Artificial selection of the Green Revolution gene Semidwarf 1 is implicated in upland rice breeding

Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1(SD1), which modulates gibberellic acid(GA) biosynthesis, plays a principal role in determining rice plant height. Mutations in SD1 reduce rice plant height and promote lodging resistance and fertilizer tolerance to increase grain production. The plant height mediated by SD1 also favors grain yield under certain conditions. However, it is not yet known whether the function of SD1 in upland rice promotes adaptation and grain production. In this study, the plant height and grain yield of irrigated and upland rice were comparatively analyzed under paddy and dryland conditions. In response to dryland environments, rice requires a reduction in plant height to cope with water deficits. Upland rice accessions had greater plant heights than their irrigated counterparts under both paddy and dryland conditions, and appropriately reducing plant height could improve adaptability to dryland environments and maintain high grain yield formation. Moreover, upland rice cultivars with thicker stem diameters had stronger lodging resistance, which addresses the lodging problem. Knockout of SD1 in the upland rice cultivar IRAT104 reduced the plant height and grain yield, demonstrating that the adjustment of plant height mediated by SD1 could increase grain production in dryland fields. In addition, an SD1 genetic diversity analysis verified that haplotype variation causes phenotypic variation in plant height. During the breeding history of rice, SD1 allelic mutations were selected from landraces to improve the grain yield of irrigated rice cultivars, and this selection was accompanied by a reduction in plant height. Thus, five known mutant alleles were analyzed to verify that functional SD1 is required for upland rice production. All these results suggest that SD1 might have undergone artificial positive selection in upland rice, which provides further insights concerning greater plant height in upland rice breeding.

The ABA synthesis enzyme allele OsNCED2^(T)promotes dryland adaptation in upland rice

Upland rice shows dryland adaptation in the form of a deeper and denser root system and greater drought resistance than its counterpart,irrigated rice.Our previous study revealed a difference in the frequency of the OsNCED2 gene between upland and irrigated populations.A nonsynonymous mutation(C to T,from irrigated to upland rice)may have led to functional variation fixed by artificial selection,but the exact biological function in dryland adaptation is unclear.In this study,transgenic and association analysis indicated that the domesticated fixed mutation caused functional variation in OsNCED2,increasing ABA levels,root development,and drought tolerance in upland rice under dryland conditions.OsNCED2-overexpressing rice showed increased reactive oxygen species-scavenging abilities and transcription levels of many genes functioning in stress response and development that may regulate root development and drought tolerance.OsNCED2^(T)-NILs showed a denser root system and drought resistance,promoting the yield of rice under dryland conditions.OsNCED2^(T)may confer dryland adaptation in upland rice and may find use in breeding dryland-adapted,water-saving rice.

Effects of Arbuscular Mycorrhizal Fungi(AMF) on Growth of Upland Rice under Soil Pb Contamination

[Objective] This study aimed to investigate the effects of arbuscular mycor-rhizal fungi （AMF） on growth of upland rice under soil Pb contamination. [Method] Using potting method, the effects of Glomus mosseae on the growth of Oryzal sati-va L. under different soil Pb concentrations （0, 300, 600 mg/kg） were investigated. [Result] According to the results, the mycorrhizal colonization rate of upland rice in-oculated with Glomus mosseae was significantly reduced （P〈0.05） with the increase of Pb concentration in soil. Compared with non-inoculation treatment, inoculation of arbuscular mycorrhizal fungi significantly improved the biomass of upland rice and Pb concentration of upland rice roots with addition of 300 mg/kg Pb but significantly reduced Pb concentration of upland rice shoots, which was consistent with the re-duced R/S （P〈0.05）; with addition of 600 mg/kg Pb, inoculation of arbuscular mycor-rhizal fungi significantly improved the biomass of upland rice roots （P〈0.05） but sig-nificantly reduced Pb concentration of upland rice shoots and roots （P〈0.05）; there was no significant difference in R/S between inoculation treatment and non-inocula-tion treatment. [Conclusion] This study indicated that inoculating Glomus mosseae under certain Pb concentrations could to some extent al eviate the toxic effects of Pb on Oryzal sativa L.

