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Ethephon was applied at 0, 625, 1250, 1875, and 2500 m·gliter-1 in 2 consecutive years to `Arbequina' olive trees to determine its effect on fruit removal with mechanical harvesting and on fruit oil composition. Ethephon increased the mechanical harvesting efficiency by 20%. Ethephon at 1250 and 1875 mg·liter-1 were the optimum treatments, resulting in 63% and 66% of the olives being mechanically harvested, respectively, with a preharvest olive drop of 10% and 11%. Leaf drop (4.6 and 4.8 kg/tree fresh weight, respectively) at these concentrations did not reduce flowering the following year. Oil acidity, peroxide value, and fatty acid composition were affected little by ethephon and the values observed were within the range of normal annual variation. These results suggest that ethephon did not modify oil quality and that its use on traditionally pruned `Arbequina' trees is not economically justifiable. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).
To test the effectiveness of different bioregulators in enhancing bell pepper (Capsicum annuum L.) yield and fruit quality, the commercial bioregulators CCC, NAA, GA3, and Biozyme® were sprayed on plants at flower initiation, followed by two additional applications at 30-day intervals. Biozyme produced a significant increase in total yield but ≈40% of the fruit were not marketable. Treatment with NAA produced the highest yield of marketable fruit. Treatments did not affect fruit firmness compared to the control. Gibberellic acid increased fruit ascorbic acid and citric acid concentrations and Biozyme, GA3, and CCC increased fruit soluble solids content. Biozyme treatment increased fruit fructose, sucrose, carotenoid, and lycopene concentration. Treatments had no effect on fruit calcium concentration or pH. Chemical names used: chlormequat chloride (CCC); naphthaleneacetic acid (NAA), gibberellic acid (GA3); GA3 + IAA (indoIe-3-acetic acid) + zeatine + micronutrients (Biozyme®).
Abstract
‘Tommy Atkins’ (Mangifera indica L.) is an important mango cultivar grown in Mexico. A new disease, causing heavy fruit loss and not yet reported in any other mango, was noted in 1973 and has since spread to all plantings of ‘Tommy Atkins’. Losses vary from 10% to 80% depending on season, less in dry than in wet years. The disease appears only on physiologically overmature fruit, and is not transmitted to healthy fruit after harvest, even in storage (3). It is a dry rot, visible at the stem end as a necrotic zone, grayish or dark in color, sometimes confused with the external color of the fruit itself. The internal tissue below the stalk end is dark brown, fibrous, extending to the pulp and stone (endocarp) and affecting the seed (Fig. 1). The cut end of the peduncle often shows darkened resin ducts.
In a 3-year experiment in two drip-irrigated orchards on the Mediterranean coast, boron (B) sprays applied at rates of 0.6 and 1.2 g per tree and a soil B application of 12 g per tree did not increase fruit set or production of Corylus avellana L. `Negret' and `Pauetet' hazelnuts with mid to low foliar B levels (14.3 to 21.8 μg·g-1 dry mass). The average fruit set and nut yields of the trials were, respectively, 66% and 3.54 kg per tree for `Pauetet', and 50% and 4.54 kg per tree for `Negret'. The lack of response to B applications might be due to 1) initial fruit set levels were high; 2) the current B recommendation guidelines (25 to 30 μg·g-1 dry mass) might be adequate for fruit set and yield; 3) the rates of B applied might be too low; and 4) weather and soil conditions, cultivars, and biennial bearing may have masked any response to foliar B application.
During three consecutive years of field experiments, three crop-covering treatments [noncovered (C), perforated polyethylene (PO, 500 holes/m2), and a nonwoven polypropylene (AO) sheet] were used to create different environmental conditions for growth of `Nagaoka 50' chinese cabbage [Brassica rapa L. (Pekinensis Group)]. The PO and AO treatments reduced solar irradiance and increased air and root temperatures compared to C plants. Plants were sampled five times each year from transplanting to harvest, and fresh and dry weights, yield at harvest, leaf pH, citric and ascorbic acid concentrations, and cell-wall fractions were determined. The PO floating row cover was the most beneficial for yield and chemical composition of chinese cabbage of the early spring crop in southern Spain, where environmental conditions during an unfavorable season can injure sensitive crops.
Field trials were conducted in two locations in Spain to determine the effect of methyl bromide (MBr) alternatives on soilborne diseases and nematodes, and strawberry (Fragaria ×ananassa) yields under high-tunnel conditions. Fumigant treatments were applied to the same plots each year. Treatments were MBr + chloropicrin (Pic) (50:50, v/v) at a rate of 400 kg·ha−1; 1,3-dichloropropene (1,3-D) + Pic (65:35, v/v) at 300 kg·ha−1; Pic at 300 kg·ha−1; dimethyl disulfide (DMDS) + Pic (50:50, v/v) at 500 kg·ha−1; propylene oxide at 550 kg·ha−1; dazomet at 400 kg·ha−1; and calcium cyanamide (Ca-cyanamide) at 700 kg·ha−1. A nontreated control was also included. Fumigation with MBr + Pic, 1,3-D + Pic, Pic, and DMDS + Pic consistently improved early and total marketable strawberry yields in both locations. This response was caused by successful soilborne fungus and nematode control, improving strawberry growth and development, which resulted in increased plant canopy diameters and higher strawberry early and total yield.