Number Of Spikelets Research Articles

The wheat sucrose synthase gene TaSus1 is a determinant of grain number per spike

Some haplotypes of the sucrose synthase gene TaSus1 are associated with thousand-grain weight (TGW) in wheat (Triticum aestivum L.). However, no mutations have been identified within the gene to test this association. The effects of TaSus1 on grain number per spike (GNS) also are largely unknown. Our previous genome-wide association study identified TaSus-A1 as a candidate gene controlling fertile spikelet number per spike (FSN). In the present study, we generated two independent mutants for the three TaSus1 homoeologs by CRISPR/Cas9-mediated genome editing. The triple mutants displayed lower FSN, GNS, grain number per spikelet (GNST), and TGW than wild-type plants. In 306 hexaploid wheat accessions, two single-nucleotide polymorphisms in TaSus-A1 contributed differently to GNS. Introgression of the two alleles into a wheat genetic background confirmed their effects. The alleles differed in geographical distribution among the accessions.

Analysis of adaptability of oat varieties and lines by productivity elements in the conditions of Kirov region

The research was carried out in 2020-2022 in the central part of the Kirov region, under varying weather conditions. In the nursery of the competitive variety testing, 3 varieties and 8 lines of hulled oats were studied in order to analyze their adaptive ability according to the elements of the productivity structure. Varieties and lines were characterized based on the sum of the ranks of the evaluation results according to the methods of S. A. Eberhart, W. A. Rassel (1966), N. A. Plokhinsky (1961), L. A. Zhivotkov et al. (1994), A. A. Rosielle and J. Hamblin (1981). There was a direct statistically significant effect of the mass of 1000 grains, the mass of grain from the panicle, the number of grains in the panicle on the yield (r = 0.62…0.85). The formation of the elements of the productivity structure depended on the hydrothermal conditions of individual periods of vegetation (r = 0.63…0.72). The method of two-factor analysis of variance revealed that the influence of the "year" factor on the elements of the productivity structure was more significant (33.7...64.3 %) than the "grade" factor (8.5...24.6 %). There have been identified lines and varieties able to form consistently high yields in contrasting weather conditions due to certain structural elements or their combined influence. A high adaptive capacity with a minimum amount of ranks was obtained by the number of spikelets in the 41h18 line (Σranks = 17), varieties Kirovsky 2 (Σranks = 14); by the number of grains in the panicle and by the weight of grains from the panicle – line 41h18 (Σranks = 14 and 15); by the weight of 1000 grains – lines 25h18, 91h18, 41h18, 50h18, 162h15 (Σranks = 21…27), varieties Medved’ and Kirovsky 2 (Σranks = 18…22). According to the total lowest sum of ranks (71...97), the Kirovsky grade 2, promising lines 25h18 and 41h18 have been identified.

Genetic Component and Character Association for Yield and Yield Component Traits in Bread Wheat (Triticum aestivum L.)

The current research involves the implementation of half diallel crosses between ten genotypes of bread wheat in 2018-2019. The parents and their F1 generation, excluding reciprocals, were then cultivated in the 2019-2020 growing season at the agriculture research farm, School of Agricultural Sciences and Engineering, IFTM University, Lodhipur Rajput, Moradabad (U.P.) and R.B. (PG) College, Mudi, Agra, using a randomized complete block design with three replications. Knowledge of type of gene action controlling target traits and genetic behaviour is a basic principle for designing an appropriate breeding procedure for the purpose of genetic improvement. Hence, the success of any selection or hybridization breeding program for developing varieties depends on precise estimates of genetic variation components for traits of interest which may be additive, dominant and non-allelic interaction effects. Significant genotype means squares and its components (parents and crosses) were obtained for all traits in both locations. Genetic components analysis found that additive (D) and Dominance (H1) was significant in all the traits. The value of mean degree of dominance was greater than additive, indicating availability of over dominance for all the traits. The present investigation revealed that grain yield was positively correlated with days to maturity, plant height, number of effective tillers per plant spike length, number of spikelets per spike, days to 50% heading and yield (q ha-1). Hence, more importance should be given to these traits while exercising selection. Based on the correlation and path studies it was reported that days to ear head emergence, days to maturity, plant height, number of effective tillers per plant, number of spikelets per spike, number of grains per spike, grain yield per plant and 1000 grain weight could be used as important selection traits in order of merit to improve productivity during designing a suitable breeding programme in wheat.

