Development of rice introgression lines with brown planthopper resistance and KDML105 grain quality characteristics through marker-assisted selection

‘Khao Dawk Mali 105’ (KDML105), a Thai aromatic rice cultivar, has been accepted in markets as a prime jasmine rice with premium prices. It has been extensively used as a parental line to develop new cultivars for rainfed lowland areas in Thailand because of its favorable quality and fragrance. However, this cultivar is highly susceptible to brown planthopper (BPH), a phloem sap-feeding insect pest of rice. The main objective of this study was to combine KDML105 essential grain quality traits with BPH resistance from the donor cultivar, ‘Rathu Heenati’. The linkage drag between Bph3 and Wx^a alleles was successfully broken by phenotypic and marker-assisted selections. All introgression lines (ILs) developed in this study showed a broad spectrum resistance against BPH populations in Thailand and had KDML105 grain quality standards. Finally this study was revealed that the ILs can be directly developed into BPH resistant varieties or can be used as genetic resources of BPH resistance to improve rice varieties with the Wx^b allele in rice breeding programs.     

Yield formation of CO2-enriched hybrid rice cultivar Shanyou 63 under fully open-air field conditions

Hybrid indica rice (Oryza sativa L.) cultivars play an important role in rice production system due to its heterosis, resistance to environmental stress, large panicle and high yield potential. However, no attention has been given to its yield responses to rising atmospheric [CO₂] in conjunction with nitrogen (N) availability. Therefore we conducted a free air CO₂ enrichment (FACE) experiment at Yangzhou, Jiangsu, China (119°42′0′′E, 32°35′5′′N), in 2004–2006. A three-line hybrid indica rice cv. Shanyou 63 was grown at ambient and elevated (ca. 570 μmol mol⁻¹) [CO₂] under two levels of supplemental N (12.5 g Nm⁻² and 25 g Nm⁻²). Elevated [CO₂] had no effect on phenology, but substantially enhanced grain yield (+34%). The magnitude of yield response to [CO₂] was independent of N fertilization, but varied among different years. On average, elevated [CO₂] increased the panicle number per square meter by 10%, due to an increase in maximum tiller number under enrich [CO₂], while productive tiller ratio remained unaffected. Spikelet number per panicle also showed an average increase of 10% due to elevated [CO₂], which was supported by increased plant height and stem dry weight per tiller. Meanwhile, elevated [CO₂] caused a significant enhancement in both filled spikelet percentage (+5%) and individual grain weight (+4%). Compared with the two prior FACE studies on rice, hybrid indica rice cultivar appears to profit much more from elevated [CO₂] than japonica rice cultivar (ca. +13%), not only due to its stronger sink generation, but also enhanced capacity to utilize the carbon sources in a high [CO₂] environment. The above data has significant implication with respect to N strategies and cultivar selection under projected future [CO₂] levels.     

不同炭硅处理对水稻抗倒伏特性和产量的影响

以越光品种为试验材料,研究了生物炭与硅肥配施对水稻抗倒伏特性、茎秆强度、化学物质含量、酶活性的影响及相互关系。结果表明,花生壳生物炭与硅肥配施显著降低了水稻节长,增加了茎粗,进而降低了水稻的倒伏指数和倒伏面积率,并提高了茎秆中的淀粉、木质素和纤维素含量及木质素关键酶活性。其中,7.5 t/hm²生物炭与45 kg/hm²硅肥基施、叶面喷施0.02%硅肥的处理表现最优,该处理显著增强了越光的抗倒伏性,第1、第2和第3节的倒伏指数分别比对照下降36.42%、30.19%和26.83%,并实现了增产。相关分析表明,水稻的倒伏指数、倒伏面积率与茎秆强度呈极显著负相关;茎秆中淀粉、纤维素和木质素含量与茎秆强度呈显著或极显著正相关,与倒伏指数和倒伏面积率呈显著或极显著负相关;木质素含量与PAL、TAL、4CL和CAD等酶的活性呈显著正相关。研究结果可为优质水稻越光的抗倒伏栽培提供科学依据和技术支持。     

QTL analysis of panicle morphology response to irrigation regime in aerobic rice culture

