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Abstract

Growth studies of field-seeded hybrid and open-pollinated asparagus (Asparagus officinalis L.) were conducted to determine the differences in shoot, bud, and crown growth during the first season after seeding and to determine growth relationships between shoot and crown variables that indicate critical periods of bud and crown production. F1 hybrid (UC 157) and UC800 open-pollinated (OP) asparagus seedlings emerged 4 to 6 weeks after seeding. A lag phase of shoot and root growth lasted 4 to 5 weeks after emergence in both cultivars. UC157 initiated more roots and accumulated more fern and crown fresh weight than UC800 early in the season, but by harvest crowns were not different in root and bud number, fresh weight, or fructose content (crown quality). Root/shoot ratios increased from a 2:1 ratio 6 weeks after emergence to 8:1 (UC157) and 6:1 (UC800) 23 weeks after emergence. Shoot/bud ratios stabilized from an approximate 2:1 ratio initially to an approximate 1:2 ratio 18 weeks after emergence. Bud production in the F1 and OP cultivars increased 6 and 10 weeks after emergence, respectively, and continued unabated up to crown harvest 23 weeks after emergence. Shoot number and fresh weight were not correlated highly with bud number. The number of roots vs. buds and the crown vs. fern fresh weights were correlated highly and were the best indicators of quality crown production. Vigorous fern development throughout the growing season increased the potential to produce higher-quality large crowns.

Open Access

Abstract

Asparagus (Asparagus officinalis L.) root filtrate (RF) depressed asparagus seedling emergence in a sterile peat–vermiculite medium. In a medium inoculated with Fusarium oxysporum f. sp. asparagi (FO), the effect was magnified. The response to RF dose, regardless of level of FO infestation, was quadratic. Comparisons with a sucrose solution of the same percentage of soluble solids as the RF suggested that reduced emergence may have been due in part to enhancement of FO growth by the energy source added to the medium. However, after germinating seeds in RF until radicle emergence, then rinsing and transferring them to FO-inoculated medium, emergence was reduced relative to controls. Therefore, depression of emergence apparently related both to an autotoxin somehow predisposing young radicles and/or hypocotyls to increased FO infection and to stimulation of FO in the rhizosphere by the soluble solids content of the root exudate. Infection was confirmed to be the only role of FO: sterilization of the spore suspension by Millipore (0.2 µm) filtration eliminated pathogen toxicity.

Open Access

Abstract

Aqueous extracts of asparagus (Asparagus officinalis L.) roots inhibited seed germination in tomato and lettuce, but not in cucumber. The extracts reduced hypocotyl growth in lettuce, shoot growth in asparagus, and inhibited radicle elongation in barley, lettuce, and asparagus. Seedling growth in tomato and two cultivars of wheat were not affected. Inhibition was concentration-dependent. Radicle growth in ‘Grand Rapids’ lettuce was sensitive to an extract concentration as low as 0.05 g dry root tissue/100 ml H2O. Asparagus radicles were more sensitive than asparagus shoots. In one experiment, phytotoxicity of crude extract was not altered by autoclaving. Aqueous root extracts of A. racemosis Willd. also inhibited germination and radicle growth in ‘Grand Rapids’ lettuce. A crude extract was purified by solvent partitioning, and charcoal adsorption, cation exchange, and thin-layer chromatography (TLC). A band from the TLC was found to fluoresce under ultraviolet light, react with phenolic-sensitive localization reagents, and inhibit the growth of lettuce and asparagus radicles.

Open Access
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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.

Open Access

Abstract

Series of greenhouse experiments were made to determine the effects of different endomycorrhizal fungi on the growth of oat (Avena sativa L., cv. Alma), strawberry (Fragaria × ananassa, cv. Redcoat), leek (Allium porrum L., cv. American Flag), apple (Malus domestica Borkh., cv. Beautiful Arcade), and asparagus (Asparagus officinalis L., cv. Mary Washington) plants which were grown in a calcined montomorillonite clay (Turface) medium and fertilized with a Long Ashton nutrient solution at 100 ml/week·pot (20 cm diameter). Plants were inoculated with 1 g of fresh ash (Fraxinus americana L.) roots harboring the different fungi. Out of 6 endomycorrhizal inocula used, 4 were well-identified: Gigaspora calospora (Nicol. & Gerd.) Gerd & Trappe, Glomus epigaeus Daniels & Trappe, Glomus macrocarpus Tul. & Tul., var. macrocarpus, and Glomus monosporus Gerd. & Trappe. The results indicate that Turface is a good growing medium for this type of study, as it permits good plant growth and abundant mycorrhiza formation with standard growing conditions. The fungi used produced different effects according to plant host. There was no correlation between the percentage of root infection and the stimulation of growth in the case of strawberry. Contrarily, there was a significant correlation (1% level) in the case of apple, asparagus, leek, and oats plants. No fungal specificity of the endophyte for the host plant was observed. The unknown endomycorrhizal species had effects on plant growth comparable to those of Glomus epigaeus with apple and strawberry plants.