Effects of Arbuscular Mycorrhizal Fungi on Upland Rice Oxidative Stress Induced by Cu and Pb Contamination in Soil

[Objective] This study aimed to investigate the effect of arbuscular mycor-rhizal fungi on upland rice oxidative stress induced by Cu and Pb contamination in soil. [Method] The upland rice seeds were sowed in pots, in which the soil was previously mixed with a certain amount of Glomus mosseae and 0, 100 and 200 mg/kg Cu, or 0, 300 and 600 mg/kg Pb. In the control treatment, Glomus mosseae was inactivated before mixed into the soil. Then, the physiological and chemical properties of the aboveground parts of rice plants were measured at mature stage. [Result] Compared with the control treatment （NM）, Glomus mosseae （GM） treat-ment inhibited the POD, CAT and SOD activity while increased the soluble protein content under 100 mg/kg Cu and 300 mg/kg Pb treatment, improved the POD and CAT activity and soluble protein content while decreased SOD activity under 200 mg/kg Cu. SOD and POD activity showed no significant difference between NM and GM treatment under 600 mg/kg Pb, but the CAT activity was enhanced and soluble protein content was decreased. [Conclusion] This study wil provide theoretical refer-ence for bioremediation of soil heavy metal pol ution.

Effects of Arbuscular Mycorrhizal Fungi (AMF) on Distribution of Pb Forms in Rhizosphere of Upland Rice

[Objective] The aim was to study the effects of AMF on distribution of Pb in different chemical forms in rhizosphere soil of upland rice. [Method] A pot experiment was conducted to explore effects of AMF inoculation on distribution of Pb in different forms in rhizosphere of rice (Oryzal sativa L.) with Pb in different concentrations (0, 300 and 600 mg/kg). [Result] With inoculation adopted, mycorrzhial colonization rate of upland rice under Pb pdlution root declined substantially with Pb increasing in soils (P<0.05). Compared with non-inoculation, rhizosphere pH significantly enhanced by inoculation; when Pb was at 300 mg/kg, glomalin content in soils improved significantly by inoculation; when Pb was at 600 mg/kg, glomalin content in soils declined substantially (P<0.05). In addition, inoculation significantly improved contents of Pb in exchangeable and organic forms, but lowered Pb in carbonate bound and Fe-Mn oxides bound forms (P<0.05). [Conclusion] The research indicated that AMF inoculation would change distribution of Pb in different forms in rhizosphere soils of upland rice.

Effects of Mulching Mode on Canopy Physiological, Ecological Characteristics and Yield of Upland Rice

The effects of mulching mode on population physiology and ecology of rice were studied using a combination P88S/1128 as the material under three mulching cultivation modes including plastic film mulching, straw mulching and liquid film mulching, as well as bare cultivation (control). The results indicated that mulching mode had significant effects on micro-meteorological factors and individual growth of rice, as shown by an increase of relative humidity, a better internal micro-meteorological environment of rice population, a significant reduction under the rice canopy temperature, especially during high-temperature periods. Rice plants under mulching cultivation conditions displayed a stronger transpiration and lower leaf temperature, thereby improving the ability of anti-high temperature stress and markedly increasing the photosynthetic rate. Furthermore, the yield components of rice were significantly optimized under mulching cultivation, of which with plastic film mulching displayed the highest grain number per panicle and seed-setting rate, and a yield increase of 16.81% compared with the control; and with straw mulching displayed an increase of effective panicle number and a 9.59% increase of total yield compared to the control.

Arbuscular Mycorrhizal Fungi Colonization in Upland Rice as Influenced by Agrochemical Application

Mycorrhizal status of rice under upland conditions was studied using potted seedlings, Percentage of arbuscular mycorrhizal fungi （AMF） root colonization varied between 17.35% and 37.18% over an age series of 7 to 70 days old rice plants, AMF root colonization was increased up to 35-42 days, beyond which the root colonization steadily declined, The vesicles appeared after two weeks and reached their maximum intensity on the 35th day. The arbuscules were formed late on the 42^rd day （2.93%） and slightly varied up to the 70^th day （3.03%）. Higher dosage of urea application suppressed plant growth whereas the superphosphate treatment had no marked impact on plant growth. Generally, application of these agrochemicals registered less influence on the hyphal colonization of AMF in rice plants, whereas arbuscular colonization was adversely affected by higher dosages of fertilizers. There were pronounced decreases in both the plant growth and their AMF colonization due to the application of systemic fungicides, carbendazim and thiophanate methyl. The application of single sprays of fungicides was less deleterious over multiple sprays.

