Early Vigour Research Articles

Branching response to stem density and its impact on yield in hybrid potato grown from true seeds and seedling tubers

ContextHybrid potato crops can be grown from true potato seeds or from seedling tubers. True-seed-grown plants produce lower marketable tuber yield than seedling-tuber-grown plants, because of their low early vigour and distinct growth and development patterns, notably in term of main stem number and stem branching. These differences are pivotal for yield formation but their impacts on crop performance and yield are not well understood. ObjectivesWe quantified the differences between the propagule types (true seeds vs seedling tubers) in their branching responses to stem density and assessed to what extent these differences contribute to differences in crop development and tuber production. MethodsTwo field experiments were conducted in different years, planting transplants from true seeds and pre-sprouted seedling tubers from the same genotype, while controlling their stem density per unit area. Responses in stem branching and biomass partitioning to stem density were quantified on individual main stems, followed by an evaluation of the impact of these responses on crop performance. ResultsOn individual main stems in both propagule types, higher stem density decreased branch development, decreased the number of branches above- and belowground, resulted in shifts in aboveground branch distribution towards lower branching orders, and led to smaller tuber sizes. However, such branching responses were stronger in true-seed-grown plants than in seedling-tuber-grown plants. At crop level, differences between propagule types were significant in canopy duration, number of tubers, tuber size distribution and marketable yield, but there was no stem density effect. ConclusionOur results emphasized the differences between propagule types in branching and its impact on crop development and tuber yield, due to the absence of stem density effects. Propagule type effects could be attributed to intrinsic differences between propagule types in branching control, growth habit and source-sink relations. These effects are relevant for hybrid potato breeding and require further research. Management practices were partly responsible for year-to-year differences in branching and yield formation, which highlights their significance for hybrid potato production.

Mapping and quantifying unique branching structures in lentil (Lens culinaris Medik.)

BackgroundLentil (Lens culinaris Medik.) is a globally-significant agricultural crop used to feed millions of people. Lentils have been cultivated in the Australian states of Victoria and South Australia for several decades, but efforts are now being made to expand their cultivation into Western Australia and New South Wales. Plant architecture plays a pivotal role in adaptation, leading to improved and stable yields especially in new expansion regions. Image-based high-throughput phenomics technologies provide opportunities for an improved understanding of plant development, architecture, and trait genetics. This paper describes a novel method for mapping and quantifying individual branch structures on immature glasshouse-grown lentil plants grown using a LemnaTec Scanalyser 3D high-throughput phenomics platform, which collected side-view RGB images at regular intervals under controlled photographic conditions throughout the experiment. A queue and distance-based algorithm that analysed morphological skeletons generated from images of lentil plants was developed in Python. This code was incorporated into an image analysis pipeline using open-source software (PlantCV) to measure the number, angle, and length of individual branches on lentil plants.ResultsBranching structures could be accurately identified and quantified in immature plants, which is sufficient for calculating early vigour traits, however the accuracy declined as the plants matured. Absolute accuracy for branch counts was 77.9% for plants at 22 days after sowing (DAS), 57.9% at 29 DAS and 51.9% at 36 DAS. Allowing for an error of ± 1 branch, the associated accuracies for the same time periods were 97.6%, 90.8% and 79.2% respectively. Occlusion in more mature plants made the mapping of branches less accurate, but the information collected could still be useful for trait estimation. For branch length calculations, the amount of variance explained by linear mixed-effects models was 82% for geodesic length and 87% for Euclidean branch lengths. Within these models, both the mean geodesic and Euclidean distance measurements of branches were found to be significantly affected by genotype, DAS and their interaction. Two informative metrices were derived from the calculations of branch angle; ‘splay’ is a measure of how far a branch angle deviates from being fully upright whilst ‘angle-difference’ is the difference between the smallest and largest recorded branch angle on each plant. The amount of variance explained by linear mixed-effects models was 38% for splay and 50% for angle difference. These lower R2 values are likely due to the inherent difficulties in measuring these parameters, nevertheless both splay and angle difference were found to be significantly affected by cultivar, DAS and their interaction. When 276 diverse lentil genotypes with varying degrees of salt tolerance were grown in a glasshouse-based experiment where a portion were subjected to a salt treatment, the branching algorithm was able to distinguish between salt-treated and untreated lentil lines based on differences in branch counts. Likewise, the mean geodesic and Euclidean distance measurements of branches were both found to be significantly affected by cultivar, DAS and salt treatment. The amount of variance explained by the linear mixed-effects models was 57.8% for geodesic branch length and 46.5% for Euclidean branch length.ConclusionThe methodology enabled the accurate quantification of the number, angle, and length of individual branches on glasshouse-grown lentil plants. This methodology could be applied to other dicotyledonous species.

