Landscape crop diversity contributes to higher pollination effectiveness and positively affects rapeseed quality in Mediterranean agricultural landscapes.

Pollination is crucial for biodiversity and food security. Heterogeneous agricultural landscapes have a positive effect on pollinator abundance and enhance crop production and quality. In this study, we explored the effects of three landscape features (past crop diversity measured as the Equivalent Richness of crop functional Groups in the previous year [ERGp], semi-natural habitat percentage [SNH], and mean field size [MFS]) and pollinator densities (wild bees [WB] and honey bees [HB]) on pollination and seed quantity and quality in rapeseed crops. Surveying the pollinator density in 20 rapeseed fields revealed a positive relationship with ERGp in the landscape. A pollinator exclusion experiment compared bagged and open-pollinated self-compatible rapeseed plants and revealed insect pollination effectiveness (fruits per flower and number of seeds per pod) and seed quality (oil content). Seed parameters were evaluated in relation to pollinator density (WB-HB) and landscape characteristics. The ERGp emerged as a crucial landscape feature that positively impacted WB density. When insect pollinators were excluded, plants exhibited reduced pollination effectiveness and seed quality. Analysis of open-pollinated plants highlighted ERGp as the most influential variable, positively affecting both sets of parameters. The MFS and SNH showed different but important relationships. Total tocopherol and α-tocopherol were positively correlated with pollinator density in HB, whereas WB showed a positive correlation with γ-tocopherol levels. Increased ERGp positively affected pollinator density and pollination effectiveness, thereby improving oilseed rape production quantity and quality. This study provides new insights into agroecosystem management and pollinator-friendly practices.

Germination characteristics associated with nicosulfuron resistance in Amaranthus retroflexus L.

Nicosulfuron-resistant biotype (R) and -sensitive biotype (S) Amaranthus retroflexus L. seeds were subjected to different temperature, light, salt, osmotic potential, pH value and burial depth treatments. The difference in germination response of two populations to the above abiotic environmental factors was used to study the fitness cost of nicosulfuron-resistance evolution in A. retroflexus. The aim is to find a powerful tool for weed control in the presence of evolutionary resistance selection. The results of this experiment showed that the germination rate and germination index in S population were generally higher than that in R population. When the salt stress was 80 mM, the water potential was -0.1 Mpa ~ -0.4 Mpa, and under strong acid and alkali conditions, the germination index in S population was prominently higher than that in R population (p<0.05). The delayed seed germination in R population indicated that its nicosulfuron resistance may be linked to seed biochemical compositions that altered seed germination dynamics. The resistant and sensitive biotype of A. retroflexus had differently favourable adaptability in diverse environments. Salt, osmotic potential and pH value are not the major constraints for A. retroflexus germination, however, A. retroflexus are strongly responsive to temperature, light and burial depth. Considering that seeds of A. retroflexus are unable to reach the soil surface beyond the depth of 6 cm, deep inversion tillage before sowing may be an effective and economical weed management tool for the control of nicosulfuron resistant A. retroflexus.

Ultrasonic treatment can improve maize seed germination and abiotic stress resistance.

Constant-frequency ultrasonic treatment helped to improve seed germination. However, variable-frequency ultrasonic treatment on maize seed germination were rarely reported. In this study, maize seeds were exposed to 20-40 kHz ultrasonic for 40 s. The germination percentage and radicle length of maize seeds increased by 10.4% and 230.5%. Ultrasonic treatment also significantly increased the acid protease, α-amylase, and ß-amylase contents by 96.4%, 73.8%, and 49.1%, respectively. Transcriptome analysis showed that 11,475 differentially expressed genes (DEGs) were found in the ultrasonic treatment and control groups, including 5,695 upregulated and 5,780 downregulated. Metabolic pathways and transcription factors (TFs) were significantly enriched among DEGs after ultrasonic treatment. This included metabolism and genetic information processing, that is, ribosome, proteasome, and pyruvate metabolism, sesquiterpenoid, triterpenoid, and phenylpropanoid biosynthesis, and oxidative phosphorylation, as well as transcription factors in the NAC, MYB, bHLH, WRKY, AP2, bZIP, and ARF families. Variable-frequency ultrasonic treatment increased auxin, gibberellin, and salicylic acid by 5.5%, 37.3%, and 28.9%, respectively. Abscisic acid significantly decreased by 33.2%. The related DEGs were upregulated and downregulated to varying degrees. Seed germination under the abiotic stress conditions of salt stress (NaCl solution), drought (PEG solution), and waterlogging (water-saturated sand bed) under ultrasonic treatment were promoted, radicle length was significantly increased by 30.2%, 30.5%, and 27.3%, respectively; and germination percentage by 14.8%, 20.1%, and 21.6%, respectively. These findings provide new insight into the mechanisms through ultrasonic to promote maize seed germination.

