Single Panicle Research Articles

Principal Component Analysis of Yield and Its Attributing Traits in Recombinant Inbred Lines of Rice Under Submerged Condition (Oryza sativa L.)

Rice, Oryza sativa L., is the world's most important staple crop, feeding more than half of the world's population. The phenotype of plant is the result of interaction of many factors and final yield is the sum of total effect of several component factors. Therefore evaluation of genetic variability forms the basis for any crop improvement programme, the success of which depends on sufficient genetic variability among genotypes so as to permit effective selection. Hence Evaluation of Principle Component Analysis (PCA)of recombinant inbred lines (RILs) was done at phenotypic level under submerged conditions to reduce a large series of data into smaller number of components by looking for groups that have very strong inter-correlation in a set of variables and each component explained per cent variation to the total variability. The RIL population was derived from an inter-specific cross between BPT5204 and HPR14 parents. A study was conducted using 1256 Recombinant Inbreed Lines submerged condition in the two seasons at College of Agriculture V.C. Farm, Mandya with nine agro-morphological traits and a principle component analysis was carried out. Out of nine principle components, four exhibited Eigenvalue more than one governing 77.74% variance and 69.86% variance in the summer and kharif seasons respectively. The highest positive Eigenvalue was observed for total number of tillers, productive tillers, non-productive tillers and fallowed by single plant yield in PC1 in the summer and kharif season respectively. The highest positive Eigenvalue was observed for five panicle weight, single panicle length, single plant yield and plant height in PC2 of summer and kharif season respectively. Indicating their pronounced effect on the overall variation in the Recombinant Inbreed Lines of Rice.

Effect of biochar on biochemical properties of saline soil and growth of rice

To amend physical properties of coastal saline soil for rice production, six biochar treatments (0, 0.5, 1, 2, 4 and 6 kg biochar per m2 soil) were set up as CK, T1, T2, T3, T4 and T5, respectively and their effect on the biochemical properties of coastal saline soil and rice growth characteristics were evaluated in a barrel planting experiment. The results showed that compared with CK (with no biochar added), the soil EC of T1 and T2-T5 was reduced by 11.5 %, but increased by 8.8–62.9 %, respectively. The available potassium and organic matter contents of T1-T5 increased ranging from 3.7-10.2 % to 8.0–46.8 %, respectively. With the increase of the biochar amount, the urease activity of soil in the 0–10 cm deep soil showed an increasing trend by 194.8–744.6 % with T1-T5, compared with that of the CK treatment. The activity of alkaline phosphatase in soil increased first and then decreased, and its increment with T1-T5 was between 28.2 and 64.8 % in comparison with that of CK. With more biochar added to soil, the leaf dry weight, root dry weight, total dry matter mass, total root length, single panicle quality and weight per 100 grains showed a trend of increase first and then decrease. The highest incremental values of all measurements were obtained with T1 by 21.8 %, 23.9 %, 13.8 %, 33.9 %, 30.8 % and 11.6 % respectively, compared with those with CK. However, adding biochar in soil demonstrated insignificant effect on the weight of single panicle, panicle length, stem thickness, tillers, setting rate, soil hydrolyzable nitrogen, available phosphorus content, rice protein, amylose, and taste quality among all treatments. In summary, the application of 0.5 kg m−2 biochar can improve the biochemical properties of saline soil and therefore increase rice yield.

Effect of mechanical tillage treatments intensity on weed infestation and yield of quinoa (Chenopodium quinoa Willd.)

