Panicle Stage Research Articles

Eigen vector-based classification of pearl millet crop in presence of other similar structured (sorghum and maize) crops using fully polarimetric Radarsat-2 SAR data

The effect of structure and phenology of dryland crops on SAR scattering mechanisms is under explored and under reported. This study aims to understand the complex scattering mechanisms occurring in similar structured crops and to discriminate pearl-millet crop using single date Radarsat-2 SAR data. The study arrived at few significant findings that the panicle stage isthe critical stage for discriminating pearl-millet from similar structured sorghum and maize crops. Alpha angle extracted from eigen-vector based decomposition was identified as the discriminating factor. Average alpha value almost reached 55° due to dihedral scattering occurring in the prominent panicles which emerge early in pearl millet compared to maize and sorghum. Wishart H-A-α technique discriminated pearl millet, maize and sorghum crops with a producer's accuracy of about 87.8%, 71.6% and 71.4%, respectively. Paddy was classified with highest accuracy of 95.8% due to occurrence of dominant double bounce scattering in most of the fields.

UAV-based partially sampling system for rapid NDVI mapping in the evaluation of rice nitrogen use efficiency

Rapid acquisition and mapping of normalized difference vegetation index (NDVI) values is essential for a timely evaluation of nitrogen use efficiency (NUE) in sustainable agriculture. The zonal nutrient management techniques for sustainable agriculture require timely and efficient NDVI data collection and analysis capabilities, – a need that is still rarely addressed. However, as with the use of manned aircraft, the primary limitation of established unmanned aerial vehicle (UAV) imaging technologies is the limited time window for large-area data collection. Furthermore, as the spatial resolution increases, the post-processing time generally becomes longer. To overcome problems associated with the need for rapid data acquisition and post-processing, we have developed a UAV-based sensor system called the Accurate and Speed Scanner (AS-Scanner). The data acquisition accuracy and NDVI mapping speed of the system were assessed. According to the results of a ground-level experiment, the mean absolute error (MAE) between the reflectance data of the AS-Scanner and the corresponding data of the ASD FieldSpec 3 spectrometer is less than 1.11%. Furthermore, results of a plot-level experiment suggest that the NDVI values of a raw point cloud from AS-Scanner-based UAV platform (AS-NDVI) and UAV-mounted MicaSense RedEdge camera (REG-NDVI) are highly correlated (0.54 < R2 < 0.57, p < 0.01). In a map-level experiment, the interpolated, 15 m × 15 m pixel size AS-NDVI values were in good agreement with the REG-NDVIs over a 4.01 ha (40100 m2) rice field (0.55 < R2 < 0.65, p < 0.01). The average processing times of the inverse distance weighted (IDW, 0.45 s), kriging linear (KL, 0.73 s), and nearest neighbor (NN, 1.05 s) interpolations of the AS-Scanner data prove that it is possible to efficiently create NDVI maps using data from the sensor. Besides, the effect of the varying solar irradiance values on the AS-NDVIs was analyzed under varied illumination conditions. Moreover, the AS-NDVIs were also used to assess the NUE in a paddy rice field at the panicle stage. The results show that nutrients can be effectively assessed using AS-Scanner data. Despite some disadvantages such as the potential of NDVI value saturation over dense canopies, the AS-Scanner provides a method for quickly obtaining reasonable spatial resolution crop information for agricultural nutrient monitoring and management. This also offers the potential to reduce environmental pressure which may be caused by untimely estimation of NUE.

Study of anther dehiscence, pollen viability and stigma receptivity in rice (Oryza sativa L.)