A phenotypic integration approach to breeding seedlings for early vigor and drought resistant traits

Silphium is being domesticated as a new perennial biomass and oilseed crop. As a consequence of selection to improve yield, seedling´s growth and survival are expected to be affected indirectly. The phenotypic integration theory predicts that selection acts on the correlation structure among root and leaf traits. In order to assess the possibility of breeding simultaneously for early vigor and drought tolerance in Silphium integrifolium, two goals were proposed: 1) to assess trait coordination within and between plant modules in improved and wild accessions, and 2) to evaluate the effectiveness of leaf traits as selection criteria to develop vigorous and drought tolerant seedlings. Improved accessions were selected using three criteria: 1) seed yield (SEED); 2) leaf traits related to fast growth (FAST) or 3) slow growth (SLOW). FAST and SEED accessions accumulated biomass faster and had higher leaf area-root length ratio, than SLOW and wild. FAST´s traits were related to early aboveground vigor such as thinner leaves and higher specific leaf area, but roots were more superficial and their volume smaller, which is linked to low vigor and soil exploration. This has consequences for early outperformance of weeds and soil evaporation reduction, but may also imply tradeoffs, diminishing resistance to drought. We conclude that leaf traits cannot be used to select for vigorous and drought resistant seedlings, because the lack of coordination between leaves and roots. Nonetheless, phenotypic integration suggests that leaf traits can be used to select Silphium varieties for different target environments.

Introgression of early shoot vigour in wheat modifies root systems, increases competitiveness and provides options for integrated weed management

Abstract Background and aims Weeds are a major biotic stressor impacting crop production. Improving the competitiveness of wheat (Triticum aestivum L.) could provide a useful tool in integrated weed management. While wheat typically exhibits conservative early growth, early vigour has been increased through long-term recurrent selection for greater early biomass and leaf area. However, the influence of integrating such vigour into breeding lines for improving competitive ability remains to be explored. Methods In replicated controlled environment experiments, the effect of breeding early shoot vigour on root development and below-ground competitiveness was carefully examined. Physical and chemical characteristics of wheat vigour lines were assessed and compared with commercial cultivars in hydroponics and field soil experiments. Measurements included early root growth, rhizosheath size and growth responses in the presence of annual ryegrass, a major weed in wheat production. Results The vigorous lines exhibited larger leaf widths, increased cell file number, increased total root length and larger rhizosheaths compared with commercial parents. Numerous secondary metabolites with known allelopathic effects on weeds were detected in the roots and the rhizosphere, and significant allelochemical level differences observed between distilled water and soil water extract-treated plants. Although the vigour lines were significantly more competitive than the commercial cultivars against ryegrass, they produced similar levels of phytotoxic secondary metabolites. Conclusion Competition below-ground was strongly suppressive of ryegrass for the more vigorous genotypes suggesting that breeding with shoot vigour had pleiotropic effects on key root traits for below-ground wheat competitiveness.

Genome-Wide Association Study of Early Vigour-Related Traits for a Rice (Oryza sativa L.) japonica Diversity Set Grown in Aerobic Conditions.