The absence of registered herbicides for quinoa cultivation poses a significant challenge in achieving effective weed control through alternative methods. Field experiments, in two growing seasons (2021 and 2022) using different intensities of weed control treatments in quinoa were carried out at the Swojczyce Research and Teaching Station of the Wroclaw University of Environmental and Life Sciences. Three varieties of quinoa: Titicaca, Vikinga, and Zeno were sown at 50 cm inter-row spacing. Weeding treatments with a weeder were performed at BBCH (Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie) phases 13, 17, and 50, with the choice of 1, 2, or 3 treatments. In the variant with 3 weed control treatments, all weeds in the rows were removed at the end of June after the last treatment and evaluation of weed infestation. The varieties responded similarly to the weeding treatments, and the differences in the parameters determined resulted from morphological characteristics. Three inter-row weeding treatments reduced weed count by 70.5% and weed weight by 56.4%. As a result of the increased intensity of weeding treatments, the weed structure changed, and the proportion of common lambsquarters (Chenopodium album L.) increased while that of other dicotyledonous species decreased. Mechanical treatment also had a positive effect on the morphological features of quinoa plants and seed yield. Compared to the control, it increased by 35.8%. The study showed the strong competitiveness of common lambsquarters against quinoa. The biomass of a single quinoa plant and the weight of a single panicle were negatively correlated with the biomass of common lambsquarters. The practical application of inter-row weeding on soils with common lambsquarters in the seed bank may not have the expected economic effect.

Analyzing Nitrogen Effects on Rice Panicle Development by Panicle Detection and Time-Series Tracking.

Detailed observation of the phenotypic changes in rice panicle substantially helps us to understand the yield formation. In recent studies, phenotyping of rice panicles during the heading-flowering stage still lacks comprehensive analysis, especially of panicle development under different nitrogen treatments. In this work, we proposed a pipeline to automatically acquire the detailed panicle traits based on time-series images by using the YOLO v5, ResNet50, and DeepSORT models. Combined with field observation data, the proposed method was used to test whether it has an ability to identify subtle differences in panicle developments under different nitrogen treatments. The result shows that panicle counting throughout the heading-flowering stage achieved high accuracy (R2 = 0.96 and RMSE = 1.73), and heading date was estimated with an absolute error of 0.25 days. In addition, by identical panicle tracking based on the time-series images, we analyzed detailed flowering phenotypic changes of a single panicle, such as flowering duration and individual panicle flowering time. For rice population, with an increase in the nitrogen application: panicle number increased, heading date changed little, but the duration was slightly extended; cumulative flowering panicle number increased, rice flowering initiation date arrived earlier while the ending date was later; thus, the flowering duration became longer. For a single panicle, identical panicle tracking revealed that higher nitrogen application led to earlier flowering initiation date, significantly longer flowering days, and significantly longer total duration from vigorous flowering beginning to the end (total DBE). However, the vigorous flowering beginning time showed no significant differences and there was a slight decrease in daily DBE.

Growth Performances of BRRI dhan55 under Integrated Nutrient Management

Integrated nutrient management is vital for the development and growth of rice (Oryza sativa L.), but they are rarely used nowadays due to the widespread use of inorganic fertilizers. So, the current research was executed to determine the effect of organic amendments on different growth parameters of BRRI dhan55. A field investigation was managed at the Plant Pathology field lab, Sylhet Agricultural University, from November 2018 to April 2019. Different combinations of organic amendments (T1= Recommended Fertilizer Dose, RFD which includes TSP 100g 10 m-2, MoP 100g 10 m-2, Gypsum 50g 10 m-2, Zinc 15g 10 m-2, T2= RFD with vermicompost 2kg 10 m-2, T3= RFD with vermicompost 4 kg 10 m-2, T4= RFD with cowdung 2 kg 10 m-2, T5= RFD with cowdung 4 kg 10 m-2, and T6= RFD with Biochar 4 kg 10 m-2) were used in a RCBD (Randomized Complete Block Design) with three replications. The existing results showed that RFD with biochar treatments showed better performance in terms of the initial weight of grain (50.70 g), clean grain weight (48.55 g), and number of non-effective grains per panicle (27.67) and tiller per hill (12.07). T2 (RFD with vermicompost 2 kg 10 m-2) treatments demonstrated better results in parameters such as weight of grain from a single panicle (4.04 g), single panicle grain weight (3.90 g), panicle length (24.77 cm), and grain per panicle (153.00). Biomass (34.56 g) and above-ground length parameters (90.00 cm) performed better with the T4 treatment (RFD with 2 kg 10 m-2 of cowdung). T6 treatments were showed the highest grain yield (10.71 t ha-1) followed by T3 treatments. Therefore, the present results recommended that organic amendments could be a better supplement than inorganic amendments for the growth performance of BRRI dhan55.