A present study was carried on floral biology of rice that cover anther dehiscence, pollen viability and stigma receptivity was carried out with the aim to improve the efficiency of hybridisation in rice breeding work at the Experimental farm of Regional Agriculture Research Station, Karjat (Raigad) during kharif 2016. In this study, three CMS lines viz., IR58025A, RTN 12A and RTN17A and four testers i.e., Chedo Local, CR-2829-PLN-36, NPQ-49 and RP-5898-19-8-6-1-1-1 of rice were used. The results reported that the time required for dehiscence of anther ranged from 8 - 20 minutes in testers of rice. The results showed that time of anthesis in both the CMS lines and testers of rice since 08.00 AM. In the pollen viability study, results suggested that pollens are more viable from single minute to 11 minutes after anther dehisced at fully blooming stage. The range of pollen viability percentage was observed from 90.79% to 94.92%. However, there are variations among the genotypes for the optimum viability of pollen at maximum blooming stage. In both CMS lines and testers of rice, maximum blooming stage of panicles was recorded 9.00 am to 1.00 pm while 8.00-11.00 days took for fully completion of anthesis. In CMS lines of rice, receptivity of stigma ranged from 36 to 42 hrs (two to three days). There was no difference in stigma receptivity stages among the three CMS lines of rice. Thus, the precise knowledge of floral biology, which includes structural and functional aspects of rice inflorescence, is essential for breeders to plan and execute breeding strategies.

Heterosis analysis and underlying molecular regulatory mechanism in a wide-compatible neo-tetraploid rice line with long panicles

BackgroundNeo-tetraploid rice, which is a new germplasm developed from autotetraploid rice, has a powerful biological and yield potential and could be used for commercial utilization. The length of panicle, as a part of rice panicle architecture, contributes greatly to high yield. However, little information about long panicle associated with heterosis or hybrid vigor is available in neo-tetraploid rice.ResultsIn the present study, we developed a neo-tetraploid rice line, Huaduo 8 (H8), with long panicles and harboring wide-compatibility genes for pollen and embryo sac fertility. All the hybrids generated by H8 produced significant high-parent yield heterosis and displayed long panicles similar to H8. RNA-seq analysis detected a total of 4013, 7050, 6787 and 6195 differentially expressed genes uniquely belonging to F1 and specifically (DEGFu-sp) associated with leaf, sheath, main panicle axis and spikelet in the two hybrids, respectively. Of these DEGFu-sp, 279 and 89 genes were involved in kinase and synthase, and 714 cloned genes, such as GW8, OsGA20ox1, Ghd8, GW6a, and LP1, were identified and validated by qRT-PCR. A total of 2925 known QTLs intervals, with an average of 1~100 genes per interval, were detected in both hybrids. Of these, 109 yield-related QTLs were associated with seven important traits in rice. Moreover, 1393 non-additive DEGs, including 766 up-regulated and 627 down-regulated, were detected in both hybrids. Importantly, eight up-regulated genes associated with panicle were detected in young panicles of the two hybrids compared to their parents by qRT-PCR. Re-sequencing analysis depicted that LP (a gene controlling long panicle) sequence of H8 was different from many other neo-tetraploid rice and most of the diploid and autotetraploid lines. The qRT-PCR results showed that LP was up-regulated in the hybrid compared to its parents at very young stage of panicle development.ConclusionsThese results suggested that H8 could overcome the intersubspecific autotetraploid hybrid rice sterility caused by embryo sac and pollen sterility loci. Notably, long panicles of H8 showed dominance phenomenon and played an important role in yield heterosis, which is a complex molecular mechanism. The neo-tetraploid rice is a useful germplasm to attain high yield of polyploid rice.

Deep Learning for Mango (Mangifera indica) Panicle Stage Classification

Automated assessment of the number of panicles by developmental stage can provide information on the time spread of flowering and thus inform farm management. A pixel-based segmentation method for the estimation of flowering level from tree images was confounded by the developmental stage. Therefore, the use of a single and a two-stage deep learning framework (YOLO and R2CNN) was considered, using either upright or rotated bounding boxes. For a validation image set and for a total panicle count, the models MangoYOLO(-upright), MangoYOLO-rotated, YOLOv3-rotated, R2CNN(-rotated) and R2CNN-upright achieved weighted F1 scores of 76.5, 76.1, 74.9, 74.0 and 82.0, respectively. For a test set of the images of another cultivar and using a different camera, the R2 for machine vision to human count of panicles per tree was 0.86, 0.80, 0.83, 0.81 and 0.76 for the same models, respectively. Thus, there was no consistent benefit from the use of rotated over the use of upright bounding boxes. The YOLOv3-rotated model was superior in terms of total panicle count, and the R2CNN-upright model was more accurate for panicle stage classification. To demonstrate practical application, panicle counts were made weekly for an orchard of 994 trees, with a peak detection routine applied to document multiple flowering events.

