Volume 24, No. 1, 2002

Download cover and Contents

SYMPOSIUM: Testing Native Species (free download)
Seed Size and Seed Weight in Some Lotus (Fabaceae) Species (free download)

(pp. 9-15)
The Challenge: High Quality Seed of Native Plants to Ensure Successful Establishment
Kenneth P. Vogel
Native species are planted to re-vegetate former cropland, degraded pastures and  rangelands, mined lands, “natural areas”, roadside right-of-ways, and other land management areas with plants, usually perennials, to stabilize and provide desirable classes of vegetation. Acceptable stands need to be obtained in a reasonable time.

Seed of native plants varies widely in seed quality factors including seed size, purity, dormancy, germination, and vigor. Seed quality tests required for sale of native seeds usually include germination, purity, and hard or dormant seeds. These laboratory tests do not always predict the capability of a seed lot to establish a stand under field conditions and do not give the seed user enough information to determine planting rate. The number of emerged seedlings per gram of seed in species specific stress tests may be a method of quantifying seed quality that is predictive of the seed’s capability of producing a stand under field conditions. A standardized establishment test based on a unit of weight could be used to  directly calculate planting rates.
Download entire article

(pp. 16-25)
Purity Testing in the Andropogoneae
Larry J. Prentice
Varying analysis reports on the same lot of seed in the chaffy rangegrasses create problems in marketing for the seed owner. Wide ranges in the percentage of pure seed for these difficult native species are reported when results are compared between laboratories and between analyses within a laboratory. This paper explains the procedures for obtaining the working sample in Andropogon gerardii, (big bluestem), Andropogon halli, (sand bluestem), Schizachyrium scoparius (little bluestem) and Sorghastrum nutans (Indiangrass).

These four species have similar spikelet characteristics and thus can be considered as one for determining the percent pure seed methodology. The basics of determining what is classified in the Rules for Testing Seeds as a seed unit, and what comprises pure seed and inert are explained and shown so that an analyst unfamiliar with these species can successfully perform an accurate analysis. The proper steps and mechanics of conducting the purity analysis, proper sampling of the seed lot and methods to subdivide the submitted sample down to the working sample size are explained. Information on easier and faster ways to separate the filled seed units from the empty seed units is included as an aid to the analyst. With an understanding of the proper interpretation of procedures in the Rules for Testing Seeds the purity testing differences can be greatly diminished for these four species.
Download entire article

(pp. 26-35)
A Philosophy of Dormancy Testing in Native Species
Miller B.McDonald
Native species are primarily undomesticated crops that possess high levels of seed dormancy. Seed technologists use prechill, predry, scarification, and leaching techniques during germination testing to break this dormancy. The objective of this report is to show that, while germination is increased, each of these approaches create seed stress that reduces seed viability and germination, thereby providing growers and buyers of native species incorrect information concerning the plant performance ability of the seed lot. To more accurately portray the seed quality of native species, it is proposed that a TZ test be conducted prior to the germination test to identify the viability of the seed lot followed by a germination test to determine the present performance potential of the seed lot.
Download entire article

(pp. 36-42)
Three-Part Purity for Native Species
Sharon K Davidson
Testing of native species lends many problems to seed analysts across the United States. Besides purity and germination decisions, there is also confusion encountered when reporting seed testing results. The Rules for Testing Seeds of the Association of Official Seed Analysts (AOSA, 2000) require a four part purity analysis, incorporating Handbook 25, Uniform Classification of Weed and Crop Seeds (AOSA, 1999), for determining what is other crop or weed seed. This causes problems for the analyst and the consumer. A three part purity analysis as used by International Seed Testing Association (ISTA, 1999) combines both crop and weed seeds under one classification ‘other species’, which alleviates many of the problems encountered in reporting seed test results.Combining other crop and weed contaminates into one classification, which is represented as a single percentage, other species, on the label would harmonize seed trade around the world.
Download entire article

(pp. 43-51)
Testing Native Species with Deep Dormancy
Nancy Vivrette* and Aleta Meyr
Testing for purity and viability of native species with deep dormancy can be difficult. A protocol is provided for obtaining a working sample, determining percent germination, determining total viability and reporting results for native species not included in the Rules for Testing Seeds (AOSA, 2001).
Download entire article