Improving the Allocation of Light-Temperature Resources and Increasing Yield of Rice through Early Sowing and Increasing Nitrogen

This study explored the effects of the sowing stage and nitrogen application rate on the grain yield and its allocation of light-temperature resources over a 9-year experiment from 2011 to 2019. Measurement indicators include the effective accumulative temperature on different growth durations, leaf area index (LAI), above-ground biomass production, and harvest index (HI). Methods: A split-plot design was arranged in the treatment, with N supply as the main plot and the sowing stage as the subplot. The main plots consisted of two nitrogen treatments: low nitrogen (LN: 120 kg ha−1) and high nitrogen (HN: 180 kg ha−1). The subplots contained two sowing stages: the early sowing stage (ES) and the late sowing stage (LS). Results: Compared with LNLS, LNES, and HNLS from 2011 to 2019, HNES of HHZ increased the grain yield by 9.5%, 2.5%, and 5.3%, while the difference in grain yield in YY8 was higher than HHZ, especially under HNES. Compared with LNLS, LNES, and HNLS from 2011 to 2019, HNES of HHZ increased the panicle number by 6.0%, 5.9%, and 1.0%, and HNES of YY8 increased by 12.7%, 11.4%, and 3.8%. Compared with HNLS of HHZ, LNES, LNLS, and HNES decreased the spikelets per panicle by 2.3%, 2.9%, and 1.1%, and decreased by 3.5%, 1.9%, and 2.2% in YY8. The early sowing or increasing N supply significantly increased the dry matter accumulated, grain weight, LAI, and HI. The higher grain yield in LNES was more closely related to the average temperature and the number of spikelets per panicle. The grain yield in HNES was more dependent on the effective accumulative temperature. Conclusions: Sowing in mid-May and increasing the N application (180 kg ha−1) are beneficial to the allocation of light temperature and the increase in yield. Therefore, this research provides a theoretical basis for improving rice yield and optimizing the utilization of light-temperature resources in the future.

Genotypic variation of adaptive and yield component traits of introduced grain oats (Avena sativa L.) grown in Bangladesh

Oat (Avena sativa L.) is considered a nutritious cereal. Its demand has surged across the globe steadily for half a decade, including in Bangladesh. Because there is no local variety, the current supply in Bangladesh solely relies on imports. This study aimed to introduce grain oats from the United States of America (U.S.A.) to Bangladesh and determine the extent of their adaptability and yield in this new environment. One hundred oat accessions were introduced in collaboration between North South University, Bangladesh and the University of Florida, U.S.A. They were evaluated in field conditions from November 2019 to April 2020 in the Dinajpur district, Bangladesh in two replicated measurements of 13 morphological traits with RCBD design. The broad-sense heritability ranged from 11.7% to 90.0% for the measured traits. The yield-related trait, spikelet numbers, was positively correlated with height (0.30), dry weight (0.46), and harvest index (0.42) but negatively correlated with heading (-0.05), flowering date (-0.05), and tiller numbers (-0.16). Growth habit was negatively correlated with height (-0.07) and dry weight (-0.25). Principal components 1 and 2 explained 43.01% of the variability and were strongly influenced by heading and flowering date. Cluster analysis assigned the genotypes into six main clusters, and the analysis showed that spikelet numbers, growth habit, height, harvest index, and heading date were key yield-contributing and adaptive traits. Identifying traits highly correlated with oat yield could be useful for developing new varieties adapted to Bangladesh environments. This study is a pioneer; it paved the way to breed new high-yielding grain oat varieties for Bangladesh

Effect Seed Soaking of Moringa Leaf Extract on Grain Yield and its Component of Three Bread Wheat Cultivars

