Kent J Bradford

• PhD
• Managing Director at University of California, Davis

Seed storage life in tropical areas is shortened by high humidity and temperature and the general inaccessibility to dehumidifying and refrigeration systems, resulting in rapid decreases in seed viability in storage as well as a high incidence of fungal and insect infestations. The dry chain, based on rapid and deep drying of seeds after harvest fo...

Athelia rolfsii, causal agent of “southern blight” disease, is a soilborne fungal pathogen with a wide host range of more than 500 species. This study's objectives were to (i) quantify the effects of two environmental factors, temperature and soil moisture, on germination of A. rolfsii inoculum (sclerotia), which is a critical event for the onset o...

Seeds of mung bean (Vigna radiata (L.) R. Wilczek) are subject to loss of viability due to aging and damage from pulse beetles (or bruchids; Callosobruchus spp.) infestation during storage. We investigated whether seed drying using desiccants and hermetic packaging would prevent or ameliorate these consequences of storage. Sun-dried mung bean seeds...

Achieving rapid and uniform stand establishment in crops requires a combination of high-quality seeds and appropriate environmental conditions. In particular, temperature and soil moisture (or water potential) are the major factors influencing germination in the field. In this chapter, we focus on the application of population-based threshold (PBT)...

In the coming decades, maintaining a steady food supply for the increasing world population will require high-yielding crop plants which can be productive under increasingly variable conditions. Maintaining high yields will require the successful and uniform establishment of plants in the field under altered environmental conditions. Seed vigor, a...

Seeds of mung bean (Vigna radiata (L.) R. Wilczek) are subject to loss of viability due to aging and damage from pulse beetles (or bruchids; Callosobruchus spp.) infestation during storage. We investigated whether seed drying using desiccants and hermetic packaging would prevent or ameliorate these consequences of storage. Sun-dried mung bean seeds...

A B S T R A C T Seeds of mung bean (Vigna radiata (L.) R. Wilczek) are subject to loss of viability due to aging and damage from pulse beetles (or bruchids; Callosobruchus spp.) infestation during storage. We investigated whether seed drying using desiccants and hermetic packaging would prevent or ameliorate these consequences of storage. Sun-dried...

Brassica oleracea is an important crop species that at early growth stages may exhibit failure of the apical growing point, an abnormality called “blindness”. The occurrence of blindness is promoted by exposure to low temperatures during imbibition and germination, but the causes of sensitivity to such conditions are unknown. We combined three anal...

Key message Bet-hedging is a complex evolutionary strategy involving morphological, eco-physiological, (epi)genetic and population dynamics aspects. We review these aspects in flowering plants and propose further research needed for this topic. Bet-hedging is an evolutionary strategy that reduces the temporal variance in fitness at the expense of a...

Seed conservation in rural communities of low-and middle-income countries located in tropical areas is particularly problematic, due to high relative humidity that promotes insect and fungal infestations and leads to rapid losses in seed viability. Seed conservation in those areas is affected by unreliable power supplies that do not allow the use o...

Flavor is a key attribute defining melon fruit quality and driving consumer preferences. We characterized and compared fruit ripening patterns (ethylene, respiration), physicochemical properties (rind/flesh color, firmness, soluble solids, acidity), aroma volatiles, and flavor-related sensory attributes in seven melon genotypes differing in shelf l...

Seed germination is a critical developmental phase for seedling establishment and crop production. Increasing salinity stress associated with climatic change can pose a challenge for seed germination and stand establishment of many crops including lettuce. Here, we show that water soluble carbon nanoparticles (CNPs) can significantly promote seed g...

We quantified the seed germination responses of chicory (Cichorium intybus L.; Asteraceae) to heat, water and salt stresses using hydrothermal time (HTT) and halothermal time (HaloTT) models. We extended the HaloTT model based on NaCl concentration to include supra-optimal temperatures. The HTT and HaloTT models enabled quantitative comparison of t...

