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- Author or Editor: K. Uriu x
Chloride and boron toxicity symptoms and tissue concentrations were characterized and distinguished in kiwifruit. Dormant cane, bud, emerging leaves, blade and petiole samples were taken from February through October 1989 from three vineyards - a high chloride, a high boron and a low boron, low chloride control. Chloride toxicity symptoms started showing in early summer on basal leaves. By late summer, necrosis symptoms were on mid-shoot and leaves near the shoot terminal. In boron toxicity, interveinal chlorotic areas appeared first followed by marginal necrosis. Symptoms were seen on basal leaves in early spring, progressively affecting upper leaves by harvest. The high chloride vineyard accumulated chloride from early spring with the petiole concentrating more chloride than the blade. In the high boron vineyard, boron increased greatly in the blade but not in the petiole. Another sampling procedure other than mid-season leaf samples could be emerging leaves for detecting high chloride and dormant cane tips, buds or emerging leaves for high boron.
Radial trunk growth measured by the Verner dendrometer was reduced markedly due to competition for assimilates and water by greatly stimulated fruit growth resulting from the application of 2,4-D. These responses were accompanied by reduced water tension within the 2,4-D-treated trees, as indicated by less diurnal trunk shrinkage than that which occurred in control trees.
Concentrations of several mineral elements in leaflets of Pistacia vera L. cv. Kerman, did not differ significantly with leaflet position. Thus, leaflets may be used instead of whole leaves in leaf sampling. Analyses of leaflets indicated that N, P, and Zn concn were relatively high initially. They then dropped rapidly during leaf expansion, reaching a steady state in early summer. Manganese increased from an initially low level and then remained fairly constant. Potassium, Mg, Cl, and B behaved similarly to Mn, but reached constant levels later in the season. Leaves from bearing branches were lower in N and P, but higher in K than leaves from nonbearing branches. It is recommended, in determining mineral element status, that leaves from nonbearing branches be sampled during the month prior to harvest, as most elements are then at a steady state.
Boron(B) deficiency in almond (Prunus dulcis Mill.) is characterized by leaf tip scorch, leaf drop, twig dieback, brown gummy areas in the endocarp, and embryo abortion followed by nut drop in May. Additional symptoms revealed by our work include failure of flowers to set nuts and lateral bud drop. Lack of production in part or in all of the free canopy causes spurs to elongate leading to a “willow twig” symptom on the small fruitwood. This can be confused with the nonproductive “bull” syndrome or with virus bud failure (ABFV or PRSV). Comparative leaf, pericarp, or kernel analysis in May gave a better indication of low B than did leaf analysis in August. In August, analyzing the hulls (mesocarp and exocarp) gave better separation between deficient and adequate trees than did leaf, kernel, or shell analysis. B critical levels for almond leaves should be re-evaluated since deficiency symptoms occur at currently accepted “adequate” levels.
Water potential, diffusive resistance, and abscisic acid (ABA) were measured at 10-12 day intervals from May to October in leaves from irrigated and non-irrigated peach (Prunus persica L. cv. Fay Elberta) trees, and measurements were taken at intervals from sunrise to sunset on September 8. Leaf water potential, before sunrise, was between −5 and −8 bars in irrigated trees during the entire season whether drip irrigated at 100% evapotranspiration (ET) or 50% ET. Non-irrigated trees showed a decrease in pre-dawn leaf water potential with time, following a pattern similar to that of decreasing soil moisture. Leaf water potential values taken during the afternoon were not associated with soil moisture and did not reflect the stressed condition of the trees. In non-irrigated trees stomatal resistance at mid-day increased rapidly after mid-summer as leaf water potential decreased. ABA concentration in leaves from irrigated trees ranged from 30 to 80 ng/g fresh wt during the entire season. In non-irrigated trees the ABA concentration increased sharply after mid-summer; this was associated with an increase in leaf diffusive resistance and a decrease in leaf water potential. Diurnal variations in leaf water potential were associated with changes in soil moisture, air temperature, relative humidity, and stomatal resistance. Leaf diffusive resistances were similar for all treatments until 1100 hr after which a notable increase occurred with increasing stress, ultimately leading to stomatal closure. ABA concentrations in leaves from irrigated and non-irrigated trees increased as leaf diffusive resistance increased; however in stressed trees, high levels of ABA in the morning were not associated with closed stomata.
Withholding irrigation of walnut trees (Juglans regia L. cv. Ashley) for one growing season significantly reduced trunk growth and kernel weight. Tree survival and return cropping were unaffected. When irrigation was resumed kernel weight was significantly heavier than that from trees irrigated the previous year.
Split-pit of ‘Dixon’ cling peaches was correlated with all 3 variables in a multivariable cultural system study involving differential N applications, irrigations, and crop loads. Any factor that enhanced fruit size contributed to increased split-pit. Fruit size at reference date was more important than fruit size at harvest. In different years fruits of the same size at reference date or at harvest did not necessarily have the same amount of split-pit. Fruit set was more important than other factors in determining fruit size at thinning. Crop load after thinning influenced split-pit where fruit set was moderate; however, where fruit set was light split-pit was severe regardless of thinning and where fruit set was heavy split-pit was of minor concern regardless of thinning. Early thinning accomplished about reference date (10 days after beginning of pit hardening in 80% of fruit) increased split-pit over thinning 2 weeks later. Maintenance of high soil moisture (< 40% used) after reference date increased split-pit over that of less frequently irrigated plots. Manipulation of cultural factors cannot satisfactorily control split-pit, but may considerably influence its occurrence.
A study was undertaken to determine the seasonal dynamics of leaf and fruit K content and the influence of tree K status and fruit growth on leaf and fruit K accumulation rates in French prune (Prunus domestics L. cv. d'Agen). Mature trees in a commercial orchard were treated with various rates of K2 SO4. (O to ≈20 kg/tree) in the fall. Fruit dry weight yield per tree at harvest and fruit K content were higher for high-K trees, but fruit percent K (by dry weight) was ≈1.0% for all trees. Leaf scorch and subsequent abscission severely reduced the canopy of K-deficient trees. Significant positive linear relationships between leaf and fruit K accumulation rates existed for the periods of 28 Apr.-28 May (May) and 28 May-7 July (June). A significant negative linear relationship existed between these two criteria from 7 July-3 Aug. (July). May (0.237 mg K per fruit-day) and July (0.267 mg K per fruit-day) mean fruit K accumulation rates were similar, but both were significantly higher (P = 0.001) than those for June (0.140 mg K per fruit-day). Mean leaf K accumulation rates for May (- 0.007 mg K per leaf-day) and July (-0.010 mg K per leaf-day) were similar, but both were significantly (P = 0.001) less than for June (0.005 mg K per leaf-day). Potassium per fruit accumulation was highest in trees with highest K status. Periods of net leaf K efflux and influx did not precisely correlate with fruit growth stages measured by fruit dry weight. The period of lowest fruit K accumulation (28 May-7 July) coincided with the period of maximum dry matter accumulation by the kernel. After 7 July, all increases in fruit dry weight and K content were due to mesocarp growth.
Maleic hydrazide (MH) was readily translocated in the apricot tree, as indicated by inhibition of shoot growth and seed abortion in the fruits. However, cambial activity was undisturbed, and trunk growth proceeded normally.
An antitranspirant film was used as a research tool to determine which part of the sweet cherry (Prunus avium L.) fruit is the principal path for absorption of external water (rain). Antitranspirant applied to the entire fruit surface reduced water intake to half that of control fruit or fruit treated only on the top and/or bottom. A preliminary field trial investigated the film’s “rain-coating” effect as a possible means for reducing cherry cracking.