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Abstract

The effect of salinity on germination, first-year growth, and spear and fern yield of asparagus (Asparagus officinalis L.) was determined in germination dishes, crocks, and field plots, respectively. Saline treatments were imposed by irrigating with water that contained equal weights of NaCl and CaCl₂. Spear yield was reduced 2.0% for each unit increase in salinity above 4.1 d S · m⁻¹. Yield reduction was attributed primarily to a reduction in individual spear weight. Mature asparagus plants would be considered the most salt-tolerant crop commercially available. Asparagus possessed nearly the same salt tolerance for germination and spear production with soil salinities <7.2 d S·m⁻¹. Above 7.2 dS·m⁻¹, germination was less salt-tolerant. First-year growth was significantly more salt-sensitive than growth in subsequent years.

Abstract

Soluble sugar and starch levels and translocation of ¹⁴C-Iabeled photoassimilates in receptacles of pollinated, nonpollinated, and auxin-treated strawberry flowers (Fragaria × ananassa Duch. ‘Fern’) were examined from 0 to 144 hr after anthesis and correlated with fruit set and initial growth. Receptacle dry weight of nonpollinated flowers increased very little during the experimental period, whereas receptacles of pollinated and auxin-treated flowers showed a gain in dry weight within 24 hr, which continued throughout the experimental period. However, ¹⁴C accumulation in flower receptacles did not reflect the initial differences in growth, indicating that recently fixed ¹⁴C-labeled photosynthate was not the source for the observed dry weight increases. Analysis of carbohydrate pool sizes in treated receptacles indicated no consistent correlation between pool sizes and fruit set and initial growth. Thus, fruit set and initial growth in strawberry is not limited by the capacity of receptacles either to mobilize current source leaf assimilates or accumulate carbohydrates.

Seedlings of Syn 4-56 hybrid asparagus were planted in May, 1990 on loamy sand in the irrigated Central Sands region of Wisconsin. Treatments were unsuppressed living mulches of perennial ryegrass, Dutch white clover, a mixture of ryegrass and clover and cultivated bare ground. Ammonium nitrate was banded at rates of 90, 45, and 0 kg/ha across all treatments. Measurements of weed populations, asparagus growth, and soil and tissue nitrogen levels were made in 1990 and 1991. Soil nitrate and ammonium levels were measured in 30 cm increments to a depth of 90cm. In 1990, asparagus fern growth was greater in the bare ground controls than in any of the mulch treatment plots. In 1991, asparagus growth in the clover-based mulches was greater than that in the ryegrass mulch, although also still less than that of the bare ground control. Total accumulated nitrogen in clover-based mulch plots at the end of each season was more than twice the level of that of either the grass mulch or the cultivated plots. Percent nitrogen in asparagus tissue varied with mulch treatment: in 1991, the %N was higher in the asparagus tissue grown with clover than either that grown with the grass or on bare ground. Weed control in all mulch plots was good; in clover plots it was nearly 100%.

On Sept. 23, 1988, 12-month-old greenhouse-grown `Mary Washington', `Emerald', `UC 157 F<sub>1</sub>' and `UC 157 F₂' asparagus seedlings were sprayed with dikegulac solutions ranging from 0 to 750 mg·l^-1 with 150 mg·l^-1 increments. The potted plants were then transferred to a lathhouse to simulate the weather conditions in the field. No significant shoot emergence occurred prior to killing frosts and low temperatures in December. The rise of the temperature in Jan. and Feb. 1989, promoted shoot emergence in all cultivars; but `Mary Washington' did not respond to the treatments. At 600 mg·l<sup>-1</sup>, the chemical increased shoot emergence in `Emerald', `UC 157 F<sub>1</sub>' and `UC 157 F₂' by a respective cumulative average of 310, 161 and 305% over the control on 2 Feb. After intervening killing frosts and low temp, at the resumption of growth in late February 1989, `UC 157 F,' and `Mary Washington' were first to respond to the residual effects of the chemical, giving at 750 mg·l^-1 a respective cumulative increase of 65 and 77% over the control. Dikegulac did not affect the height and dry weight of `Mary Washington' ferns. But it reduced the height of `Emerald' without affecting its dry weight.

Azolla (Azolla filiculoides) is a floating fern that maintains a symbiotic relationship with an N-fixing blue-green algae. In many parts of Asia, azolla is used as a green manure in flooded rice cultivation. Taro (Colocasia esculenta) grown under flooded conditions is used to produce a traditional Hawaiian staple, poi. Azolla has been present in Hawaii for many years, but is not used in a controlled way for either nutrient augmentation of production sites or weed suppression. In this experiment, azolla was removed from a stream on the island of Kauai and multiplied in a nursery pond. Phosphoric acid was added to the nursery pond as a nutrient (P = 5 ppm) at 5-day intervals to accelerate azolla growth. Azolla was moved from the nursery pond and added to taro production plots at a seeding rate of 488 kg·m^–2. Phosphoric acid was used in production plots to hasten coverage of the water surface by azolla. Ten days after azolla inoculation, production plots were covered and taro seed pieces were planted. Weed dry weights from conventional and azolla covered plots were recorded 91 days after taro planting. Taro corms were harvested 315 days after planting. Weed dry weight in azolla plots was 86% less than conventional plots. Azolla delayed taro maturity, causing a 41% reduction in marketable corm yield.