Determination of the most susceptible phenological stage of rice panicles to infection by species of Fusarium graminearum

ABSTRACT Occurrence of rice seeds infected by Fusarium graminearum has shown the importance of identifying the most favorable phenological stage of panicles to grain infection. The experiments were conducted in two crop seasons under greenhouse conditions, using the rice hybrid INOV CL. The phenological stages during inoculation were complete booting, full heading and flowering. All plots were inoculated using two isolates of Fusarium graminearium species complex 15A (F. graminearium - 15-ADON) and FmNiv (F. meridionale - Nivalenol). Disease severity was estimated at weekly intervals and was used to calculate the area under the disease progress curve (AUDPC), while panicles were collected to determine the percentage of spotted grains and Fusarium incidence. Percentage of spotted grains and incidence of F. graminearum and F. meridionale were greater when inoculation was made during flowering stage, significantly differing from heading and booting stages. Rice flowering stage is more susceptible to infection by F. graminearum and F. meridionale, inducing higher disease severity and incidence of spotted grains, as well as presence of fungi in the grains. Flowering was the most susceptible stage in the two crop seasons for both isolates, and the complete booting stage presented the lowest values of AUDPC.

Rapid diagnosis of nitrogen status in rice based on Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS)

BackgroundAn effective and expeditious approach to assess plant nitrogen status is urgently needed in rice production and management as the conventional chemical methods are laborious and time-consuming.ResultsFourier transform infrared photoacoustic spectroscopy (FTIR-PAS) was used to record the spectra of rice leaves for the effective diagnosis of nitrogen nutrition status. The band in the wavenumber range of 1680 to 1630 cm−1 was associated with amide I and that from 1570 to 1510 cm−1 with amide II. We attempted to use this information to characterize the nitrogen status in rice plants at different growth stages. The ratio of photoacoustic intensity of amide II to amide I was measured and applied as nitrogen status index, and considering the yields, the ratio showed a positive linear correlation (R2 = 0.9) with the total nitrogen of rice leaves. The ratio at the tillering and full panicle stages were more suitable for diagnosis, a ratio of 0.4–0.55 indicated an adequate nitrogen status, ratios lower than 0.4 indicated a poor nitrogen status; whereas ratios greater than 0.55 indicated excessive nitrogen supply.ConclusionOur study provides an effective and rapid strategy for nitrogen-supply assessment in rice based on FTIR-PAS, which can guide rational fertilization in rice production.

Application of Controlled-Release Urea Enhances Grain Yield and Nitrogen Use Efficiency in Irrigated Rice in the Yangtze River Basin, China

The use of controlled-release urea (CRU) has been recommended over that of conventional urea to improve rice grain yield and nitrogen use efficiency. However, the underlying agronomical and physiological mechanisms need to be better understood. In this study, field trials over four site-years, and a big container experiment were carried out to explore CRU effects on rice yield and NUE, with the main aims to identify the key yield components contributing to the superior rice yield with CRU use, and to evaluate differences in dry matter, nitrogen (N) accumulation, translocation and yield formation with different N fertilizer practices. Four N treatments were investigated: control with 0 kg N ha−1 (CK), farmers' fertilizer practice (FFP) with 150 kg N ha−1 as urea basal application, modified fertilizer practice (MFP) with 150 kg N ha−1 as split urea application (40% at transplanting, 30% at tillering and 30% at the panicle stages), and CRU treatment with 150 kg N ha−1 as CRU basal application. Results showed that the CRU increased rice yields by 10.8 and 5.6% over FFP and MFP, respectively. The N recovery efficiency and N agronomic efficiency for CRU were significantly higher than that obtained from MFP and FFP treatments. The analysis of yield components revealed that the higher grain yields using CRU were accounted for mainly by increased panicle and spikelet numbers per m2, which resulted from higher N uptake. In addition, results from the container experiment with comparable experimental design to field trials illustrated that both post-anthesis dry matter production and translocation were critical for high grain yields using CRU, while the former seemed more important. Relative to MFP and FFP, CRU maintained higher flag leaf SPAD and photosynthetic rate, as well as higher root oxidation activity (ROA) and N uptake during grain filling. Furthermore, CRU increased the activities of key enzymes involved in N assimilation in flag leaves, including GS, GOGAT, and NR. CRU effects on such underground and aboveground processes were proposed to contribute to high rice yield.

