-polluted sites in China. The species sensitivity distribution (SSD) method was used to construct the SSD curves for the calculation of the Cd threshold by analyzing the experimental data. The sensitivity analysis results based on the SSD curves revealed that the sensitivities to Cd in rice varieties under the same tillage system were substantially different but almost the same under different tillage systems. These results can help select rice varieties with low Cd sensitivity for crop safety. Different tillage systems at the same site varied in their influence on Cd threshold values. Cd threshold values under early rice-late rice (e.g., 0.27, 0.28 mg/kg in Xiangtan City) and early rice-vegetable (e.g., 0.26, 0.31 mg/kg in Xiangtan City) tillage systems were roughly lower than that under the early rice-fallow tillage system (e.g., 0.33, 0.35 mg/kg in Xiangtan City). Notably, the influence of tillage systems resulted in Cd threshold values being generally lower than the Cd risk screening values of the current Chinese soil environmental quality standard. Analysis of the influence of different tillage systems on the Cd threshold is beneficial for the optimization of farmland soil environmental quality standards.

Relationship between starch fine structure and simulated oral processing of cooked japonica rice.

Simulated oral processing can be used to evaluate the palatability of cooked rice. Previously, we established a simulated oral processing method using a texture analyzer equipped with a multiple extrusion cell probe (TA/MEC). However, the relationship between oral processing and starch fine structure remains unknown. In this study, we analyzed the oral processing properties using TA/MEC and characterized the starch fine structure of japonica rice by size-exclusion chromatography (SEC) and fluorophore-assisted capillary electrophoresis (FACE). The relationship between starch fine structure and oral processing of cooked japonica rice was further investigated. Cooked rice structure contains fast-breakdown (Type I structure), slow-breakdown (Type II structure) and unbreakable structures (Type III structure). Fast-breakdown and slow-breakdown structure were positively correlated with the content of amylose and shorter amylopectin branches. The content of longer amylopectin branches was positively correlated with the contribution of unbreakable structure. The results indicated that cooked japonica rice varieties with more amylose and shorter amylopectin branches tend to form a harder texture and need more work to break down the fast and slow breakdown structures related to rice kernel fragmentation. Meanwhile, cooked japonica rice varieties possess stronger molecular entanglements due to their longer amylopectin branches and contribute more to the breakdown of unbreakable structures. These results can guide breeders to select rice varieties with desirable eating qualities for cultivation.

Differing responses of root morphology and physiology to nitrogen application rates and their relationships with grain yield in rice

Root morphology and physiology influence aboveground growth and yield formation in rice. However, root morphological and physiological differences among rice varieties with differing nitrogen (N) sensitivities and their relationship with grain yield are still unclear. In this study, rice varieties differing in N sensitivity over many years of experiments were used. A field experiment with multiple N rates (0, 90, 180, 270, and 360 kg ha−1) was conducted to elucidate the effects of N application on root morphology, root physiology, and grain yield. A pot experiment with root excision and exogenous application of 6-benzyladenine (6-BA) at heading stage was used to further verify the above effects. The findings revealed that (1) under the same N application rate, N-insensitive varieties (NIV) had relatively large root biomass (root dry weight, length, and number). Grain yield was associated with root biomass in NIV. The oxidation activity and zeatin (Z) + zeatin riboside (ZR) contents in roots obviously and positively correlated with grain yield in N-sensitive varieties (NSV), and accounted for its higher grain yield than that of NIV at lower N application rates (90 and 180 kg ha−1). (2) The root dry weight required for equal grain yield of NIV was greater than that of NSV. Excision of 1/10 and 1/8 of roots at heading stage had no discernible effect on the yield of Liangyoupeijiu (NIV), and it significantly reduced yield by 11.5% and 21.3% in Tianyouhuazhan (NSV), respectively, compared to the treatment without root excision. The decrease of filled kernels and grain weight after root excision was the primary cause for the yield reduction. Root excision and exogenous 6-BA application after root excision had little influence on the root activity of NIV. The oxidation activity and Z + ZR contents in roots of NSV decreased under root excision, and the increase in the proportion of excised roots aggravated these effects. The application of exogenous 6-BA increased the root activity of NSV and increased filled kernels and grain weight, thereby reducing yield loss after root excision. Thus, the root biomass of NIV was large, and there may be a phenomenon of “root growth redundancy.” Vigorous root activity was an essential feature of NSV. Selecting rice varieties with high root activity or increasing root activity by cultivation measures could lead to higher grain yield under lower N application rates.

Study of Variability in Seed Morphology, Screening of Seed Borne Fungi and Uses of Rarely Cultivated Indigenous Rice Landraces (Oryza sativa L.) of Kerala, India

Background: Conservation is the key to sustainability. Kerala is known to be a host to number of traditional rice varieties, which are dying at a rapid pace. The first and foremost step in the conservation of traditional germplasm sources is to assess the various qualitative and quantitative features. Various scientists across the globe, have been studying the genetic diversity, morphological characteristics and fungal activities on rice since appreciable amount of time. This has proved to be helpful in sustenance and refinement of the rice varieties. Methods: Variability was accessed for quantitative and qualitative characters for 30 landraces. Notable variability was observed in the quantitative characters of the selected landraces. Highest variability was seen in ratio of length/breadth (l/b) without husk (25.55), followed by 50 kernel weight (25.51), kernel breadth without husk (21.21), ratio l/b with husk (19.19), kernel breadth with husk (17.90), kernel length without husk (16.58) and kernel length with husk (13.91). A dendrogram was generated by Ward’s method from the data acquired. Ten selected rice varieties were screened for seed borne fungi by standard blotter paper method. The percentage of disease incidence and percentage of frequency were calculated. Result: The rice varieties Choman and Ponnaryan showed highest percentage of disease incidence (100). Lowest percentage of disease incidence was seen in Kumkumashala and Gandhakashala. Highest frequency of occurrence was shown by Aspergillus sps. Other fungal species reported were Chaetomium sps., Curvularia sps., Helminthosporium sps., Unidentified sps. from Dematiaceae, Phoma sps. and Trichococcus sps.