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The effects of six freestanding training systems (Open Center, Untrained, 2-Scaffold V, 4-Scaffold V, Leaning V, and Central Leader at tree densities of 161, 161, 245, 375, 375, and 300 trees/acre, respectively) on yield and tree growth of `Redhaven' on Lovell rootstock were evaluated. Open-center and untrained trees were largest and had greatest yields per tree. The 2-scaffold V had the greatest production in kilograms per acre. Early productivity was related to tree density and pruning severity, not tree size. Training systems had no effect on fruit size.
Timing of budbreak in response to winter chilling is a critical factor in the suitability of peach [Prunus persica (L.) Batsch] cultivars to moderate climates such as that in the southeastern United States. Much of the research on chilling and dormancy has used excised cuttings or potted trees exposed to various treatments and forced under controlled conditions. Light is not generally considered an important factor in such experiments, and the effect of light during forcing has been little studied. The objective of this research was to compare light versus dark conditions during forcing as well as the effects of different colors of light during forcing. Our results showed that after chilling had been minimally satisfied, peach floral and vegetative budbreak occurred faster when forced in the presence of light than when forced in darkness. Light increased budbreak rate as well as the total percentage of budbreak. Red, yellow, and fluorescent light were more promotive in increasing budbreak than blue, green, infrared, or incandescent light, suggesting a role for phytochrome. Promotive effects of light were less when buds had received enough natural chill and heat to break within a week of forcing at 18 °C. In conclusion, light during forcing can have a significant effect of budbreak and needs to be considered when doing research on chilling and dormancy.
Response to chilling temperatures is a critical factor in the suitability of peach [Prunus persica (L.) Batsch] cultivars to moderate climates such as in the southeastern United States. Time of bloom depends on the innate chilling requirement of the cultivar as well as the timing and duration of cold and warm temperatures experienced by the buds. Most current chilling models have considered dormancy break a sequential process: after appropriate chilling is received, a fixed amount of heat accumulation will produce bloom. This research shows that as chilling exposure increases, the time and heat accumulation required for peach floral budbreak decreases in an exponential relationship. When chilling is ample, a sequential, two-part dormancy model is adequate to describe budbreak, and increased chilling has little effect on heat requirement. In lower-chilling situations relative to a particular cultivar, the curvilinear relationship between chilling and heat requirement results in more heat being required for budbreak. This relationship, in conjunction with the range of chilling requirement found among the buds on a tree, results in an extended, asymmetrical budbreak.
The Arkansas tree fruit research program has a history of involvement in rootstock development. The elements of rootstock development are rootstock cultivar testing and rootstock breeding and evaluation. Research is focused on apple and peach rootstocks. Rootstock testing is done in conjunction with the NC-140 cooperative uniform rootstock research project. Currently, there are 10 NC-140 trials in progress for apples, peaches, pears, and cherry rootstocks in Arkansas. The Arkansas rootstock breeding projects were established in the early 1970s as components of the fruit breeding program. The objectives are to develop apple and peach rootstocks which are adaptable to the Arkansas edaphic and adaphic conditions, have size control, have some degree of pest resistance, and are efficient in production. To date, 92 apple rootstock selections have been made and 41 are still in early evaluation for propagation and growth characteristics, while 56 peach rootstocks have been selected and are in early evaluation. Arkansas apple rootstocks selections are sequentially numbered with numbers preceded by AAR (ex: AAR-92). Peach rootstocks selections are numbered with numbers preceded by APR. Data from 2 NC-140 apple rootstock trials were presented and discussed.