2020. Hydrothermal sensitivities of seed populations underlie fluctuations of dormancy states in an annual plant community. Ecology. Appendix S1. Figure S1. Germination time courses (markers) and fitted curves (lines) by sub-optimal and supra-optimal HTT models, in seeds of a guild of desert annual plants after-ripened in the field for different du...

Plant germination ecology involves continuous interactions between changing environmental conditions and the sensitivity of seed populations to respond to those conditions at a given time. Ecologically meaningful parameters characterizing germination capacity (or dormancy) are needed to advance our understanding of the evolution of germination stra...

Melon (Cucumis melo L.) is a commercially important horticultural crop worldwide that exhibits extensive phenotypic and genetic variation. Texture is one of the key attributes defining melon fruit quality and overall consumer preference. The aim of this research was two-fold: first, to characterize and compare differences in fruit sensory and instr...

Even as increasing populations put pressure on food supplies, about one-third of the total food produced for human consumption is wasted with the majority of loss in developing countries occurring between harvest and the consumer. Controlling product dryness is the most critical factor for maintaining quality in stored nonperishable foods. The high...

Intraspecific trait variation within natural populations (i.e. intra‐population trait variation, IPTV) is the basic source for selection and can have significant ecological consequences. Higher IPTV may increase a population's niche breath and benefit interspecies competition under a resource‐limited environment, thus affecting the ability of a spe...

Seeds offer a unique perspective from which to view biology. An individual seed is an autonomous biological entity that must rely on its own resources (and resourcefulness) to persist after dispersal and to time its transition to germination and seedling growth to coincide with environmental opportunities for survival. At the same time, seed biolog...

Purpose This paper analyzes the potential returns to value-chain actors from employing desiccant bead drying and hermetic storage technology. Design/methodology/approach Information was collected from 175 different onion (Allium cepa L.) seed value chain actors in Nepal. Four different business models for the introduction of new bead drying and...

The sections in this article are Introduction Imbibition and Water Relations of Seed Germination Testa/Endosperm Restraint and Embryo Growth Potential Approaches to Identify Additional Genes Involved in Germination

The sections in this article are Introduction Types and Phenology of Seed Dormancy Environmental Control of Dormancy Approaches to Modeling Seed Dormancy Examples of Seed Dormancy Models Population‐Based Threshold Models of Seed Dormancy Conclusions and Future Directions

CRISPR/Cas9 is a transformative tool for making targeted genetic alterations. In plants, high mutation efficiencies have been reported in primary transformants. However, many of the mutations analyzed were somatic and therefore not heritable. To provide more insights into the efficiency of creating stable homozygous mutants using CRISPR/Cas9, we ta...

Background Even as increasing populations put pressure on food supplies, about one-third of the total food produced for human consumption is wasted, with the majority of loss in developing countries occurring between harvest and the consumer. Controlling product dryness is the most critical factor for maintaining quality in stored non-perishable fo...

Strigolactones (SLs) and related butenolides, originally identified as active seed germination stimulants of parasitic weeds, play important roles in many aspects of plant development. Two members of the D14 α/β hydrolase protein family, DWARF14 (D14) and KARRIKIN INSENSITIVE2 (KAI2) are essential for SL/butenolide signaling. The third member of th...

Gene flow is a natural process that occurs among sexually-compatible individuals in which cross pollination can result in viable seeds. Gene flow between individuals within and among populations via pollen occurs only when they have concurrent geography, overlapping flowering times, and share common pollinators. Given a population size sufficient t...

Declines of seed viability in storage and losses of stored commodities due to fungal spoilage and insect pests are promoted by high moisture content. However, measuring seed or grain moisture content in the field can be difficult, particularly in rural locations in developing countries. Because seed/commodity moisture content is uniquely related to...

Seed germination is responsive to diverse environmental, hormonal and chemical signals. Germination rates (i.e. speed and distribution in time) reveal information about timing, uniformity and extent of germination in seed populations and are sensitive indicators of seed vigour and stress tolerance. Population-based threshold (PBT) models have been...

Seed drying and storage methods are critical for maintaining the quality of seed for planting, particularly in warm, humid regions where seed deterioration is rapid. A zeolite-based desiccant drying system (Drying Beads TM) and hermetic storage containers can preserve seed quality and extend seed storage life. This study focused on the potential re...