Aerobic rice production is a relatively new system in which rice is direct-seeded and grown in non-flooded but well-watered conditions to improve water productivity. Early vigour-related traits are likely to be important in aerobic conditions. This study aimed to identify quantitative trait loci (QTL) and candidate genes associated with early vigour-related traits in aerobic conditions using a japonica rice diversity set. Field experiments and glasshouse experiments conducted under aerobic conditions revealed significant genotypic variation in early vigour-related traits. Genome-wide association analysis identified 32 QTL associated with early vigour-related traits. Notably, two QTL, qAEV1.5 and qAEV8, associated with both early vigour score and mesocotyl length, explained up to 22.1% of the phenotypic variance. In total, 23 candidate genes related to plant growth development and abiotic stress response were identified in the two regions. This study provides novel insights into the genetic basis of early vigour under aerobic conditions. Validation of identified QTL and candidate genes in different genetic backgrounds is crucial for future studies. Moreover, testing the effect of QTL on yield under different environments would be valuable. After validation, these QTL and genes can be considered for developing markers in marker-assisted selection for aerobic rice production.

Durum wheat (Triticum turgidum L. var. durum) root system response to drought and salt stresses and genetic characterization for root-related traits.

Abiotic stresses such as drought and salt are significant threats to crop productivity. The root system adaptation and tolerance to abiotic stresses are regulated by many biochemical reactions, which create a complex and multigenic response. The present study aims to evaluate the diversity of root responses to cyclic abiotic stress in three modern durum wheat varieties and one hydric stress-tolerant landrace in a pot experiment from seedling to more advanced plant development stages. The genotypes responded to abiotic stress during the whole experiment very differently, and at the end of the experiment, nine out of the 13 traits for the landrace J. Khetifa were significantly higher than other genotypes. Moreover, single sequence repeat (SSR) genetic analysis revealed high polymorphism among the genotypes screened and interesting private alleles associated with root system architecture traits. We propose that the markers used in this study could be a resource as material for durum wheat breeding programs based on marker-assisted selection to increase the vegetal material with high drought and salt stress tolerance and to identify candidates with strong early vigor and efficient root systems. This study provides appropriate genetic materials for marker-assisted breeding programs as well as a basic study for the genetic diversity of root traits of durum wheat crops.

Early vigour: A key to drought tolerance in cassava based on physiological and biochemical traits including inherent non-enzymatic antioxidant activity

An experiment was conducted with drought-tolerant and susceptible genotypes to find out the key traits that determine drought tolerance in cassava. The drought-tolerant clone 8S501 and the two susceptible clones H-97 and CR43-11 were planted in the field in a Randomized Block Design and the drought stress was imposed when the plants were three months old. The observations were measured at the beginning of the stress period (0-stress), 30 and 75 days of stress. The repeated measures ANOVA stated that there were significant differences among the genotypes, stress duration and their interaction for the majority of the traits. Growth, development and tuber yield of cassava was not significantly affected up to 30 days of drought stress. There was a greater decline in LA, TBM, CGR, RGR and NAR between 30 and 75 days of drought stress suggesting that measures are to be taken if drought stress prolongs for more than 30 days to realize optimum growth and yield of cassava. There was no increment in TY and PSR after 30 days of stress. A greater reduction was observed from 30 to 75 days of stress in leaf TC and CP content. There was a considerable increase in proline and total phenols content in the leaf from 30 to 75 days of stress. The inherent free radical scavenging activity measured as DPPH, FRAP and ABTS assays also demonstrated a notable increase in antioxidant activity at 75 days of drought stress. The early vigour in terms of initial high leafiness, leaf area, tuber yield, proportion of storage roots and total biomass in the first three months after planting facilitated the clone 8S501 to effectively tolerate the drought stress conditions.