HFR1 antagonizes ABI4 to coordinate cytosolic redox status for seed germination under high-temperature stress.

Seed germination and dormancy represent critical phases in the life cycle of plants, tightly regulated by endogenous phytochrome levels and environment signals. High temperatures (HT) induce the overaccumulation of reactive oxygen species (ROS) and increase abscisic acid (ABA), thereby inhibiting seed germination. Our previous findings showed that HT induced the burst of reactive nitrogen species (RNS), increasing the S-nitrosylation modification of HFR1, which effectively blocks seed germination. Importantly, stabilizing HFR1 has been shown to significantly mitigate the inhibitory effect of HT on seed germination. In this study, we reported that HT increased the protein abundance of ABI4, a crucial component in ABA signaling, which in turn activates the expression of RbohD while suppressing the expression of VTC2. This leads to the rapid generation of ROS, thereby inhibiting seed germination. Consistently, the seed germination of abi4 mutant showed insensitivity to HT with lower ROS level during seed germination, whereas transgenic lines overexpressing ABI4 showed reduced germination rates accompanied by elevated ROS levels. Furthermore, we noted that HFR1 interacts with ABI4 to sequester its activity under normal conditions. However, HT-induced ROS triggered the degradation of HFR1, consequently releasing ABI4 activity. This activation of ABI4 promotes RbohD expression, culminating in a ROS burst that suppresses seed germination. Thus, our study unveils a novel function for ABI4 in regulating ROS level and seed germination under HT stress. Throughout this process, HFR1 plays a critical role in restraining ABI4 activity to maintain an optimal endogenous ROS level, thereby ensuring seed germination under favorable environmental conditions.

Tail-dependence of masting synchrony results in continent-wide seed scarcity.

Spatial synchrony may be tail-dependent, meaning it is stronger for peaks rather than troughs, or vice versa. High interannual variation in seed production in perennial plants, called masting, can be synchronized at subcontinental scales, triggering extensive resource pulses or famines. We used data from 99 populations of European beech (Fagus sylvatica) to examine whether masting synchrony differs between mast peaks and years of seed scarcity. Our results revealed that seed scarcity occurs simultaneously across the majority of the species range, extending to populations separated by distances up to 1800 km. Mast peaks were spatially synchronized at distances up to 1000 km and synchrony was geographically concentrated in northeastern Europe. Extensive synchrony in the masting lower tail means that famines caused by beech seed scarcity are amplified by their extensive spatial synchrony, with diverse consequences for food web functioning and climate change biology.

The Use of Imaging to Quantify the Impact of Seed Aging on Lettuce Seed Germination and Seedling Vigor.

The decline in seed quality over time due to natural aging or mishandling requires assessing seed vigor for resilience in adverse conditions. Accelerated aging (AA) methods simulate seed deterioration by subjecting seeds to high temperatures and humidity. Saturated salt accelerated aging (SSAA) is an AA method adopted for small seeds like lettuce (Lactuca sativa). In this study, we subjected seeds of two lettuce cultivars ('Muir' and 'Bauer') to SSAA by sealing them in a box containing 40 g/100 mL of a sodium chloride (NaCl) solution in a dark growth chamber at 41 °C for 24, 48, and 72 h with a control. We monitored their vigor using embedded computer cameras, tracking the projected canopy size (PCS) daily from sowing to harvest. The cultivar 'Muir' exhibited consistent PCS values across the treatments, while 'Bauer' showed PCS variations, with notable declines after prolonged aging. The germination rates dropped significantly after 48 and 72 h of SSAA. A nonlinear regression model revealed a strong relationship between PCS and shoot dry weight across harvests and cultivars (R2 = 0.93, RMSE = 0.15, p < 0.001). The research found that the projected canopy size and shoot dry weight increased over time with significant differences in treatments for the cultivar 'Bauer' but not for 'Muir,' with the canopy size being a strong predictor of dry weight and no significant impact from the SSAA treatments. This study highlights cultivar-specific responses to aging and demonstrates the efficacy of our imaging tool in predicting lettuce dry weight despite treatment variations. Understanding how aging affects different lettuce varieties is crucial for seed management and crop sustainability.

