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M. Pilar Bañados, Carolina Alvarez, and Alejandra Soto

To evaluate the effect of the time of primocane tipping on harvest date of `Heritage' red raspberry in the central valley of Chile (southern hemisphere), we tipped primocanes at three dates during the 1996–97 growing seasons: in Nov. 1996 (PN), Dec. 1996 (PD), and Jan. 1997 (PJ). Tipping was done manually at a 1.10-m height. Harvest date, fruit quality, and yield component was evaluated in the control and three tipping dates. A difference of 75 days on the initiation of harvest date was detected among treatments. Harvest date initiation was on 20 Jan. for the control with no tipping and for PN, 3 Mar. for PD, and 4 Apr. for PJ. Fruit of the PN treatment was smaller and lighter than the rest of the treatments; however, little differences in soluble solids, acidity, and pH were detected among treatments. Primocane lateral number was 14 for the control treatment and decreased to seven in tipped primocanes. Lateral length increased largely with tipping treatments: 7.8 cm in the control, 30 cm in PN, 29 cm in PD, and 42 cm in PJ. Fruit per lateral ranged between 6.2 in control and 12.2 in PD. Yields estimation for the fall production were 8.5 t/ha in the control, and increased to 12 t/ha estimated for the PJ treatment. The time of primocane tipping had an important effect on `Heritage' red raspberry harvest date, lateral length, and estimated yield.

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M. Pilar Bañados, Gary D. Coleman, and Tony H. H. Chen

In poplar (Populus deltoides) a 32kDa bark storage protein (BSP) accumulates during the fall, and is a major form of stored nitrogen during overwintering. This protein is induced by short-day (SD) photoperiod and may play an important role in nitrogen cycling in the plant. To determine the effect of plant nitrogen status upon BSP gene expression, poplar plants were grown in controlled environmental chambers under either SD or long-day (LD) photoperiods and watered with either 5, 10, 50, and 100 mM NH4NO3 for four weeks. [15N]-NH4NO3 was applied during the first and third weeks. SDS-PAGE and western blot analysis were used to detect the relative amounts of BSP. RNA gel blot analysis was used to determine the changes in BSP gene expression. BSP accumulation was enhanced by increasing levels of nitrogen under both photoperiods, however, SD photoperiod appears to moderate the response. These results indicate that BSP gene expression is dependant upon the nutritional status of the plant. [15N] analysis will also be presented.

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Bernadine C. Strik, John R. Clark, Chad E. Finn, and M. Pilar Bañados

A survey of worldwide blackberry (Rubus spp.) production was conducted in 2005. Results indicated there were an estimated 20,035 ha of blackberries planted and commercially cultivated worldwide, a 45% increase from 1995. Wild blackberries still make a significant contribution to worldwide production, with 8000 ha and 13,460 Mg harvested in 2004. There were 7692 ha of commercially cultivated blackberries in Europe, 7159 ha in North America, 1640 ha in Central America, 1597 ha in South America, 297 ha in Oceania, and 100 ha in Africa. Worldwide production of cultivated blackberries was 140,292 Mg in 2005. Of the blackberry area worldwide, 50% was planted to semierect cultivars, 25% to erect, and 25% to trailing types. ‘Thornfree’, ‘Loch Ness’, and ‘Chester Thornless’ were the most important semierect types, and ‘Brazos’ and ‘Marion’ the most common erect and trailing types, respectively. In general, erect and semierect cultivars are grown for fresh market and trailing cultivars for processing. Fresh fruit are usually picked into the final container in the field, whereas 75% of trailing blackberries for processing are picked by machine. Common production problems are reported. Production systems for field-grown blackberry differ with type grown and region. For example, in Mexico, production systems are modified to extend the production season for ‘Tupy’ and other erect-type cultivars from mid-October to June. Organic blackberry production is expected to increase from the 2528 ha planted in 2005. An estimated 315 ha of blackberries were grown under tunnels, mainly to protect against adverse weather and target high-priced markets. Based on this survey, there may be 27,032 ha of commercial blackberries planted worldwide in 2015, not including production from harvested wild plants.

