(pp. 7-13)
The Future of Seed Technology Testing and Training
Miller B. McDonald
I presented a keynote speech to the AOSA/SCST meetings in Williamsburg, Virginia in June, 2011. The choice of topic was mine, but I was encouraged to give a philosophical discourse that drew on my greater than 35 years of experience with the members of the two societies. Moreover, I view a keynote address as an important opportunity to challenge contemporary thinking and process with new views and roles—ones that could be viewed as controversial.
That’s acceptable in my mind if it causes reasoned debate about how to do things better. The objective of a keynote should be to present new ideas that make people ponder them, get out of the “comfort” box, become creative and think differently. With this preface, I present my opinions regarding the future of seed technology testing and training, its challenges, opportunities and new approaches.
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(pp. 15-25)
Seed Aging/Repair Hypothesis Leads to New Testing Methods
Alison Powell and Stan Matthews
ABSTRACT:
The overall aim of seed testing is to give reassurance about seed quality to those involved in international trade in seed and to end-users. The significance and importance of using seed tests based on research and validation before inclusion in the International Seed Testing Association (ISTA), Rules for Seed Testing, is emphasised, with reference to the physiological aspects of seed quality, germination and vigor.
The reduced germination rate following aging, as measured by mean germination time (mean delay to radicle emergence), is interpreted as the time needed for the metabolic repair of the deleterious effects of aging before germination can proceed. Evidence in support of this seed aging/ repair hypothesis is presented from recent internationally co-ordinated research and by a re-examination of existing vigor tests (accelerated aging, controlled deterioration, cold and cool tests and so-called seedling growth tests). This hypothesis is the basis of a rapid, new vigor test, the radicle emergence (RE) test, which has been validated and introduced to the ISTA Rules for maize. Advantages of the RE test and its application to a wide range of other species are described. Aging not only delays RE but also increases leakage from the seeds, the level of which relates to their ability to produce a normal or abnormal seedling. This leads to the possible application of measurements of leachate conductivity to assess germination and in vigor tests. The potential for using molecular methods to test seed quality through detection of DNA damage, ligase activity and other cellular damage is discussed.
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(pp. 27-34)
A Review: What is the Future for Research and Graduate Training in Seed Science and Technology?
Dennis M. TeKrony
The development of the discipline of Seed Science and Technology in land grant universities during the past 50 years provided leadership in this area in both public agencies and the private seed industry. This leadership promoted applied and basic research at these universities and led to the publication of many scientific papers in seed (Seed Technology, Seed Science and Technology and Seed Science Research) as well as crop science journals.
This effort resulted in the development of many seed science courses and the publication of several excellent seed textbooks that were widely used in training both undergraduate and graduate students in Seed Science and Technology. The graduates from these land grant universities filled many key positions in seed certification, foundation seed, seed testing, seed research and extension in the public sector as well as in seed production, seed quality control and seed research in the seed industry. The faculty in some of these programs also provided an extensive curriculum for training many students in Seed Science and Technology in South America, Asia and Africa. Thus, the foundation has been laid. However, the critical question is: will this effort continue and what is the future for research and graduate training in Seed Science and Technology?
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(pp. 35-37)
Phytosanitary Risk Assessment and Molecular Seed Health Tests: Time to Make the Connection
Gary Munkvold
Seed health tests based on polymerase chain reaction (PCR) methods are now widely available, but very few of these methods have been standardized, validated and approved for phytosanitary seed testing in international trade. In a 2009 review of seed health tests approved by the International Seed Testing Association (ISTA), International Seed Health Initiative (ISHI), or National Seed Health System (NSHS), I found that only three of 75 approved tests were nucleic-acid based (Munkvold, 2009).
The potential advantages of PCR-based tests are not in dispute, considering the potential for accuracy, rapidity, quantification, objectivity, and simultaneous detection of multiple pathogens (e.g., Mumford et al., 2006; van Doorn et al., 2009). Many of these methods are very useful for quality control purposes, but their implementation in phytosanitary certification has been slow and inconsistent. Inconsistent implementation of PCR-based tests in phytosanitary testing has resulted in several missteps, adding to the reluctance of many seed industry pathologists and regulatory officials to embrace these methods for phytosanitary decisionmaking. A key obstacle to their effective implementation in this arena is a poor understanding of the connection between results of PCR-based tests and the actual risk of disease or pathogen introduction. This question must be addressed through careful research before we will see the widespread and effective adoption of PCR-based seed health tests for phytosanitary certification in international seed trade.
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(pp. 41-49)
Priming Effects on Germination and Lipid Peroxidation of Chickpea (Cicer arietinum) Seedlings Under Salinity Stress
Rozbeh Farhoudi* and Maryam Makkizadeh Tafti
ABSTRACT:
A laboratory experiment was conducted to evaluate the effects of halo priming on germination, seedling growth and lipid peroxidation of chickpea (Cicer arietinum L.) seeds under salinity stress. The experimental design was a two-factor factorial arranged in a completely randomized design, with six replications.