Lettuce (Lactuca sativa) seeds exhibit thermoinhibition, or failure to complete germination when imbibed at warm temperatures. Chemical mutagenesis was employed to develop lettuce lines that exhibit germination thermotolerance. Two independent thermotolerant lettuce seed mutant lines, TG01 and TG10, were generated through ethyl methanesulfonate mut...

Significance Annual plants adapt to their environments by matching their life cycles, particularly seed germination and flowering, to the appropriate seasons. Although genetic evidence has suggested connections among genes regulating seed dormancy and flowering, specific mechanisms for such coordination are unknown. We report that a gene [ DELAY OF...

Early life- cycle events play critical roles in determining the population and community dynamics of plants. The ecology of seeds and their germination patterns can determine range limits, adaptation to environmental variation, species diversity, and community responses to climate change. Understanding the adaptive consequences and environmental fi...

The government of Nepal has approved different policies and legislation related to seed and emphasized the importance of quality improvement in the seed sector. However, the public and private sectors face problems to access quality assurance services, maintain the quality of seeds and supply based on the demand to the consumer. Considering the sit...

Seeds of most lettuce (Lactuca sativa L.) cultivars are susceptible to thermoinhibition, or failure to germinate at temperatures above ~28{degree sign}C. A Quantitative Trait Locus (QTL) associated with high temperature germination capacity (Htg9.1) was identified from a primitive accession (PI251246) of L. sativa. The Htg9.1 effect was validated w...

Thermoinhibition is the failure of seeds to germinate when imbibed at warm but not excessively high temperatures. Such seeds can generally complete germination when the temperature is reduced, but extended exposure to high temperatures may induce secondary dormancy. Plant hormones, particularly abscisic acid (ABA), gibberellins (GA) and ethylene, a...

Process-based models of development predict developmental rates and phenology as a function of physiological responses to multiple dynamic environmental factors. These models can be adapted to analyze diverse processes in evolutionary ecology. By linking models across life stages, they can predict life cycles and generation times. By incorporating...

Seed respiration is known to be related to seed vigour and quality, but other than indirectly via the tetrazolium test, has not been widely utilised as a seed quality test. A novel fluorescence-based method of measuring oxygen levels inside closed spaces enables the measurement and analysis of the respiratory patterns of individual seeds. The Q2 in...

This updated and much revised third edition of Seeds: Physiology of Development, Germination and Dormancy provides a thorough overview of seed biology and incorporates much of the progress that has been made during the past fifteen years. With an emphasis on placing information in the context of the seed, this new edition includes recent advances i...

Echinochloaoryzicola(syn.E. phyllopogon) is an exotic weed of California rice paddies that has evolved resistance to multiple herbicides. Elimination of seedlingsthroughcertain weed control methods can limit the spread of this weed, but is contingent on accurate predictions of germination and emergence timing, which are influenced by seed dormancy...

Seeds are very diverse in their shape and size. In the mature state they contain an embryo, the next generation of plant, surrounded by a protective structure (the seed and/or fruit coat) and, in species in which the nutritive reserves are not stored within the cotyledons, by an alternative storage tissue (endosperm, perisperm, or megagametophyte)....

Dormancy is the temporary failure of a seed to complete germination under favorable conditions. It allows for the dispersal of seeds in space and time. There are several types of dormancy, which include physical, mechanical, or chemical inhibition by the covering layers of the embryo, the inability to germinate because of an undifferentiated or imm...

Seed germination refers to the physiological process culminating in the emergence of the embryo from its enclosing coverings, which can include the endosperm, perisperm, testa, or pericarp. The absorption of water by the seed (imbibition) activates metabolic processes that subsequently lead to expansion of the embryo and penetration of the radicle...

Thermoinhibition, or failure of seeds to germinate at warm temperatures, is common in lettuce (Lactuca sativa) cultivars. Using a recombinant inbred line population developed from a lettuce cultivar (Salinas) and thermotolerant Lactuca serriola accession UC96US23 (UC), we previously mapped a quantitative trait locus associated with thermoinhibition...