Grain-Filling Characteristics in Extra-Large Panicle Type of Early-Maturing japonica/indica Hybrids

Early-maturing japonica/indica hybrids (EJIH) have recently been released, performing a yield potential of 13.5 t ha−1 and greater yield increase over conventional japonica rice (CJ) and hybrid indica rice (HI) in production. More spikelets per panicle and improved grain-filling efficiency underlined the basis for the superior yield performance of EJIH. However, few studies are available on the panicle traits and grain-filling characteristics of EJIH, as well as their differences to CJ and HI. In our study, two EJIH, two CJ, and two HI cultivars with similar growth patterns were grown in the same fields. EJIH had a 12.2–18.8% increased (p < 0.05) grain yield relative to CJ and HI, mainly attributed to their higher daily grain yield. Although it had a lower panicle per m2, EJIH exhibited 28.0–38.3% more (p < 0.05) spikelets per m2 from an increase of 58.0–87.8% (p < 0.05) in spikelets per panicle than CJ and HI. Compared with CJ and HI, EJIH had a higher single panicle weight and more grains in the six parts of the panicle, especially in the upper secondary branches (US) and middle secondary branches (MS). EJIH exhibited a higher leaf area index (LAI), leaf area duration (LAD), leaf photosynthetic rate, and SPAD values after heading, which helped increase shoot biomass weight at heading and maturity and post-heading biomass accumulation. For CJ and HI, the grain-filling dynamics of grains in the six parts were all well simulated by the Richards equation. For EJIH, the grain-filling dynamics of grains in the lower secondary branches (LS) were well fitted by the logistics equation, with the Richards equation simulating grain positioning on the other five parts. EJIH had a lower mean grain-filling rate (GRmean) and longer days and grain filling amounts (GFA) during early, middle, and late stages than CJ and HI. Our results suggest EJIH gave a yield advantage over CJ and HI through a higher daily grain yield. The panicle traits and grain-filling characteristics differed greatly among the three cultivar types. Compared with CJ and HI, EJIH had lower GRmean and higher days and more grains in the panicle during early, middle, and late stages, which contributed to an increased GFA after heading, improved filled-grain efficiency, and higher grain yield.

Improvements in Plant Morphology Facilitating Progressive Yield Increases of japonica Inbred Rice since the 1980s in East China

Grain yield was greatly increased during the genetic improvement of japonica inbred rice since the 1980s in Jiangsu, east China; thus, an improved plant morphology should be expected, considering that plant morphology is a decisive factor determining grain yield. Twelve representative japonica inbred rice released from 1983 to 2013 were grown in the same fields in 2019 and 2020. Grain yield increased (p < 0.01) at 63.3 kg ha−1 year−1 across 2 years among rice cultivars released in different periods. The genetic improvement in grain yield was associated with increased spikelets per panicle. Single panicle weight, number of primary and secondary branches, and number of grains on primary and secondary branches were all increased with a year of release. Generally, the width of top three leaves positively correlated (while angle of top three leaves and light extinction coefficient negatively) correlated (p < 0.01) with year of release. Leaf area per tiller and leaf area index at heading and maturity, specific leaf weight, leaf photosynthetic rate, and SPAD values after heading were all increased linearly with year of release. Plant height exhibited a positive (p < 0.01) trend with year of release, as well as stem weight per tiller and K and Si concentrations of stem. Spikelets per panicle, width of top three leaves, plant height, and leaf area index, and specific leaf weight after heading positively correlated (while angle of top three leaves and light extinction coefficient negatively) correlated (p < 0.01) with grain yield and single panicle weight. Our results suggested that modern japonica inbred rice exhibited expanded sink size by spikelets per panicle, higher leaf area through leaf width, optimized leaf photosynthetic capacity, lower leaf angle and light extinction coefficient, and enhanced stem strength. These improved plant morphologies facilitated yield increases of japonica inbred rice since the 1980s in east China.

Source-Sink Manipulation Affects Accumulation of Zinc and Other Nutrient Elements in Wheat Grains.