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M. Pilar Bañados, Bernadine C. Strik, David R. Bryla, and Timothy L. Righetti

The effects of nitrogen (N) fertilizer application on plant growth, N uptake, and biomass and N allocation in highbush blueberry (Vaccinium corymbosum L. ‘Bluecrop’) were determined during the first 2 years of field establishment. Plants were either grown without N fertilizer after planting (0N) or were fertilized with 50, 100, or 150 kg·ha−1 of N (50N, 100N, 150N, respectively) per year using 15N-depleted ammonium sulfate the first year (2002) and non-labeled ammonium sulfate the second year (2003) and were destructively harvested on 11 dates from Mar. 2002 to Jan. 2004. Application of 50N produced the most growth and yield among the N fertilizer treatments, whereas application of 100N and 150N reduced total plant dry weight (DW) and relative uptake of N fertilizer and resulted in 17% to 55% plant mortality. By the end of the first growing season in Oct. 2002, plants fertilized with 50N, 100N, and 150N recovered 17%, 10%, and 3% of the total N applied, respectively. The top-to-root DW ratio was 1.2, 1.6, 2.1, and 1.5 for the 0N, 50N, 100N, and 150N treatments, respectively. By Feb. 2003, 0N plants gained 1.6 g/plant of N from soil and pre-plant N sources, whereas fertilized plants accumulated only 0.9 g/plant of N from these sources and took up an average of 1.4 g/plant of N from the fertilizer. In Year 2, total N and dry matter increased from harvest to dormancy in 0N plants but decreased in N-fertilized plants. Plants grown with 0N also allocated less biomass to leaves and fruit than fertilized plants and therefore lost less DW and N during leaf abscission, pruning, and fruit harvest. Consequently, by Jan. 2004, there was little difference in DW between 0N and 50N treatments; however, as a result of lower N concentrations, 0N plants accumulated only 3.6 g/plant (9.6 kg·ha−1) of N, whereas plants fertilized with 50N accumulated 6.4 g/plant (17.8 kg·ha−1), 20% of which came from 15N fertilizer applied in 2002. Although fertilizer N applied in 2002 was diluted by non-labeled N applications the next year, total N derived from the fertilizer (NDFF) almost doubled during the second season, before post-harvest losses brought it back to the starting point.

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David R. Bryla, Bernadine C. Strik, M. Pilar Bañados, and Timothy L. Righetti

A study was done to determine the macro- and micronutrient requirements of young northern highbush blueberry plants (Vaccinium corymbosum L. ‘Bluecrop’) during the first 2 years of establishment and to examine how these requirements were affected by the amount of nitrogen (N) fertilizer applied. The plants were spaced 1.2 × 3.0 m apart and fertilized with 0, 50, or 100 kg·ha−1 of N, 35 kg·ha−1 of phosphorus (P), and 66 kg·ha−1 of potassium (K) each spring. A light fruit crop was harvested during the second year after planting. Plants were excavated and parts sampled for complete nutrient analysis at six key stages of development, from leaf budbreak after planting to fruit harvest the next year. The concentration of several nutrients in the leaves, including N, P, calcium (Ca), sulfur (S), and manganese (Mn), increased with N fertilizer application, whereas leaf boron (B) concentration decreased. In most cases, the concentration of nutrients was within or above the range considered normal for mature blueberry plants, although leaf N was below normal in plants grown without fertilizer in Year 1, and leaf B was below normal in plants fertilized with 50 or 100 kg·ha−1 N in Year 2. Plants fertilized with 50 kg·ha−1 N were largest, producing 22% to 32% more dry weight (DW) the first season and 78% to 90% more DW the second season than unfertilized plants or plants fertilized with 100 kg·ha−1 N. Most DW accumulated in new shoots, leaves, and roots in both years as well as in fruit the second year. New shoot and leaf DW was much greater each year when plants were fertilized with 50 or 100 kg·ha−1 N, whereas root DW was only greater at fruit harvest and only when 50 kg·ha−1 N was applied. Application of 50 kg·ha−1 N also increased DW of woody stems by fruit harvest, but neither 50 nor 100 kg·ha−1 N had a significant effect on crown, flower, or fruit DW. Depending on treatment, plants lost 16% to 29% of total biomass at leaf abscission, 3% to 16% when pruned in winter, and 13% to 32% at fruit harvest. The content of most nutrients in the plant followed the same patterns of accumulation and loss as plant DW. However, unlike DW, magnesium (Mg), iron (Fe), and zinc (Zn) content in new shoots and leaves was similar among N treatments the first year, and N fertilizer increased N and S content in woody stems much earlier than it increased biomass of the stems. Likewise, N, P, S, and Zn content in the crown were greater at times when N fertilizer was applied, whereas K and Ca content were sometimes lower. Overall, plants fertilized with 50 kg·ha−1 N produced the most growth and, from planting to first fruit harvest, required 34.8 kg·ha−1 N, 2.3 kg·ha−1 P, 12.5 kg·ha−1 K, 8.4 kg·ha−1 Ca, 3.8 kg·ha−1 Mg, 5.9 kg·ha−1 S, 295 g·ha−1 Fe, 40 g·ha−1 B, 23 g·ha−1 copper (Cu), 1273 g·ha−1 Mn, and 65 g·ha−1 Zn. Thus, of the total amount of fertilizer applied over 2 years, only 21% of the N, 3% of the P, and 9% of the K were used by plants during establishment.