Fertilization, the fusion of pollen and egg nuclei, produces a diploid zygote, which differentiates into the embryo, the vital next generation of the plant. Embryo development, or embryogenesis, is accompanied by the production of storage tissues, such as the endosperm or megagametophyte, and the maternal integument layers, which in the mature seed...

The seed stage of the higher plant life cycle allows for the survival of individual species, as well as populations, over long periods of time. Emergence of seedlings from the soil seed bank depends on a range of environmental factors of which water and temperature are the most important. The existence of germination response thresholds for (soil)...

The synthesis of stored reserves occurs during the seed growth period following histodifferentiation. The reserves are located within the embryo itself or in an alternative storage tissue, e.g., the endosperm of cereal grains and the cotyledons of dicot seed crops. Sucrose is the major source of carbon for reserve synthesis, and amino acids the nit...

Mobilization of the major reserves within seed storage tissues occurs following the completion of germination to provide nutrients for the growing seedling until it becomes autotrophic. Starch, hemicelluloses, triacylglycerols (oils), and proteins are mobilized by distinct suites of enzymes, many of which are transcribed and synthesized de novo. St...

Many seeds are capable of surviving dehydration at maturity, in which state they can survive for long periods (up to hundreds of years in some cases) and resume growth when rehydrated. However, deteriorative chemical processes continue in dry seeds, resulting in their gradual loss of vigor and eventual death. The rate of loss of seed viability is d...

Opportunities for diversifying the management of weedy populations may be enhanced through accurate predictions of seedling emergence, because the timing and success of control measures often hinges on the timing of weed emergence. We used population‐based threshold models to establish the temperature, moisture and oxygen conditions for optimum ger...

Lettuce (Lactuca sativa L.) and onion (Allium cepa L.) seeds have relatively short longevity during storage and their germination is sensitive to environmental stress. Seed priming (controlled hydration followed by drying) can improve seed germination under stressful conditions, inducing faster and more uniform germination over broader temperature...

A number of genes and proteins are expressed in a tissue- or cell layer-specific manner. Spatial patterns of gene expression are critical to understanding gene function. Tissue printing provides a simple and rapid method to analyze localization of mRNA and protein at the tissue and cellular levels. This is especially convenient for gene expression...

Thermoinhibition, or failure of seeds to germinate when imbibed at warm temperatures, can be a significant problem in lettuce (Lactuca sativa L.) production. The reliability of stand establishment would be improved by increasing the ability of lettuce seeds to germinate at high temperatures. Genes encoding germination- or dormancy-related proteins...

As both Pima cotton ( Gossypium barbadense L.) and Acala (Upland; G. hirsutum L.) are grown in the southwestern United States, understanding gene flow within and among these species is important to maintain genetic purity. In small scale and commercial fields, gene flow decreased exponentially from 1.44% at 1 m to less than 0.50% at 10 m in Acala c...

Genetically improved varieties and their delivery through high quality seeds have been essential contributors to yield increases that have allowed crop production to keep pace with population growth. However, as global population continues to expand and economies improve, crop production will need to double again by 2050 to meet demand. To do this...

Lettuce (Lactuca sativa L.) seeds have poor shelf life and exhibit thermoinhibition (fail to germinate) above ∼25°C. Seed priming (controlled hydration followed by drying) alleviates thermoinhibition by increasing the maximum germination temperature, but reduces lettuce seed longevity. Controlled deterioration (CD) or accelerated ageing storage con...

Specialty crops, which include fruits, vegetables, nuts, turf and ornamental crops, are important components of human diets and provide environmental amenities1. In 2007, such crops represented ~40% of the $140 billion in total agricultural receipts, despite being cultivated on just 4% of the total cropped area.

Seeds of most cultivated varieties of lettuce (Lactuca sativa L.) fail to germinate at warm temperatures (i.e., above 25–30°C). Seed priming (controlled hydration followed by drying) alleviates this thermoinhibition by increasing the maximum germination temperature. We conducted a quantitative trait locus (QTL) analysis of seed germination response...