Steps toward developing legume cover crop varieties: Study of biomass and nitrogen partitioning and within‐plant δ115N variation of faba bean at different growth stages

AbstractModern legumes are engineered to enhance nutrient allocation to grains and maximize harvest index (HI) and yield. Breeding legumes for cover crop requires optimizing source‐sink relationship to prolong nutrient allocation to vegetative organs, support post‐flowering nodule activity, and extend biological nitrogen fixation (BNF). We studied the variation of faba bean (Vicia faba) germplasm for biomass (DM) and nitrogen (N) allocation to plant organs at the lower and upper parts of the canopy. Three genotypes were established during the 2019 and 2020 growing seasons, and DM, N, and δ15N of upper and lower leaves, stems, pods, seeds, and pod shells were quantified at vegetative, first‐pod, and full‐pod stages. Of the three genotypes, PI 678631 displayed early vigor, allocated more DM and N in vegetative organs, and accumulated more total DM and N than Windsor and PI 655333 by first‐pod stage. The advantage of PI 678631 over the other two genotypes seemed to be associated with smaller allocation of DM and N in pods at early reproductive phase. These findings support existing variations within faba bean germplasm that can be used to improve its ecosystem service as cover crop. Within‐plant variation of δ15N was minimal, suggesting that under favorable soil N and moisture where N remobilization is low, vegetative organs can serve as proxies to estimate the entire plant %Ndfa (proportion of plant N derived from the atmosphere) prior to plant maturity. The δ15N of plant organs at vegetative and early‐pod stages were similar and consistent with the only whole plant δ15N measurement in 2020.

Phenotypic variability for early drought stress resistance in tetraploid wheat accessions correlates with terminal drought performance

AbstractDurum wheat (Triticum durum Desf.) is a fundamental staple food for the countries of the Mediterranean basin. Climate change is predicted to cause a trend of increasing drought severity in this region in the near future, necessitating the improvement of durum wheat's resilience to drought stress. Using polyethylene glycol to simulate water scarcity, early vigour parameters in germinating seeds are quickly, easily and affordably assessed. Many screenings, however, only consider the seedling stage; consequently, genotypes identified as promising for cultivation in drought scenarios, may not show such features if drought appears in later phenological phases, as happens in Mediterranean climatic areas, generally prone to terminal drought. The correlation between drought stress resistance during the seedling stage (early vigour) and later stages in the life cycle is elusive due to the lack of scientific efforts. Here we used polyethylene glycol screening to classify fifty‐five tetraploid wheat accessions into three clusters (susceptible, medium resistant and highly resistant to drought), based on morpho‐physiological traits. These accessions included durum wheat cultivars and landraces, as well as ancestors like durum emmer wheat and wild emmer wheat. The results of the screenings were combined with subsequent pot experiments using nine randomly selected accessions, imposing terminal drought, and evaluating their performance. Principal component analysis was performed on data for net photosynthesis, stomatal conductance, transpiration and grain yield. Notably, the genotypes that performed best in the pot experiments were also those that performed well in the screening. Highly resistant candidates had in fact higher physiological and performance parameters than susceptible candidates. In summary, polyethylene glycol screening of germinating seeds resulted to be suitable to predictively evaluate drought resistance in tetraploid wheat accessions under terminal drought conditions, typical of Mediterranean climate zones. The reported data, thus evidence of how this inexpensive and simple method might be efficiently applied for large‐scale phenotyping.

The impact of PEG-induced drought stress on early vigour traits of bread wheat

ABSTRACT A total of 11 genotypes from the collection of 101 bread wheat genotypes, with desirable traits in terms of increased tolerance to drought, were chosen for parents and eight crosses were performed. Number of seminal roots (NSR), total root length (TRL), root dry mass (RDM), number of shoots per plant (NS), main shoot length (MSL), shoot dry mass (SDM), number of leaves per plant (NL), leaf area per plant (LA), leaf dry mass (LDM), aboveground dry mass (ADM), SDM/LDM, RDM/ADM were analysed at the boot stage (Z45). The F1 progeny had on average higher mean values (P < 0.001) than parents for four traits: RDM, NS, LA and RDM/ADM. The highest broad sense heritability values were determined for RDM (97.6%) and NSR (93.9%). Factor analysis indicated that a large root system, higher RDM and TRL are associated with higher NS, NL, LA and LDM. For Euclid x CHI-4 and WWBMC2 x Ingenio combinations the highest heterosis values were observed for TRL (34.1%) and SDM (23.7%), for RDM (28.6%) and LA (26.8%), respectively. PEG-induced drought stress in the seedling stage, in most of the new germplasm, caused an increased redistribution of dry matter in the root compared to the stem.