The first factor was salinity level (0 and 100 mmol NaCl) and the second was priming treatment (1, 2 and 3% NaCl and KNO3 solutions). Under salinity stress, seed priming significantly improved germination and seedling fresh weight and decreased mean germination time and lipid peroxidation, compared to the control. Seed priming with 1 and 2% solutions of KNO3 significantly improved germination, seedling growth, and peroxidase activity, and decreased lipid peroxidation compared to NaCl priming. Potassium nitrate priming treatments are simple, cheap and do not involve expensive chemicals and sophisticated equipment.
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(pp. 51-60)
Planting Date Affects Cowpea Seed Yield and Quality at Southern Guinea Savanna, Nigeria
S.R. Akande, S.A. Olakojo, S.A Ajayi, O.F. Owolade, J.A. Adetumbi, O.N. Adeniyan and B.A. Ogunbodede
ABSTRACT:
Cowpea [Vigna unguiculata (L.) Walp.] is widely grown across Nigeria, but there is a dearth of information on best production practices yielding high quality seeds of improved varieties, which is indispensable for increasing productivity. Field experiments were conducted during the growing seasons of 2008 and 2009 at Ilorin, Southern Guinea Savanna of Nigeria to determine appropriate planting dates under rainfed conditions that would yield high quality seed.
Five improved varieties were planted over a period of 4 months (June, July, August and September) each year. Data was collected on yield, seed quality and related traits. Significant differences in mean seed yield attributable to plant date effects were detected each year. In 2008, the highest seed yield was recorded for the July planting with a mean value of 1681.35 kg ha−1. In 2009 however, the highest seed yield was recorded for the August planting (1914.49 kg ha−1). In both years, cowpea varieties took longer to attain 50% maturity when planted in August while those planted in September matured earlier than plants from seeds planted in other months. Significantly higher incidence of Choanephora pod rot and Cercospora leaf spot were observed for June plantings each year. Seed lots from August and September plantings resulted in significantly higher germination than those planted in June and July. August was recommended for planting cowpea in Ilorin and its environs for optimum seed yield with high quality, but with continuous monitoring of rainfall patterns.
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(pp. 61-77)
Sample Size with Finite Populations and Imperfect Diagnostic Tests for Pooled Samples
Osval Antonio Montesinos-López, Abelardo Montesinos-López, José Crossa and Kent M. Eskridge
ABSTRACT:
Group testing methods are used for classifying and estimating a proportion when the response is binary (0 or 1) and the proportion to be estimated is lower than 10%. Group testing techniques are becoming increasingly popular due to their considerable savings in time and money compared to more traditional testing methods. Until now, group testing formulas derived for determining sample size when classifying or estimating a proportion have been based on the assumption of an infinite population.
However, in many cases, the population is finite and appropriate formulas are needed to determine sample size. For this reason, a new formula is proposed to determine the required sample size for estimating the proportion (p) that ensures narrow confidence intervals (CI) in finite populations with imperfect diagnostic tests (tests whose sensitivity and specificity are less than 100%). With this formula there is a γ probability that the (1–α)100% confidence interval will be narrower than a specified value, ω. The proposed formula determines the
number of groups (ɡF) needed to estimate the proportion of interest and ensures with high probability that the observed CI will be narrower than ω. We show how to use the proposed formula and provide tables relevant for practical applications. Finally, we present an R program that may be used to determine sample size for finite group testing problems.
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(pp. 79-86)
Regeneration of Russian Wildrye Foundation Seed and its Effect on Genetic Diversity and Linkage Disequilibrium
Ivan W. Mott, Kevin B. Jensen and Steven R. Larson
ABSTRACT:
Maintaining the genetic integrity and performance of released cultivars over multiple generations of seed increase continues to be of concern in cross-pollinating grasses. It is not an uncommon practice when seed supplies are low or foundation seed is not available to designate registered seed as foundation seed (re-foundationed), which adds one or more certified generations to the cultivar.
Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski] is a cross-pollinating, cool-season, bunchgrass native to steppe and semidesert regions of Eurasia. Amplified fragment length polymorphism(AFLP) analysis was used to test the effect of additional generations on the molecular genetic diversity and linkage disequilibrium within and among original foundation seed (1986), re-foundationed seed from registered seed (1992) and certified seed (2002) of the cultivar ‘Bozoisky-Select’, along with cultivars ‘Vinall’ and ‘Mankota’. Average similarity coefficients within generations fell from 0.6031 in original foundation seed to 0.5920 in certified seed four generations later, while the average similarity coefficient between generations fell from 0.6031 to 0.5826, respectively. Principal coordinates analysis (PCoA) grouped individuals of Vinall and Mankota into their respective groups, and grouped all Bozoisky-Select individuals into one indivisible group. Linkage disequilibrium (LD) trended toward a loss of LD over generations of seed production, but the change was not significant. Although there were slight decreases in genetic similarity over four generations of seed production, the changes were not enough to cause subdivisions of Bozoisky-Select seed using PCoA. The re-foundation of seed from registered seed in 1992 did not result in significantly decreased LD in the 2002 certified Bozoisky-Select seed.