In water-efficient rice production, grain yield is often constrained by panicle size. The objective of this study was to genetically dissect the response of panicle morphology to irrigation regimes in aerobic rice culture. We grew ‘Akihikari’ (a lowland japonica cultivar) × ‘IRAT109’ (an upland japonica cultivar) backcross inbred lines in aerobic soils with full or limited irrigation for 2 years, and examined 4 panicle traits—number of florets per panicle (FPP), number of primary branches per panicle (BPP), number of florets per primary branch (FPB), and frequency of pre-flowering floret abortion (%FA)—and grain yield. QTLs for BPP were detected in both the irrigation regimes but QTLs for FPB and %FA were detected mostly only in either of the irrigation regimes. The QTL for FPP on chromosome 2 (RM3421–RM213) coincided with that for yield under full irrigation, showing that this QTL is related to sink capacity and yield potential in aerobic rice culture. On the other hand, the QTL for FPB on chromosome 1 (RM3148–RM243) coincided with that for yield under limited irrigation, when water deficit was moderate. The QTL for root axis length at vegetative stage, previously identified in the same mapping population, was located near this region. This study unravelled the complicated genetic control on panicle morphology in aerobic rice culture, and suggested the positive roles of the dehydration avoidance mechanism by vigorous root growth on panicle size and yield under dry soil conditions.     

Differences in lamina joint anatomy cause cultivar differences in leaf inclination angle of rice

ABSTRACT

Leaf erectness is an important agronomic trait for improving canopy photosynthesis in rice. It is well known that leaf inclination angle (LIA) decreases after expansion during ripening. However, the high-yielding indica cultivar ‘Takanari’ retains a greater LIA during ripening than the high-quality japonica cultivar ‘Koshihikari’. To clarify the cause of the cultivar difference in LIA, we investigated anatomical characteristics of the lamina joint of a flag leaf. We found a close linear correlation between LIA at the centre and at the base of the leaf blade in both cultivars during ripening. The length of the lamina joint increased significantly more on the adaxial side of a leaf (the margin of the collar) than on the abaxial side (the abaxial side of the central part of the collar) in ‘Koshihikari’ after leaf expansion, but there was no clear difference in ‘Takanari’. We found a close linear correlation between the ratio of lamina joint length on the adaxial to abaxial sides and LIA in ‘Koshihikari’ and ‘Takanari’ during ripening. In ‘Koshihikari’, the average length of cells on the adaxial side increased significantly after leaf expansion, with no significant increase in that on the abaxial side and no significant change in cell number on either side. In ‘Takanari’, cell length and cell number showed no significant changes on either side of the lamina joint. We conclude that the cultivar difference in LIA during ripening is caused mainly by cell elongation on the adaxial side of the lamina joint.

List of Abbreviations: k: light extinction coefficient; LIA: leaf inclination angle; QTL: quantitative trait locus     

水稻半矮秆基因sd1对农艺性状的影响

比较了从7份半矮秆品种／高秆品种的B₇F₂中分离的高矮秆近等基因系,sd1基因抑制了节间伸长,从基部到倒第1节及穗长分别为高秆的38. 2%, 26. 0%, 48. 0%, 71. 1%和 92. 6%,缩短程度逐步减轻。sd1基因还可促进有效穗数、结实率和收获指数的提高而使矮秆类型的产量潜力高于高秆类型,但sd1基因并不影响抽穗天数、每穗粒数和千粒重。对sd1基因的多效性以及秆高和穗数的关系进行了讨论。     

Yield and growth characteristics of erect panicle type rice (Oryza sativa L.) cultivar,Shennong265 under various crop management practices in Western Japan