The experiment was carried out at Research Station of College of Agriculture Engineering University of Baghdad/AL-Jadiriya during 2022-2023 season to study the effect of seed soaking with Moringa leaf extract (MLE) on grain yield and its component of three bread wheat cultivars. A split-plots arrangement according to RCBD was used with three replications. The first factor was bread wheat cultivars (Rasheed, Buhooth 22, Buhooth 10) as a main plots, and the second factor was soaking of wheat seeds with three concentrations (1%, 3%, 5% in addition to 0% tap water as control) as sub-plots. The results showed that cultivar Rasheed gave highest means for number of spikes (388m-2), number of spikelets (23.49 spikelets spike-1), weight of 1000 grain (40.55 g), and grain yield (4.012 t h-1). In addition, the results showed that soak wheat seeds with 3% gave highest means for number of spikelets (23.08 spikelets spike-1), number of grains per spike (51.07 grains spikes-1), weight of 1000 grain (41.71g) and grain yield (4.255 t h-1). The interaction between cultivars and MLE concentrations it was significant in all studied traits except for the number of spikes.

Effectiveness of the use of biopreparations and fungicides in the cultivation of spring wheat in the forest-steppe of the Priobye

The data on the effectiveness of using chemical, fungal and bacterial fungicides to treat seeds and crops of spring soft wheat in order to limit harmfulness of major diseases are presented. The research was conducted in 2020–2022 on chernozem leached forest-steppe of the Novosibirsk region Priobye. Chemical seed protectant Scarlet and its mixture with Vitaplan were the most effective dressers in the fight against root rots. It has been demonstrated that although biopreparations are inferior in efficiency to chemical ones, they act for a longer period of time and protect the plant from the disease for a longer period of time. Seed dressing with chemical preparation reduced the development of leaf diseases by 53–58%, and with biopreparations – by 34–41%. Titul 390 was the most effective of the vegetation treatments – 60–98%. The efficiency of the biopreparations was 42–64% in the years of moderate disease development. In the years of strong development of septoriosis or powdery mildew, the efficiency of biopreparations did not exceed 22–30%. The biological preparations had a growth-stimulating effect on the plants: they increased the flag leaf area by 22–39%. The seed treatment showed an increasing trend in the number of spikelets, grains per ear and grain weight per ear. Application of the preparations during the vegetation period increased reliably the ear length by 16–28%, the number of spikelets – by 15–20, grains – by 24–31, grain weight per ear – by 33–51%. At seed dressing the greatest increase in the yield (0.15 t/ha) was provided by Scarlet, when using a mixture of biological and chemical preparations it amounted to 0.11 t/ha. When treated during the growing season, chemical fungicide increased the yield by 0.33 t/ha, while biopreparations increased the yield by 0.11–0.14 t/ha. Complex use of chemical preparations (Scarlet + Titul 390) provided the maximum yield increase – 0.62 t/ha, from the joint use of chemical and biological preparation the yield increased by 0.15–0.33 t/ha. The biological preparations increased this indicator by 0.13–0.23 t/ha. It has been concluded that it is possible to select combinations of chemical and biological preparations that can control phytosanitary situation and provide acceptable yield.

Unraveling the genetic basis of grain number-related traits in a wheat-Agropyron cristatum introgressed line through high-resolution linkage mapping

