Viability Equation Research Articles

Derivation of seed viability constants (KE and CW) and prediction of longevity of Solanum aethiopicum seeds

The seed viability equation uses species viability constants to predict seed longevity under different storage conditions. There are already established universal values of constants that account for the effect of temperature on seed longevity (CH and CQ) which can be applied to different crop species. However, constants accounting for the effect of seed moisture (CW) and genotype (KE) are species-specific. This study aimed to derive viability constants and predict seed longevity for African eggplant (Solanum aethiopicum) under genebank conditions. The seeds were subjected to experimental storage at 40°C and different seed moisture contents (6, 8, 10 and 12%) for 120 days to derive survival curves and hence, CW and KE. CW and KE values for S. aethiopicum were 3.32 and 7.4978, respectively. The validation of the derived constants show that they can be used to predict seed longevity of other seed lots within the same species. The genebank curators and other commercial seed technologists may be able to accurately predict longevity of African eggplant seeds under cold dry storage conditions using the improved viability equation and the constants established in this research.

Seed Science and Technology. Volume 51 Issue 3 (2023)

This issue of Seed Science and Technology has a collection of articles that contribute to seed quality, which will be of interest to both farmers and the seed industry. The articles span diverse topics: germination treatments, vigour testing methods, viability equations and management of seed-borne inoculum. However, the majority of articles focus on germination treatments to break dormancy and provide uniform field emergence. Besides this, a review article on seed quality enhancement using seed priming will be highly informative to seed producers to enhance seed quality and hence benefit farmers in particular in developing countries. Many of the species studied are less explored and some are on the verge of extinction, requiring immediate attention. Overall, this issue will be of interest to a wide range of readers, including farmers, seed companies, researchers and conservationists.

Seed viability constants and the decline in germination rates for radish: a combined viability equation and population-based threshold model analysis

Aside from the leaves and roots, radish seedlings are consumed as a "microgreen". Production of microgreens requires high viability, high vigour seeds. Knowledge of the rates of loss of viability and vigour decline during storage would therefore be useful for radish sprout production, but also in relation to the conservation of radish germplasm in seed genebanks. Seeds of radish 'Kaiware', a microgreen cultivar, were stored hermetically at seven moisture levels between 6% and 13% at 50°C. Seed viability (germination after removal from storage) was scored daily to determine germination progress curves. One-step analysis was used to simultaneously fit the population-based threshold (PBT) model describing the decline in germination rates with ageing and to estimate the effects of MC on longevity according to the viability equation. KE and CW were estimated as 6.54 and 3.22, respectively. The ageing-time constant for the PBT model, age, increased as a function of storage moisture content, reflecting the faster decline in vigour at higher MC. The validity of the viability constants was tested by predicting viability loss in seeds of a different radish cultivar, 'Sango Purple', stored at 45°C and 8.61% MC.

Germination and viability of wild sunflower species seeds stored at room temperature and low humidity for 38 years

The effects of prolonged storage on the germination and viability of seeds of sunflower crop wild relatives stored under less-than-optimal conditions in working genebanks is not known. Seeds of two wild annual species, Helianthus annuus (common wild sunflower) and annual H. petiolaris (prairie sunflower), were stored at room temperature (20 to 22°C) and low humidity of ∼ 22% in the laboratory for 38 years. Germination of stored annual sunflower seeds was 5.5%, while that of prairie sunflower seeds was 0.75%, compared with the germination of freshly harvested seeds of 34.7 and 18.5%, respectively. Tetrazolium, a vital stain, indicated that the seeds were alive. The viability equations were used to predict final viability of the stored seeds. Using the three tests of viability (germination with and without gibberellic acid, and tetrazolium staining), all appeared to underestimate the actual condition of the stored seeds of annual sunflower, but provided better predictions for prairie sunflower. This study indicated that wild sunflower seeds can be stored at less than ideal conditions in working genebanks where viability decreases over time reducing germination, but gibberellic acid treatment can sustainably increase germination to produce a number of plants to maintain the genetic integrity of the original stored seeds often used in long-term prebreeding programmes.

Seed ageing, survival and the improved seed viability equation; forty years on

Seed Science and Technology storage environment, and the implications for seed ageing and seed quality, including likely seedling emergence. Developments in seed science, and anhydrous biology more widely, associated with that well-cited paper are summarised here.