Molecular Variation and Application from Aerospace Mutagenesis in Upland Rice Huhan 3 and Huhan 7

To further improve upland rice varieties Huhan 3 and Huhan 7, seed samples were sent to outer space with two recoverable spaceships for approximately 1 and 5 d and were propagated for 7 and 5 generations, respectively. Phenotypic analysis revealed that the morphological traits and the protein and amylose contents of grains changed. Characterization of genomic mutations by the gene-associated simple sequence repeat （SSR） and insertion-delete （InDel） markers indicated that the mutation pattern was very complex. Most of the mutations occurred at the 3＇- or 5＇-end of the fragments in the simple sequence repeat fragment. Reverse transcription-polymerase chain reaction （RT-PCR） assay showed that mutations in those parts of the SSR affected their gene expression, indicating that gene associated markers would be helpful to isolate functional genes. Field survey for breeding also revealed that more lines with high yield, high quality and drought-tolerance could be selected through aerospace breeding. The results indicate that aerospace mutagenesis resulted in molecular variation, as well as physiological and morphological changes for rice breeding.

Evaluation of stability and yield potential of upland rice genotypes in North and Northeast Thailand

The planting of upland rice is one cropping option in area with limited water availability and low soil fertility in North and Northeast Thailand. The varietal selection was determined by grain yield potential, wide adaptation, and good stability. This study was aimed at evaluation of indigenous upland rice germplasm for yield and yield stability in multi-locations. Thirty-six upland rice genotypes collected from six provinces of the North and Northeast Thailand and one check variety （Sewmaejan） were assessed under five locations in the rainy seasons of 2009 and 2010. The experiment was laid out in a randomized complete block design with three replications. The genotype grain yield was highly affected by location （59.90%）, followed by genotypes （G）xlocation （L） interaction （12.80%） and genotype （6.79%）. The most suitable location for the genotype eval- uation was L3 （Khon Kaen-KKU 10） which associated with stability of grain yield for all genotypes. Furthermore, biplot and regression analysis indicated that genotype numbers 6 （Jaowmong 1）, 10 （Neawmong 1）, 18 （Neawdum 1）, 19 （Leamna）, 20 （Prayaleamkang）, 32 （Kunwang 2）, and 33 （Kunwang 3） showed great yield stability over five locations. The genotypes will be applicant for upland rice production area and parental base in breeding program.

Variability in Grain Quality Characters of Upland Rice of Assam,India

The grain quality of 100 uplandlahu rice genotypes from Assam, India was assessed. The characteristics measured were grain length, grain width, cooked grain length, cooked grain width, grain elongation ratio after cooking, grain widening ratio after cooking, alkali spreading value, gel consistency, as well as starch, amylose, amylopectin and total soluble sugar contents. Considerable genetic variability among the 100 rice genotypes was observed for the characteristics under study. Analysis of vadance revealed highly significant differences among the genotypes for all the characteristics. The difference between genotypic coefficient of variation （GCV） and phenotypic coefficient of variation （PCV） was very small for all the characteristics analyzed. High GCV and PCV were found in the characteristic of total soluble sugar content followed by alkali spreading value. The high values for these traits signify the scope for selection to develop superior genotypes. High heritability was recorded in all the characteristics analyzed along with diverse genetic advance which varied from 9.71% to 52.83%. The characteristic of total soluble sugar content showed high heritability with high genetic advance, whereas alkali spreading value and grain widening ratio presented high hedtability with moderate genetic advance. This implies that these characteristics are mainly under additive gene effects and could be relied upon further selection based on phenotypic performance. The genotypic correlation coefficient was higher than the phenotypic correlation coefficient, indicating strong inherent associations among the characteristics studied.