The role of zinc fertilization and its interaction with nitrogen and phosphorus starter fertilization on early maize development and grain yield

The early planting of maize in temperate growing areas leads to yield and quality benefits, although a low soil temperature can affect the early nutrient uptake and delay plant development. Not only can the nitrogen (N) and phosphorus (P) uptake be limited, but that of zinc (Zn) can also be affected. Moreover, the application of N and P at early growth stages can result in an enhancement of maize growth. Two field experiment were carried out in North Italy during the 2012–14 period to: i) evaluate the most effective Zn application strategy by comparing seed, soil and foliar applications with an untreated control; ii) investigate the role of a Zn seed treatment on the early development and yield of maize grown in three different types of soils. The effect of Zn application was compared, in both experiments, to starter NP fertilization in bands at planting, according to a full factorial design. Zn fertilization significantly enhanced the early vigor and yield of the maize, although the effects were less pronounced than those of the NP fertilizer. Among the Zn fertilization strategies, maize growth was quicker for the seed and soil applications than for the foliar application or the untreated control. The former application significantly increased the plant height at stem elongation (+32%), shortened the planting-flowering period by 1 day, and increased the grain yield by 4%. Overall, the application of NP starter fertilizer shortened the planting-flowering period by 4.5 days and increased the yield by 10%, compared to the unfertilized control. In the second experiment, higher plant vigor indices were detected in all the soils for the NP starter fertilization (+22–27%) and for the Zn seed treatment (+3–9%) than in the controls. The NP starter fertilization reduced the grain moisture at harvest by 2.3% and increased grain yield by 14%, while the Zn treatment significantly increased the kernel weight but did not affect the grain yield or the moisture content. The interaction between the NP fertilization and the Zn treatment was never significant. Thus, the positive effect of Zn on the early vigor was an additional benefit to that produced by the starter NP fertilization. The study demonstrated that a Zn application at planting, with both a seed dressing and a soil treatment, significantly enhanced the early growth of different maize hybrids, in different growing seasons and soils, although the use of a NP starter fertilization led to more consistent agronomic benefits. Furthermore, the combination of NP and Zn starter fertilization resulted in a further advantage for all the considered production situations.

Characterization of Buffelgrass (Cenchrus ciliaris L.) Germplasm Using DUS Descriptors

The present study was carried on thirty seven Cenchrus genotypes during rabi, 2022-23. Tweleve traits were recorded as per the descriptors provided by PPV &amp; FRA and several genotypes possessed unique traits that aids in genotype identification. The traits viz.,Growth habit ,Anothcyanin coloration on nodes, Node colour, Leaf blade altitude, Leaf blade pubescence, Awns distribution, Awns colour, Leaf colour, and Early vigour showed significant variation among genotypes. Quantitative Characters viz., Plant height, Leaf length (cm), Leaf width (cm), Inter-nodal length (cm), Nodes on tiller, Panicle length (cm), Tillers/Plant, Green fodder yield were recorded. The traits, Plant height, No. of tillers plant and green fodder yield recorded significant critical difference between the genotypes. Hence utmost care would be given for these characters while in the selection process of Cenchrus ciliaris crop improvement.

