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  • Author or Editor: Edward A. Stahly x
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Abstract

Calcium concentration of ‘Golden Delicious’ (Malus × domestica Borkh.) apples was reduced with a single, early application of 50 ppm TIBA. Early, midseason, and late sequences of 3 sprays of CaCl2 (3.6 g/1) were applied to evaluate timing effectiveness for increasing fruit Ca concentration and decreasing fruit pitting. Mid-June, July, and August sprays increased fruit Ca concentration less than later sprays, but more effectively reduced fruit pitting. Chemical name used: 2,3,5-triiodobenzoic acid (TIBA).

Open Access

Abstract

β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1 H-1,2,4-triazole-1-ethanol (paclobutrazol) is one of a new class of plant growth regulators that affect both vegetative and reproductive components of fruit tree growth (1-3). The movement and fate of absorbed paclobutrazol must be established to better understand its persistence and mode of action. Accordingly, we have developed an analytical method for quantifying low levels of paclobutrazol extracted from plant tissue.

Open Access

Abstract

Rootlets of apple trees in low As soil and trees in arsenic-toxic soil in northcentral Washington were compared for mycorrhizal development. Healthy trees had abundant, vigorous rootlets that were mostly intensely mycorrhizal. Stunted trees, in contrast, had moderately abundant and badly stunted rootlets that were sparsely mycorrhizal. The symptoms expressed by apple trees in high As soils thus appear to prominently include a mycorrhizal deficiency.

Open Access

Abstract

Five-year-old ‘Anjou’ pear trees (Pyrus communis L.) were sprayed with (2-chloro-ethyl)trimethylammonium chloride (chlormequat) (1500 ppm), (2-chloroethyl)phosphonic acid (ethephon) (250 or 500 ppm), or succinic acid-2,2-dimethylhydrazide (daminozide) (1000 ppm) plus ethephon (250 ppm) 4 or 6 weeks after full bloom (AFB) for 2 consecutive seasons. Chlormequat increased fruit set after 1 application, but 2 applications of the other chemicals were required to increase fruit set. Two consecutive years of chlormequat applications increased yieid about 50%, 2,3,5-Triiodobenzoic acid (TIBA) (50 ppm) applied 4 weeks AFB did not affect fruit set, but induced many short shoots of ‘Anjou’ pear trees.

Open Access

Abstract

The accumulation of Ca and K in the cortex of fruits of ‘Golden Delicious’ apple (Malus domestica Borkh.) from trees sprayed with 2,3,5-triiodobenzoic acid (TIBA) was measured during 2 growing seasons. TIBA reduced the rate of Ca accumulation in treated fruits within 2 or 3 weeks of application, and the slower rate of accumulation persisted through most of the season. K accumulation in the latter part of the growing season was enhanced by TIBA. The cortex of treated fruits was lower in Ca and higher in K than that of untreated fruits at harvest. In 1 year, TIBA-treated fruit had a higher dry weight and higher N content than unsprayed fruit. Bitter pit appeared in fruit from all treated trees both years.

Open Access

Abstract

Calcium translocation into the fruit of the ‘Golden Delicious’ apple was restricted by applications of 2,3,5-triiodobenzoic acid (TIBA) applied 2, 4, and 6 weeks after anthesis whereas Ca translocation into the leaves and into the shoots was virtually unaffected. Ca translocation was measured by introducing 0.01 m CaCl2 + 45Ca into the cut end of previously sprayed shoots and by measuring 45ca translocation into various parts. TIBA applied nearer to anthesis was more effective in decreasing Ca translocation.

Open Access

Abstract

When ‘Golden Delicious’ apple fruit (Malus domestica Borkh.) Ca concentration was depressed by 2,3,5-triiodobenzoic acid (TIBA), 3 sprays of Ca(NO3)2 increased fruit Ca concentration and visibly reduced fruit pitting and internal breakdown. TIBA application at intervals from full bloom stopped Ca accumulation in the skin, but not in the flesh. Consequently, it appears that Ca moves into the flesh for a longer period after bloom, but at a slower rate than it does into the skin. TIBA was the only one of several growth regulators used that reduced fruit Ca concentration. Although within a given year Ca was associated with pitting, low-Ca fruit did not pit every year. Apparently, low Ca predisposes fruit to pitting, but pit development is associated with unknown factors.

Open Access

Abstract

Mature bearing pear [Pyrus communis L. ‘Beurre d’Anjou’ (‘Anjou’)] trees in an arid climate were irrigated weekly at 125% of pan evaporation (wet), biweekly at 100% of pan evaporation (normal), or irrigated only twice (dry) during the summer (1980, 1981), and were fertilized with and without 0.9 kg of supplemental N. Prior to final fruit harvest in 1981, depletion of available soil moisture (ASM) averaged 10%, 16.7%, and 89% for the wet, normal, and dry treatments, respectively. Mid-day leaf water potential (ψL) was correlated with the level of ASM only on bright days of high vapor pressure deficit. Stomatal conductance (κs) and transpirational flux density (F) of dry treatment leaves was lower than that of either wet or normal treatment leaves ψL exceeded −1.4 to −1.7 MPa. Resistance to vapor (water) transport (Rν) of fruit was independent of irrigation regime. Terminal buds had set on shoots from all 3 irrigation regimes at 58 days after full bloom (AFB) in 1981, but resumed growth on normal and wet treatment shoots at 87 days AFB. On 7 of 10 sampling dates during 1981, dry treatment fruit weighed less than normal or wet treatment fruit.

Open Access

Abstract

Mature bearing pear [Pyrus Communis L. ‘Beurre d'Anjou’ (‘Anjou’)] trees were irrigated weekly at 125% of pan evaporation (wet), biweekly at 100% of pan evaporation (normal), or irrigated only twice (dry) during the summers of 1980 and 1981. Fruit Ca concentration of dry treatment fruit generally was greater than the concentration in normal or wet treatment fruit. Although irrigation treatment did not consistently alter fruit K or Mg concentration, the K/Ca ratio of normal or wet treatment fruit typically was greater than that for dry treatment fruit. Dry treatment fruit had the lowest concentrations of peel and flesh N from 42–144 days after full bloom in 1981, resulting in lower N/Ca ratios than normal or wet treatment fruit. Fruit from the lower half of tree canopies had a greater Ca concentration resulting in lower N/Ca and K/Ca ratios than in fruit from the upper canopy positions. The lowest incidence of fruit disorders (alfalfa greening and cork spot) occurred in the dry treatment trees. Fruit disorders, especially cork spot, were positively correlated with increased irrigation, shoot growth, fruit N and K concentrations, fruit N/Ca and K/Ca ratios, and early (5-1-81) levels of fruit B, Fe, Mn, and Zn, but negatively correlated to Ca. Although there was no significant effect of irrigation treatment on bloom density in 1981, fruit set was reduced in trees subjected to the dry irrigation regime.

Open Access