BackgroundGrain number per spike (GNS) is a pivotal determinant of grain yield in wheat. Pubing 3228 (PB3228), a wheat-Agropyron cristatum germplasm, exhibits a notably higher GNS.ResultsIn this study, we developed a recombinant inbred line (RIL) population derived from PB3228/Gao8901 (PG-RIL) and constructed a high-density genetic map comprising 101,136 loci, spanning 4357.3 cM using the Wheat 660 K SNP array. The genetic map demonstrated high collinearity with the wheat assembly IWGSC RefSeq v1.0. Traits related to grain number and spikelet number per spike were evaluated in seven environments for quantitative trait locus (QTL) analysis. Five environmentally stable QTLs were detected in at least three environments. Among these, two major QTLs, QGns-4A.2 and QGns-1A.1, associated with GNS, exhibited positive alleles contributed by PB3228. Further, the conditional QTL analysis revealed a predominant contribution of PB3228 to the GNS QTLs, with both grain number per spikelet (GNSL) and spikelet number per spike (SNS) contributing to the overall GNS trait. Four kompetitive allele-specific PCR (KASP) markers that linked to QGns-4A.2 and QGns-1A.1 were developed and found to be effective in verifying the QTL effect within a diversity panel. Compared to previous studies, QGns-4A.2 exhibited stability across different trials, while QGns-1A.1 represents a novel QTL. The results from unconditional and conditional QTL analyses are valuable for dissecting the genetic contribution of the component traits to GNS at the individual QTL level and for understanding the genetic basis of the superior grain number character in PB3228. The KASP markers can be utilized in marker-assisted selection for enhancing GNS.ConclusionsFive environmentally stable QTLs related to grain number and spikelet number per spike were identified. PB3228 contributed to the majority of the QTLs associated with GNS.

SpykProps: an imaging pipeline to quantify architecture in unilateral grass inflorescences

Abstract Background Inflorescence properties such length, spikelet number, and their spatial distribution across the rachis, are fundamental indicators of seed productivity in grasses and have been a target of selection throughout domestication and crop improvement. However, quantifying such complex morphology is laborious, time-consuming, and commonly limited to human-perceived traits. These limitations can be exacerbated by unfavorable trait correlations between inflorescence architecture and seed yield that can be unconsciously selected for. Computer vision offers an alternative to conventional phenotyping, enabling higher throughput and reducing subjectivity. These approaches provide valuable insights into the determinants of seed yield, and thus, aid breeding decisions. Results Here, we described SpykProps, an inexpensive Python-based imaging system to quantify morphological properties in unilateral inflorescences, that was developed and tested on images of perennial grass (Lolium perenne L.) spikes. SpykProps is able to rapidly and accurately identify spikes (RMSE < 1), estimate their length (R2 = 0.96), and number of spikelets (R2 = 0.61). It also quantifies color and shape from hundreds of interacting descriptors that are accurate predictors of architectural and agronomic traits such as seed yield potential (R2 = 0.94), rachis weight (R2 = 0.83), and seed shattering (R2 = 0.85). Conclusions SpykProps is an open-source platform to characterize inflorescence architecture in a wide range of grasses. This imaging tool generates conventional and latent traits that can be used to better characterize developmental and agronomic traits associated with inflorescence architecture, and has applications in fields that include breeding, physiology, evolution, and development biology.

Dissection and validation of a promising QTL controlling spikelet number on 5B in bread wheat.

Five environmentally stable QTLs for spikelet number per spike and days to heading were identified using a high-genetic map containing 95,444 SNPs, among which QSns.ucas-5B was validated using residual heterozygous line at multiple environments. Spikelet number per spike (SNS) and days to heading (DTH) play pivotal roles in the improvement of wheat yield. In this study, a high-density genetic map for a recombinant inbred lines (RILs) population derived from Zhengnong 17 (ZN17) and Yangbaimai (YBM) was constructed using 95,444 single-nucleotide polymorphism (SNP) markers from the Wheat660K SNP array. Our study identified a total of five environmentally stable QTLs for SNS and DTH, one of which was named QSns.ucas-5B, with a physical interval of approximately 545.4-552.1 Mb on the 5BL chromosome arm. Importantly, the elite haplotype within QSns.ucas-5B showed a consistent and positive effect on SNS, grain number and weight per spike, without extending the days to heading. These findings provide a foundation for future efforts to map and clone the gene(s) responsible for QSns.ucas-5B and further indicate the potential application of the developed and validated InDel marker of QSns.ucas-5B for molecular breeding purposes, aimed at improving wheat grain yield.