Estimation of seed viability constants (KE,CW) for lentil (Lens culinaris)

Orthodox seed longevity systematically increases with reduction in temperature and moisture content, as described by the Ellis and Roberts viability equations. These equations have species-specific parameters which quantify the inherent longevity of seeds of a particular species and their sensitivity to change in moisture content. This research investigated the effect of moisture content on lentil ( Lens culinaris) seed longevity during experimental storage. Seeds of an elite breeding line were stored under hermetic conditions at six different moisture contents (7.6, 8.1, 8.8, 10.1, 11.5, 12.6%) at 60°C. Ability to germinate was determined at scheduled intervals, and longevity (σ) was estimated for each treatment. The values of the constants KE (8.0008) and CW (3.746) were estimated using linear regression, by plotting log σ against log moisture content, combined with the universal temperature constants (CH = 0.0329, CQ = 0.000478). The application of these moisture constants (KE and CW) was tested by comparing the predicted viability loss of two lentil accessions with their observed longevity under hermetic storage at 12.0% moisture content and 45°C. The validity of these constants for predicting lentil seed longevity was proven, with an R2 = 0.912 (P < 0.001).

Effect of storage conditions on seed quality of soybean (<i>Glycine max</i> L.) germplasm

<abstract> <p>Soybean is one of the most important oil seed crops. However, soybean seed is structurally weak and inherently short-lived, making the crop vulnerable to long period storage. Thus, it is crucial to study the effect of storage conditions on the quality of soybean seeds (<italic>Glycine max</italic> L.). The genetic material consisted of 10 soybean varieties, whose seeds were stored under both cooling (refrigerator) and room temperature conditions and were subsequently subjected to germination test, electric conductivity test and estimation of free fatty acids percentage. In order to determinethe long-term effects of storage on seed quality, all genotypes were subjected to accelerated ageing at 40℃ up to 48 days and viability equation was used to determine the Ki value. Overall findings revealed the significant effect of storage conditions on seed quality and, at the same time, underlined the beneficial effect of storage under cooling conditions, which is expressed as higher germination percentage, reduced electric conductivity and free fatty acids percentage and improved storage longevity. Further, our data provide conclusive evidence for the qualitative superiority of the varieties Adonai, Celina and Neoplanta, especially upon storage under cooling conditions, as they were characterized by higher germination percentage and improved tolerance to storage (storage potential).</p> </abstract>

Royal Botanic Gardens, Kew’s Seed Information Database (SID): A compilation of taxon-based biological seed characteristics or traits

The Seed Information Database (SID) is one of the Royal Botanic Gardens (RBG), Kew's strategic databases in the public domain (http://data.kew.org/sid). SID is a compilation of taxon-based information on a range of biological seed characteristics or traits for about 52,564 seed plant taxa. Assembling and mobilizing such data involved challenges in establishing data standards for specific seed traits and taxonomy and integrating data sets from different sources. Data are derived from seed collections stored at the RBG Kew’s Millennium Seed Bank (MSB) and from other published and unpublished sources. Seed traits data available in SID includes (number of records in brackets): storage behaviour (24,926), seed weights (86,287) seed dispersal (5,377), germination (54, 453), oil content (4,526), protein content (3,603), morphology (599), morphology images (1,741), halophytes (1,546) and viability constants (72). Database can be searched for any, or all of these categories by clade, order, family, genus, or species. SID also offers various online tools useful for ex situ seed conservation and storage (e.g. seed viability equation to predict the proportion of seeds in a population that are viable after any period of storage in a wide range of environments). SID data has been used by a wider community (general public, researches, conservationists, policymakers, etc.) in a range of disciplines including biodiversity conservation, food security, climate change, agriculture, and seed industry across the globe for large-scale analysis, modelling, predicting, or describing plant seed traits.

Longevity of 285 seed lots of wheat in hermetic storage compared with independent estimates from the seed viability equation

The longevity in hermetic storage at 40°C with 14.1-15.7% moisture content of 285 seed lots of wheat (Triticum aestivum L., cv. Tybalt), harvested at or before maturity from control or modified environments under rain shelter or after simulated rainfall in three consecutive years (2010-12), was compared with independent estimates from the seed viability equation and previously-published viability constant values for wheat. Around half of the observations provided good agreement with these independent estimates of longevity, but some of the seed lots harvested close to maturity in 2012, or before the end of the seed-filling phase in 2011, survived longer in storage than prior estimates.