(pp. 52-61)
Sources of Laboratory Test Result Variation in Warm-Season Grasses
T. J. Gutormson* and A. L. Patin
Variation in laboratory test results on native warm season grasses is a current issue in the seed industry. To determine if these concerns were real, samples of big bluestem (Andropogon gerardii Vitman), sand bluestem (Andropogon halli Hack), little bluestem [Schizachyrium scoparium (Michx.) Nash], Indiangrass [Sorghastrum nutans (L.) Nash], switchgrass (Panicum virgatum L.) and side oats grama [Bouteloua curtipendula (Michx.) Torr.] were tested in three seed testing laboratories. Samples for each species were split from one seed lot and mailed immediately to two of the three laboratories.

All seed lots were tested for purity, germination, dormant seed, tetrazolium, PLSV (pure live seed based on viability) and PLST (pure live seed based on tetrazolium) for each species within a time period of three months. The two seed lots of sideoats grama showed differences in viable seed, tetrazolium, PLSV and PLST among laboratories. The three seed lots of Indiangrass showed little variation among the three laboratories, except seed lot two which had differences in the percentage germination + dormant of 5 + 84 and 84 + 6 % when tested by laboratories A & B, respectively. Big bluestem seed lots had the greatest differences between laboratories of all species tested. The three seed lots tested showed variation in purity, germination + dormant and tetrazolium, however the PLSV responses on seed lots one and three were nearly identical. Two sand bluestem seed lots showed similar PLS responses between laboratories, however seed lot one had different viable and tetrazolium responses. Switchgrass responses for viable, tetrazolium, PLSV, PLST and pure seed were very uniform across the three seed lots and laboratories. Germination plus dormant responses on switchgrass did show significant differences. It appears variation is real between laboratories for certain tests and species. Six sources of variation were identified: 1) Non-flowable nature of seed units, 2) Maturity of seed units, 3) Seed company sampling and mixing uniformity, 4) Laboratory subsampling and mixing uniformity, 5) Purity testing methods and individual technologist, and 6) Viability and dormancy breaking methods used. Continued study and cooperation between seed companies and testing laboratories is needed to work towards further identifying and developing methods which reduce variation in test results of warm season native grasses.
Download entire article

(pp. 65-75)
Matriconditioning Improves the Quality and Protein Level of Medium Vigor Hot Pepper Seed
S. Ilyas*, G.A.K. Sutariati, F.C. Suwarno, and Sudarsono
The objective of this study was to invigorate medium vigor hot pepper seed using matriconditioning. In one experiment, medium (80% germination, 2 year-old) vigor seeds of hot pepper were subjected to various invigoration treatments. In the subsequent experiment, medium and high (95% germination, 1 year-old) vigor hot pepper seeds were subjected to matriconditioning treatment at 15°C for 6 days using

sawdust (210 μ particle size) moistened with 100 μM GA3. In the later experiment, the ratio of seed to sawdust to GA3 solution in the matriconditioning treatment was 1:2:5. Seed quality of matriconditioned medium vigor seed was enhanced over the untreated seed as indicated by a higher percent of germination, improved vigor index, and speed of germination. The total protein isolated from matriconditioned seed was 16% higher than that from untreated. Meanwhile, total protein isolated from high vigor seed was 10% higher than that from medium vigor seed. Qualitative changes in the profiles of total protein isolated from matriconditioned seeds occurred within the 76, 45, 38, 30 and 20 kDa polypeptides. Matriconditioning with sawdust and GA3 offers an alternative for improving seed quality of hot pepper seeds.
Download entire article

(pp. 76-88)
Dimensional and Density Data and Relationships for Seeds of Agricultural Crops
Stuart O. Nelson
Dimensions of seeds of twenty different agricultural crops were determined by caliper measurements. Individual seed weights were obtained, and mean seed volumes were determined by air-comparison pycnometer measurements for use in determining seed densities. Seed densities ranged from 1.002 g/cm3 for safflower, Carthamus tinctorious L., to 1.460 g/cm3 for milled rice, Oryza sativa L. Test weight (bulk density) measurements were also taken and moisture contents were determined by standard tests.

