The effects of shoot length, fruit density, thinning patterns, and light levels on crop quality of peach (Prunus persica Batsch.) were investigated. On shoots 50 and 75 cm long, fruits were thinned to produce several distribution patterns, with peaches concentrated in the bottom, middle, or distal portion of the shoot, or uniformly spaced along the shoot at two fruit densities (≈10 or 15 cm between fruit). The lower fruit density on the longer shoots resulted in larger fruits. At the same fruit density, fruits clustered in the distal section of the shoot were smaller, with lower soluble solids concentration (SSC) and a smaller percentage of the exocarp colored red than for the other spacing patterns. Photosynthetically active radiation (PAR) was negatively correlated with the percentage of green exocarp and positively correlated with the percentage of red exocarp. However, the low correlation coefficients (0.45 and 0.50, respectively) indicate that even low light levels can result in substantial red pigment development in peach fruit.
Several planting treatments modified vegetative and reproductive growth of young, own-rooted peach (Prums persica) trees evaluated at two levels of irrigation in a high-density orchard (5000 trees/ha). Trees planted in auger holes, narrow herbicide strips, and in fabric-lined trenches, but not those from raised beds, were smaller than control trees set in holes dug with a shovel. After two growing seasons, trees planted in the fabric-lined trenches were smaller and had more flowers per node and greater flower bud densities than trees in other planting treatments. Yield efficiency was greatest for this treatment, although fruit size was small throughout the orchard. Irrigation rates did not affect fruit yield or size. The effects of irrigation rate on vegetative growth were small compared to differences among planting treatments.
One of the most important aspects of designing an experiment is determining sample size. Without prior experience, estimation of the amount of variation that will be encountered during data collection is difficult. This information is necessary to decide the number of replicates needed. Recently, Marini (1985) and Marini and Trout (1984) have published reports on the sample size needed to determine treatment effects in peach tree growth and yield studies. However, this type of information is lacking for sample sizes required to detect differences in net photosynthesis in peach. This note attempts to assist researchers in determining correct sample size.
A sensor for measuring photosynthetically active radiation was constructed using a silicon photocell in combination with a glass absorption filter. A trimmer potentiometer was used for standardization of sensor output. The sensors were calibrated using a commercially available quantum sensor. Average correlation coefficient between constructed sensors and the standard was 0.94. The sensors had a quantum response, were sensitive only in the wavelengths between 400 and 700 nm, exhibited a linear response to varying PAR light levels, and were inexpensive to construct.
A procedure was developed for detecting daily changes in the rate of growth and development of leaves and fruit of peach [Prunus persica (L.) Batsch.]. Quantitative morphological stages of leaf and fruit development were determined for 3 cultivars, transformed into growth rates, and used as dependent variables for regression on a variety of daily environmental variables: maximum and minimum temperature, degree hours, precipitation, solar radiation, estimated soil moisture (Thornthwaite method), 1- to 3-day lags of these variables, quadratic and cubic transformations, and selected 2-variable products of the basic variables. Prediction equations performed well in tests from different years, locations, and cultivars. Maximum and minimum temperature, precipitation, soil moisture, and age were the most important variables for the leaf growth prediction equation. In the fruit growth prediction equation, maximum and minimum temperature, soil moisture, and age were most important.
The effects of BA alone or in combination with GA4+7 and with either daminozide or a surfactant on growth and lateral development of peach [Prunus persica (L.) cv. Redhaven] were evaluated at 4 stages of terminal growth. BA + GA4+7 at 500 ppm or 1000 ppm daminozide was the most effective treatment for inducing lateral development when applied at terminal growth of 15-20 cm or 31-36 cm. BA + GA4+7 increased both tree height and average internode length for all treatments. BA with either surfactant or daminozide was not effective in inducing lateral shoot formation and caused shorter internodes and retarded tree growth in all treatment combinations except 250 ppm + 1000 ppm daminozide. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA) and (1α,2β,4aα,4bβ,10β)-2,4a,7-trihydroxy-l-methyl-8-methylenegibb-3-ene-l,10-dicarboxylic acid 1,4a-lactone (GA4+7).
The cover depicts a cross-sectional photomicrograph of a root from peach treated with a soil application of paclobutrazol. The 14-μm section was taken about 2 mm from the root apex. The tissue was fixed and embedded by conventional methods similar to those described by Sass (8), then doublestained with safranin and fast green. Photomicrographs were taken at × 180 with Ektachrome film (Kodak) using a Leitz Dialux 20 research microscope equipped with an Orthomat automatic microscope camera.
The influence of hormone concentration, date of cutting collection, rooting medium, shoot position, cutting type, and wounding on the rooting of semi-hardwood ‘Hayward’ kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. Deliciosa] cuttings was evaluated. The highest percent rooting was obtained with cuttings from the apical (88%) and medial (66%) portion of current season's growth. Higher rooting percentages were obtained when shoots were collected mid-June to mid-July rather than September. Two-node cuttings wounded through the lower bud were given higher root quality ratings than wounded one-node cuttings, although rooting percentages were similar. Treatment with IBA at 4.0 or 6.0 g·liter–1 resulted in similar rooting percentages (58% and 69%, respectively) of two-node cuttings, but root ratings were higher with 6.0 g·liter–1. Cuttings rooted in vermiculite were given higher root quality ratings than those in perlite or 1 peat : 1 perlite (v/v) and had a higher percentage of rooted cuttings than those in peat:perlite. Chemical name used: 1H-indole-3-butyric acid (IBA).
Factorial combinations of ± root pruning (RP) and ± summer pruning (SP) were initiated in 1991 as subplots within a Redhaven/Lovell study of orchard training systems: Open Center (OC), Y-Trellis (YT), Central Leader (CL), and Meadow Orchard (MO) established in 1985. Root pruning was imposed at bloom (March 28) at 76 cm from the trunk to a depth of 45 cm. Summer pruning consisted of preharvest removal of water sprouts (June 5). Canopy density, quantified by transmittance of PAR radiation through the canopy, was greatest in OC and MO and least in YT and CL systems. SP and RP treatments further reduced canopy density by 35 to 80%. There were no main or interactive effects of SP and RP on 1991 yields or fruit quality, and also no interactive effects of orchard systems with SP and RP. Thus, SP and RP reduced canopy density without negative effects on fruit. RP, however, advanced harvest date by ca 4 days. A parallel study was also initiated in 1991 to determine the effects of root pruning distance (30, 60, 90 cm from the trunk, or no RP) on canopy density, yield, and fruit quality of mature, OC-trained Redhaven/ and Jefferson/Lovell. Reduction in canopy density without loss of yield or fruit size was obtained at a RP distance between 60 and 90 cm.
Various techniques have been used for emasculation of rosaceous fruits; fingernails, scalpels, and tweezers are typical tools (1, 3, 5, 7). Emasculation tools for stone fruits have been made from a hacksaw and from square-jawed forceps with cut out corners (6). Barrett and Arisumi (2) devised an instrument that consisted of a pair of scissors with a triangular notch in the blade whose width could be adjusted by an adjustable arm or set screw.