RICE RESILIENCE IN THE FACE OF CLIMATE CHALLENGES EXPLORING DROUGHT RESPONSE IN RICE GENOTYPES

Climate change is posing significant challenges to agriculture, threatening global food security. Among these challenges, drought stress is a formidable obstacle to rice production, a staple food for billions. Drought stress disrupts vital physiological processes, causing yield losses and impacting grain quality. Developing drought-tolerant rice varieties is essential to ensure food production and farmers' livelihoods. This study explores the drought tolerance potential of six Basmati rice genotypes: Basmati 198 (G1), Basmati 385 (G2), Rachna basmati (G3), Super Basmati (G4), Shaheen basmati (G5), and Basmat 2000 (G6). These genotypes have previously demonstrated submergence tolerance. By subjecting them to drought stress, we aim to assess their adaptability to multiple stressors, crucial in changing climates. A Randomized Complete Block Design was employed, ensuring methodological rigor. Seedlings were transplanted into the field, and drought stress was induced during the booting stage. We monitored various traits, including plant height, productive tillers, panicle length, spikelet numbers, fertility, branches, biological yield, grain yield, and harvest index. Statistical analyses revealed significant genotype-specific responses to drought. Results showed significant differences among genotypes under both control and drought conditions, underscoring genetic variability. Drought stress significantly impacted most traits. Basmat 2000 (G6) demonstrated superior performance under drought conditions. Clustering analysis revealed genetic diversity among genotypes, offering insights for breeding programs. Correlation analysis highlighted the importance of specific traits for grain yield. In conclusion, this study contributes to understanding genetic diversity among Basmati rice genotypes under drought stress. The findings emphasize the need for developing drought-tolerant rice varieties and offer valuable insights for sustainable rice cultivation in changing climates.

Development and characterization of a line with substitution of chromosome 4B of wheat Triticum aestivum L. on chromosome 4Hmar of wild barley Hordeum marinum ssp. gussoneanum (4x).

Introgressive hybridization is the main method of broadening the genetic diversity of bread wheat. Wild barley Hordeum marinum ssp. gussoneanum Hudson (2n = 4x = 28) has useful agronomical traits, such as high resistance to stress factors, that could be a potential source of new genes for bread wheat improvement. This study aimed to evaluate the possibility of introgression of H. marinum chromosomes into the genome of bread wheat using an incomplete amphiploid H. marinum ssp. gussoneanum (4x)-T. aestivum (Pyrotrix 28) (2n = 54) carrying the cytoplasm of wild barley. For this purpose, we crossed the line of bread wheat variety Pyrotrix 28 with an incomplete amphiploid, and then selected cytogenetically stable 42-chromosome plants with a high level of fertility in hybrid progeny. Genomic in situ hybridization (GISH) revealed a pair of H. marinum chromosomes in the genome of these plants. C- banding analysis confirmed that bread wheat chromosome 4B was replaced by wild barley chromosome 4Hmar. SSR markers Xgwm368 and Xgwm6 confirmed the absence of chromosome 4B, and EST markers BAWU808 and BAW112 identified chromosome 4Hmar in the genome of the isolated disomic wheat-barley substitution line. The study of this line showed that the substitution of chromosome 4B with chromosome 4Hmar resulted in a change of some morphological traits. It included intense anthocyanin coleoptile coloration, specific for H. marinum, as well as a lack of purple coloration of the ears in the leaf sheath, specific for Pyrotrix 28. Line 4Hmar(4B) showed increased performance for several traits, including plant height, number of spikes and tillers per plant, spikelet and grain number in the main spike, grain number per plant, but it had decreased values of 1000-grain weight compared to wheat. Cytogenetic stability and fertility of line 4Hmar(4B) indicated a high compensation ability of barley 4Hmar for wheat chromosome 4B and confirmed their homeology.

