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  • Author or Editor: Luther Waters Jr. x
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High levels of sphagnum peat in the growing medium promoted growth of asparagus (Asparagus officinalis L. cv. Viking 2K) in a greenhouse study. Application of NH4NO3 > 1 g/pot (84 kg·ha-1 equivalent) was detrimental to root growth. High N rates and high organic matter levels decreased fibrous root development. Shoot dry weight was highly correlated with fleshy root number, root dry weight, and shoot vigor.

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Abstract

Increasing the P rates from 0 to 20 ppm increased shoot and crown fresh and dry weight, plant height, and fleshy root and bud production in 10-week-old asparagus (Asparagus officinalis L.) seedlings. Increasing K rates from 0 to 200 ppm decreased the production of fleshy roots relative to buds. Shoot production progressively increased as N rates increased from 100 to 200 ppm in conjunction with P rates increasing from 10 to 20 ppm. The partitioning of dry weight into crowns predominated over that partitioned into shoots in any combination of N rate from 0 to 200 ppm, and P rate from 0 to 20 ppm. With P rates held constant at 0 to 20 ppm, however, increasing the N rates from 0 to 200 ppm tended to reduce the partitioning rate into crowns and enhanced partitioning into the shoots. Nutrient solutions containing at least 20 ppm P and 100 ppm N and K are recommended in vermiculite-perlite-peat media natively low in NPK.

Open Access

Abstract

Cowpea [Vigna unguiculata (L.) Walp] has not been considered as a doublecrop alternative in the midwestern United States. Forage potential of cowpea following green peas (Pisum sativum L.) was studied in two field experiments in central and southern Minnesota. Dry-matter yield was higher in 1981 than in 1982 for all cowpea cultivars tested. Increasing the plant population improved yields for ‘California Black-eye Number 5’, ‘Alabama Giant Blackeye’, ‘Freezegreen’, and the breeding lines MN 139, MN 150, and Au 704, but not for ‘Colossus’. In vitro dry matter digestibility (IVDMD) was >63% for both stems and leaves in all cultivars and was not affected by plant population. Crude protein (CP) in leaves exceeded 20% for all treatments. We conclude that cowpea has excellent potential for supplying high-quality forage from double-cropping systems in the midwestern United States.

Open Access

Abstract

Equal half-root systems of cowpea seedlings were achieved with a split-root technique. By use of a high humidity chamber and growth pouches, it was determined that the survival rate of seedlings with bisected root systems was greater than 95%, and the development of the half root systems was uniform and adequate. There were no marked differences in growth and development of plants when treatments were applied to different halves of the root system. However, there was evidence of Zn translocation from noninoculated half-root systems which received Zn, to inoculated half-roots not receiving Zn, which resulted in increased nodulation and N2 fixation. This result supports reports of a direct relationship of Zn nutrition to nodulation and N2 fixation.

Open Access

Abstract

Single applications of ancymidol at 0.03, 0.12, 0.50, or 1.0 mg/plant were soil applied to asparagus seedlings (Asparagus officinalis L.) 3.5, 5.5, or 7.5 weeks after seeding. Increasing ancymidol rates from 0.03 to 1.0 mg/plant decreased bud number, fern dry weight, but not shoot number at all application times. When ancymidol was applied at 1.0 mg/plant at 3.5 weeks it reduced fleshy root production, but in plants treated at 5.5 to 7.5 weeks, it did not reduce fleshy root production. Increasing ancymidol rates from 0.03 to 1.0 mg/plant reduced the crown dry weight of plants 5.5 weeks and younger. Ancymidol from 0.03 to 1.0 mg/plant applied to 3.5-week-old plants increased the partitioning of dry matter into fern rather than crowns, but delaying application to 7.5 weeks after seeding reversed this relationship suggesting increased carbohydrate storage. Application of ancymidol from 0.03 to 1.0 mg/plant to plants 5.5-weeks-old or younger was considered detrimental to plant growth. Ancymidol at 0.50 mg/plant or less applied to 7.5-week-old plants enhanced the production of a stocky, compact transplant. Chemicals used. Ancymidol: α-cycloprophyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol.

Open Access

This study was conducted to determine if changes in the raffinose: sucrose ratio in embryos of shrunken-2 sweet corn (Zea mays L.) hybrids were related to differences in seed leachate conductivity between two hybrids harvested at four maturities and artificially dried to 0.10 g H2O/g fresh weight. The ratio of raffinose: sucrose differed for `Crisp N' Sweet 710' (CNS) and `How Sweet It Is' (HSII). The mass ratio of raffinose: sucrose in CNS was >0.3 in seed harvested between 0.44 to 0.64 g H2O/g fresh weight and increased as seed dried from the initial harvest moisture to 0.10 g H2O/g fresh weight. Raffinose: sucrose ratios of HSII were <0.3 at all harvests between 0.55 to 0.72 g H2O/g fresh weight, but changes during desiccation were not as pronounced. Leachate conductivity of whole seeds of CNS and HSII decreased as seeds were harvested at progressively lower moisture contents. We suggest that a higher raffinose: sucrose ratio may be indicative of increased seed vigor in shrunken-2 hybrids.