Effect of simulated flooding during rice seed development and maturation on subsequent seed quality

AbstractThe resilience of seed quality in rice (Oryza sativaL.) to flooding was investigated. Pot-grown plants of thejaponicacv. Gleva, theindicacv. IR64, and the introgressed line IR64-Sub1 were submerged in water, to simulate flooding, for 3‒5 days at different stages of seed development and maturation. Mean seed weight, pre-harvest sprouting, ability to germinate, and subsequent longevity in air-dry storage were assessed. Whereas seed quality in both IR64 and IR64-Sub1 was resilient to submergence, in Gleva the longer the duration of submergence and the later in development when plants were submerged the greater the pre-harvest sprouting. Thousand seed dry weight was reduced more by submergence in Gleva than IR64 or IR64-Sub1. At harvest maturity, few pre-harvest sprouted seeds were able to germinate upon rehydration after desiccation to 11‒12% moisture content. Seed longevity of the non-sprouted seed fraction in air-dry hermetic storage (40°C, 15% moisture content) was not affected greatly by submergence, but longevity of thejaponicarice was less than that of theindicarices due to the former's steeper seed survival curves. Longevity of the twoindicarices was predicted well by the seed viability equation and previously published estimates of viability constants for rice. The greater dormancy of IR64 and IR64-Sub1, compared with Gleva, enhanced resilience to pre-harvest sprouting and reduced thousand seed dry weight from plant submergence. There was little or no effect of plant submergence on subsequent air-dry storage longevity of non-sprouted seeds in any genotype.

The longevity of desorbing and adsorbing rice seeds

AbstractIn each of two experiments, freshly harvested seeds of two cultivars of rice were dried and then rehydrated to different moisture levels. In experiment 1, seed equilibrium relative humidity (eRH) and moisture content (MC) were determined at each moisture level so that moisture desorption and adsorption isotherms could be constructed. Seed storage experiments were also carried out for seeds equilibrated at each moisture level, in sealed aluminium foil packets at 45°C. In experiment 2, storage experiments at 45°C were carried out on seeds dried to 12% MC and seeds dried to lower moisture levels and then rehydrated to 12% MC.The moisture adsorption isotherm was shifted to lower MC at a given eRH compared with the desorption isotherm. This hysteresis effect was seen both when seeds were dried to <6% MC and then allowed to adsorb moisture to different levels, and when seeds were dried to different levels (10, 8, 6 or 4% MC) and then allowed to adsorb moisture up to 12% MC. The log-log relationship between seed longevity, σ [the standard deviation of the normal distribution of seed deaths over time, as defined in the Ellis and Roberts (1980) seed viability equations] and seed storage MC did not vary depending on whether the seeds were desorbing or adsorbing moisture. The relationship between σ and eRH was better described by a log-log model than a log-linear model and did vary depending on whether seeds were desorbing or adsorbing moisture: at a given eRH, the longevity of adsorbing seeds was greater than that of desorbing seeds. The implications for seed storage are discussed.

Generation of a Predictive Score for Ixazomib Response in Multiple Myeloma

Multiple myeloma (MM) is the second-most common hematopoietic malignancy in the United States accounting for 1% of all cancers and 10% of all hematologic malignancies. Despite recent improvements in treatment strategies including the emergence of proteasome inhibitors (PIs) as effective chemotherapeutic agents, MM still remains difficult to cure with median survival rate of around 7 years, primarily due to wide inter-individual variation in response to treatment. We believe such heterogeneity in response to PIs is governed by the underlying molecular characteristics of the tumor including alterations in gene expression profile (GEP).In the current study, we used a panel of Human Myeloma Cell Lines (HMCLs) representing the gamut of biological and genetic heterogeneity in MM to evaluate the gene expression signatures associated with response to the second-generation PI Ixazomib and produced a predictive score (PI score) for Ix response.HMCLs (n=45) were treated with increasing concentrations of Ixazomib used as single agent and half maximal inhibitory concentration (IC50) values were determined using cell viability equation. Gene expression profiling data was obtained as publicly available data from the Keats lab website at TGen (http://www.keatslab.org/myeloma-cell-lines).Genes with high expression value and high standard deviation beyond the median values were pre-filtered and log expression values were normalized by subtracting mean expression of individual genes across all the samples and the housekeeping genes (GAPDH). Subsequently, analysis of correlation between Ix IC50 data and GEP data and the False Discovery Rate (FDR) based on 1000 random permutations were performed to identify true patterns of genes that are highly predictive of Ix response and to look for the top genes that could discriminate between the top sensitive and top resistant cell lines. Gene clusters were identified that correlated with response and will be presented. Our results will demonstrate in vitro modeling of response using GEP approaches that may provide predictive scoring algorithms of a defined set of genes that will be useful in clinical evaluation of drug choice in treating individual patients. DisclosuresNo relevant conflicts of interest to declare.