Improvement of Upland Rice Variety by Pyramiding Drought Tolerance QTL with Two Major Blast Resistance Genes for Sustainable Rice Production

Varalu is an early maturing rice variety widely grown in the rainfed ecosystem preferred for its grain type and cooking quality.However,the yield of Varalu is substantially low since it is being affected by reproductive drought stress along with the blast disease.The genetic improvement of Varalu was done by introgressing a major yield QTL,qDTY_(12.1),along with two major blast resistance genes i.e.Pi54 and Pi1 through marker-assisted backcross breeding.Both traits were transferred till BC_(2) generation and intercrossing was followed to pyramid the two traits.Stringent foreground selection was carried out using linked markers as well as peak markers(RM28099,RM28130,RM511 and RM28163)for the targeted QTL(qDTY_(12.1)),RM206 for Pi54 and RM224 for Pi1.Extensive background selection was done using genome-wide SSR markers.Six best lines(MSM-36,MSM-49,MSM-53,MSM-57,MSM-60 and MSM-63)having qDTY_(12.1) and two blast resistance genes in homozygous condition with recurrent parent genome of 95.0%-96.5% having minimal linkage drag of about 0.1 to 0.7 Mb were identified.These lines showed yield advantage under drought stress as well as irrigated conditions.MSM-36 showed better performance in the national coordinated trials conducted across India,which indicated that improved lines of Varalu expected to replace Varalu and may have an important role in sustaining rice production.The present study demonstrated the successful marker-assisted pyramiding strategy for introgression of genes/QTLs conferring biotic stress resistance and yield under abiotic stress in rice.

Genome-Wide Association Study of Nitrogen Use Efficiency and Agronomic Traits in Upland Rice

Genome-wide association study(GWAS)was performed for 16 agronomic traits including nitrogen use efficiency(NUE)and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38390 single nucleotide polymorphism(SNP)markers.This panel was evaluated under rainfed upland conditions in Madagascar in two consecutive cropping seasons with two contrasted nitrogen input levels.Using another set of five grain traits,we identified previously known genes(GW5,GS3,Awn1 and Glabrous1),thus validating the pertinence and accuracy of our datasets for GWAS.A total of 369 significant associations were detected between SNPs and agronomic traits,gathered into 46 distinct haplotype groups and 28 isolated markers.Few association signals were identified for the complex quantitative trait NUE,however,larger number of quantitative trait loci(QTLs)were detected for its component traits,with 10 and 2 association signals for nitrogen utilization efficiency and nitrogen uptake efficiency,respectively.Several detected association signals co-localized with genes involved in nitrogen transport or nitrogen remobilization within 100 kb.The present study thus confirmed the potential of GWAS to identify candidate genes and new loci associated with agronomic traits.However,because of the quantitative and complex nature of NUE-related traits,GWAS might have not captured a large number of QTLs with limited effects.

Effects of Sowing Methods on Upland Rice in Lowland Rice-Vegetable Sequence in Inland Valley

Triple cropping in the inland valleys of southwestern Nigeria is technically possible but the third crop between the main crop and vegetables has poor establishment due to soil saturation. Identification of appropriate sowing methods is required in this niche. A field experiment was conducted at the University of Agriculture, Abeokuta, Nigeria in 2007/2008 and 2008/2009 cropping seasons to evaluate the effect of sowing methods on the performance of upland rice （Oryza spp.） in a lowland rice-vegetable sequence. The first, second, and third crops in the sequence were planted in May, September and December, respectively. Two upland rice varieties, namely New Rice for Africa 1 （NERICA 1） and ITA 150 constituted the main plot treatments while the subplot treatments were sowing methods. The mean grain yield of lowland rice for two years was 7.74 t ha^-1. The fluted pumpkin had a fresh leaf weight of 14.78 t ha^-1. The grain yields of the two upland rice varieties （1.81 and 1.85 t ha^-1） and sowing methods which ranged between 1.63 and 2.05 t ha^-1 were similar in both cropping seasons. However, the interaction of variety by sowing methods had a significant effect on grain yield. Transplanting and pre-germinated broadcast had the highest grain yield for NERICA 1 while dry broad cast and pre-germinated dibbled had the highest in ITA 150. Hence, the productivity of triple cropping in the inland valley was enhanced by sowing methods.