Effects of enhanced UV-B radiation on the content of flavonoids in mesophyll cells of wheat

The content of flavonoids in mesophyll cells of wheat was studied under the condition of enhanced UV-B radiation intensity. In this experiment, four groups of six days of control were treated with He-Ne laser group (L), enhanced UV-B radiation group (B), He-Ne laser and UV-B combined treatment group (B + L ), Normal light group (CK). Since the flavonoids carry some unsubstituted hydroxyl or glycosyl groups, it is a polar compound. By the 'similar compatibility' principle, they have some level of solubility in polar solvents, such as methanol, ethanol, n-butanol, propanol, and water. In this experiment, 70% ethanol was used to extract flavonoids. Finally, the total content of flavonoids in mesophyll cells was determined by visible spectrophotometry. The OD value of flavonoids was determined by rutin reagent 'The standard curves because rutin is a representative of flavonoids, it scavenging the role of free radicals significantly. The results showed that when the UV-B UV radiation intensity was enhanced, the content of flavonoids in wheat mesophyll cells increased, that is, the content of flavonoids in wheat leaves was higher than that in UV-B Strength was positively correlated. The results showed that the content of flavonoids in the mesophyll cells of the four control groups was the same as that of the B group&gt; BL group&gt; CK group&gt; L group. With the prolonging of the treatment time of wheat, the content of flavonoids in wheat leaves at jointing-booting stage was significantly higher than that in seedling stage and panicle stage. This means that flavonoids are a protective substance that absorbs UV-B in plants, that is, the absorption of UV-B by flavonoids reduces the damage of UV-B to organs in plants [8] [10]; UV-B The smaller the damage, the less the content of flavonoids; laser damage caused by UV-B have a certain role in the repair. In this study, we further studied the effect of enhanced UV-B radiation on the content of flavonoids in mesophyll cells of wheat. The effects of UV-B radiation on the content of flavonoids in wheat were studied. Whether it has a very important significance for wheat has become a stress [5].

Nitrogen losses, use efficiency, and productivity of early rice under controlled-release urea

Ammonia (NH3) volatilization and nitrogen (N) surface runoff from rice (Oryza sativa L.) paddies contribute to air and water pollution in China and everywhere else. The purposes of this study were to assess N losses through NH3 volatilization and surface runoff and to determine the grain yield and N use efficiency (NUE) of early rice in double rice cropping system in southern China. We implemented six treatments viz., control with 0kgNha−1 (CK), basal application and split application (1/2 at transplanting, 1/4 at tillering, and 1/4 at panicle stages) of urea (U), and basal applications of three controlled-release urea (CRU) sources (polyurethane-coated urea [CRU-1], degradable polymer-coated urea [CRU-2], and water-based polymer-coated urea [CRU-3]) all applied at 165kgNha−1. Results showed that CRU-1 and CRU-2 significantly reduced NH3 volatilization (23 to 62%) and N surface runoff losses (8 to 58%) compared with U. Precipitation and ammonium-nitrogen (NH4-N) concentration in surface water from rice paddy were predominant factors defining N losses through NH3 volatilization and surface runoff. Application of CRU reduced NH4-N concentration and pH of surface water and N losses through surface runoff. The CRU produced similar (−3 to 4%) or higher (5–16%) rice grain yields and increased NUE (3 to 34%) and N uptake (3–55%) compared with U. Polymer-coated urea can reduce environmental risks of N losses through volatilization and surface runoff while maintaining rice yield and N uptake, it also enhances NUE compared with urea in double rice cropping system in southern China.

Reducing nitrogen losses through ammonia volatilization and surface runoff to improve apparent nitrogen recovery of double cropping of late rice using controlled release urea.