Wheat bZIPC1 interacts with FT2 and contributes to the regulation of spikelet number per spike

Key messageThe wheat transcription factor bZIPC1 interacts with FT2 and affects spikelet and grain number per spike. We identified a natural allele with positive effects on these two economically important traits.Loss-of-function mutations and natural variation in the gene FLOWERING LOCUS T2 (FT2) in wheat have previously been shown to affect spikelet number per spike (SNS). However, while other FT-like wheat proteins interact with bZIP-containing transcription factors from the A-group, FT2 does not interact with any of them. In this study, we used a yeast-two-hybrid screen with FT2 as bait and identified a grass-specific bZIP-containing transcription factor from the C-group, designated here as bZIPC1. Within the C-group, we identified four clades including wheat proteins that show Y2H interactions with different sets of FT-like and CEN-like encoded proteins. bZIPC1 and FT2 expression partially overlap in the developing spike, including the inflorescence meristem. Combined loss-of-function mutations in bZIPC-A1 and bZIPC-B1 (bzipc1) in tetraploid wheat resulted in a drastic reduction in SNS with a limited effect on heading date. Analysis of natural variation in the bZIPC-B1 (TraesCS5B02G444100) region revealed three major haplotypes (H1–H3), with the H1 haplotype showing significantly higher SNS, grain number per spike and grain weight per spike than both the H2 and H3 haplotypes. The favorable effect of the H1 haplotype was also supported by its increased frequency from the ancestral cultivated tetraploids to the modern tetraploid and hexaploid wheat varieties. We developed markers for the two non-synonymous SNPs that differentiate the bZIPC-B1b allele in the H1 haplotype from the ancestral bZIPC-B1a allele present in all other haplotypes. These diagnostic markers are useful tools to accelerate the deployment of the favorable bZIPC-B1b allele in pasta and bread wheat breeding programs.

Dosage response to reduced height‐1 (Rht‐1) loss‐of‐function mutations and characterization of slender phenotype in hexaploid wheat

AbstractThe reduced height (Rht‐1) genes in wheat (Triticum aestivum L.) are integral in controlling plant height. Previous studies in other plant species have demonstrated that loss‐of‐function mutations in their orthologous Rht‐1 genes results in plants with a slender phenotype illustrated by increased plant heights, sterility, and a constitutive gibberellic acid (GA3) response; however, this phenotype has not been described in wheat. In this study, nonsense alleles occurring in the GRAS domain of Rht‐A1, B1, and D1 were combined to create single, double, and triple Rht‐1 mutants. Homozygous lines possessing none, one, two, or three Rht‐1 stop mutations were grown in replicated field trials in three environments to assess agronomic traits. Germination tests to measure GA3 responsiveness and gene expression analysis via RNA‐seq were also performed. Rht‐1 triple mutants exhibited a slender phenotype characterized by rapid growth, elongated coleoptiles and internodes, elongated spikes, decreased tiller and spikelet number, and sterile heads. The presence of a single functional Rht‐1 gene resulted in a normal phenotype. Differences in plant height among the Rht‐1 double mutants, Rht‐1 single mutants, and Rht‐1 all wild‐type dosages trended toward increased plant height with increased Rht‐1 stop mutation dosage. Differences in Rht‐1 homeolog gene expression did not equate to differences in plant height between the different Rht‐1 stop mutations.

Identification of robust yield quantitative trait loci derived from cultivated emmer for durum wheat improvement.

Durum wheat (Triticum turgidum ssp. durum L.) is an important world food crop used to make pasta products. Compared to bread wheat (Triticum aestivum L.), fewer studies have been conducted to identify genetic loci governing yield-component traits in durum wheat. A potential source of diversity for durum is its immediate progenitor, cultivated emmer (T. turgidum ssp. dicoccum). We evaluated two biparental populations of recombinant inbred lines (RILs) derived from crosses between the durum lines Ben and Rusty and the cultivated emmer wheat accessions PI 41025 and PI 193883, referred to as the Ben×PI 41025 (BP025) and Rusty×PI 193883 (RP883) RIL populations, respectively. Both populations were evaluated under field conditions in three seasons with an aim to identify quantitative trait loci (QTLs) associated with yield components and seed morphology that were expressed in multiple environments. A total of 44 and 34 multi-environment QTLs were identified in the BP025 and RP883 populations, respectively. As expected, genetic loci known to govern domestication and development were associated with some of the QTLs, but novel QTLs derived from the cultivated emmer parents and associated with yield components including spikelet number, grain weight, and grain size were identified. These QTLs offer new target loci for durum wheat improvement, and toward that goal, we identified five RILs with increased grain weight and size compared to the durum parents. These materials along with the knowledge of stable QTLs and associated markers can help to expedite the development of superior durum varieties.

