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The objective was to study selected physiological characteristics of the canopy and examine changes in dry matter partitioning between the root and shoot in two genetically reduced size growth types (dwarf and pillar) relative to the standard growth type. The dwarf phenotype had reduced leaf/root ratio, less allocation of dry matter to woody tissue and more to leaf tissue, high net photosynthesis, and lower leaf respiration compared to the standard and pillar phenotypes. The dwarf and pillar types had greater resistance to water flow than the standard type. Genetic changes in growth habit significantly alter many physiological parameters of peach tree growth and structure.
Our objective was to evaluate the dry-matter partitioning between the roots and shoots of two genetically size-controlled peach [Prunus persica (L.) Batsch] types, dwarf and pillar, compared to a full-sized standard peach type. Compared to the pillar and standard types, the dwarf type had a reduced leaf: root ratio, less allocation of dry matter to woody tissue and more to leaf tissue. Genetically size-controlled peach trees have a smaller root system, but a lower leaf: root ratio and may require modified soil and water management techniques to ensure high productivity.
Hand-thinning (Prunus persica L. Batsch) “Y”-trained peach trees at bloom and 51 days after full bloom (DAFB) was compared to mechanical fruit thinning 51 DAFB using a spiked-drum and an impact shaker. The spiked-drum shaker removed more fruit from horizontal branches than from vertical branches, yet did not selectively remove either large or small fruit. Bloom thinning by hand increased fruit size compared to postbloom thinning 51 DAFB, and both postbloom mechanical thinning techniques were as effective as postbloom hand thinning. The spiked-drum shaker may be a better thinning technique than the impact shaker because it transfers less shaking energy to the fruit, can be used in high-density plantings, and does not contact the trunk, lessening the potential for tree damage.
The purpose of these studies was to compare two mechanical means of thinning with hand thinning peaches 40-60 days after full bloom. A spiked-drum canopy shaker and a trunk impacter shaker were used to thin `Loring' peach trained to `Y' shape. Initial studies demonstrated that the spiked-drum shaker removed more fruit from horizontal than vertical branches. The spiked-drum shaker did not preferentially remove larger or smaller fruit. The yield of large fruit was not significantly different for hand or mechanically thinned trees when fruit was thinned 40-60 days after full bloom.
Length and distribution of the roots of 2-year old cv. `Flordaprince' peach trees grown under polyethylene greenhouse were studied over a two year period. The self-rooted, micropropagated trees were spaced 4.9 m between the row and 70, 52 and 42 cm. along the row to obtain a density of 3000, 4000 and 5000 trees/ha respectively. Orchard was clean cultivated, mulched along the row with black plastic fabric 1 m wide, and drip fertigated. Soon after harvest, for each density, the root system of one tree was totally excavated and root length, distribution, dry weight and nutrients content were determined. Total root length per tree was negatively related to planting density in two-year old trees (470, 380 and 320 m/tree respectively for 3000, 4000 and 5000 trees/ha). The shallowest root systems were found at 5000 trees/ha density and their length was unchanged from year to year. Root length density, ranging from 220 to 250 m/m), was only slightly affected by spacing in the two years. The roots were evenly distributed between the two sides of the rows.