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(pp. 87-107)
Standard Purity and Germination Laboratory Methods for Eastern Gamagrass (Tripsacum dactyloides)
C.L.H. Finneseth and R.L. Geneve
ABSTRACT:
Eastern gamagrass [Tripsacum dactyloides (L.) L.] is a warm-season, perennial grass native to large areas across North America. Plantings are commonly established from seed, but seed quality is a barrier to establishment. The objective here is to review the standard laboratory purity method and to outline a germination protocol that can be used for routine assessment of eastern gamagrass seed lots for planting purposes.
A survey of 21 laboratories determined that at least 9 germination procedures are currently in use. A comparison of a single seed lot as reported by 10 laboratories was used to determine variation in test results. Additional seed lots were germinated on substrates with and without KNO3 and subjected to prechilling and presoaking treatments. Based on the results presented here, a preliminary germination method using between blotters, blotter-lined Petri dishes or rolled towels as the substrate, and a germination temperature regime of alternating 20/30 °C, with count dates of 7 and 14 d is recommended for routine laboratory analysis.
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(pp. 111-118)
Osmopriming Duration Influence on Germination, Emergence and Seedling Growth
of Sorghum
A. Singh, R. Dahiru and M. Musa
ABSTRACT:
Seed osmopriming can be a sustainable method of improving crop establishment, uniform emergence and field growth. Laboratory and greenhouse studies were carried out during the 2010 cropping season in Sokoto, Nigeria, to study the effect of seed osmopriming duration on the germination, emergence and growth of sorghum seeds.
Treatments consisted of 3 osmopriming durations (imbibing seeds in 1% KNO3 salt solutions for 6, 8 and 10 h), a hydropriming treatment (imbibition in water for 10 h) and an unprimed control. Treatments were laid out in a completely randomized design replicated 4 times. Osmopriming and hydropriming resulted in higher seed germination, emergence, plant height and dry matter accumulation compared to the unprimed control. Both hydropriming and osmopriming of sorghum seed can be used for improved field performance. However, osmopriming in KNO3 salt solutions for at least 6 h resulted in better field establishment and seedling growth than hydropriming.
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(pp. 119-126)
Assessment of Seed Storage Alternatives for Rivercane (Arundinaria gigantea)
D.M. Neal, B.S. Baldwin, G.E. Ervin, R.L. Jolley, J.J.N. Campbell, M. Cirtain, J. Seymour and J.W. Neal
ABSTRACT:
Canebrakes [stands of Arundinaria gigantea (Walter) Muhl.] provide important wildlife habitat, promote stream bank stabilization and improve water quality, making them ideal focal points for riparian restoration projects. However, availability of viable seeds for seedling production is limited due to infrequent flowering events, naturally low seed viability, the recalcitrant nature of seeds and failure of flowering stands to produce seeds. The purpose of this study was to examine seed storage methods that can extend stored seed viability and germination for future use in rivercane seedling production for restoration programs.
To evaluate effect of container type and storage temperature, seed germination percentages were compared for two storage container types, paper and plastic bag, at three storage temperatures, −5, 5, and 21 °C, over 5 months. The highest germination was for seeds stored at sub-zero temperatures (−5 °C) in plastic bags. Rivercane seed is recalcitrant in nature, requiring storage methods that assure moisture retention and low temperatures that minimize cellular metabolic processes.
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(pp. 129-138)
Seed Treatment of Minor Crops
Gizele Ingrid Gadotti*, Candida Renata Jacobsen Farias and Geri Eduardo Meneghello
ABSTRACT:
A recent Brazilian law (IN no. 1 of February, 2010) regulated the use of agrochemicals for crops classified as minor crops, i.e., small-scale crops that do not generate enough economic returns to justify investments in developing specialized pest control products by the chemical industry.
The law was a step forward in the use and control of agrochemicals for species that previously had no approved pesticides, and for which producers often used either inappropriate or contraband products to satisfy pesticide needs. Unfortunately, this inappropriate use is still the case regarding seed treatment, and it negatively impacts seed and crop exports. It also diverges from appropriate crop production methods that utilize environmentally sound practices with minimal use of pesticides per unit area. A law addressing minor uses for seed treatment is of fundamental importance, and the recent development of laws regulating minor uses of products for crops of lower economic importance is an important step towards extending these minor uses to seed treatment.
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(pp. 139-144)
Apical Bud Pinching in Okra (Abelmoschus esculentus): a Review
S.W. Patil, B.M. Aher, A.A. Sakure and A.B. Dahake
ABSTRACT:
Okra [Abelmoschus esculentus (L.) Moench] is one of the most important vegetable crops grown extensively throughout India during the summer and rainy seasons. Apical bud pinching, or nipping, is a well-known practice for breaking apical dominance to encourage lateral growth, thereby increasing the potential fruiting area.
Growth, productivity, and seed quality are increased with pinching at early compared to later stages of growth, providing sufficient time for regeneration of vegetative parts, enhancing production of branches, and also resulting in increased photosynthetic activity, accumulation of more photosynthates, and ultimately resulting in increased seed size and yield. In this paper, the effects of apical pinching on growth, yield and quality of okra are reviewed, with a view to promoting this practice in commercial production, as well as presenting information about associated field management practices and special treatments for obtaining higher okra yields.
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