Phenotyping and predicting wheat spike characteristics using image analysis and machine learning

AbstractImprovements in trait phenotyping are needed to increase the quantity and quality of data available for genetic improvement of crops. In this study, we used moderate throughput image analysis and machine learning as a pipeline for phenotyping a key wheat spike characteristic: spikelet number per spike. A population of 594 soft red winter wheat inbred lines was evaluated in the field for 2 years and images of wheat spikes were taken and used to train deep‐learning algorithms to predict spikelet number. A total of 12,717 images were used to train, test, and validate a basic regression convolutional neural network (CNN), a visual geometry group application regression model, VGG16, the ResNet152V2 model, and the EfficientNetV2L model. The EfficientNetV2L model was the most accurate, having the lowest mean absolute error, second lowest root mean square error, and highest coefficient of determination (mean absolute error [MAE] = 0.60, root mean square error [RMSE] = 0.79, and R2 = 0.90). The ResNet152V2 model was slightly less accurate with a slightly better fit (MAE = 0.61,m RMSE = 0.78, and R2 = 0.87), followed by the basic CNN (MAE = 0.75, RMSE = 1.00, and R2 = 0.74) and finally by the VGG16 (MAE = 1.51, RMSE = 1.29, and R2 = 0.076). With an average error of just above one half of a spikelet, utilizing image analysis and machine learning counting methods could be used for multiple breeding applications, including direct selection of spikelet number, to provide data to identify quantitative trait loci, or for training whole genome selection models.

Effects of the core heading date genes Hd1, Ghd7, DTH8, and PRR37 on yield-related traits in rice.

We clarify the influence of the genotypes of the heading date genes Hd1, Ghd7, DTH8, and PRR37 and their combinations on yield-related traits and the functional differences between different haplotypes. Heading date is a key agronomic trait in rice (Oryza sativa L.) that determines yield and adaptability to different latitudes. Heading date 1 (Hd1), Grain number, plant height, and heading date 7 (Ghd7), Days to heading on chromosome 8 (DTH8), and PSEUDO-RESPONSE REGULATOR 37 (PRR37) are core rice genes controlling photoperiod sensitivity, and these genes have many haplotypes in rice cultivars. However, the effects of different haplotypes at these genes on yield-related traits in diverse rice materials remain poorly characterized. In this study, we knocked out Hd1, Ghd7, DTH8, or PRR37, alone or together, in indica and japonica varieties and systematically investigated the agronomic traits of each knockout line. Ghd7 and PRR37 increased the number of spikelets and improved yield, and this effect was enhanced with the Ghd7 DTH8 or Ghd7 PRR37 combination, but Hd1 negatively affected yield. We also identified a new weak functional Ghd7 allele containing a mutation that interferes with splicing. Furthermore, we determined that the promotion or inhibition of heading date by different PRR37 haplotypes is related to PRR37 expression levels, day length, and the genetic background. For rice breeding, a combination of functional alleles of Ghd7 and DTH8 or Ghd7 and PRR37 in the hd1 background can be used to increase yield. Our study clarifies the effects of heading date genes on yield-related traits and the functional differences among their different haplotypes, providing valuable information to identify and exploit elite haplotypes for heading date genes to breed high-yielding rice varieties.