Tissue culture is a useful means to clonally propagate new ornamental plant selections, particularly when plant material is limited and/or conventional propagation methods are ineffective. An efficient in vitro multiplication protocol was established to propagate a new goatsbeard hybrid (Aruncus dioicus, × A. aethusifolia). The hybrid is of interest because it exhibits a dwarf habit, delicate white flower panicles and fern-like leaves, yet is tolerant to heat and humidity. Experiments were conducted to evaluate explant type (nodes, stems, leaves, and floral parts), disinfestation procedures, and media formulations including varying concentrations of 6-benzylaminopurine (BAP) and naphthalene acetic acid (NAA). Rapid plant regeneration was obtained with a shoot organogenesis system using a half strength Murashige and Skoog medium supplemented with 4.4 μmol BAP, 0.54 μmol NAA, 30 g·L^-1 sucrose, and 3.0 g·L^-1 GelGro. Studies compared the performance and yield of plants rooted using different in vitro and ex vitro methods. Ex vitro rooting of shoots during greenhouse acclimatization under mist was most effective. Regenerated plants exhibited uniform and rapid growth, and performed well in greenhouse and field evaluations.

The effects of regenerant wastewater irrigation and high concentrations of Ca²⁺, K⁺, Mg²⁺, and Cl^– on growth and ion uptake of nine species of landscape plants were studied. Significant differences in chloride tolerance were detected among the species. Generally, the species that had greater uptake of chloride grew less than species that took up less amounts of chloride. Lace fern (Athyrium filix-femina Roth.) had the highest tissue Cl concentration and was the most affected. Hydrangea (Hydrangea macrophylla Ser.) also had high tissue Cl concentration, but showed no growth reduction. Its tolerance was attributable to a high tissue Ca concentration. The data suggest that in the species tested, higher tissue Ca concentrations were positively correlated with plant tolerance to Cl. Overall, the Cl^– concentration in the wastewater seems to be the factor most likely to create problems for the landscape plants. However, severe negative effects will probably be noticed only for very sensitive plant species, but it is important to determine this before applying regenerant irrigation water.

With recent advances in N analyzers, the Dumas method becomes more attractive as a replacement for Kjeldahl N. Kjeldahl N (K_N):Dumas N (D_N) ratios were determined for anthurium (A), orchid (O), fern (F) and turf (T). Dry tissues were ground to pass a 20-mesh seive. D_N was determined using 0.2 g of sample and a Leco FP-428. K_N was determined by digesting 0.4 g tissue with a CuO/TiO/K₂SO₄ catalyst and 10 mL H₂SO₄ at 450°C for 2 hr. Ammonium in the digest was assayed by colorimetry (Lachat analyzer). Overall (n=397 obs.), D_N was a good estimator of K_N: K_N = 0.90^(p<0.01) D_N + 0.09^(p=0.03), R²=0.93, over the 0.4-6.6 N range. K_N:D_N ratio was significantly (p<0.01) affected by plant type. Ratios of 0.85 for A, 0.92 for T, 0.99 for O, and 1.00 for F may be used to estimate K-N from D-N for the diagnosis of N nutrition, along with existing interpretative data.

The science of botany is often daunting to people who are training to become Master Gardener volunteers. However, the range of natural diversity of plants as well as practical information about plant anatomy are essential foundations for other parts of Master Gardener training. I will present a botany module that I have developed over the past 5 years. The module focuses on relevance to the trainee and builds on basic information to examine more complex aspects of botany, all in the space of the 3–6 hours often allotted for basic botany training. It begins with a “tour” of the plant kingdom and plant relatives like algae and fungi, mosses, liverworts, and ferns. I follow this with basic morphology of stems, roots, and leaves; this basic morphology is used to answer the question of how water and minerals move from the soil into and throughout plants, even reaching the height of the tallest tree. A short segment on mycorhizzae reinforces water and mineral transport, while providing a link to the plant kingdom tour. The mycorhizzal section also reinforces or complements training on soils, which is often presented in another portion of the training schedule. Finally, a segment on flowers introduces basic terminology and winds up a discussion of how to recognize monocotyledons and dicotyledons. Several optional hands-on activities help active learners assimilate the information and provide needed reflective time for more traditional learners. The module has been adopted as the official OSU Extension Master Gardener™ Program botany module in Oregon.

Mary Washington, UC157F₁, and UC157F₂ asparagus cultivars were grown from 1-year-old crown under greenhouse conditions in 30-liter pots containing Pro-Mix medium. The roots were cut to 10 cm prior to planting on 12 Feb. 1991. On July 12, 1991 the plants were transferred outdoors and sprayed with BA, GA_4/7 and Promalin at 400 mg. liter^-1 using tap water as control. On July 16, 1991 the treated ferns were cut at ground level and the plants were returned to the greenhouse, and arranged in a RCB design. Seven reps with one pot/rep were used. Data on time of emergence of first shoots were recorded daily until all pots had produced at least 1 shoot. When all plants had sprouted, cumulative number of all shoots/pots was recorded weekly thereafter over 5 weeks. BA and Promalin reduced time of emergence of shoots and increased the number of shoots/plant. GA_4/7 had no effect on shoot emergence or shoot number.