Weed Management in Rainfed Upland Rice Fields under Varied Agro-Ecologies in Nigeria

The demand for rice to meet the dietary need in low-income countries is expected to witness an exponential rise as the population increases.Meeting the rice demand domestically has remained challenging due to significant yield loss caused by several biotic and abiotic factors.Among these factors,one of the most important is the high weed pressure that ravages the upland rice ecology.In Nigeria,several independent weed control techniques,such as physical,chemical and cultural methods,have been recommended and adopted for weed control across varying rice upland ecologies.However,outcomes of these approaches when used independently have not consistently led to an increase in yield.There remains an outstanding deficit between the actual yield and the potential rice yield.This review aimed to identify potential research gaps,and quest effective and sustainable weed management strategies in smallholder upland rice farming systems in Nigeria.A critical analysis of studies suggests the potential of sustainable weed management practices if adopted and adapted smartly in different upland ecologies in Nigeria.Competitiveness of upland rice against weeds can be enhanced through strategic integration of weed competitive cultivars,optimum nitrogen application timings(within weed-free periods),uniform plant spacing,and high seeding rates,with conventional herbicide/manual weed control practices.However,such management practices can only be engaged where inputs are supplied on time and the technical know-how is extended to farmers.The review equally highlights potential research gaps for further studies.

Determination of Upland Rice Cultivar Coefficient Specific Parameters for DSSAT (Version 4.7)-CERES-Rice Crop Simulation Model and Evaluation of the Crop Model under Different Temperature Treatments conditions

To develop basis for strategic or arranged decision making towards crop yield improvement in Thailand, a new method in which crop models could be used is essential. Therefore, the objective of this study was to measure cultivar specific parameters by using DSSAT (v4.7) Cropping Simulation Model (CSM) with five upland rice genotypes namely Dawk Pa-yawm, Mai Tahk, Bow Leb Nahng, Dawk Kha 50 and Dawk Kahm. Experiment was laid out in a Completely Randomized Design (CRD) with split plot design. Results showed that five upland rice genotypes had significantly affected each other by different temperature treatments (28°C, 30°C, 32°C) with grain yield, tops weight, harvest index, flowering, and maturity date. At the same time, all the phenological traits had highly significant variation with the genotypes. The cultivar specific parameters obtained by using a temperature tolerant cultivar (Basmati 385) with five upland genotypes involved in the DSSAT4.7-CSM. Model evaluation results indicated that utilizing the estimated cultivar coefficient parameters, model simulated well with varying temperature treatments as indicated by the agreement index (d-statistic) closer to unity. Hence, it was estimated that model calibration and evaluation was realistic in the limits of test cropping seasons and that CSM fitted with cultivar specific parameters can be used in simulation studies for investigation, farm managing or decision making. This electronic document is a “live” template. The various components of your paper [title, text, heads, etc.] are already defined on the style sheet, as illustrated by the portions given in this document.

Extent of Reduction of the Fallow Period and Its Impact on Upland Rice Production in the Nongowa Chiefdom of Kenema District in Eastern Sierra Leone

Slash-and-burn agriculture is the common practice for upland rice intercropping system in Sierra Leone and it has been blamed for the loss of forest vegetation across the country. Shortening of the fallow period in the Eastern region of Sierra Leone has implications on agricultural food production and the persistence of the remaining tropical rainforest. This study was therefore undertaken to assess: 1) the extent of reduction of the fallow period in the Nongowa Chiefdom of Kenema District;2) the causes of reduction in the fallow period;3) farmers’ perception of the relevance of fallow period and the implications of reduction of fallow period on crop production. The study revealed a drastic reduction of the fallow period in the chiefdom with a mean of 3.8 years which falls far below the country mean fallow period of 8.8 years as estimated by FAO. Farmers pointed out that the reduction of the fallow period was as a result of land scarcity due to competing land uses such as large scale commercial agriculture, logging, mining, charcoal burning and expansion of settlements. Farmers agreed that a fallow period of at least 10 years is necessary for upland rice production. Farmers were aware of the impact of reduction of the fallow period on upland rice production and were able to estimate rice yields based on the age of the fallow. Also, farmers have attempted to adapt to the constraints posed by shorter fallow periods by selection of rice varieties to suit the length of the fallow periods.