To better understand the source–sink flow and its relationships with zinc (Zn) and other nutrients in wheat (Triticum aestivum L.) plants for biofortification and improving grain nutritional quality, the effects of reducing the photoassimilate source (through the flag leaf removal and spike shading) or sink (through the removal of all spikelets from one side of the spike, i.e., 50% spikelets removal) in the field of the accumulation of Zn and other nutrients in grains of two wheat cultivars (Jimai 22 and Jimai 44) were investigated at two soil Zn application levels. The kernel number per spike (KNPS), single panicle weight (SPW), thousand kernel weight (TKW), total grain weight (TGW) sampled, concentrations and yields of various nutrient elements including Zn, iron (Fe), manganese (Mn), copper (Cu), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg), phytate phosphorus (phytate-P), phytic acid (PA) and phytohormones (ABA: abscisic acid, and the ethylene precursor ACC: 1-aminocylopropane-1-carboxylic acid), and carbon/N ratios were determined. Soil Zn application significantly increased the concentrations of grain Zn, N and K. Cultivars showing higher grain yields had lower grain protein and micronutrient nutritional quality. SPW, KNPS, TKW (with the exception of TKW in the removal of half of the spikelets), TGW, and nutrient yields in wheat grains were most severely reduced by half spikelet removal, secondly by spike shading, and slightly by flag leaf removal. Grain concentrations of Zn, N and Mg consistently showed negative correlations with SPW, KNPS and TGW, but positive correlations with TKW. There were general positive correlations among grain concentrations of Zn, Fe, Mn, Cu, N and Mg, and the bioavailability of Zn and Fe (estimated by molar ratios of PA/Zn, PA/Fe, PA × Ca/Zn, or PA × Ca/Fe). Although Zn and Fe concentrations were increased and Ca was decreased in treatments of half spikelet removal and spike shading, the treatments simultaneously increased PA and limited the increase in bioavailability of Zn and Fe. In general, different nutrient elements interact with each other and are affected to different degrees by source–sink manipulation. Elevated endogenous ABA levels and ABA/ACC ratios were associated with increased TKW and grain-filling of Zn, Mn, Ca and Mg, and inhibited K in wheat grains. However, the effects of ACC were diametrically opposite. These results provide a basis for wheat grain biofortification to alleviate human malnutrition.

Efficiency of humic preparations in sugar sorghum in the black earth steppe of the Saratov right bank

In the conditions of the right bank of the Saratov region, the responsiveness of sugar sorghum varieties (Kapital, Sahara, Seviliya, Volonter, Chaika) to the application of humic preparations (K-Humate-Na with trace elements, Reasil Forte Carb-N-Humic and Reasil Forte Seed Start) was studied at the experimental field of “Rosorgo”. The aim of the research was to determine the greatest stimulating effect of humic preparations on selection-valuable traits, including seed yield. Pre-sowing treatment of seeds and vegetative plants with K-Humate-N with trace elements (a dose of 1.0 l/t+1.0 l/ha) proved to be the most effective in cultivating Chaika, Kapital and Sahara varieties. Depending on the variety, this allowed an additional 0.94-1.22 t/ha of seeds to be collected. The influence of Reasil Forte Carb-N- Humics (dose 1.0 l/t+2.0 l/ha) on the yield of Seviliya and Volonter varieties was quite high. The use of the drug increased seed productivity by an average of 0.85-0.94 t/ha over two years of testing. Humic preparations had a stimulating effect on the sowing quality of seeds, the length of the panicle and the weight of seeds from a single panicle.