Effect of Fertilisation Regime on Maise Yields

Using natural fertilisers in agriculture improves quantity and quality yields. They introduce macronutrients (nitrogen, phosphorus, and potassium) and micronutrients into the soil. Enriching the soil with organic substances through fertilisation with digestates requires the farmer to have considerable knowledge and accuracy in dosing due to the need to comply with permissible concentrations of macronutrients. The availability of nutrients in a digestate is closely dependent on the substrates used in the biogas plant, and it cannot be stated unequivocally that better yields of field crops will be achieved by using it as manure. Therefore, the authors conducted a two-year study of the effect of the fertilisation method on maise yields. Based on the research carried out, the fertiliser suitability of the digest was confirmed. Plants fertilised with it were characterised by the highest (compared to other fertilisation methods) grain yield (of 12.07 Mg per hectare on average). In addition, they were characterised by adequate plant height (3.15 m on average). The observations also indicate good emergence and satisfactory early vigour.

Agronomic strategies to enhance the early vigor and yield of maize part II: the role of seed applied biostimulant, hybrid, and starter fertilization on crop performance.

Maize cropping systems need to be re-designed, within a sustainable intensification context, by focusing on the application of high-use efficiency crop practices, such as those that are able to enhance an early plant vigor in the first critical growth stages; such practices could lead to significant agronomic and yield benefits. The aim of this study has been to evaluate the effects of the cultivation of hybrids with superior early vigor, of the distribution of starter fertilizers at sowing, and of the seed application of biostimulants on promoting plant growth and grain yield in full factorial experiments carried out in both a growth chamber and in open fields. The greatest benefits, in terms of plant growth enhancement (plant height, biomass, leaf area) and cold stress mitigation, were detected for the starter fertilization, followed by the use of an early vigor hybrid and a biostimulant seed treatment. The starter fertilization and the early vigor hybrid led to earlier flowering dates, that is, of 2.1 and 2.8 days, respectively, and significantly reduced grain moisture at harvest. Moreover, the early vigor hybrid, the starter NP fertilization, and the biostimulant treatment increased grain yield by 8.5%, 6.0%, and 5.1%, respectively, compared to the standard hybrid and the untreated controls. The combination of all the considered factors resulted in the maximum benefits, compared to the control cropping system, with an increase in the plant growth of 124%, a reduction of the sowing-flowering period of 5 days, and a gain in grain yield of 14%. When choosing the most suitable crop practice, the diversity of each cropping system should be considered, according to the pedo-climatic conditions, the agronomic background, the yield potential, and the supply chain requirements.

Agronomic strategies to enhance the early vigor and yield of maize. Part I: the role of seed applied biostimulant, hybrid and starter fertilization on rhizosphere bacteria profile and diversity.

The sustainable intensification of maize-based systems may reduce greenhouse-gas emissions and the excessive use of non-renewable inputs. Considering the key role that the microbiological fertility has on crop growth and resilience, it is worth of interest studying the role of cropping system on the rhizosphere bacterial communities, that affect soil health and biological soil fertility. In this work we monitored and characterized the diversity and composition of native rhizosphere bacterial communities during the early growth phases of two maize genotypes of different early vigor, using a nitrogen (N)-phosphorus (P) starter fertilization and a biostimulant seed treatment, in a growth chamber experiment, by polymerase chain reaction-denaturing gradient gel electrophoresis of partial 16S rRNA gene and amplicon sequencing. Cluster analyses showed that the biostimulant treatment affected the rhizosphere bacterial microbiota of the ordinary hybrid more than that of the early vigor, both at plant emergence and at the 5-leaf stage. Moreover, the diversity indices calculated from the community profiles, revealed significant effects of NP fertilization on richness and the estimated effective number of species (H2) in both maize genotypes, while the biostimulant had a positive effect on plant growth promoting community of the ordinary hybrid, both at the plant emergence and at the fifth leaf stage. Our data showed that maize genotype was the major factor shaping rhizosphere bacterial community composition suggesting that the root system of the two maize hybrids recruited a different microbiota. Moreover, for the first time, we identified at the species and genus level the predominant native bacteria associated with two maize hybrids differing for vigor. These results pave the way for further studies to be performed on the effects of cropping system and specific crop practices, considering also the application of biostimulants, on beneficial rhizosphere microorganisms.