Synergistic effects of melatonin and 24-epibrassinolide on chickpea water deficit tolerance.

BACKGROUND: Water deficiency stress reduces yield in grain legumes, primarily due to a decrease in the pods number. Melatonin (ML) and 24-epibrassinolide (EBL) are recognized for their hormone-like properties that improve plant tolerance to abiotic stresses. This study aimed to assess the impact of different concentrations of ML (0, 100, and 200 µM) and EBL (0, 3, and 6 µM) on the growth, biochemical, and physiological characteristics of chickpea plants under water-stressed conditions. RESULTS: The study's findings indicated that under water-stressed conditions, a decrease in seed (30%) and pod numbers (31%), 100-seed weight (17%), total chlorophyll content (46%), stomatal conductance (33%), as well as an increase in H2O2 (62%), malondialdehyde content (40%), and electrolyte leakage index (40%), resulted in a 40% reduction in chickpea plants grain yield. Our findings confirmed that under water-stressed conditions, seed oil, seed oil yield, and seed protein yield dropped by 20%, 55%, and 36%, respectively. The concurrent exogenous application of ML and EBL significantly reduces oxidative stress, plasma membrane damage, and reactive oxygen species (ROS) content. This treatment also leads to increased yield and its components, higher pigment content, enhanced oil and protein yield, and improved enzymatic and non-enzymatic antioxidant activities such as catalase, superoxide dismutase, polyphenol oxidase, ascorbate peroxidase, guaiacol peroxidase, flavonoid, and carotenoid. Furthermore, it promotes the accumulation of osmoprotectants such as proline, total soluble protein, and sugars. CONCLUSIONS: Our study found that ML and EBL act synergistically to regulate plant growth, photosynthesis, osmoprotectants accumulation, antioxidant defense systems, and maintain ROS homeostasis, thereby mitigating the adverse effects of water deficit conditions. ML and EBL are key regulatory network components in stressful conditions, with significant potential for future research and practical applications. The regulation metabolic pathways of ML and EBL in water-stressed remains unknown. As a result, future research should aim to elucidate the molecular mechanisms by employing genome editing, RNA sequencing, microarray, transcriptomic, proteomic, and metabolomic analyses to identify the mechanisms involved in plant responses to exogenous ML and EBL under water deficit conditions. Furthermore, the economical applications of synthetic ML and EBL could be an interesting strategy for improving plant tolerance.

Effects of flowering period on floral traits, pollinator behavior and seed production of David's mountain laurel (Sophora davidii).

Sophora davidii is a cross-pollinated plant with important ecological protection and medicinal value in China, but its seed yield is low due to backward and nonstandard production technology. Therefore, we divide the flowering period of Sophora davidii into initial, full and final flowering period, measuring the floral morphology, pollen viability, stigma receptivity, nectar volume and nectar concentration, foraging behavior of pollinators, fertilization physiology, seed yield and quality through field observation and indoor testing to explore whether the flowering period affects the floral traits, pollinator behavior and seed production of plants. Our results revealed that the nectar volume, nectar concentration, pollen viability and stigma receptivity at full flowering period were the highest. The single visit time and visit time per flower of Chinese honey bees were the longest in the full flowering period, while the number of transfer, visit frequency and number of touching stigma were the least. The visiting number of the bees was the most and the most active in the full flowering period. The bees pollination not only improved the pollen amount, germination rate, pollen tube length and the ovule number of S. davidii, but also their effect was the most obvious in full flowering period. The principal component analysis showed that pollination by Chinese honey bees during the whole flowering period of S. davidii was the best way to produce seeds. We can conclude that flowering period affects flower traits, foraging behavior of pollinators, seed yield and quality of S. davidii.

Effect of seed priming with auxin on ROS detoxification and carbohydrate metabolism and their relationship with germination and early seedling establishment in salt stressed maize.

