An index “internal slope” derived from the cumulative frequency distribution of individual seed leachate conductivities is related to seed quality; the larger the index value the less variation among individual seeds in a sample (100 seeds) and the higher the seed quality. We have recently developed data acquisition/instrurment control/data smoothing/data analysis software which accesses frequency and cumulative frequency distributions of individual seed conductivities and the derived index on an almost continuous basis from the start of the first soaking.
At present, lack of convergence with regard to curve fitting may occur necessitating multiple sampling times. A “window in time” approach is described whereby index estimates during a two-hour interval within the index stability phase are averaged. Evidence of the method's ability to assess seed vigor will be presented.
Cucumber plants )Cucumis sativa cv. Beta-al-pha) were grown in a glasshouse in pots of sand with 3 NaCl levels in the nutrient solution (0.40 and 60 mM) and placed in four large water baths controlled at different temperatures (13, 18,23, and 28°C). The increase of NaCl levels decreased the vegetative growth, seed yield, and seed quality, while the increase of root zone temperature up to 23C° increased the vegetative growth, seed yield and quality. Whereas, 28°C showed lower effect than 23°C. Ethylene production and the content of proline and free amino acids were increased with increasing NaCl levels. The increase of root zone temperature till 23°C decreased ethylene production, proline, and free amino acids contents. Zero NaCl (as control) obtained with 23°C root zone temperature appeared to be the best for the over-all growth, seed yield and seed quality of cucumber plants.
Interest in direct-seeding establishment of wildflowers as a component of landscape planting has continued to increase. Seed may be very expensive. Information is needed on the quality of seed available to consumers and the landscape industry. The goal of this work was to assess the level and consistency of seed quality available from the wildflower seed production/marketing industry. Eleven species of native prairie forb wildflowers and eight species of “garden” wildflowers from seven companies were purchased in 1992 and 1993 and subjected to germination testing. Germination procedures were those of AOSA where available, or generalized from the literature when no guidelines existed. Results showed significant variation among wildflower species, among companies supplying the same species, and over the two seed years tested in the study. These data reinforce the need for seed quality testing and reporting as a part of the sales of wildflower seed.
This research examines the potential of seed hydration for improving sweet corn (Zea mays L.) seed performance, especially for plantings in cool (10°–15°C) soils. In addition to the effect of hydration treatments, the influence of seed quality and cultivar was evaluated using electrolyte leakage tests and seedling growth cold tests. Seed hydration treatments included seed hardening (a wetting/drying cycle), seed moisturizing (placing seed in moist vermiculite), and osmoconditioning, which were compared to a dry seed control. Hardening and moisturizing treatments improved early emergence by as much as 20%, while osmoconditioning significantly lowered field emergence. Seed moisturizing and hardening also improved uniformity of emergence, and reduced the number of days required to attain 50% or 75% emergence. Seed hydration treatments were effective with the three levels (high, medium, and low) of seed quality and the three cultivars (‘Jubilee’, ‘Midway’, and ‘Reward’) studied.
Disease management is an important step in any crop establishment system. Emergence of field-seeded crops may take several weeks for many species and represents a vulnerable stage of plant growth. This paper considers various biological, chemical, and physical seed treatments for improved seed performance. The role of seed quality and cultural practices in seedling establishment also is reviewed. Multidisciplinary approaches to improving horticultural crop establishment are promising.
Seed weight, germination, seedling emergence, and yields were examined following desiccation of southernpea [Vigna unguiculata (L.) Walp cv. Mississippi Purple] plants with glyphosate [N-(phosphonomethyl)glycine]. Dry seed weight was not reduced by the desiccation process; however, seed quality of those treated at immature stages was reduced. Germination, seedling emergence, and yield from seed desiccated at immature stages were significantly less than from seeds desiccated at more mature stages of development. No differences were apparent between desiccation at mature stages and the control.
Application of systemic fungicides to sweet potato (Ipomoea batatas (L.) Lam.) increased the total number of healthy seed harvested 50% by increasing pod set, number of seed per pod and the proportion of healthy seed. Insecticides aldicarb and naled gave dramatic responses and increased the number of seedlings obtained per parent plant 2- to 5-fold. Insect damage appeared to be an important cause of low seed set and low seed quality in sweet potato.
Carrot (Daucus carota L. cv. Danvers) seed were produced at plant spacings of 0.05, 0.10, 0.20, and 0.30 m in 0.80-m rows to give populations of 25, 13, 6, and 4 plants/m2. Samples from the adjacent commercial carrot seed field provided an additional density of 36 plants/m2. Seed yield, harvest index, and seed quality were evaluated with respect to umbel order and plant density. Phenological development was unaffected by plant density, but plant height increased significantly as density increased. The number of umbels per plant and the number of seeds per umbel decreased with increasing plant density, while seed weight was unaffected. The proportion of the seed contributed by primary umbels increased from 20% at the lowest to 60% at the highest density. Seed yield per plant declined continuously as population increased, but seed yield per unit area increased to a maximum at 12 plants/m2, then declined. Total biological yield (above-ground biomass) rose to a plateau level with increasing plant population. Ceiling biological yield coincided with maximum seed yield. Seed quality within each umbel order, assessed by germination percentage and rate, seedling growth, embryo length, and abnormal or embryoless seeds, was unaffected by plant density, but consistently decreased from primary to tertiary umbel orders. Harvest index (seed yield/biological yield) was highly correlated with seed quality. The relationship between harvest index and plant density in carrot seed production may be useful in optimizing plant populations for maximum seed yield and quality.
Four planting and harvest dates yielded 16 lots of `Ruddy' red kidney beans (Phaseofus vulgaris L.) that were canned immediately after harvest in the fall and from storage in January and April. Late planting resulted in a high percentage of acceptable beans, but time of harvest had little effect on subsequent canning quality. The most important defect was transverse splitting from the hilum. Hilum splits, drained weight, cooked weight, and seed size were all negatively correlated with acceptability. Seed size was the most important factor determining quality, with the smallest seeds exhibiting the fewest splits. Length of storage had significant but small effects on canned seed quality.
In former days a vegetable grower would plant many times more seed than the plants he needed, to ensure a stand even if the seed quality were poorer than expected. Any excess seedlings were thinned out by hand, and the crop was harvested by hand, involving several harvests, with no concern for uniform maturity. Today the situation is different. Labor is expensive and becoming more so. The trend is toward mechanization, which requires precision planting or planting to a stand, with a once-over harvest. Only high-quality seed will do the job.