Effective Treatments for the Successful Establishment of Milkweed (Calotropis procera L.) under Water Deficit

The application of superabsorbents to soils and seed coatings is a pre-sowing seed treatment method that is commonly used to improve early vigor and establish stability and uniformity under water deficit conditions. To evaluate the interaction of seed coating and superabsorbent on Calotropisprocera L. (milkweed) under water deficit conditions, a greenhouse experiment was conducted. The experiment was conducted with four coating material levels (non-coated seeds and seeds coated with peat moss, vermicompost, and canola residue), four growth medium levels (soil, sand + soil, soil + 2 g superabsorbent, and soil + 4 g superabsorbent), and three field capacity regimes (25, 50%, and 100%) in a completely randomized design factorial arrangement with four replications. Reducing the field capacity from 100 to 25% led to decreased growth (shoot and root dry weights and leaf area) and chlorophyll content. The activities of SOD, CAT, APX antioxidant enzymes, and proline increased under drought stress. The use of superabsorbent polymers in growth media enhanced growth indices and chlorophyll content and decreased the activity of antioxidant enzymes and proline under water deficit conditions. The highest chlorophyll and growth indices were observed when 4 g of superabsorbent was added to the growth medium under drought stress. The application of 4 g of superabsorbent to the growth medium reduced the activity of antioxidant enzymes and proline. The use of seed coatings improved the growth indices, antioxidant enzyme activity, and chlorophyll content under drought stress. The most adaptive morphological and physiological responses to water stress were observed in the vermicompost-coated seeds. The vermicompost coating containing a superabsorbent polymer (4 g/kg soil) proved to be the best for establishing milkweed under mild (50% FC) and severe water deficits (25% FC).

Identification of a Seed Vigor–Related QTL Cluster Associated with Weed Competitive Ability in Direct–Seeded Rice (Oryza Sativa L.)

Direct seeding of rice (Oryza sativa L.) is a low-labor and sustainable cultivation method that is used worldwide. Seed vigor and early vigor are important traits associated with seedling stand density (SSD) and weed competitive ability (WCA), which are key factors in direct-seeded rice (DSR) cultivation systems. Here, we developed a set of chromosome segment substitution lines with Xiushui134 as receptor parent and Yangdao6 as donor parent and used these lines as a mapping population to identify quantitative trait loci (QTLs) for seed vigor, which we evaluated based on germinability–related indicators (germination percentage (GP), germination energy (GE), and germination index (GI)) and seedling vigor–related indicators (root number (RN), root length (RL), and shoot length (SL) at 14 days after imbibition) under controlled conditions in an incubator. Ten QTLs were detected across four chromosomes, of which a cluster of QTLs (qGP11, qGE11, qGI11, and qRL11) co-localized on Chr. 11 with high LOD values (12.03, 8.13, 7.14, and 8.75, respectively). Fine mapping narrowed down the QTL cluster to a 0.7-Mb interval between RM26797 and RM6680. Further analysis showed that the QTL cluster has a significant effect (p < 0.01) on early vigor under hydroponic culture (root length, total dry weight) and direct seeding conditions (tiller number, aboveground dry weight). Thus, our combined analysis revealed that the QTL cluster influenced both seed vigor and early vigor. Identifying favorable alleles at this QTL cluster could facilitate the improvement of SSD and WCA, thereby addressing both major factors in DSR cultivation systems.