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Sweet corn (Zea mays L. var. rugosa Bonaf.) seed carrying the mutant endosperm gene shrunken-2 (sh2) are very susceptible to seed rot and pre- and post-emergence damping off. Experiments were conducted to determine if selected organic solvents were suitable carriers for fungicide infusion of sh2 sweet corn seed for improved germination and stand establishment. Seed of `Florida Staysweet' and `Crisp-n-Sweet 710' were immersed in acetone, cyclohexane, decahydronaphthalene (Decalin), dimethylsulfoxide (DMSO), ethanol, or xylene for 5 seconds, 0.25, 0.50, 1.0, 2.0, 4.0, or 8.0 hours, air-dried, and subjected to a cold-stress test. Total germination and percentage of normal seedlings in both cultivars were significantly decreased after 8 hours of immersion in acetone. Average seedling dry weight, however, did not decrease. DMSO was highly toxic to both cultivars. Ethanol increased seed mortality with increasing immersion times. Cyclohexane, Decalin, and xylene caused erratic responses in all measured variables as immersion time increased. In a second experiment, the effects of immersion time up to 4 hours in acetone on germination and vigor of 11 sh2 cultivars were compared. There was no correlation between cultivar germination or vigor and immersion in acetone. Results indicate acetone could be used to infuse fungicides into the seed of some sh2 cultivars without compromising seed germination or vigor. However, each sh2 cultivar must be screened individually to determine if it is a suitable candidate for organic solvent infusion of fungicides.

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The objective of this study was to examine seed maturity at harvest as it relates to seed vigor in two commercial shrunken-2 (sh2 J sweet corn hybrids (Zea mays L. var rugosa Bonaf., cvs. Florida Staysweet, Crisp N' `Sweet 710). Seed harvest began at 0.76 g H2O/g fresh weight in 1987 and at 0.70 g H2O/g fresh weight in 1988 and 1989, and was continued at gradually declining moisture levels until frost. In five different tests of seed performance, seed of `Florida Staysweet' (FLASS) harvested between 0.23 to 0.57 g H2O/g fresh weight in 1987 possessed the highest seedling vigor. In 1988 and 1989, maximum vigor was achieved by FLASS seed harvested from 0.40 to 0.60 g H2O/g fresh weight and `Crisp N' Sweet 710' (CNS) seed harvested from 0.45 to 0.65 g H2O/g fresh weight. Standard germination test, seedling growth cold test (SGCT), and seed leachate conductivity provided the most consistent results to `determine optimum seed maturity. Seed weight was not as reliable an indicator of seed vigor in 1988 and 1989 as it was in 1987, and endosperm and embryo weights did not correlate with seedling vigor in any year.

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Abstract

To understand early development of seed quality, seed lots of sweet corn (Zea mays L.) inbred PGG-27B were harvested from an increase field at 10 stages of maturity, beginning when kernel moisture was at 59% and continuing to 19% kernel moisture content (42 to 103 days after pollination, respectively). Seed lots were dried, hand-shelled, sized, and tested for standard germination and subjected to the seedling growth cold test (SGCT). Endosperm, embryo, and kernel dry weights, and endosperm : embryo (END:EMB) ratios were monitored as the seed matured. Field tests were planted to determine the influence of kernel maturity, grade, and hydration on stand establishment and early seedling growth. Seeds were partially hydrated by mixing with moist vermiculite and screening from the substrate when seeds had reached 30% moisture content. Results from hydrated seeds were compared to those from seeds at ≈10% seed moisture to determine the effect of presowing seed hydration on seedling establishment. The seed hydration effect depended on the environment, but seed size was shown consistently to influence emergence and early seedling dry weight. Seed harvested at 45% to 54% moisture had better stand establishment than seed harvested at the more typical moisture of near 35%. The stage of maturity, determined by kernel moisture, at which PGG-27B was harvested had little effect on standard germination. Hydrating the seed prior to the SGCT improved seedling growth for all early kernel maturities and all seed grades. Embryo dry weight of composite samples increased steadily up to the fifth harvest period (38% seed moisture), then leveled off. Kernel and endosperm dry weights were more variable at the fifth harvest than at others, but followed the same general pattern. The ratio of END:EMB dry weight decreased from the first to the fifth harvest, where it continued at a value near 4.9 through harvest 10. Seed moisture at harvest, seed size, and presowing seed hydration were shown to influence the seed quality of PGG-27B.

Open Access

A series of experiments exploring the effect of seed moisture and transplant management techniques was conducted with sh2 and su sweet corn (Zea mays L.). The use of seed and transplants in a progression of developmental stages from dry seed to moistened seed to 14-day-old transplants showed that moistened seed had no impact on plant `growth and development. Use of transplants generally had little impact beyond decreasing percent survival and plant height. Increasing the age of transplants reduced the time to maturity and harvest. Increasing the size of the transplant container (paper pot) decreased the time to harvest for younger seedings, but had no other effects. Premoistened seed were successfully held at 10C for up to 72 hours without damage following moisturization. Delays in irrigation of up to 2 days after planting moistened seed had no detrimental effects on sweet corn emergence and growth.

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