As crucial stages in the plant ontogeny, germination and seedling establishment under adverse conditions greatly determine staple crop growth and productivity. In the context of green technologies aiming to improve crop yield, seed priming is emerging as an effective approach to enhance seed vigor and germination performance under salt stress. In this study, we assess the efficiency of seed priming with indole-3-acetic acid (IAA) in mitigating the adverse effects of salt stress on maize (Zea mays L.) seedlings during germination and early seedling stages. In unprimed seeds, salt stress reduced germination indices, and seedling (both radicle and coleoptile) growth, together with decreased tissue hydration. However, seed priming using IAA significantly improved maize salt response, as reflected by the increased seed germination dynamics, early seedling establishment, and water status. Besides, seedlings from IAA-primed seeds showed a higher activity of α-amylase, resulting in increased sugar contents in roots and coleoptiles of salt-stressed plants. Further, IAA-seed priming stimulated the accumulation of endogenous IAA in salt-stressed seedlings, in concomitance with a significant effect on reactive oxygen species detoxification and lipid peroxidation prevention. Indeed, our data revealed increased antioxidant enzyme activities, differentially regulated in roots and coleoptiles, leading to increased activities of the antioxidant enzymes (SOD, CAT and GPX). In summary, data gained from this study further highlight the potential of IAA in modulating early interactions between multiple signaling pathways in the seed, endowing maize seedlings with enhanced potential and sustained tolerance to subsequent salt stress.

An ecotype-specific effect of osmopriming and melatonin during salt stress in Arabidopsis thaliana.

BACKGROUND: Natural populations of Arabidopsis thaliana exhibit phenotypic variations in specific environments and growth conditions. However, this variation has not been explored after seed osmopriming treatments. The natural variation in biomass production and root system architecture (RSA) was investigated across the Arabidopsis thaliana core collection in response to the pre-sawing seed treatments by osmopriming, with and without melatonin (Mel). The goal was to identify and characterize physiologically contrasting ecotypes. RESULTS: Variability in RSA parameters in response to PEG-6000 seed osmopriming with and without Mel was observed across Arabidopsis thaliana ecotypes with especially positive impact of Mel addition under both control and 100 mM NaCl stress conditions. Two ecotypes, Can-0 and Kn-0, exhibited contrasted root phenotypes: seed osmopriming with and without Mel reduced the root growth of Can-0 plants while enhancing it in Kn-0 ones under both control and salt stress conditions. To understand the stress responses in these two ecotypes, main stress markers as well as physiological analyses were assessed in shoots and roots. Although the effect of Mel addition was evident in both ecotypes, its protective effect was more pronounced in Kn-0. Antioxidant enzymes were induced by osmopriming with Mel in both ecotypes, but Kn-0 was characterized by a higher responsiveness, especially in the activities of peroxidases in roots. Kn-0 plants experienced lower oxidative stress, and salt-induced ROS accumulation was reduced by osmopriming with Mel. In contrast, Can-0 exhibited lower enzyme activities but the accumulation of proline in its organs was particularly high. In both ecotypes, a greater response of antioxidant enzymes and proline accumulation was observed compared to mechanisms involving the reduction of Na+ content and prevention of K+ efflux. CONCLUSIONS: In contrast to Can-0, Kn-0 plants grown from seeds osmoprimed with and without Mel displayed a lower root sensitivity to NaCl-induced oxidative stress. The opposite root growth patterns, enhanced by osmopriming treatments might result from different protective mechanisms employed by these two ecotypes which in turn result from adaptive strategies proper to specific habitats from which Can-0 and Kn-0 originate. The isolation of contrasting phenotypes paves the way for the identification of genetic factors affecting osmopriming efficiency.

Germination response to winter temperature changes with seed shape and length of temperature exposure.

In many regions, the climate is changing faster during winter than during the other seasons, and a loss of snow cover combined with increased temperature variability can expose overwintering organisms to harmful conditions. Understanding how species respond to these changes during critical developmental times, such as seed germination, helps us assess the ecological implications of winter climate change. To address this concern, we measured the breaking of seed dormancy and cold tolerance of temperate grassland species in the lab and field. In the lab, we ran germination trials testing the tolerance of 17 species to an extreme cold event. In the field, we deployed seeds of two species within a snow manipulation experiment at three locations and measured germination success biweekly from seeds subjected to ambient and reduced snow cover from winter into spring. From lab trials, cold tolerance varied among species, with seed germination decreasing <10%-100% following extreme cold events. Cold tolerance was related to seed traits, specifically less round seeds, seeds that required cold stratification, and seeds that mature later in the season tended to be more impacted by extreme cold temperatures. This variation in seed cold tolerance may contribute to altered community composition with continued winter climate change. In the field, germination increased through late winter, coinciding with the accumulation of days where temperatures were favorable for cold stratification. Through spring, germination success decreased as warm temperatures accumulated. Collectively, species-specific seed cold tolerances and mortality rates may contribute to compositional changes in grasslands under continued winter climate change.

