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Open access

Patrick J. Breen and Lloyd W. Martin

Abstract

Abundant (‘Hood’ and ‘Benton’) and poor (‘Olympus’) runnering cultivars of strawberry (Fragaria × ananassa Duch.) were grown in a milled-bark medium over an 8- or 16-fold range of slow-release ureaform N. Growth was poor or normal at low and intermediated rates of N, but inhibited at high rates. Number of leaves, crowns, and runners and subsequent inflorescence and flower production were frequently less than maximum at the highest level of N (4.8 gN/liter bark medium). Applied N had a significant effect on the number of crowns/plant, inflorescences/crown and flowers/inflorescence. In all cultivars, percent N in leaves in August, or in the entire shoot in November, showed a significant linear relationship with applied N. ‘Hood’ accumulated a higher concentration of N in both parts than ‘Olympus’ or ‘Benton’. Flower production in all cultivars was significantly correlated with the percent N in the shoot in November. Although the optimum range of applied N was similar for all cultivars, ‘Olympus’ was the most responsive to N in terms of increased leaf and flower production. When maximum values are compared, ‘Olympus’ in one year produced over 40% more leaves and 75% more flowers but at least 74% fewer runners than ‘Hood’ or ‘Benton’. ‘Benton’ was the only cultivar that at low and intermediate rates of applied N averaged less than one inflorescence/crown. Crown production by the 3 cultivars was not significantly different and high levels of applied N failed to increase the number of crowns available for flower initiation above those obtained at intermediate rates.

Free access

Neil C. Bell, Bernadine C. Strik, and Lloyd W. Martin

Primocanes of `Marion' trailing blackberry plants were suppressed by cutting them off at ground level in either late April, May, June, or July 1991 and 1992. An unsuppressed control was included in which primocanes were not cut. A single cane was removed from each replication of the five primocane suppression dates at monthly intervals from mid-November to mid-February 1991-92, and from mid-November to mid-January 1992-93. One-node samples were exposed to controlled freezing at temperatures of 4, -6, -9, -12, -15, and -18C in November through February. In December and January, the-6 temperature was replaced with-21C. After 5 days at room temperature following freezing, growing point, budbase, vascular, and pith tissues were evaluated for tissue browning on a 1 to 5 scale. The LT50 developed for each suppression date was compared to the control. July-suppressed plants were generally hardiest for all tissues. June-suppressed plants were somewhat less hardy than July-suppressed plants, while April-, May- and unsuppressed plants were comparable and least hardy. Cane tissues of July-suppressed and unsuppressed plants had a higher level of soluble carbohydrates than other suppression dates.

Free access

Neil C. Bell, Bernadine C. Strik, and Lloyd W. Martin

Primocanes of `Marion' trailing blackberry plants (Rubus spp.) were suppressed by cutting them off at ground level in either late April, May, June, or July 1991 and 1992. A control was included in which primocanes were not cut. Four canes per plant were trained in either August or February, with all other canes being removed and measured. Yield data were collected in 1992 and 1993, after which yield components were measured. Cane diameter was greatest for unsuppressed plants and declined with later primocane removal date. Cane length was greatest for unsuppressed and April-suppressed plants. Internode length decreased and main cane percent budbreak increased with later suppression date. Cane number and total main cane length per plant were increased in April-, May-, and June-suppressed plants in 1992 and for April- and June-suppressed plants in 1993. Consequently, yield of April-suppressed plants exceeded that of unsuppressed plants in 1992. Yield of April-, May-, and June-suppressed plants exceeded that of unsuppressed plants in 1993. August-trained plants yielded 46% more than February-trained plants, primarily because of higher percent budbreak on main canes. August-trained plants also produced longer canes with more nodes and a greater number of fruit per main cane lateral.

Open access

A. Richard Renquist, Patrick J. Breen, and Lloyd W. Martin

Abstract

Two field plantings of strawberries [Fragaria × ananassa Duch. cv. Olympus] were grown with and without black polyethylene mulch at 3 levels of drip irrigation and differential irrigation was maintained after plant establishment for 1 month in 1977 and 2 months in 1978. During the driest portion of each year the soil water potential at 20 cm depth remained above −0.5 bars for the highest level of irrigation, and fell below −11 bars at the lowest level. Mulch conserved soil moisture at the 2 lower irrigation levels in 1977, but this effect was minor in 1978. Vegetative growth was increased by both irrigation and mulch. The number of leaves produced during the first growing season was 30% (1977) and 25% (1978) greater in the high than the low-irrigation regime. Mulching improved leaf production 27% (1977) and 14% (1978). Most of these vegetative differences between treatments were still apparent at fruit harvest the following July. During a second year of treatments on the 1977 planting, the number of leaves was further enhanced by mulch and high irrigation. At the subsequent fruit harvest, 2-year-old plants had more leaves than those 1 year old, but the leaf area per plant averaged 27% lower. Leaf and crown dry weights of either 1- or 2-year-old plants at fruit harvest were slightly greater due to irrigation and significantly higher due to mulch, whereas root dry weight was unaffected by either treatment. The amount of summer irrigation required to sustain vigorous vegetative growth in mulched plants was only one third that of unmulched strawberries.