Symptoms and yield loss caused by rice stripe mosaic virus

BackgroundRice stripe mosaic virus (RSMV) is a tentative new Cytorhabdovirus species in family Rhabdoviridae transmitted by the leafhopper Recilia dorsalis. Although the virus was first detected in southern China in 2015, few studies have investigated rice symptoms and yield losses caused by RSMV infection.MethodsIn this study, we observed and systematically compared symptoms of three virally infected, representative varieties of indica, hybrid and japonica rice and determined the yield parameters of the artificially inoculated plants.ResultsThe three RSMV-infected cultivated rice varieties exhibited slight dwarfing, striped mosaicism, stiff, crinkled or even twisted leaves, an increased number of tillers, delayed heading, cluster-shaped shortening of panicles and mostly unfilled grains. Slight differences in symptom occurrence time were observed under different environmental conditions. For example, mosaic symptoms appeared earlier and crinkling symptoms appeared later, with both symptoms later receding in some infected plants. Yield losses due to RSMV also differed among varieties. The most serious yield reduction was experienced by indica rice (cv. Meixiangzhan), followed by hybrid indica rice (cv. Wuyou 1179) and then japonica (cv. Nipponbare). Single panicle weight, seed setting rate and 1000-kernel weight were reduced in the three infected varieties compared with healthy plants—by 85.42, 94.85 and 31.56% in Meixiangzhan; 52.43, 53.06 and 25.65% in Wuyou 1179 and 25.53, 49.32 and 23.86% in Nipponbare, respectively.ConclusionsOur findings contribute basic data for field investigations, formulation of prevention and control strategies and further study of the pathogenesis of RSMV.

Susceptibility of Rice to Oebalus pugnax (F.) (Hemiptera: Pentatomidae) Feeding at Different Levels of Grain Maturity and Impacts on Insecticide Termination.

The stages of rice, Oryza sativa L. (Poales: Poaceae), grain maturity that are most susceptible to rice stink bug, Oebalus pugnax (F.), damage have been identified; however, the stage at which they are no longer capable of causing appreciable damage during grain maturity is unclear. The objective of this study was to determine the susceptibility of rice to rice stink bug feeding at different levels of grain maturity and determine an insecticide termination timing. Rice stink bug damage was examined using five levels of grain maturity described as percent of kernels reaching mature straw coloration referred to as hard dough (20, 40, 60, 80, and 100%) across a range of infestation levels using single panicle sleeve cages and large cages. Hybrid and conventional cultivar rice panicles at 20, 40, and 60% hard dough were found to be susceptible to indirect yield loss, as two rice stink bugs per panicle resulted in over 7% peck. In large cage trials, 25 rice stink bugs caused 0.7-1% peck to hybrid and conventional rice plots at 20% hard dough. Much less damage was observed once rice reached 60% hard dough, where peck averages only reached 0.4%. Decreased damage at 60% hard dough was validated using uncaged trials where 0.4% additional peck was observed in unsprayed plots. These data indicate that rice in the early stages of hard dough is susceptible to large levels of indirect yield loss, but unless significant densities of rice stink bug are present at 60% hard dough, no more sampling or applications are necessary.

SEED YIELD AND ITS COMPONENTS IN THREE FESTUCA SPECIES

An experiment has been performed in four locations in Poland (Radzików, Leszno, Szelejewo and Nieznanice).Fifteen genotypes from three species (tall fescue - Festuca arundinacea, meadow fescue - F. pratensisand red rescue - F. rubra) were measured and observed during two consecutive years. Despite of phenologicalobservations (heading and flowering start dates), biometrical measurements (plant height, leaf dimension,number of generative stems etc.) and physiological trait (chlorophyll contents index) seed yield of singlepanicle, seed yield of plant and seed yield per plot (i.e. 50 plants) were determined.Significant effects of years, locations and genotypes were calculated for mentioned species for almost alltested traits. Multiple linear regression analysis was used to estimate major predictors of seed yield. It resultedin different numbers of predictors for different species. For meadow fescue five, for red fescue – three and fortall fescue – only two statistically significant predictors were selected. For all species leaf width and numberof generative stems were statistically significant and had positive weights. For meadow and red fescue – alsoseed yield from single inflorescence was significant with positive weight. Our results demonstrate that leafwidth together with number of steams and single panicle yield are the most important determinants of plantseed yield in three Festuca species.