Controlled release fertilizer can reduce nitrogen losses to the environment while increasing grain yield and improving apparent nitrogen recovery (ANR) of rice. However, few studies have evaluated the comparative efficacy of different polymer-coated urea products on nitrogen (N) losses, ANR, and N uptake of rice. A 2-year field experiment was conducted to compare the effects of three different types of polymer-coated urea fertilizer on nitrogen losses through NH3 volatilization and surface runoff to the environment, ANR, grain yield, and N uptake as compared to conventional urea of rice. Six treatments including (1) control with 0kg N ha-1 (CK), (2) basal application of urea (Ub), (3) split application (Us) of urea (50% at transplanting, 25% at tillering, and 25% at panicle stages), (4) CRU-1 (polyurethane-coated urea), (5) CRU-2 (degradable polymer-coated urea), and (6) CRU-3 (water-based polymer-coated urea) all applied at 165kg N ha-1. It was found that CRU-2 resulted in the highest grain yield and panicle numbers among the N fertilization treatments in 2013 and 2014. Applying CRU could help increase N uptake in rice, reduce N losses through NH3 volatilization and surface runoff, and hence improve ANR. Its single dose can meet the nutrient demand of the rice plant. Controlled release urea could be adopted as an effective mitigation alternative to retard N losses through NH3 volatilization and surface runoff while improving ANR of double cropping of late rice.

Response of 2A Clone grape to GA3 sprays for berry thinning as influenced by cane regulation on two training systems under tropical conditions

With an aim to minimize manual thinning in 2A Clone of ‘Thompson Seedless’ grapevine trained on bower and extended Y trellis and grafted on “Dogridge” rootstock, investigations were carried out in growers’ vineyards around Nashik, Maharashtra during 2013–14. Gibberellic acid (GA3) was sprayed at 10 ppm thrice or 15 ppm twice. Since the response to GA3 for berry thinning is stage specific, attempts were made to induce uniform bud break by retaining the canes of uniform diameter, consequently achieve uniformity in the stage of panicles that is ideal for GA3 sprays. Efficacy of GA3 sprays in reducing the cluster compactness on different training systems (bower or extended Y trellis) and with cane regulation was assessed. Less cane diameter but more uniform bud break was observed on extended Y trellis and cane regulated vines. Uniformity in the stage of panicle was not influenced by either the training system or cane regulation. Clusters were less compact in spite of the larger berries on Y trellis with two sprays of GA3 @ 15 ppm. Although this combination was highly effective in reducing the cluster compactness, clusters in all the treatments were in the range of loose to wellfilled. Cane regulation coupled with two sprays of GA3 @ 15 ppm or retention of all canes coupled with three sprays @ 10 ppm resulted in more yield. These interactions were more pronounced on bower. Total soluble solids content and berry specific gravity were more on extended Y trellis while the titratable acids content was less on this trellis in cane-regulated vines. Taking cluster compactness, yield and quality into consideration, two sprays of GA3 at 15 ppm on extended Y trellis but three sprays @ 10 ppm on bower, with or without cane regulation were found best.

Overexpression of Peptide-Encoding OsCEP6.1 Results in Pleiotropic Effects on Growth in Rice (O. sativa).

Plant peptide hormones play an important role in regulating plant developmental programs via cell-to-cell communication in a non-cell autonomous manner. To characterize the biological relevance of C-TERMINALLY ENCODED PEPTIDE (CEP) genes in rice, we performed a genome-wide search against public databases using a bioinformatics approach and identified six additional CEP members. Expression analysis revealed a spatial-temporal pattern of OsCEP6.1 gene in different tissues and at different developmental stages of panicle. Interestingly, the expression level of the OsCEP6.1 was also significantly up-regulated by exogenous cytokinin. Application of a chemically synthesized 15-amino acid OsCEP6.1 peptide showed that OsCEP6.1 had a negative role in regulating root and seedling growth, which was further confirmed by transgenic lines. Furthermore, the constitutive expression of OsCEP6.1 was sufficient to lead to panicle architecture and grain size variations. Scanning electron microscopy analysis revealed that the phenotypic variation of OsCEP6.1 overexpression lines resulted from decreased cell size but not reduced cell number. Moreover, starch accumulation was not significantly affected. Taken together, these data suggest that the OsCEP6.1 peptide might be involved in regulating the development of panicles and grains in rice.