Erect panicle rice cultivars utilize solar energy effectively and have improved ecological growing conditions. Among such cultivars, Shennong265 has been grown successfully throughout Northern China. Nevertheless, no studies have yet examined the relationships between crop dry matter productivity, weather conditions, and nitrogen uptake of the erect panicle type rice cultivar in Japan. The objective of our study was to evaluate the productivity of erect panicle rice Shennong265 in Western Japan under varied conditions. Three rice cultivars, Shennong265, Nipponbare, and Takanari were grown in the field under different fertilizer and plant density conditions in Western Japan; using this information, we compared yield and growth characteristics of Shennong265 with those of Nipponbare and Takanari. Although Shennong265 had radiation use efficiency similar to that of the high yielding cultivar (Takanari) and much higher leaf nitrogen content than Takanari and Nipponbare, the average grain yield of Shennong265 grown under normal fertilizer and plant density conditions was approximately 6.9 t ha^?1 as against 6.2 t ha^?1 for Nipponbare and 9.6 t ha^?1 for Takanari. These results suggest that, while Shennong265 has a high yield potential, the environmental conditions including climate, fertilizer, and planting period provided in this study were not suitable for achieving its maximum yield. The reduced performance of Shennong265 may be caused by insufficient fertilizer after heading and by shorter growth periods, as well as by the climate of Western Japan. Additional fertilizer application during the heading stage and earlier transplanting may be needed to obtain higher Shennong265 yields in Western Japan.     

Yield, grain quality and water use efficiency of rice under non-flooded mulching cultivation

Plastic film or straw mulching cultivation under non-flooded condition has been considered as a new water-saving technique in rice production. This study aimed to investigate the yield performance in terms of quality and quantity and water use efficiency (WUE) under such practices. A field experiment across 3 years was conducted with two high-yielding rice cultivars, Zhendao 88 (a japonica cultivar) and Shanyou 63 (an indica hybrid cultivar) and four cultivation treatments imposed from transplanting to maturity: traditional flooding as control (TF), non-flooded plastic film mulching (PM), non-flooded wheat straw mulching (SM), and non-flooded no mulching (NM). Compared with those under the TF, root oxidation activity, photosynthetic rate, and activities of key enzymes in sucrose-to-starch conversion in grains during the grain filling period were significantly increased under the SM, whereas they were significantly reduced under the PM and NM treatments. Grain yield showed some reduction under all the non-flooded cultivations but differed largely among the treatments. The reduction in yield was 7.3–17.5% under the PM, 2.8–6.3% under the SM, and 39–49% under the NM. The difference in grain yield was not significant between TF and SM treatments. WUE for irrigation was increased by 314–367% under the PM, 307–321% under the SM, and 98–138% under the NM. Under the same treatment especially under non-flooded conditions, the indica hybrid cultivar showed a higher grain yield and higher WUE than the japonica cultivar. The SM significantly improved milling, appearance, and cooking qualities, whereas the PM or the NM decreased these qualities. We conclude that both PM and SM could significantly increase WUE, while the SM could also maintain a high grain yield and improve quality of rice. The SM would be a better practice than the PM in areas where water is scarce while temperature is favorable to rice growth, such as in Southeast China.     

Impact of elevated CO2 concentration on inter-subspecific hybrid rice cultivar Liangyoupeijiu under fully open-air field conditions

Hybrid rice cultivar plays an important role in rice production system due to its high yield potential and resistance to environmental stress. Quantification of its responses to rising CO₂ concentration ([CO₂]) will reduce our uncertainty in predicting future food security and assist in development of adaptation strategies. Using free air CO₂ enrichment (FACE), we measured seasonal changes in growth and nitrogen (N) uptake of an inter-subspecific hybrid rice cultivar Liangyoupeijiu grown under two levels of [CO₂] (ambient and elevated by 200 μmol mol⁻¹) and two levels of N fertilization in 2005–2006. Average across the 2 years, FACE increased crop growth rate similarly by 22%, 24% and 23% in the periods from transplanting to panicle initiation (PI), PI to heading and heading to maturity, which was mainly attributed to an increase in green leaf area index rather than the greater net assimilation rate. Grain yield increased greatly under FACE as a result of similar contributions by panicle number per unit area, grain number per panicle and individual grain yield. Final aboveground N acquisition showed a 10.4% increase under FACE, which resulted from enhanced N uptake at both vegetative and reproductive growth stages. Compared with previous FACE studies on final productivity of two inbred japonica cultivars, inter-subspecific hybrid cultivar appears to profit more from elevated [CO₂], which mainly resulted from its greater enhancement in photosynthetic production during reproductive growth due to a lack of N limitations late in the season.     