Model analysis of genotypic difference in the variation of the duration from heading to flower opening based on the flower position on a panicle in high-yielding rice cultivars

There is a large variation in the number of days from heading to flower opening among flowers attached to a single panicle in rice (Oryza sativa L.). However, the details of order and timing of flower opening among flowers and the differences between genotypes in the variation have not been well described. In the present study, we developed a mathematical model to characterize the differences between genotypes in the relationship between the relative position of the flowers on a panicle and the number of days to their openings after heading, using three high-yielding rice cultivars, Tequing, Hokuriku 193, and Momiroman. Our model used the standardized panicle structure: each flower position was scaled based on the number of primary branches, the number of secondary branches on a primary branch, and the number of flowers on a branch. The parameters provided by the model described the variation of the number of days from heading to flower opening for each flower attached to different position on a panicle in each cultivar, so that the parameters could describe the genotypic difference in the variation. Generally, the model analyses showed that the primary branch had a greater effect on the number of days from heading to flower opening than the secondary branch within a primary branch and the position of the flowers within a secondary branch. In term of the genotypic difference among the examined cultivars, Momiroman took more 3–5 days to complete opening of all the flowers on a panicle after heading than the other cultivars. The model analyses showed that the longer duration in Momiroman was caused by the larger difference in days to flower opening among flowers on a single secondary branch and the two-days longer lag until the flowers started opening after heading. Our analyses also suggested that the genotypic difference in the number of branches did not affect the genotypic difference in duration from heading to flower opening among the cultivars examined here. We discussed the application of this model to understand genotypic differences in the relationship between the time required for flower opening and final grain weight.

Registration of ‘Titan’ Southern Medium‐Grain Rice

‘Titan’ (Reg. No. CV‐151, PI 680613), is an early‐maturing and short‐statured medium‐grain rice cultivar (Oryza sativa L.) developed at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC), near Stuttgart, AR. It was approved for release in February 2016 by the University of Arkansas System Division of Agriculture Experiment Station. Titan was derived from the three‐way cross (‘M‐206’//‘Bengal’/‘Lafitte’) F1/‘Jupiter’ made at the RREC in 2006 and initiated as a F4:5 bulk of a single panicle row STG09PR‐81‐087 in the Puerto Rico winter nursery in spring 2010. In 45 statewide and multistate yield trials conducted from 2012 to 2015, Titan had a 4% yield advantage (statistically insignificant) over the predominant commercial cultivar Jupiter; however, it matured about 6 d earlier than the latter. Titan possesses both Pi‐z and Pi‐ks blast resistance genes compared with Jupiter, which only has the Pi‐ks gene, and Titan has a better resistance to both leaf and neck blast, which are caused by the fungal pathogen Magnaporthe grisea (T.T. Hebert). Titan has a typical southern medium‐grain rice quality with an apparent amylose content of 15.0% and gelatinization temperature of 62.8°C, both very similar to that of Jupiter; however, Titan has a much larger kernel size than Jupiter. Titan is well adapted to the medium‐grain rice growing regions in the US Mid‐South. The release of the medium‐grain cultivar Titan will provide rice producers with an improved medium‐grain cultivar for rice production in Arkansas and the Mid‐South.

Molecular and Morphological Characterisation of Back Cross Generations for Yield and Blast Resistance in Rice

Blast caused by Pyricularia oryzae is one of the major constraints limiting rice production globally. Study was undertaken at TNAU, India using a set of selected genotypes including cultivated varieties and (Near Isogenic Lines) NILs and they were screened for blast resistance both genotypically and phenotypically. Genetic diversity was studied among the genotypes and those which are diverse in blast resistance but had similar morphological and quality traits were selected as parents for breeding programme. Selected genotypes were crossed and advanced to further generations up to BC4F1 by marker assisted back crossing. Genetic variability and heritability parameters were assessed among these segregating generations for yield and resistance traits and their trend in each generation was analysed. The disease resistance traits showed high variability in segregating generations as the parents were selected based on the diversity in disease reaction and therefore gives scope for improvement through selection. High heritability coupled with low genetic advance was found in all characters in the segregating generations except single plant yield and panicle length.

Genetic dissection of ozone tolerance in rice (Oryza sativa L.) by a genome-wide association study.