Boron Nutrition Under Intermittent Flooding and Drying Condition Seems Sustainable Nutrient Management Technique in Rice

Abstract Water saving rice cultivation is emerging technique to couple with irrigation water shortage due to climate change all over the world. Major issue in these techniques is to compromise yield and quality fatalities because of higher unfilled grain due to nutrients deficiency. Boron fertilization seems to be big management technique to improve rice agriculture due to having imperative role in pollen viability. Thus, a field experiment was conducted to see the impact of boron fertilization both with basal and foliar application methods in water saving rice cultivation systems. Boron, with basal (3 kg borax/acre) and foliar (2% boron) was applied at different growth stages in rice crop grown under various rice cultivation systems; flooded rice, intermittent flooding and drying and aerobic rice. Boron fertilization both with basal and foliar application technique resulted in improved crop performance in all cultivation systems. Rice plants recorded highest yield, yield attributing parameters like productive tillers, panicle length and grain weight with boron fertilization. Quality parameters like sterile kernels, abortive kernels, opaque kernels were significantly reduced with boron fertilization in all rice cultivation systems. Furthermore, normal kernels were enhanced with basal and foliar application of boron nutrition. Likewise, maximum water use efficiency was recorded in foliar application of boron at panicle stage under intermittent flooding and drying condition. Foliar application of boron nutrition at panicle initiation stage was found to be most appropriate in water saving rice cultivation systems.

Yields and Yield Components of Maize (Zea Mays L.) and Soybean (Glycine Max) as Affected by Different Tillage Methods

Abstract At the experiment station of the Krizevci College of Agriculture, yield and yield components of maize (Zea mays L.) and soybean (Glycine max) grown in rotation under five different methods of tillage were investigated. The aim of this study was to determine the effect of different tillage methods on yield and yield components of maize and soybean. The results and the determined number of plants per hectare of maize and soybean show that more favorable conditions for germination are in variants where ploughing performed in the autumn (variants C, D and E). During a four-year study, the minimum number of plants per hectare of maize and soybean was found in variant A. The dry season in panicle stage of maize in 2006 has lowered yields compared to 2008, and the drought in 2007 during the seed-filling period reduced the yield and the 1000 kernel weight of soybean compared with 2009 in all variants of tillage methods. The highest grain yield of maize was recorded in variant B. During 2006, with the unfavorable weather conditions, the lowest grain yield of maize was recorded in variant E with intensive tillage treatment. The highest yield of soybean was recorded in variant E, but there were no statistically significant differences compared to variants with the reduction of additional tillage interventions (variant B, C and D). With respect to maize grain and soybean seed yield, variant A was the lowest. Considering the achieved yields of maize grain, there is a possibility of reducing additional tillage interventions, whilst for achieving higher yield of soybean seed intensive tillage is recommended.

Enhanced expression of OsSPL14 gene and its association with yield components in rice (Oryza sativa) under low nitrogen conditions

Nitrogen use efficiency (NUE) in rice crop is the need of the hour for reduction of nitrous oxide emission resulting from excess nitrogen (N) fertilizer application and also in reduction of cost of cultivation. Ten rice genotypes were grown under low and recommended dose of N application and characterized in terms of parameters related to yield, yield related components and NUE indicators. Wide genetic variability under low N conditions was observed with significant variation for 15 yield related parameters in interactions of genotypes and treatment. Limitation of N has led to the decrease of all yield and yield related parameters, but for grain filling % and 1000 grain weight. Two genotypes, Rasi and Varadhan have shown minimum differences between low and recommended N conditions. Correlation analysis of various yield components showed the importance of the secondary branches for the total grains under low N. Expression analysis of OsSPL14 (LOC_Os08g39890) gene reported to be associated with increased panicle branching and higher grain yield through real time PCR in leaf and three stages of panicle has shown differential temporal expression and its association with yield and yield related components across the genotypes. The expression of OsSPL14 at panicle stage 3, has shown correlation (P<0.05) with N% in grain. Since OsSPL14 is a functional transcription activator, its association of expression in leaf and three panicle stages with yield components as observed in the present study suggests the role of nitrogen metabolism related genes in plant growth and development and its conversion into yield components in rice.