Evaluating Rice Biodiversity and Yields of Upland Rice Landraces Grown in Shifting Cultivation in Bandarban,Bangladesh

Shifting cultivation,popularly known as jhum,is a dominant form of agriculture in the Chattogram Hill Tracts(CHT)of Bangladesh with upland rice being the major component of the system.The region is known for its rice biodiversity,which is under threat.This study was an attempt to explore the extent of rice biodiversity and variation in rice yields observing 81 randomly selected shifting cultivation plots from 26 dispersedly located mountainous villages in four sub-districts of Bandarban,one of three districts of the CHT.A total of 28 landraces of upland rice was grown in shifting cultivation.Highest number of landraces(16)was found in sub-district Thanchi.Three landraces most frequently observed were Gunda,Maemonsing and Sadabinni.Rice grain yield varied between 1.421 t ha-1 and 3.442 t ha-1 across landraces with the highest being recorded for Patobi.Landrace Dilon the lowest yield.Relative performance of landraces Kobrokbinni,Maemonsing,Monthon,Patobi and PD were superior to standard BRRI dhan83 and Gunda in relation to grain yield.Some of these landraces having wider adaptability may be released as varieties.

Agronomic Performance of Cultivars of Upland Rice in the Southern of the Region of Rondonia,Brazil

The upland rice is grown in most Brazilian states. However, in many of them the yield obtained is low. The choice of cultivar more suited to a particular environment can contribute to increased productivity of this crop. This research aimed to evaluate the performance of a hybrid cultivar of upland rice (Ecco) and five conventional cultivars (BRS Monarca, BRS Primavera, AN Cambará, BRS Sertaneja and BRS MG Curinga) in two environments (Vilhena and Cerejeiras). The tests were conducted in the agricultural year 2010/2011. We evaluated the following characteristics: tillering, panicle number per unit area, number of filled grains per panicle sterile, mass of grains per panicle, 1000 grain weight, grain yield (kg·ha-1) and whole grain yield. There was no cultivar x environment interaction for all traits. Greater tillering, higher panicle number per area, higher productivity and yield of whole grains in the municipality of Cerejeiras were observed, while the highest number of sterile grains per panicle was obtained in Vilhena. The hybrid Ecco highlighted in relation to all other cultivars is in relation to tillering, panicle number per area and grain yield. The municipality of Cerejeiras is the most suitable for the cultivation of upland rice.

Preliminary studies on radiant spectrum of the leaves of the paddy and upland rice

To study the property of the radiant spectrum(RS),i.e.absorption,reflectance and trans-mission ratio.Four upland rice varieties i.e.Haogelao,Hongkuo—laoshuya,Chengjiang—ludao,and IRAT—109,and four paddy ricevarieties Xifeng,Akihikari,Zhongbai 4,andYuefu were sown at Beijing on dry land in themiddle May,1992 and 1993.The plants weretreated with drought stress during seedling,booting,heading and flowering stages.It wasrainy season or intermittent irrigation duringother period.The RS and the chlorophyll con-tent of the third leave of seedlings and that offlag leave at heading—flowering period weremeasured with UV—190 model spectrometer.The results are shown in Fig 1 and Fig 2.There were little difference of RS in 800-200 mn and chlorophyll content between theleaves of paddy and upland rice during seedlingstage (Fig 1).However,remarkable differ-

Introduction of Brazil upland rice in China

In 1992,the government of Brazil presented nine crop varieties to China.One of them is Brazil up-land rice IAPAR9.It was evaluated for commercial usage in China by China National Rice Re-search Institute(CNRRI).From 1993 to 1997,IAPAR9 was planted in Jiangxi Province in large area successfully.The