Open Access

Abstract

Numerous asparagus (Asparagus officinalis L.) hybrids have been developed worldwide during the past 20 years. Most are clonal hybrids. The French (INRA) breeding program has successively introduced double, clonal, three-way all-male, and F1 (mixed or all-male) hybrids. Because these hybrids are evaluated at different locations during different years, a composite comparison of all cultivars is not feasible. A ranking index has been developed to make useful the huge volume of heterogeneous data that has been accumulated from the many trials during the past 10 years. This index is based for each hybrid on 2 years of comparative harvest data at four locations from about 40 hybrids and check cultivars at each location and each year. Using these rank indexes, the different types of hybrids can be compared one with another and with foreign hybrids. These indexes show that 1) all-male F1 and three-way hybrids tend to have high total yield and earliness; 2) F1 mixed hybrids are likely to have relatively large spear diameter; 3) double, clonal, and foreign hybrids produce the most attractive spears; 4) the general superiority of all-male hybrids is confirmed; 5) the four characters that are the major breeding objectives—early yield, high total yield, large spear size, and attractive spear appearance—are difficult, but not impossible, to combine into one hybrid. The indexes also show that, in spite of general trends, individual hybrids outstanding in all characteristics can be found in each type of hybrid.

Open Access

New Jersey `Syn 4' asparagus (Asparagus officinalis, L.) was grown on a sandy loam soil to compare plant survival and yield of asparagus grown from crowns and transplants under four irrigation treatments: sprinkler (SPR), surface trickle (ST), subsurface trickle (SST), and no irrigation (NI). While plant survival of crowns was not appreciably influenced by any irrigation treatment, survival of transplants was significantly increased by SST. Total and marketable yields from crowns and transplants were similar in the first harvest season (year 3). However, in years 4 and 5, the yield of crowns was higher than that of transplants. Subsurface trickle increased yield from transplants in years 4 and 5 and increased yield from crowns in year 5. All irrigation methods significantly increased both spear production (spear/ha) and average spear weight. Subsurface trickle irrigation resulted in the largest increase over NI in total yield and spear production.

Free access

Asparagus officinalis L. cv. Centennial established with transplants in 1983 was maintained with tillage or a no-till (NT) system to evaluate effects of tillage on yield and plant growth in a mature asparagus planting. Metribuzin or metribuzin + napropamide at 1.12 and 1.68 kg a.i./ha, respectively, were used for weed control in both tillage regimes. Marketable yields were assessed for 5 years. In 1989, in addition to yield data, destructive harvests of entire plants were made every 3 weeks from March to November to evaluate the effect of tillage on fern, crown, and bud growth, and carbohydrate status. Yields were reduced by tillage from 12% to 50% from 1985 to 1989. There were no herbicide effects nor was there an effect on yield due to an interaction between herbicides and tillage. All indices of growth measured for NT exceeded those in tilled plots, although seasonal patterns of growth were similar in both. Crown and fern weight, bud cluster, and bud and fern counts were higher by 178%, 175%, 152%, 161%, and 195%, respectively, in NT than in tilled plots. The metribuzin + napropamide combination did not reduce fern fresh weight or yield, but significantly reduced the number of bud clusters, buds, and ferns when compared to metribuzin alone. Chemical names used: 4-amino-(1,1-dimethylethyl)-3-(methylthio)-l (metribuzin); 2,4-triazin-5(4H) -one, N,N-diethyl-2-(naphthalenyloxy)-propanamide (napropamide).

Free access
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Net photosynthesis from whole plants of eight asparagus (Asparagus officinalis L.) genotypes was measured at two locations in an open infrared gas analysis system. Measurements started at about the completion of full fern growth, which occurred at the end of July and lasted through the season until fern senescence in late September. Net photosynthesis of the eight genotypes ranged from 15.67 to 27.79 μmol·m-2·s-1. Significant differences (P < 0.1) in net photosynthesis were found among the eight genotypes. Both yield and specific leaf mass (SLM) were correlated significantly with net photosynthesis. We suggest that specific leaf mass can be used as a criterion for selecting genotype of high photosynthetic ability. Daily photosynthetic rate patterns were studied and appear to be related to daily changes of stomatal conductance. Seasonal changes of asparagus' photosynthetic activity were studied. High photosynthetic activity was observed from July through August. Photosynthetic activity decreased greatly in September along with the fern maturation and unfavorable changes in environmental conditions.

Free access
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Fern vigor indices and estimates of percent marketable yield (PMY) were used to determine alternative measures of asparagus (Asparagus officinalis L.) marketable yield. Total yield was highly correlated (0.75 ≤ r ≤ 0.91), and marketable yield was not correlated with fern vigor indices. The products of fern vigor indices and seasonal PMYs were highly predictive of marketable yield (r 20.95). When the products of each daily PMY estimate and fern vigor index for the same season were determined, then averaged over years, <30% of correlations with marketable yield were ≥0.90, and r values varied considerably during the season. The products, averaged for 2 years, of fern vigor index and mean PMY estimated from combinations of three harvest dates during the season, except from the first harvest week, were associated with marketable yield. For the 40 3-day average estimates of PMY examined, 95% of Pearson correlation coefficients were ≥0.90 and all were ≥0.88. Thus, fern vigor index and PMY estimates from three harvest dates may be used to predict temperate zone marketable yield, decreasing labor requirements for yield trials, and facilitating evaluation of many experimental hybrids.

Free access