Collectively, these data supplement the limited seed density data currently available in the literature for reference. The product of three orthogonal dimensions (length, width and thickness) was calculated for each kind of seed. A volume coefficient was determined as the ratio of the measured mean volume to the orthogonal-dimension product. The dimensionless volume coefficients, which ranged from 0.222 for oil-type sunflower, Helianthus annuus L., seeds to 0.588 for sweetclover, Melilotus officinalis Lam., seeds, are useful in estimating seed volume from seed dimensional data.With use of the appropriate volume coefficient, seed density can be estimated for a particular kind of seed from seed weight and dimensions, and the potential utility of this concept is demonstrated for single lots of three kinds of seed.
Download entire article

(pp. 89-99)
Integrating Matriconditioning with Chemical and Biological Seed Treatments to Improve Vegetable Crop Stand Establishment and Yield under Tropical Conditions
C. Andreoli* and R. V. de Andrade
Poor stand establishment of vegetables is attributable to low seed vigor and high susceptibility to stressful biotic and abiotic soil environments. The objective of this paper was to describe the effect of matriconditioning integrated with fungicide,GA and biological seed treatments on performance of vegetable crops, and their effectiveness on physiological and biochemical changes. Matriconditioning ameliorated the performance of eggplant and tomato seeds in 1999 field plantings in Brazil. Reduction in time to 50% (T50) emergence in conditioned seeds ranged from

4 days in eggplant to 2 days in tomato. Further improvement in emergence rate occurred by inclusion of gibberellin (GA4+7) during conditioning. Eggplant and tomato seed germination is influenced by endospermcell layer digestion by GA-induced enzymes,which reduce mechanical restraints to the embryo. Pre-sowing seed conditioning in the presence of Bacillus subtilis proved effective in increasing sweet corn shoot dry weight in the field, but the addition of GA during matriconditioning in sweet corn had a negative effect. Fungicide added to brittle genotype sweet corn seeds with or without conditioning improved the final percentage emergence by 140 and 125% when compared to non-conditioned seeds. Osmoconditioning with PEG reduced the emergence rate and shoot weight production of both hybrids. Electrolyte leakage was greater in brittle sweet corn seeds carrying the bt2 gene compared to the sugary type, and in both cases, matriconditioning reduced the leakage. Matriconditioning with or without biological seed treatment may be a feasible strategy in improving stand and yield of sweet corn of lower seed quality under tropical conditions.
Download entire article

(pp. 103-107)
Germination Ecology of Two Savanna Tree Species, Tamarindus indica and Prosopis africana
Idu MacDonald*, A. C. Omonhinmin, I. A. Ogboghodo,
Various methods of seed scarification including concentrated sulphuric acid, alcohol; methanol, ethanol, iso-propanol, butanol and hot water (100°C), were applied on seeds of Tamarindus indica L. and Prosopis africana Guill and Peri., to improve germination and assess seed vigor. The highest germination and germination energy (Germ. En.) for T. indica occurred following pre-treatment in methanol for 10 minutes (70% germination; 42, Germ. En.), while better response was obtained for P. africana following pretreatment in ethanol for 10 minutes (58% germination; 38, Germ. En.), and Conc. H2SO4, for 5 minutes (60% germination; 38, Germ. En.).
Download entire article

(pp. 108-116)
Identification of Annual and Perennial Ryegrass Using Reversed-Phase High-Performance Liquid Chromatography
Glenn W. Freeman* and Marcello J.Mangano
Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC) of cereal grain proteins has received much attention in recent years as a quick and efficient means of cultivar identification. A study of perennial ryegrass (Lolium perenne L.) and annual ryegrass (Lolium multiflorum Lam.) was undertaken to determine if RP-HPLC could be adapted to the identification of these species.

Chromatograms of different cultivars of the two species studied all had distinct peak patterns, which correlated with each kind. Protein analysis of single seeds accurately differentiated annual ryegrass seeds from perennial ryegrass seeds.Mixtures of ryegrass seeds were analyzed and compared. A lower limit of 10% annual ryegrass in perennial ryegrass was detected by monitoring changes of area under the peaks of the chromatograms. RP-HPLC was shown to be a quick, repeatable and reliable method of ryegrass species identification for a general screening of seed lots.
Download entire article