Individual or successiveseed priming with nitric oxide and calcium toward enhancing salt tolerance of wheat crop through early ROS detoxification and activation of antioxidant defense.

Despite the considerable efforts reported so far to enhance seed priming, novel ideas are still needed to be suggested to this sustainable sector of agri-seed industry. This could be the first study addressing the effect of nitric oxide (NO) under open field conditions. The impacts of seed redox-priming using sodium nitroprusside (SNP) and osmo-priming with calcium chloride (CaCl2), both applied individually or successively, were investigated under salinity stress conditions on wheat plants (Triticum aestivum L.). Various parameters, including water relations, growth, yield, photosynthetic pigments, and antioxidant activities (enzymatic and non-enzymatic), were recorded to assess the outcomes of these priming agents on mitigating the negative impacts of salinity stress on wheat plants. Water consumptive use (ETa) and irrigation water applied (IWA) decreased with seeds priming. Successive priming with SNP + CaCl2 induced the greatest values of crop water productivity (CWP), irrigation water productivity (IWP), seed index, grain yield and grain nitrogen content.Under salinity stress, the dry weight of plants was decreased. However, hydro-priming and successive chemical priming agents using combinations of calcium chloride and sodium nitroprusside (CaCl2 + SNP & SNP + CaCl2) preserved growth under salinity stress.Individual priming with sodium nitroprusside (SNP) and calcium chloride (CaCl2) resulted in the lowest recorded content of sodium in the shoot, with a value of 2 ppm. On the other hand, successive priming using CaCl2 + SNP or SNP + CaCl2 induced the contents of potassium in the shoot, with values of 40 ppm and 39 ppm, respectively. Malondialdehyde decreased in shoot significantly withapplicationof priming agents. Successive priming with CaCl2 + SNP induced the highest proline contents in shoot (6 µg/ g FW). The highest value of phenolics and total antioxidants contents in shoot were recorded under successive priming using CaCl2 + SNP and SNP + CaCl2.Priming agents improved the activities of ascorbate peroxidase and catalase enzymes. The successive priming improved water relations (ETa, IWA, CWP and IWP) and wheat growth and productivity under salinity stress more than individual priming treatments.

Remotely sensed crown nutrient concentrations modulate forest reproduction across the contiguous United States.

Global forests are increasingly lost to climate change, disturbance, and human management. Evaluating forests' capacities to regenerate and colonize new habitats has to start with the seed production of individual trees and how it depends on nutrient access. Studies on the linkage between reproduction and foliar nutrients are limited to a few locations and few species, due to the large investment needed for field measurements on both variables. We synthesized tree fecundity estimates from the Masting Inference and Forecasting (MASTIF) network with foliar nutrient concentrations from hyperspectral remote sensing at the National Ecological Observatory Network (NEON) across the contiguous United States. We evaluated the relationships between seed production and foliar nutrients for 56,544 tree-years from 26 species at individual and community scales. We found a prevalent association between high foliar phosphorous (P) concentration and low individual seed production (ISP) across the continent. Within-species coefficients to nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) are related to species differences in nutrient demand, with distinct biogeographic patterns. Community seed production (CSP) decreased four orders of magnitude from the lowest to the highest foliar P. This first continental-scale study sheds light on the relationship between seed production and foliar nutrients, highlighting the potential of using combined Light Detection And Ranging (LiDAR) and hyperspectral remote sensing to evaluate forest regeneration. The fact that both ISP and CSP decline in the presence of high foliar P levels has immediate application in improving forest demographic and regeneration models by providing more realistic nutrient effects at multiple scales.

Optimizing water relations, gas exchange parameters, biochemical attributes and yield of water-stressed maize plants through seed priming with iron oxide nanoparticles.