Tropospheric ozone causes various negative effects on plants and affects the yield and quality of agricultural crops. Here, we report a genome-wide association study (GWAS) in rice (Oryza sativa L.) to determine candidate loci associated with ozone tolerance. A diversity panel consisting of 328 accessions representing all subgroups of O. sativa was exposed to ozone stress at 60 nl l(-1) for 7h every day throughout the growth season, or to control conditions. Averaged over all genotypes, ozone significantly affected biomass-related traits (plant height -1.0%, shoot dry weight -15.9%, tiller number -8.3%, grain weight -9.3%, total panicle weight -19.7%, single panicle weight -5.5%) and biochemical/physiological traits (symptom formation, SPAD value -4.4%, foliar lignin content +3.4%). A wide range of genotypic variance in response to ozone stress were observed in all phenotypes. Association mapping based on more than 30 000 single-nucleotide polymorphism (SNP) markers yielded 16 significant markers throughout the genome by applying a significance threshold of P<0.0001. Furthermore, by determining linkage disequilibrium blocks associated with significant SNPs, we gained a total of 195 candidate genes for these traits. The following sequence analysis revealed a number of novel polymorphisms in two candidate genes for the formation of visible leaf symptoms, a RING and an EREBP gene, both of which are involved in cell death and stress defence reactions. This study demonstrated substantial natural variation of responses to ozone in rice and the possibility of using GWAS in elucidating the genetic factors underlying ozone tolerance.

Heterotic Classes and Utilization Patterns in Chinese Foxtail Millet [&amp;lt;i&amp;gt;Setaria italica&amp;lt;/i&amp;gt; (L.) P. Beauv

Utilization of heterosis to develop hybrid cultivars can significantly increase yield of most crops including foxtail millet. However, previous foxtail millet hybrid cultivars have been largely developed from crosses between sterile lines and conventional varieties or between sterile lines and varieties that are geographically distent from the sterile lines. The research on classification of heterotic classes and determinetaion of heterotic patterns has not been reported, which results in uncertainty in selection of parents for crosses and delays progress in utilization of high yielding hybrids in large-scale commercial production. In this study, a core collection of 128 accessions from China was grouped into six classes using combined analyses of population structure, pedigree, and clustering. The classification was conducted based mainly on molecular clustering of genotypic data, also considered the population structure and mathematical clustering using phenotypic data, and was finally validated through pedigree analysis. According to the transgressive and superstandard heterosis for grain yield, plant height, panicle length, panicle diameter, single panicle weight, grain weight per panicle, and 1000-grain weight collected from an incomplete-diallel-cross experiment, we identified six superior heterosis patterns (C2/C1, C2/C4, C2/C5, C2/C6, C1/C5 and C4/C5) and four inferior heterosis patterns (C1/C3, C1/C4, C1/C6 and C4/C6), and explored their potential applications in millet hybrid breeding. This study laid a foundation for effective use of foxtail millet heterosis in improving millet hybrid yield.

Study of Flowering Pattern in Setaria viridis, a Proposed Model Species for C4 Photosynthesis Research

Green foxtail millet (Setaria viridis) has NADP-ME type of C4 photosynthesis. Because of its short life cycle, small genome size of ~515 Mb, small plant stature, high number of seed set, simple growth requirements, and wide adaptability, this diploid (2n=18) weed is proposed to be a model species for the study of C4 photosynthesis. It is also a representative of bioenergy grasses and a model for genetic study of invasive weeds. Despite having all traits of a model species, it is difficult to cross-pollinate because its flowering behavior is not well studied. We used time lapse digital recording to study the flowering time and pattern along a single panicle. We found that flowering in Setaria was triggered by the darkness of the night and when the temperature was lower than 35°C. The anthesis of all the spikelets in a panicle took up-to three nights flowering from 9:30 pm to 10:00 am in the morning. Each spikelet has three phases of anthesis during which pollination occurs. A spikelet remains open for less than three hours. The pollination time for each spikelet is less than 60 minutes. Information from this study will facilitate the geneticists and plant breeders to plan for efficient crossing of Setaria.

