A simple and rapid procedure for the purification of indole-3-acetic acid prior to gas chromatography-selected ion monitoring-mass spectrographic analysis was developed using an amino anion exchange minicolumn and a short high resolution C18 column. Since multiple samples can be prepared at one time, the procedure is more rapid and the sample preparation time is reduced to one-third that normally required. In addition, the final recovery was improved by 40 to 50% over that of a solvent partitioning procedure.

ABSTRACIThe amount of indole-3-acetic acid (IAA) was measured in peach fruits by gas chromatography-mass spectrometry-selective ion monitoring using an isotope dilution assay with I"CC6IIAA as an internal standard throughout the growing season. Ethylene evolution of the fruit was also measured. IAA levels were 25 nanograms per gram fresh weight, 18 enous IAA concentration and observed ethylene evolution were correlated, given that auxin can promote ethylene evolution (14). MATERIALS AND METHODSPlant Material. Developing fruits of Prunus persica cv Redhaven were obtained from the University of Maryland Research Farm, Silver Spring, MD. Beginning from 18 to 88 d after anthesis fruits were harvested from around the entire periphery of the tree once or twice a week for IAA and ethylene, respectively. The abscission of unpollinated flowers was completed by d 18. At 88 d after anthesis, fruits were mature, firm-ripe, and capable of softening to full-ripe within 72 h of harvest. Uniform, upright fruiting shoots of about 60 cm length at 1.8 m height were harvested at 8:00 AM and their cut bases were immediately placed in water. One shoot was cut from each of 60 trees on each sampling date. Thirty min were needed to harvest and transport the fruit to the laboratory. The fruits were removed from their shoots immediately after transport and extraction begun.To minimize fruit-to-fruit variability only basal fruits were used for analyses. Fruits displaying visible signs of senescence, disease, or insect damage were not used. On each sampling date a minimum of 10 individual peach fruits were taken for ethylene determinations. An additional 2 replicates of a minimum of 10 pooled fruits were simultaneously extracted and assayed for endogenous levels of free IAA. In addition to the above, 8 to 10 peach ovules were excised from fruits on 60, 67, 81, and 88 d postanthesis. A single replicate of pooled ovules was extracted and endogenous free IAA levels determined on each date. This sampling protocol was used to avoid potential artifacts of frozen material and allow maximum frequency of sampling time. This latter aspect was important because our primary interest was in examining trends during development.Extraction and Measurement of Free IAA. A minimum of 10 whole fruits were added to cold (-20'C) acetone; tissue:acetone ratio 3:7 (w:v). To this mixture was added 50 to 100,000 dpm of '4C-(methylene)-IAA (59 or 51.6 mCi/mmol, Amersham containing 1.2 to 23.1 ng 12C-IAA per extract) and an estimated a 10-fold greater amount of '3C6-(benzene ring)-IAA (5.05-101 sg per extract) than the amount of free IAA in the fruit (4). Thus, the '3C6-IAA served as both an internal standard and as a carrier in order to increase sample recovery. The tissues were homogenized for 2 min and allowed to equilibrate overnight at 4°C. The crude extract was filtered, and the residue washed with 70% acetone. Acetone extracts were combined and concentrated to the aqueous phase in vacuo at 45°C. The aqueous phase was chilled to 4°C, adjusted to pH 7.0, and pa...

Studies in the use of fall ethephon to delay bloom in peach and prune were carried out during 1985-87. In `Italian' prune, ethephon at 250 and 500 mg·liter-l at 10% leaf-drop stage delayed bloom 13 and 16 days, respectively. Only a 5- and 7-day bloom delay occurred when applied at 50% leaf-drop stage. Fruit set and yield were not reduced in `Italian' prune when ethephon was applied at the 50% leaf-drop stage. Early applications, from vegetative maturity to the 10% leaf-drop stage, did not reduce yield in prone when trees had been previously defoliated with 3.0% urea. Early leaf removal, before vegetative maturity, caused reduction in peach flower and fruit number. In several peach cultivars, all the ethephon treatments were detrimental to flower density, fruit set, and yield, in spite of bloom delay. The ethephon-treated prune trees yielded more than the untreated trees in 1987 as a result of frost avoidance.