Drought poses significant risks to maize cultivation by impairing plant growth, water uptake and yield; nano priming offers a promising avenue to mitigate these effects by enhancing plant water relations, stress tolerance and overall productivity. In the current experiment, we tested a hypothesis that seed priming with iron oxide nanoparticles (n-Fe2O3) can improve maize performance under water stress by improving its growth, water relations, yield and biochemical attributes. The experiment was conducted on a one main plot bisected into two subplots corresponding to the water and drought environments. Within each subplot, maize plants were raised from n-Fe2O3 primed seeds corresponding to 0 mg. L- 1 (as control treatment), 25, 50, 75, and 100 mg. L- 1 (as trial treatments). Seed priming with n-Fe2O3 at a concentration of 75 mg. L- 1 improved the leaf relative water content, water potential, photosynthetic water use efficiency, and leaf intrinsic water use efficiency of maize plants by 13%, 44%, 64% and 17%, respectively compared to control under drought stress. The same treatments improved plant biochemical attributes such as total chlorophyll content, total flavonoids and ascorbic acid by 37%, 22%, and 36%, respectively. Seed priming with n-Fe2O3 accelerated the functioning of antioxidant enzymes such as SOD and POD and depressed the levels of leaf malondialdehyde and hydrogen peroxide significantly. Seed priming with n-Fe2O3 at a concentration of 75 mg. L- 1 improved cob length, number of kernel rows per cob, and 100 kernel weight by 59%, 27% and 33%, respectively, under drought stress. Seed priming with n-Fe2O3 can be used to increase maize production under limited water scenarios.

Seed production determines the entrance to dormancy of the inflorescence meristem of Pisum sativum and the end of the flowering period.

Flowering plants adjust their reproductive period to maximize the success of the offspring. Monocarpic plants, those with a single reproductive cycle that precedes plant senescence and death, tightly regulate both flowering initiation and flowering cessation. The end of the flowering period involves the arrest of the inflorescence meristem activity, known as proliferative arrest, in what has been interpreted as an evolutionary adaptation to maximize the allocation of resources to seed production and the viability of the progeny. Factors influencing proliferative arrest were described for several monocarpic plant species many decades ago, but only in the last few years studies performed in Arabidopsis have allowed to approach proliferative arrest regulation in a comprehensive manner by studying the physiology, hormone dynamics, and genetic factors involved in its regulation. However, these studies remain restricted to Arabidopsis and there is a need to expand our knowledge to other monocarpic species to propose general mechanisms controlling the process. In this work, we have characterized proliferative arrest in Pisum sativum, trying to parallel available studies in Arabidopsis to maximize this comparative framework. We have assessed quantitatively the role of fruits/seeds in the process, the influence of the positional effect of these fruits/seeds in the behavior of the inflorescence meristem, and the transcriptomic changes in the inflorescence associated with the arrested state of the meristem. Our results support a high conservation of the factors triggering arrest in pea and Arabidopsis, but also reveal differences reinforcing the need to perform similar studies in other species.

Determination of melon seed physical parameters and calibration of discrete element simulation parameters.

To improve the accuracy of the Hami melon discrete element model, the parameters of the Hami melon seed discrete element model were calibrated by combining practical experiments and simulation tests. The basic physical parameters of Hami melon seeds were obtained through physical experiments, including triaxial size, 100-grain mass, moisture content, density, Poisson's ratio, Young's modulus, shear modulus, angle of repose, suspension speed and various contact parameters. Taking the repose angle of seed simulation as an index, the parameters of each simulation model were significantly screened by the Plackett-Burman test. The results showed that the recovery coefficient, static friction coefficient and rolling friction coefficient of Hami melon seeds had significant effects on repose angle. Based on the steepest climbing test and quadratic regression orthogonal rotation combination test, it was determined that the significant order of the influence of various contact parameters on the angle of repose was static friction coefficient, collision recovery coefficient, and rolling friction coefficient. The optimal parameter combination was obtained through the mathematical regression model between the angle of repose and various contact parameters, namely, the collision recovery coefficient of Hami melon seeds was 0.518, the static friction coefficient of Hami melon seeds was 0.585 and the rolling friction coefficient of Hami melon seeds was 0.337. Under this condition, three static seed-dropping experiments and dynamic rolling accumulation experiments were carried out. The average simulated angle of repose was 31.93°, and the relative error with the actual value was only 1.71%. The average simulated rolling accumulation angle was 51.98°, and the relative error with the actual value was only 1.92%.

