Flowers and stems (cladodes) of cactus pear [Opuntia ficus-indica (L.) Mill.] appear simultaneously in spring, and a second vegetative and reproductive flush can be obtained in early summer by completely removing flowers and cladodes of the spring flush at bloom time. The seasonal growth patterns of cactus pear fruits and cladodes were examined in terms of dry-weight accumulation and cladode extension (surface area) to determine if cladodes are competitive sinks during fruit development. Thermal time was calculated in terms of growing degree hours (GDH) accumulated from bud burst until fruit harvest. Fruits of the spring flush had a 25% lower dry weight and a shorter development period than the summer flush fruits, and, particularly, a shorter duration and a lower growth rate at the stage when most of the core development occurred. The duration of the fruit development period was better explained in terms of thermal rather than chronological time. The number of days required to reach commercial harvest maturity changed with the time of bud burst, but the thermal time (40 × 103 GDH) did not. Newly developing cladodes may become competitive sinks for resource allocation during most of fruit growth, as indicated by the cladode's higher absolute growth rate, and the fruit had the highest growth rate during the final swell of the core, corresponding to a consistent reduction in cladode growth rate. Cladode surface area extension in the first flush ceased at the time of summer fruit harvest (20 Aug.), while cladodes continued to increase in dry weight and thickness until the end of the growing season (November), and, eventually, during winter. The growth of fruit and cladodes of the summer flush occurred simultaneously over the course of the season; the cladodes had a similar surface area and a lower (25%) dry-weight accumulation and thickness than did first flush cladodes. The proportion of annual aboveground dry matter allocated to the fruits was 35% for the spring flush and 46% for the summer flush, being similar to harvest increment values reported for other fruit crops, such as peach [Prunus persica (L.) Batsch.]. Summer cladode pruning and fruit thinning should be accomplished early in the season to avoid resource-limited growth conditions that could reduce fruit and cladode growth potential.
P. Inglese, G. Barbera, and T. La Mantia
Lisa Wasko DeVetter, Rebecca Harbut, and Jed Colquhoun
resource limitation may be a contributor to biennial bearing, this study suggests that there are differences between cultivars in their ability to partition resources to both fruit and mixed bud development. The resource-allocation explanation may not fully
Brad G. Howlett, Samantha F.J. Read, Maryam Alavi, Brian T. Cutting, Warrick R. Nelson, Robert M. Goodwin, Sarah Cross, Trevor G. Thorp, and David E. Pattemore
quantify the magnitude of this resource-allocation limitation at the branch level in macadamia. This provides evidence as to whether the limit to total nut yield is due to pollination rather than a physiological limitation (such as through the availability
John E. Lloyd, Daniel A. Herms, Mary Ann Rose, and Jennifer Van Wagoner
The objective of this study was to determine if fertilization and irrigation practices in the nursery affect plant growth and stress resistance following outplanting in the landscape. Flowering crabapple (Malus) `Sutyzam', grown in containers under factorial combinations of two irrigations schedules (containers irrigated at 25% or 50% container capacity) and three rates of fertilization (N at 50, 200, 350 mg·L–1) in a nursery in 1997 were outplanted in a low maintenance landscape in 1998. Trees from the high fertility regime grew faster in the landscape the year of transplant. Tree growth in the landscape was positively correlated with N concentration in plants in the nursery and negatively correlated with concentrations of phenolics in the foliage in the landscape. However, the trees showing the greatest amount of diameter growth had the lowest concentrations of foliar phenolics. Trees with low concentrations of phenolics also exhibited a greater potential for herbivory by larvae of the eastern tent caterpillar, gypsy moth, and white-marked tussock moth. Additionally, trees exhibiting rapid growth in the landscape also had reduced photosynthesis during summer drought compared to slower growing trees, suggesting a reduced drought tolerance in the landscape. Differences in growth and stress resistance did not carry beyond the year of transplant. Our results illustrate that irrigation and fertilization methods in the nursery can influence growth post transplant, however fertilization also appears to have a significant impact on stress resistance traits of the trees. These impacts from the nursery production methods had no effect after plants had acclimated to the conditions in the landscape during the year following transplant.