One-step fitting of seed viability constants for two Australian plant species, Eucalyptus erythrocorys (Myrtaceae) and Xanthorrhoea preissii (Xanthorrhoeacea)

Long-term ex-situ seed storage under controlled conditions in gene banks has become an important tool for conserving threatened Australian plants; however, there is scant information about the seed longevity of most species. The aim of the present study was to determine whether the seed longevity of two contrasting Australian species could be modelled using the seed viability equation, and whether the universal temperature constants are applicable to these species. Seeds of Eucalyptus erythrocorys F.Muell. (Myrtaceae) and Xanthorrhoea preissii Endl. (Xanthorrhoeaceae) were aged at moisture contents ranging from 3.9 to 15.7% and temperatures between –20 and 60°C. Survival data were fitted to the seed viability equation in one step and the species constants for each species determined. Both E. erythrocorys and X. preissii seeds exhibited orthodox seed storage behaviour whose longevity could be modelled using the seed viability equation. The viability constants were KE = 8.81, CW = 4.97, CH = 0.0412 and CQ = 0.000379 for E. erythrocorys and KE = 8.77, CW = 5.29, CH = 0.0382 and CQ = 0.000473 for X. preissii. The universal temperature constants could not be used without a significant increase in error. The storage behaviour of these two Australian species is in keeping with that of orthodox species from around the world. Predictions are that E. erythrocorys will be long-lived under gene bank conditions, whereas X. preissii would be moderately long-lived. Current long-term gene bank storage conditions appear suitable for storage of these species; however, recommendations for short-term storage need to be re-evaluated.

Long-term population demography of Trillium recurvatum on loess bluffs in western Tennessee, USA

Understanding the demography of long-lived clonal herbs, with their extreme modularity, requires knowledge of both their short- and long-term survival and ramet growth patterns. The primary objective of this study was to understand the dynamics of a clonal forest herb, Trillium recurvatum, by examining temporal and small-scale demographic patterns. We hypothesized: (i) there would be more variability in the juvenile age class compared with non-flowering adult and flowering adult classes due to year-to-year fluctuations in recruitment; (ii) rates of population growth (λ) and increase (r) would be highest in non-flowering ramets due to a combination of transitions from the juvenile stage and reversions from flowering adults; and (iii) inter-ramet distances would be most variable between flowering and juvenile ramets due to a combination of clonal growth, seed dispersal by ants and ramet death over time. Census data were collected on the total number of stems in the population from 1990 to 2007, and placed within one of three life stages (juvenile, three-leaf non-flowering and three-leaf flowering). Modified population viability equations were used to assess temporal population viability, and spatial structure was assessed using block krigging. Correlations were performed using current and prior season weather to current population demography. The first hypothesis was rejected. The second hypothesis was supported: population increase (r) and growth rate (λ) were highest in non-flowering ramets. Finally, the third hypothesis was rejected: there was no apparent density dependence within this population of Trillium and no apparent spatial structure among life stages. Overall population density fluctuated over time, possibly due to storms that move soil, and prior year's temperature and precipitation. However, density remained at some dynamic stable level. The juvenile age class had greater variability for the duration of this study and population growth rate was greatest for non-flowering ramets.

EQUAÇÃO DE LONGEVIDADE PARA SEMENTES DE CAFÉ (Coffea arabica L.)

Objetivou-se equacionar a longevidade de sementes de café usando o Modelo de Probit. Valores obtidos da literatura de curvas de sobrevivência de sementes de café, armazenadas sob diferentes temperaturas e teores de água, foram transformados em probit e utilizados em regressões lineares e não lineares para determinação dos coeficientes de equações de viabilidade. Os resultados das análises permitiram concluir que: um modelo quadrático apresentou ajuste adequado, com desvio padrão de 8,9% de germinação, para equacionar a perda de germinação de sementes de café armazenadas, enquanto o modelo tradicional apresentou desvio padrão de 15,1% de germinação; a regressão não linear, comparada com a regressão linear múltipla, resultou em menores 1,5 a 2,2 vezes desvios padrão na determinação dos coeficientes da equação do desvio padrão da frequência de distribuição das sementes mortas durante o período de armazenamento (σ); e as sementes de café não apresentaram comportamento de ortodoxas, indicado pelas variações não lineares do logaritmo de σ em função das variações do logaritmo do teor de água das sementes.