Effects of gibberellic acid application after anthesis on the feeding value of double-purpose rice (Oryza sativa L.) straw at harvest

This study was to investigate the effects of gibberellic acid (GA) application after anthesis on the feeding value of double-purpose (grains as human food and straw as animal roughage) rice (Oryza sativa L.) straw at harvest. Three japonica rice cultivars Huaidao 6, Nanjing 43 and Nanjing 46 in 2009 and Huaidao 6, Nanjing 43 and Yangfujing 8 in 2010 were cultivated in Nanjing under the same management of Jiangsu area. They were sprayed GA with 45ghm−2 on the 15th d after anthesis in 2009 and on the 1st, 7th and 15th d after anthesis in 2010. At harvest, the feeding value related traits of rice straw, single panicle weight (PW) and 1000-grain weight were determined in 2 years. The fermentation quality related traits of fresh rice straw silage were determined in 2010. Nonstructural carbohydrates (NSC) and crude protein (CP) contents in rice straw were significantly increased by spraying GA, especially on the 15th d after anthesis, and the fermentation quality of rice straw silage was improved with the increase of NSC and CP contents. PW was also significantly increased by spraying GA after anthesis. The results indicated that spraying GA after anthesis could significantly improve the feeding value of straw and the panicle weight for double-purpose rice.

Outbreaks of Smut Caused by Tilletia maclaganii on Switchgrass in New York and Pennsylvania.

Switchgrass (Panicum virgatum L.) is a native perennial grass with potential as a biofuel crop. The smut fungus, Tilletia maclaganii (Berk.) Clint., is associated with significant biomass reduction in switchgrass in the Midwest (4), but has not been reported in the northeast United States in more than 60 years (New York in 1890 and Pennsylvania in 1946) (2,3). From 2007 to 2010, smutted panicles were observed on the majority of plants in stands of several switchgrass cultivars at the USDA-NRCS Plant Materials Center in Big Flats (Chemung County), NY; in production fields of several switchgrass cultivars near Meadville (Crawford County), PA; and in an ornamental bed of switchgrass in Ithaca (Tompkins County), NY. Smutted panicles emerged 3 to 4 weeks prior to healthy panicles, had a compact, club-shaped appearance, and enlarged florets with swollen ovaries that readily released a powdery mass of odorless, rusty orange-to-dark brown teliospores when pinched. The entire caryopsis of every floret within a panicle was smutted and the infected plants appeared stunted, indicative of systemic infection. The fungus from each location was identified as T. maclaganii based on host, habit, and teliospore morphology (3). Teliospores were pale yellowish brown to reddish brown, varied from globose to slightly irregular in shape, and averaged 21 μm (18 to 25 μm) in diameter. The exospore was thick (2 to 3 μm), finely verrucose, and no sheath was present. True sterile cells, pale yellow and 10 to 18 μm in diameter, were sparsely present. Teliospores germinated and formed large (40 to 60 × 3 to 6 μm), nonconjugating basidiospores within 20 h on 2% water agar (WA). Occasionally, we also found the floret-infecting species T. pulcherrima (1) on switchgrass at very low incidence in Big Flats, NY, but it was easily distinguished from T. maclaganii. Stratified seeds (3 g) of 'Shelter', washed and found to be free of teliospores, were dusted with 0.04 g of teliospores of T. maclaganii isolate Tm001NY09 (Cornell Plant Pathology Herbarium Accession CUP-67931) harvested from infected 'Shelter' in Big Flats, NY in 2009. Inoculated and noninoculated seeds were sown in seedling trays, transplanted, and evaluated at panicle emergence. There were no symptoms on plants from noninoculated seeds. Symptoms on inoculated plants were consistent with field observations and teliospores were reisolated from infected panicles and cultured on 2% WA. Teliospores harvested from a single panicle infected with Tm001NY09 were used for culturing and DNA extraction. The fully annotated sequence of the rDNA internal transcribed spacer and 5.8S regions of this isolate were deposited in GenBank (Accession No. JF745116). Smut outbreaks in New York and Pennsylvania suggest that T. maclaganii must be managed effectively if switchgrass production is to be sustainable in the Northeast.