Comparison of Physicochemical Properties of the Grains between Old- and New-Types of Rice Cultivars in Japan

Abstract

The physicochemical properties of the grains of 16 old- and 21 new-type rice cultivars in Japan were investigated in 1995 and 1996. Among the old- and new-type cultivars, we found a similar pattern of varietal differences in physicochemical properties in both years, and in both the fields with and without nitrogen fertilizer applied. Between the two types, no significant differences in the mean protein and amylose contents in the rice grain were observed. The old-type rice cultivars tended to be lower in mean maximum viscosity and breakdown values than the new- type cultivars, although the difference was not significant. Cooked rice of the old-type cultivars tended to be higher in mean hardness/adhesion ratio (H/-H) and hardness/adhesiveness ratio (H/A₃) than that of the new -type cultivars. The physicochemical properties which showed superior values in the standard partial regression coefficients against the taste of cooked rice were the protein content, breakdown value and H/-H. These, physico-chemical properties can be efficient indicators for evaluating the taste of cooked rice. The coefficient of parentage of each cultivar to cultivar Koshihikari showed tight negative correlations with amylose content, H/-H and H/A₃, and tight positive correlations with maximum viscosity and breakdown values. The coefficients showed a loose positive correlation with protein content. However, Sasanishiki, Domannaka, Chiyonishiki, Nakate shinsenbon and Rikuu 132 were superior in their physicochemical indicators, in spite of their small coefficients of parentage to Koshihikari. This suggests that a highly palatable cultivar that is widely different from Koshihikari can be developed by utilizing genetic resources with superior physicochemical indicators.     

Progress in ideotype breeding to increase rice yield potential

The ideotype approach has been used in breeding programs at the International Rice Research Institute (IRRI) and in China to improve rice yield potential. First-generation new plant type (NPT) lines developed from tropical japonica at IRRI did not yield well because of limited biomass production and poor grain filling. Progress has been made in second-generation NPT lines developed by crossing elite indica with improved tropical japonica. Several second-generation NPT lines outyielded the first-generation NPT lines and indica check varieties. China's “super” rice breeding project has developed many F₁ hybrid varieties using a combination of the ideotype approach and intersubspecific heterosis. These hybrid varieties produced grain yield of 12 t ha⁻¹ in on-farm demonstration fields, 8–15% higher than the hybrid check varieties. The success of China's “super” hybrid rice was partially the result of assembling the good components of IRRI's NPT design in addition to the use of intersubspecific heterosis. For example, both designs focused on large panicle size, reduced tillering capacity, and improved lodging resistance. More importantly, improvement in plant type design was achieved in China's “super” hybrid rice by emphasizing the top three leaves and panicle position within a canopy in order to meet the demand of heavy panicles for a large source supply. The success of “super” hybrid rice breeding in China and progress in NPT breeding at IRRI suggest that the ideotype approach is effective for breaking the yield ceiling of an irrigated rice crop.     

Quantitative effects of cultural practices on growth and yield of forage rice having short panicles

Cultivation of forage rice for whole-crop silage has been increasing in Japan and will be important in Asia. In this study, effects of cultural practices on growth and yield of a forage rice cultivar “Tsukisuzuka” having short panicle 1 allele were analysed quantitatively using linear mixed model. The contribution of basal dressing to dry yield per 1 g/m² nitrogen fertilizer was larger than that of topdressing. In addition, topdressing 30 and 20 days before heading was considered to have the disadvantage of increasing risk of lodging and panicle weight respectively. Effects of weather elements on growth of forage rice were also speculated. In tested fields, high solar radiation at seedling and tillering stage was considered important for the high yield. As the number of continuous cropping cycles increased, growth of forage rice got worse. And application of compost improved growth of forage rice. Elemental analysis of soil and plants revealed that this continuous cropping obstacle was likely to attributed to deficiency of potassium. In addition, potassium deficiency increased panicle weight of a forage rice cultivar having short panicle 1 allele. Therefore, control of potassium nutrition will be useful for both sustaining productivity (sufficient application of potassium) and seed production (restriction of potassium). These findings will be useful for improvement of cultivation method of forage rice.     