Determination of seed moisture constants (K E, C W) for the viability equation for watermelon, melon, and cucumber seeds

Determination of seed moisture constants (K E, C W) for the viability equation for watermelon, melon, and cucumber seeds

Viability equation to determine the longevity of fungicide-treated seeds of wheat stored in a conventional warehouse

The objective of this research was to determine the deterioration rate of BRS 208 and CD 104 wheat cultivar seeds, treated with fungicides, by applying the viability equation. Seeds were stored in conventional warehouses in Maua da Serra and Londrina, in the State of Parana, Brazil. Four seed lots were divided into four replications, half being treated with Carboxin + Thiran and the other half taken as controls, without treatment, and these were stored for 300 days. The germination data were transformed into probit, and a straight line was adjusted between 0 and 30 days. The treated seed lot of cv. BRS 208 stored in Londrina gave seed deterioration rates varying from 0.8.10-3 to 1.3.10-3, not differing from the values given for the similar lot stored in Maua da Serra, of 0.9.10-3. The deterioration rates of the treated seed of cv. CD 104 were 1.2.10-3 in Maua da Serra and 2.0.10-3 in Londrina, which are greater than those values given for untreated seeds of 0.4.10-3 and 0.5.10-3. This model provides an effective approach to predict the untreated and treated seed longevity of wheat for the purpose of managing seeds

Comparisons between two economically valuable forest species (Eucalyptus grandis and Pinus taeda) in relation to seed behaviour under controlled deterioration

The objectives of this work were to analyze seed behaviour under controlled deterioration and estimate viability equations for forest species Eucalyptus grandis and Pinus taeda. Desired moisture content levels were achieved from initial values after either rehydration over water or drying over silica gel, both at 25 ºC. Seed sub samples with 8 moisture contents each for E. grandis (1.2 to 18.1%, initial value of 11.3%) and P. taeda (1.5 to 19.5%, initial value of 12.9%) were sealed in laminate aluminium-foil packets and stored in incubators maintained at 40, 50 and 65 ºC. The seeds from these species exhibited true orthodox and sub-orthodox storage behaviour, respectively, however E. grandis showed higher seed storability, probably due to a different seed chemical composition. Lowest moisture content limits estimated for application of the viability equations at 65 ºC were 4.9 and 4.1 mc for E. grandis and P. taeda, on equilibrium with ±20% RH. The viability equation estimated quantified the response of seed longevity to storage environment well with K E = 9.661 and 8.838; C W = 6.467 and 5.981; C H = 0.03498 and 0.10340; C Q = 0.0002330 and 0.0005476, for E. grandis and P. taeda, respectively.

Derivation of Constants (KE, CW) for the Viability Equation for Pepper Seeds and the Subsequent Test of Its Applicability

The effect of moisture on seed longevity during experimental storage was investigated in pepper (Capsicum annuum) cultivar Demre. Seeds were stored hermetically at 7.0%, 8.6%, 9.5%, 10.5%, and 12.1% moisture content (MC; percent fresh weight basis) and 35 °C for up to 306 d. Viability (normal germination) was assessed periodically and the seed viability equation moisture constants, KE and CW, estimated by regression of log σ (the sd of distribution of seed death in time) with log MC. KE and CW values were found to be 7.767 and 4.670, respectively. The newly found moisture constants were combined with the temperature constants that had already been proposed as universal for all orthodox seeds (CH = 0.0329, CQ = 0.000478) and their validity was tested by predicting the viability loss in another pepper cultivar, Carliston. The Ki of the Carliston cultivar was determined by controlled deterioration at 40 °C and 14% MC. The observed viability loss between 30 and 270 d at 25 °C and 10% seed MC was closely related to that predicted by the equation R2 = 0.982 (P < 0.001).

Storage behaviour of two contrasting upland rice genotypes

This study investigated complaints by upland rice farmers in Ghana that their local rice cultivar "Kawomo" (Oryza glaberrima) stored better than an improved upland rice cultivar, IDSA 85 (Oryza sativa subsp. japonica), tested and selected in a Participatory Varietal Selection programme. One seed lot of "Kawomo" and two seed lots of IDSA 85, differing in initial quality, were stored hermetically at 50 oC with five (18, 15, 12, 10 and 8%) moisture contents. In the second investigation, seed of "Kawomo" was stored hermetically at the above moisture contents, but at 30 oC. Both investigations were carried out at the Seed Science Laboratory, Department of Agriculture, The University of Reading, UK. In the third investigation, 122 samples of farmer-saved seed were stored hermetically at moisture contents between 12 and 16 per cent under ambient temperature in Ghana for 6 months. Seed moisture content had a significant (P 0.10) among the two species, glaberrima rice showed marginally greater longevity than japonica rice. The viability equation also accurately predicted germination of farmer-saved seed stored under ambient (fluctuating)temperature in Ghana.