Knowledge and prediction of seasonal weed seedling emergence patterns is useful in weed management programs. Seed dormancy is a major factor influencing the timing of seedling emergence, and once dormancy is broken, environmental conditions determine the rate of germination and seedling emergence. Seed dormancy is a population-based phenomenon, bec...

Lettuce (Lactuca sativa 'Salinas') seeds fail to germinate when imbibed at temperatures above 25 degrees C to 30 degrees C (termed thermoinhibition). However, seeds of an accession of Lactuca serriola (UC96US23) do not exhibit thermoinhibition up to 37 degrees C in the light. Comparative genetics, physiology, and gene expression were analyzed in th...

Shang Fa Yang was born in Taiwan in 1932. After receiving his B.S. and M.S. degrees in Agricultural Chemistry from the National Taiwan University, he came to the United States in 1958 to pursue a Ph.D. degree at Utah State University. Following three postdoctoral years, he was hired at the University of California, Davis, in 1966 where he was a bio...

Interest in seed propagation of drumstick tree (Moringa oleifera) has created a need for information about the water relationships of its seeds. Thus, we studied the imbibition and desiccation kinetics and adsorption/desorption isotherms of drumstick tree seeds. Seeds absorbed water readily when imbibed at 23°C. After 17 h of exposure to an atmosph...

Seed thermoinhibition (inhibition of germination at warm temperatures) can reduce seedling emergence and stand establishment of cultivated lettuce (Lactuca sativa L.) when soil temperatures are warm (>25°C) at planting. Genetic variation for high temperature germination tolerance exists among accessions of lettuce and related wild species. Seeds of...

The Ellis-Roberts seed viability equation is accepted as an accurate predictor of seed longevity over a range of storage temperatures and moisture contents (MC). One application of this model is to identify different combinations of seed MC and temperature that can result in similar seed storage lifetimes. The present study was conducted to determi...

Barley (Hordeum vulgare L.) seeds (grains) exhibit dormancy at maturity that is largely due to the presence of the glumellae (hulls) that reduce the availability of oxygen (O2) to the embryo. In addition, abscisic acid (ABA) and gibberellins (GAS) interact with O2 to regulate barley seed dormancy. A population-based threshold model was applied to q...

IntroductionImbibition and Water Relations of Seed GerminationTesta/Endosperm Restraint and Embryo Growth PotentialApproaches to Identify Additional Genes Involved in Germination

The Ellis-Roberts seed viability equation is used to predict seed survival after storage at specified temperatures and moisture contents. Seed priming, which can break dormancy and accelerate germination, can also reduce seed storage life. Because primed seeds were not used in developing the Ellis-Roberts equation, the reciprocal nature of specific...

The regulatory approval process for new biotech crop varieties is said to be unduly slow and expensive, presenting important barriers to the development of new cropping technologies. To date, however, the private and social costs have not been analyzed or measured, let alone compared with alternatives. This chapter reports initial findings from our...

Seeds vary widely in the sensitivity of germination to oxygen (O 2) partial pressure, depending upon the species, temperature, dormancy state and physiological status of the seeds. Most analyses of the O 2 sensitivity of germination have focused on final germination percen-tages and estimated the O 2 percentage in air that is required to reduce ger...

In recent years, biotechnology has come to be synonymous with the use of recombinant DNA techniques to introduce genes into plant or animal genomes. Biotechnology has been applied to modify the composition of seeds as foods or raw products to improve their nutritional, flavour, postharvest or processing characteristics. Genetic changes to improve t...

The formation, dispersal and germination of seeds are crucial stages in the life cycles of gymnosperm and angiosperm plants. The unique properties of seeds, particularly their tolerance to desiccation, their mobility, and their ability to schedule their germination to coincide with times when environmental conditions are favorable to their survival...

Technological change has driven economic progress in agriculture and will continue to play a crucial role in die 21st century. The latest wave of technological change in agriculture is based on die ability to specifically modify crop genetics dirough recombinant DNA techniques. Biotech crop varieties have been adopted on a wide scale in some agrono...