Ethylene evolution was measured from greenhouse-grown 'Jerseyglo' peach fruits beginning 29 days after anthesis. Indole-3-acetic acid (IAA) levels were measured in the pericarp and seed tissues of individual fruits on a single shoot when variable ethylene evolution was noted . Despite hand-pollinating all flowers on the same day, variability within the shoot existed in fruit fresh weight, IAA levels, and ethylene evolution . Seed IAA concentration increased as fruit and seed fresh weight increased and ranged from 106 to 1572 ng . g -' . As pericarp fresh weight increased, IAA levels in this tissue decreased . Ethylene evolution rates ranged from 0 .21 to 1 .07 nl. g. -'h -'and were not correlated with IAA concentration in seed, pericarp, or the whole fruit . High rates of ethylene evolution from the whole fruit occurred prior to increased IAA concentration in the seed .Fruits were excised from field-grown `Redskin' peach trees beginning 40 days after full bloom . Fruits from field sampled shoots appeared to be more physiologically advanced than the greenhouse-grown 'Jerseyglo' fruits . Pericarp IAA concentration was low, ranging from 2 .8 to 6 .5 ng. g -' . Seed concentrations accounted for 75% of the IAA found in the fruit and ranged from 239 to 1042 ng . g -' . As with greenhouse-grown samples, whole fruit IAA concentration tended to decrease as fruits increased in fresh weight . . IntroductionPeach fruit display a double sigmoidal growth curve . During Stage I, the growth of the pericarp is rapid . Stage II, or the lag phase of growth, is characterized by rapid development of the embryo, lignification of the endocarp, and decreased pericarp growth rate . The mesocarp undergoes rapid growth by cell enlargement during Stage III . The endogenous systems which regulate these stages are not known, but several scientists have described regulating roles for hormones . Jackson [8] observed high gibberellin-like activity in the pericarp of fruits during Stage I . Ethylene production also occurs at relatively high rates at that time and 1-aminocyclopropane-1-carboxylic acid concentration peaks in the fruit [9,13,14] . These increases 38 appear to be coincident with cytokinesis of the endosperm [13] . Auxin levels are also high during Stage I [14] .A positive correlation in auxin and ethylene biosynthesis has been reported in several plant organs [23] . Endogenous IAA concentrations and rates of ethylene evolution were positively correlated in studies of peach fruit development [14] . In that work, the IAA data were obtained from pooled fruit samples ; therefore, the hypothesis that variable ethylene evolution rates were positively correlated with IAA concentration of individual fruits could not be tested .The purpose of the current study was to determine if IAA concentration is positively correlated with ethylene evolution rates on a single fruit basis . Materials and methodsPlant material. One-year-old 'Jerseyglo' peach trees grafted onto 'Halford' rootstock were planted in 20 liter pots, containing a mixture of soil :...

Additional index words. nut breeding, filbert, Corylus avellana, blanched kernels, disease resistance 'Willamette' hazelnut (Corylus avellana L.) was released in 1990 for the blanched kernel market. Compared with 'Barcelona', the leading cultivar in Oregon, 'Willamette' yields 50% more marketable kernels. Nuts have thinner, more attractive shells with fewer defects. The pellicle is removed easily with dry heat, and the resulting white kernels are of excellent quality for use in pastries and confections. 'Willamette' is the first cultivar released by the hazelnut breeding program at Oregon State Univ. (OSU). 'Barcelona' and 'Ennis', the two leading cultivars in Oregon, produce large nuts and are well suited for the in-shell market. However, the in-shell market is limited, and currently half of the Oregon hazelnut crop is cracked and sold as kernels, even though the current cultivars are poorly suited for this purpose. Expansion of the hazelnut hectarage in Oregon requires the development of