Genetic Divergence Analysis for Yield and Quality Traits in Rice (Oryza sativa L.) Germplasm under Irrigated Conditions

The present investigation was carried out to conduct genetic divergence analysis for yield and quality traits in rice (Oryza sativa L.) germplasm under irrigated conditions. The experiment was conducted at crop research farm, Department of Genetics and Plant Breeding, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences. Prayagraj. The experiment was performed with 40 rice genotypes with 13 quantitative characters and 8 qualitative characters. Analysis of variance revealed that all the genotypes showing significant at 1% level of significance for all the characters. According to mean table Shiats dhan-7, Shiats dhan-2 show greater mean in grain yield per plant. Genetic parameters show PCV greater than GCV in all the characters, the traits Grain yield per plant and biological yield exhibits greater in both GCV and PCV. Heritability showing high range of estimates in all the characters as Days to maturity, Days to 50% flowering exhibit greater among all the characters. Number of spikelets per panicle, biological yield shows highest among the characters in Genetic advance. According to D2 analysis, the total genotypes are divided into five clusters, Cluster II showing greater in Intra cluster distance, Cluster V and Cluster I combination showing greater in Inter cluster distances. The Cluster IV showing highest among the clusters in the mean of Grain yield per plant. According to percentage contribution Grain yield per plant showing highest among the characters. Quality analysis had done on 35 genotypes, based upon quality characters Hulling percentage showing genotype Ajaya greater and genotype MTU-2032 shows greater in Kernel elongation ratio.

Character Association and Path Analysis for Yield and Yield Attributing Traits in Bread Wheat [Triticum aestivum (L.) em Thell] Genotypes

The current study was conducted in Rabi 2021- 2022 at Instructional Farm, Rajasthan College of Agriculture, MPUAT, Udaipur to estimate the association among yield components and their direct and indirect influence on grain yield of bread wheat. For the overall traits under investigation, significant genotypic differences were found indicating the presence of huge amount of variation among studied genotypes. At both the genotypic and phenotypic levels, there was positive and significant correlation between grain yield and days to 50% heading, plant height, length of main spike, number of spikelet’s per spike, number of grains per spike, grain weight per spike and biological yield per plant. Plant height had the greatest positive direct impact on grain production per plant followed by biological yield per plant, number of grains per spike, days to maturity and 1000-grain weight. It is, therefore, feasible to increase the grain yield per plant in bread wheat by taking into account certain traits viz., plant height, biological yield per plant, number of grains per spike.

Selection and Yield Formation Characteristics of Dry Direct Seeding Rice in Northeast China.

Dry direct seeding rice (DSR) is an emerging production system because of increasing labor and water scarcity in rice cultivation. The limited availability of rice cultivars suitable for dry direct seeding hampers the widespread adoption of this cultivation method in Northeast China. This study aimed to investigate grain production and plant characteristics associated with dry direct seeding rice. We conducted a field experiment on 79 japonica rice cultivars in Shenyang City, Liaoning Province, Northeast China, in 2020 and 2021. This study found that the grain yield of the tested rice cultivars ranged from 5.75-11.00 t ha-1, with a growth duration lasting between 144-161 days across the cultivars. These cultivars were then categorized into high yielding (HY), medium yielding (MY), and low yielding (LY) based on daily yield by using Ward's hierarchical clustering method. The higher grain yield for HY compared to MY and LY was attributed to more spikelets per unit area. The HY alleviated the conflict between higher panicle density and larger panicle size by improving the seedling emergence rate and productive stem rate. It also significantly increased shoot biomass at maturity. The HY reduced the period between seeding and beginning of heading (BBCH 51) and the proportion of dry matter partitioned to the leaf at the heading stage. However, it also increased the accumulation of dry matter in the grain and the proportion of dry matter partitioned to the grain at maturity. Furthermore, the HY markedly increased the harvest index and grain-leaf ratio, which are beneficial to coordinate the source-sink relationship. A quadratic function predicted that 98 days is the optimum growth duration before heading (BBCH 51) for achieving maximum yield. In conclusion, for dry direct seeding rice, it is appropriate to select high-yielding japonica inbred rice cultivars with shorter growth duration before heading (about 93-102 day), higher panicle number (about 450-500 × 104 ha-1), more spikelet number per panicle (about 110-130), higher seedling emergence rate (about 70-75%), higher productive stem rate (about 60-70%), and greater harvest index (about 50-55%).