Non-target effects of the ‘push–pull’ habitat management strategy: Parasitoid activity and soil fauna abundance

We assessed the non-target effects of a habitat management system (‘push–pull’) on maize stemborer specialist natural enemy activity and soil Collembola. Two study sites in western Kenya were sampled. There were two treatments at each site, maize monocrop and ‘push–pull’. The latter comprised an intercrop of maize and Desmodium, Desmodium uncinatum Jacq., with Napier grass, Pennisetum purpureum (Schumach), as a trap crop planted around the edge of the plot (spaced 1 m from main crop). Trichogramma spp. were recovered from stemborer eggs while Cotesia sesamiae and Cotesia flavipes were recovered from stemborer larvae, and Dentichasmias busseolae from pupae. Mean number of eggs parasitized was significantly higher in the maize monocrop than in the ‘push–pull’ plots however proportions parasitized did not differ between the two systems. The number of larvae and pupae parasitized and dead from causes other than parasitism similarly did not differ between cropping systems. Proportions of larvae and pupae parasitized were significantly higher in the ‘push–pull’ than in the monocrop plots, indicating that the activity of larval and pupal parasitoids was enhanced. C. sesamiae female wasps were attracted to the volatiles from Desmodium flowers but not those from the leaves in a four-arm olfactometer bioassay. A total of 1530 individual Collembola in seven families were recovered from the plots. The ‘push-pull’ strategy did not have any significant effect on Collembola abundance and dominance. The factors underlying these observations and their implications are discussed.     

【Short Report】Identification of Chromosome Regions Affecting Leaf Area with Rice Chromosome Segment Substitution Lines

Abstract

The aim of this study was to obtain the information for improvement in source ability via expansion of a flag leaf area in rice (Oryza sativa L.). We identified chromosome regions affecting a trait (CRATs) for leaf area and confirmed their effects with two sets of chromosome segment substitution lines developed from indica landraces Kasalath or Nona Bokra as a donor under japonica cultivar Koshihikari genetic background. We detected 4 and 8 CRATs that increased leaf area by Kasalath and Nona Bokra alleles, respectively. With the Nona Bokra allele, CRAT on chromosome 7 (LA7) increased leaf area by 54% comparing to Koshihikari. LA7 maintained the contents of Rubisco and photosynthetic rate and as a result its “estimated” source ability of a flag leaf was increased by 23%. The effect of LA7 was stable under different environmental conditions, and might be useful for breeding rice with higher source ability and yield.     

Improvement of nitrogen management in rice paddy fields using chlorophyll meter (SPAD)

Optimum rate and timing application of nitrogen (N) fertilizer are most crucial in achieving high yield in irrigated lowland rice. In order to assess leaf N status, a semidwarf rice cultivar (Khazar) was grown with different N application treatments (0, 40, 80, and 120 kg N ha⁻¹ splited at transplanting, midtillering, and panicle initiation stages) in a sandy soil in Guilan Province, Iran, in 2003. The chlorophyll meter (SPAD 502) readings were recorded and leaf N concentrations were measured on the uppermost fully expanded leaf in rice plants at 10-day internals from 19 days after transplanting to grain maturity. Regression analysis showed that the SPAD readings predicted only 23% of changes in the leaf N concentration based on pooled data of leaf dry weight (N _dw) for all growth stages. However, adjusting the SPAD readings for specific leaf weight (SPAD/SLW) improved the estimation of N _dw, up to 88%. Specific leaf weight (SLW), SPAD readings, leaf area and weight as independent variables in a multiple regression analysis predicted 96% of the N _dw changes, while SPAD readings independently predicted about 80% of leaf N concentration changes on the basis of leaf area (N _a). It seems that chlorophyll meter provides a simple, rapid, and nondestructive method to estimate the leaf N concentration based on leaf area, and could be reliably exploited to predict the exact N fertilizer topdressing in rice.     