Open access

A. Richard Renquist, Patrick J. Breen, and Lloyd W. Martin

Abstract

Strawberries [Fragaria × ananassa Duch. cv. Olympus] were planted in 2 successive years and grown at 3 levels of drip irrigation, with and without polyethylene mulch. Differential irrigation was applied only during 1 (1977) or 2 (1978) months during the summer and all treatments were irrigated equally during the following spring. In both summers, the soil water potential at 20-cm depth was maintained above −0.5 bars for the highest level of irrigation and fell below −11 bars at the low level. Mulch conserved soil moisture at the 2 lower irrigation levels in 1977, but this effect was nearly absent in 1978 conditions. The highest irrigation regime had about 22% more flowers and 18% more fruit than the lowest regime in the spring of the first harvest season in both plantings. Mulch only increased flowering in the 1977 planting (12%), whereas the number of fruit was increased about 11% by mulch in both plantings. The high yield capacity of ‘Olympus’ was confirmed (37.8 MT/ha). Mulch increased the yield of the 1978 planting 18%, despite its lack of effect on the number of flowers in that year. This suggests a spring influence on yield. The highest irrigation regime out-yielded the lowest regime by 13% in the first crop of both plantings, although this increase was significant only in the 1977 planting. The second year crop of the 1977 planting yielded 21% less than the first year, and failed to show significant treatment differences in flower number or fruit yield despite much larger plant size with mulch and higher irrigation levels. The yield component which showed the greatest decline between years was the percentage fruit set. In general, mulch and greater summer irrigation increased fruit yield less dramatically than they enhanced vegetative growth. However, the 13% to 18% increases may represent a significant economic gain because the typical yield of ‘Olympus’ is much higher than other Pacific Northwest cultivars. Mulch also produced a greater water use efficiency.

Open access

A. Richard Renquist, Patrick J. Breen, and Lloyd W. Martin

Abstract

‘Olympus’ strawberries (Fragaria × ananassa (Duch.) with and without black polyethylene mulch were compared in terms of leaflet elongation and diurnal water potential (ψ) of leaves at 2 levels of drip irrigation. Mulch increased leaflet elongation at both irrigation levels, but had no appreciable effect on soil water potential at 20 cm depth, nor on leaf ψ or leaf turgor. Leaflet elongation with black polyethylene may have been favored by the increased soil temperature throughout the upper 20 cm. At the 10-cm depth, mulched, high-moisture soil was an average of 3.0°C warmer during a diurnal cycle. Greatest warming was in late afternoon and late evening in low and high moisture soil, respectively.

Open access

Jeffery L. Olsen, Lloyd W. Martin, Peter J. Pelofske, Patrick J. Breen, and Charles F. Forney

Abstract

Field grown strawberry plants (Fragaria × ananassa Duch.) of an advanced breeding selection (OR-US 4681) were harvested every 3–4 days during establishment and through fruiting the next spring. Plant dry weight and leaf area increased rapidly during mid-summer, then slowed and finally ceased in October. Absolute growth rate (AGR) peaked at 1 g dry matter/day near 1 Sept., then fell to zero by early October. Over this period, there was a decrease in weekly mean temperature (37%), solar radiation (47%), and daylength (35%). Maximum values of relative growth rate (RGR) (0.044 g/g/day) and unit leaf rate (ULR) (9 g/m2/day) were determined at the start of sampling at the end of June; both rates declined steadily thereafter. The following April through June, both plant dry weight and leaf area increased exponentially, whereas RGR remained constant at 0.02 g/g/day, and ULR rose from 5.5 to 6.5 g/m2/day. The rate of dry matter accumulation in fruit was exponential, whereas it was linear in leaf lamina and stems (crowns plus petioles). A much smaller proportion of dry matter was partitioned to leaves during fruiting than during plant establishment.

Open access

Megan Hughes, Lloyd W. Martin, and Patrick J. Breen

Abstract

Strawberries (Fragaria × ananassa Duch. cv. Hood) were grown at three levels of soil P and inoculated with either Glomus fasciculatus (Thaxter sensu Gerd.) Gerd. & Trappe or Gigaspora calospora (Nicol. & Gerd.) Gerd. & Trappe mycorrhizal fungus. P and N concentration in the aerial part of inoculated plants were higher than in controls; highest concentrations were found in plants inoculated with Glomus fasciculatus. Inoculation with this fungus also resulted in the greatest length of mycorrhizal roots and the highest percentage of total root length infected.

Free access

Margaret M. Stahler, Francis J. Lawrence, Patrick P. Moore, Lloyd W. Martin, George W. Varseveld, and W. Arden Sheets