Sibylle Stoeckli, Karsten Mody, Silvia Dorn, and Markus Kellerhals
have undesirable fruit traits ( Kellerhals et al., 2004b ), which underlines a possible resource allocation tradeoff. Evaluation of fruit quality traits is highly relevant because the fruit is the marketable product of an apple tree, and breeding for
Chengyan Yue, Jingjing Wang, Eric Watkins, Stacy A. Bonos, Kristen C. Nelson, James A. Murphy, William A. Meyer, and Brian P. Horgan
, followed by resource allocation across different projects. Table 3. Summary statistics of breeders’ ratings of challenges encountered when determining and implementing priorities when selecting a trait for inclusion in a breeding program based on a survey
Justine E. Vanden Heuvel and Carolyn J. DeMoranville
Davenport, 2006 ), a comprehensive study of both vegetative and reproductive growth patterns for multiple cranberry cultivars is lacking in the literature. This information is important, because a thorough understanding of resource allocation throughout the
Gina E. Fernandez, Laura M. Butler, and Frank J. Louws
The growth and development of three strawberry cultivars commonly grown in a plasticulture system were documented. Strawberry plants were harvested monthly and divided by roots, crown, leaves, flowers, and fruit and then dried in an oven. The dry matter production and resource allocation proceeded along a predictable pattern of development. The establishment phase was characterized by an active period of growth of root, crown and leaves in the fall. Through the winter, the plants underwent slow growth, ending in a transition period in the late winter/early spring when resources were allocated to both vegetative and reproductive growth. In the spring, all plant parts received significantly increased allocation of, or redistribution of, resources. Cultivars of California origin, `Chandler' and `Camarosa', displayed similar trends in yield, dry matter production, seasonal resource allocation, and growth analysis variables throughout the season. `Sweet Charlie', a cultivar from Florida, showed lower dry matter accumulation and relative growth rate in the spring, higher harvest index and lower yield than the California cultivars.
Justine E. Vanden Heuvel and Carolyn J. DeMoranville
Competition between fruit and upright growth in cranberry has not been previously studied, but negative correlations reported between upright length/dry weight and yield indicate that sink demand from vegetative tissues may reduce fruit production. `Stevens', `Howes', and `Early Black' uprights and fruit were collected on either a weekly or bi-weekly basis through the growing seasons of 2002–04. The data indicated a shifting of resource allocation from leaf area and dry weight accumulation to fruit growth when about 1500 growing degree days (GDD, base 4.5 °C) had accumulated. Following the initial surge in fruit growth, leaf area and dry weight accumulation resumed at roughly 2300 GDD, resulting in a competition for resources with the developing fruit until after 3000 GDD. A lag phase in fruit diameter and dry weight accumulation was noted in some cultivars in some years, and may be partially due to the resumption of leaf growth. Roots, uprights, and fruit may all compete for resources during the hottest portion of the growing season.
R. Daniel Lineberger
The World Wide Web is regarded widely as an invaluable asset to teaching and extension programs. Data supporting this assertion can be gathered actively or passively and can be analyzed to aid decision makers in matters of personnel evaluation and resource allocation. Most Web server software applications keep a log of connections by time, location, and file size transferred. The server logs of Aggie Horticulture, the Web site of the Texas Horticulture program, are analyzed bi-weekly using WebStat 2.3.4 and the number of logins, file size transferred (total and amount per sub-site), and client domain are tabulated. The number of “hits” increased from 15,000 to 120,000 per month (mid-February to mid-March of 1995 and 1996, respectively) over the last year. The logins came from 61 Internet domains representing 56 different countries. The “net” and “com” domains exhibited the greatest increase. “Active” data acquisition through a guest register at one of the sub-sites indicated that only 9% of the visitors registered. However, the data obtained from the active registrants were useful in determining the distribution of users by state and county within Texas.