机械插秧与条播对盐粳15号生育性状与品质的影响

对水稻新品种盐粳15号2018、2019年连续2年在江苏盐城地区机插和机条播2种栽培方式的种植表现进行考察,主要测试该品种的生育期安全性、叶龄、分蘖动态、产量和品质性状。结果表明,该品种在盐城地区具有安全稳定的生育期,2年机插条件下全生育期分别为158、155 d,机条播条件下全生育期分别为138、134 d。该品种分蘖能力强,机插条件下2年成穗数分别为25.8万、26.1万个/667 m^2,机条播条件下2年成穗数分别为28.8万、27.9万个/667 m^2。该品种产量潜力高,2年机插和机条播产量均在700 kg/667 m^2以上。该品种机插条件下直链淀粉含量2年分别为15.3%、15.6%,蛋白质含量分别为9.8%、9.7%;机条播条件下直链淀粉含量2年分别为16.2%、16.7%,蛋白质含量分别为9.1%、9.0%。     

Causes of differences in growth pattern,yield and quality of potatoes (Solanum tuberosum L.) in short rotations on sandy soil as affected by crop rotation,cultivar and application of granular nematicides

Summary A crop rotation experiment was carried out on a light sandy soil in 1979–1986 to study the effects of the frequency of potato cropping on yield, quality and on the occurrence of soil-borne pathogens other than potato cyst nematodes. Tuber yield decreased markedly with increasing cropping frequency, but also depended on what crops were grown in rotation with potato. Growth during the early part of the season, as well as the length of the growing period, were reduced in short rotations. The fungiVerticillium dahliae andRhizoctonia solani, and root-knot nematodes (Meloidogyne spp.) were the most important yield reducing pathogens. The effects of rotation depended on the cultivar used. The percentage of mis-shapen tubers increased with increasing cropping frequency and after application of granular nematicides, but the incidence of common scab (Streptomyces scabies) was not affected.     

矮泰引-2中半矮秆基因的分离与鉴定研究

In order to discover new semidwarf genes which can be used in breeding program in indica rice, a dwarf variety Aitaiyin 2, was crossed with a tall native cultivar Naming 6. The segregation of the F₁ generation appeared to be 9 tall:6 semidwarf:1 dwarf, which meant two semidwarf genes were involved. While Aitaiyin 2 was also crossed with two semidwarf varieties, Nanjing 11 with sd-1 and Xingui'ai with sd-g, the segregation of the F₂ generation in the former cross was 3 semidwarf:1 dwarf and that in the latter cross was 27 tall:27 semidwarf:9 dwarf:1 extra dwarf. This indicated that there were two semidwarf genes in Aitaiyin 2, one of them was allelic to sd-1 and the other was a new semidwarf gene which was nonallelic to both sd-1 and sd-g. This new semidwarf gene was named sd-t(t).     

Beta-carotene content of postharvest orange-fleshed muskmelon fruit: Effect of cultivar,growing location and fruit size

The influence of two growing locations (soil types), six fruit sizes, and two years on the postharvestBeta-carotene content of muskmelon (Cucumis melo L. var. reticulatus Naud.) fruit was studied with two different cultivars. Fully abscised commercial size fruit: 9, 12, 15, 18, 23, and 30 (fruit/0.04 M³ shipping box) had highly variableBeta-carotene contents (5.3 to 33.8 µg/g fresh weight) that varied by size class, soil type and cultivar.Beta-carotene content increased with fruit size up to a maximum, though fruit size continued to increase. Find sandy loam soil produced fruit with lessBeta-carotene content than silty clay loam soil. The cultivar Primo contained higherBeta-carotene content levels than cultivar Cruiser. Mesocarp percent moisture content for both Cruiser and Primo at both locations by fruit size was not significantly correlated (r=0.40) withBeta-carotene content. Indicating fruit cell dilution may not contribute to the differences inBeta-carotene content in different fruit size classes.Beta-carotene content of size class 18 fruit from six cultivars grown on the silty clay loam soil for two consecutive years, showed a year, and year by cultivar effect for some cultivars. Whereas, some cultivars did not differ inBeta-carotene content between the two years. This indicates a potential for controllingBeta-carotene content of muskmelon fruit at a constant, high level by careful selection of production cultivar.Mention of a trademark of propriety does not constitute a guarantee or warranty of the product by the US Department of Agriculture or Texas A&M University and does not imply its approval to the exclusion of other products that also may be suitable.