Assessment of Dormancy Level and Germination Ability of Seeds with Physiological Dormancy.

Germination test is fundamental and commonly used technique for seed dormancy and germination studies, and proper assessment of dormancy level and germination ability of a given set of seeds is prerequisite for most of the studies. However, germination is very sensitive to imbibition conditions, and dormancy development is also sensitive to growth conditions of the mother plants. In this chapter, we describe tips for plant growth and germination test mainly for physiological and molecular genetic studies with Arabidopsis. This protocol can be applied for other plant species with relatively small seeds and for various studies to analyze the effect of light, phytohormones, and other chemicals in seed germination.

A Seed Storage Protocol to Determine Longevity.

The longevity of seeds, also known as storability, is the period of time for which a seed lot maintains its viability during storage. The method aims to determine longevity of a seed lot during storage in a controlled environment. Seeds are first rehydrated to a preset water content (or relative humidity, RH) and then incubated under controlled conditions for various periods of time to allow for deterioration to occur. At increasing intervals during storage, seeds are retrieved and viability is tested by scoring germination of the seed lot (i.e., radicle protrusion). From these data, a survival curve can be drawn depicting loss of germination during time of storage from which different parameters estimating longevity can be inferred. These parameters can be used to compare longevity between different seed lots, genotypes, or species at similar storage conditions. This test can also be used as a proxy to measure seed vigor or physiological seed quality.

Low-Cost Imaging to Quantify Germination Rate and Seedling Vigor across Lettuce Cultivars.

The survival and growth of young plants hinge on various factors, such as seed quality and environmental conditions. Assessing seedling potential/vigor for a robust crop yield is crucial but often resource-intensive. This study explores cost-effective imaging techniques for rapid evaluation of seedling vigor, offering a practical solution to a common problem in agricultural research. In the first phase, nine lettuce (Lactuca sativa) cultivars were sown in trays and monitored using chlorophyll fluorescence imaging thrice weekly for two weeks. The second phase involved integrating embedded computers equipped with cameras for phenotyping. These systems captured and analyzed images four times daily, covering the entire growth cycle from seeding to harvest for four specific cultivars. All resulting data were promptly uploaded to the cloud, allowing for remote access and providing real-time information on plant performance. Results consistently showed the 'Muir' cultivar to have a larger canopy size and better germination, though 'Sparx' and 'Crispino' surpassed it in final dry weight. A non-linear model accurately predicted lettuce plant weight using seedling canopy size in the first study. The second study improved prediction accuracy with a sigmoidal growth curve from multiple harvests (R2 = 0.88, RMSE = 0.27, p < 0.001). Utilizing embedded computers in controlled environments offers efficient plant monitoring, provided there is a uniform canopy structure and minimal plant overlap.

Stress induced factor 2 is a dual regulator for defense and seed germination in Arabidopsis.

Receptor-like kinases (RLKs) constitute a diverse superfamily of proteins pivotal for various plant physiological processes, including responses to pathogens, hormone perception, growth, and development. Their ability to recognize conserved epitopes for general elicitors and specific pathogens marked significant advancements in plant pathology research. Emerging evidence suggests that RLKs and associated components also act as modulators in hormone signaling and cellular trafficking, showcasing their multifunctional roles in growth and development. Notably, STRESS INDUCED FACTOR 2 (SIF2) stands out as a representative with distinct expression patterns in different Arabidopsis organs. Our prior work highlighted the specific induction of SIF2 expression in guard cells, emphasizing its positive contribution to stomatal immunity. Expanding on these findings, our present study delves into the diverse functions of SIF2 expression in root tissues. Utilizing comprehensive physiology, molecular biology, protein biochemistry, and genetic analyses, we reveal that SIF2 modulates abscisic acid (ABA) signaling in Arabidopsis roots. SIF2 is epistatic with key regulators in the ABA signaling pathway, thereby governing the expression of genes crucial for dormancy release and, consequently, Arabidopsis seed germination. This study sheds light on the intricate roles of SIF2 as a multi-functional RLK, underscoring its organ-specific contributions to plant immunity, hormonal regulation, and seed germination.