Performance evaluation of pre-sowing seed treatments using bio-agents in transplanted aromatic rice under organic conditions

In order to minimize the effect of lower productivity issues in terms of organic rice cultivation particularly for the small and marginal farmers of the state of Assam, the present research was undertaken with an objective of improving early seedling growth characteristics in organic rice cultivation using user friendly bio-formulations in the form of seed treatment. Locally prepared five organic bio-formulations particularly Organic-Metajal, Organic-Trichojal, Organic-Beauverijal, Azospirillum spp. and BIO Phos liquid PSB formulation were used as seed treatment on a high yielding aromatic rice variety "Keteki Joha" in order to evaluate the early seedling growth characters in addition to estimating the enzymatic activity by alpha amylase and lipid peroxidation under laboratory conditions. Among all the bio-agents, Org-Trichojal(T3) was found to be most effective in terms of achieving highest percentage of early vigour and seedling growth. Seed treatment with Org-Metajal (T2) and Org-Trichojal (T3)showed higher activity of alpha-amylase and lowest activity for peroxidise which had also reflected the better performance in germination and vigour indicators. While on the other hand, bio-formulations including Org-Metajal (T2).Organic-Beauverijal, Azospirillum spp. and BIO Phos were also found to be effective in improving growth as compared to the control.

Genetic mapping and transcriptome profiling of a chickpea (Cicer arietinum L.) mutant identifies a novel locus (CaEl) regulating organ size and early vigor.

Chickpea is among the top three legumes produced and consumed worldwide. Early plant vigor, characterized by good germination and rapid seedling growth, is an important agronomic trait in many crops including chickpea, and shows a positive correlation with seed size. In this study, we report a gamma-ray-induced chickpea mutant with a larger organ and seed size. The mutant (elm) exhibits increased early vigor and contains higher proline that contributes to a better tolerance under salt stress at germination, seedling, and early vegetative phase. The trait is governed as monogenic recessive, with wild-type allele being incompletely dominant over the mutant. Genetic mapping of this locus (CaEl) identified it as a previously uncharacterized gene (101503252) in chromosome 1 of the chickpea genome. There is a deletion of this gene in the mutant with a complete loss of expression. In silico analysis suggests that the gene is present as a single copy in chickpea and related legumes of the galegoid clade. In the mutant, cell division and expansion are affected. Transcriptome profiling identified differentially regulated transcripts related to cell division, expansion, cell wall organization, and metabolism in the mutant. The mutant can be exploited in chickpea breeding programs for increasing plant vigor and seed size.

Towards increased shading capacity: A combined phenotypic and genetic analysis of rice shoot architecture

Societal Impact StatementRice farming is transitioning from transplanting rice seedlings towards the less labour‐intensive and less water‐demanding method of directly seeding rice. This, however, is accompanied by increased weed proliferation. To tackle this issue, this study seeks to identify how the crop itself can better suppress weeds, with a focus on light competition via shading. Using a rice diversity panel, traits were identified that contribute to enhanced shading capacity, and these traits were encapsulated into a single shading capacity metric. This was followed by the identification of the genetic loci underpinning variation in the core traits. The identified haplotypes can be used in breeding programmes to improve weed suppression by rice, thus contributing to sustainable agriculture.Summary In modern rice farming, one of the major constraints is weed proliferation and the entailed ecological impact of herbicide application. This requires increased weed competitiveness in current rice varieties, achieved via enhanced shade casting to limit the growth of shade‐sensitive weeds. To identify traits that increase rice shading capacity, we exhaustively phenotyped a rice diversity panel of 344 varieties at an early vegetative stage. A genome‐wide association study (GWAS) revealed genetic loci underlying variation in canopy architecture traits linked with shading capacity. The screen shows considerable natural variation in shoot architecture for 13 examined traits, of which shading potential is mostly determined by projected shoot area, number of leaves, culm height and canopy solidity. The shading rank, a metric based on these core traits, identifies varieties with the highest shading potential. Five genetic loci were found to be associated with canopy architecture, shading potential and early vigour. Identification of traits contributing to shading capacity and underlying allelic variation will serve future genomic‐assisted breeding programmes. Implementing the presented genetic resources for increased shading and weed competitiveness in rice breeding will make its farming less dependent on herbicides and contribute towards more environmentally sustainable agriculture.