Effect of nitrogen management during the panicle stage in rice on the nitrogen utilization of rice and succeeding wheat crops

Background and aimsThe main objectives of this paper were to investigate the absorption and utilization of nitrogen applied at the panicle stage in rice for promoting and protecting spikelet and the effect of residual nitrogen on the utilization of nitrogen in the succeeding wheat crop in the rotation system. MethodsA field experiment was combined with a mini-plot experiment with 15N labelled urea applied at the panicle stage in rice. The experiments included three nutrient management treatments: F, S1 and S2. 126kgNha−1, 120kgN ha−1, 72kgNha−1 labeled with 30 atom% excess 15N were applied in rice, respectively. Results(1) Compare to conventional fertilizer management (F), the optimized fertilizer management (S1&S2) reduced the amount of nitrogen applications, whereas the rice and wheat yield did not decrease, and nitrogen use efficiency was improved. (2) At rice harvest, 4.7–10.7% of the fertilizer 15N was found in the 0–20cm profile. The fertilizer 15N absorbed by the wheat during the period from jointing to heading accounted for 37.0%-51.1% of the total 15N absorbed. (3) The sum of the ratio of nitrogen absorption from the rice panicle fertilizer applied to the crops (rice and wheat) and ratio of soil residue nitrogen in the wheat field were ordered S2>S1>F. ConclusionThe optimized fertilization management reduced the loss of the rice nitrogen in the rice–wheat rotation system through improved recycling of rice panicle nitrogen applied in the crop-soil system.

Ecology and Diversity of Cyanobacteria in &amp;lt;i&amp;gt;Kuttanadu&amp;lt;/i&amp;gt; Paddy Wetlands, Kerala, India

Algae are one of the major groups of soil microflora in agricultural lands. Among algae, the bluegreens are considered to be very valuable in agriculture. The role of them in soil fertility enhancement has been extensively studied worldwide. Sustainable utilization of an organism for any human purpose depends on how successfully the ecology of the same is thoroughly understood. Kuttanadu is a unique tropical paddy-wetland. Ecology of blue-green-algae and the exact diversity of the same in the zone remained unexplored. This is the first report of the blue-green-algal community of Kuttanadu in relation to different soil-regions, seasons, and crop-growth-stages. A rich blue-green-algal diversity of 64 species, with Oscillatoriales as the dominants (38%), is observed in these paddy-fields. The highest values for all the ecological parameters analyzed were found in the Lower Kuttanadu soil region, during Virippu season, at panicle stage of the crop whereas the lowest values for most of the parameters were observed in Upper Kuttanadu soils during puncha season at the seedling and panicle stages. The species richness and diversity index showed positive correlation to crop seasons. Apart from the specific soil and climatic factors, the total number of blue green algal isolates showed positive correlation to total nitrogen and phosphorus in the soils.

Relationship between Initiation Stage of Panicle and Leaf Number in Sweet Sorghum

Relationship between Initiation Stage of Panicle and Leaf Number in Sweet Sorghum

Transcriptomic analysis of floral initiation in litchi (Litchi chinensis Sonn.) based on de novo RNA sequencing.

Comparative transcriptome analysis of litchi ( Litchi chinensis Sonn.) buds at two developmental stages revealed multiple processes involving various phytohormones regulating floral initiation, and expression of numerous flowering-related genes. Floral initiation is a critical and complicated plant developmental process involving interactions of numerous endogenous and environmental factors, but little is known about the complex network regulating floral initiation in litchi (Litchi chinensis Sonn.). Illumina second-generation sequencing is an efficient method for obtaining massive transcriptional information resulting from phase changes in plant development. In this study, comparative transcriptomic analysis was performed with resting and emerging panicle stage buds, to gain further understanding of the molecular mechanisms involved in floral initiation in litchi. Abundance analysis identified 5,928 unigenes exhibiting at least twofold differences in expression between the two bud stages. Of these, 4,622 unigenes were up-regulated and 1,306 were down-regulated in panicle-emerging buds compared with resting buds. KEGG pathway enrichment analysis revealed that unigenes exhibiting differential expression were involved in the metabolism and signal transduction of various phytohormones. The expression levels of unigenes annotated as auxin, cytokinin, jasmonic acid, and salicylic acid biosynthesis were up-regulated, whereas those unigenes annotated as abscisic acid biosynthesis were down-regulated during floral initiation. In addition, 188 unigenes exhibiting sequence similarities to known flowering-related genes from other plants were differentially expressed during floral initiation. Thirteen genes were selected for confirmation of expression levels using quantitative-PCR. Our results provide abundant sequence resources for studying mechanisms underlying floral initiation in litchi and establish a platform for further studies of litchi and other evergreen fruit trees.