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Brian A. Kahn

Paprika pepper (Capsicum annuum L.) plants were subjected to a single, destructive harvest in either October, November, or December to determine an optimal month for once-over harvest. Studies were conducted at two locations in Oklahoma each year for 2 years. Total and marketable fruit yields were highest with October harvest dates in three of the four experiments. Marketable fruit red pigment intensity decreased between the November and December harvest dates at both locations in the second year. When the crop is established by transplanting, paprika harvest should be completed during October in the southwestern United States.

Open access

M. E. Austin and R. E. Williamson

Abstract

Fruits of rabbiteye blueberry (Vaccinium ashei Read cv. Tifblue) were harvested by hand and an overrow mechanical harvester for 2 years. Machine harvest increased ground loss of marketable fruit over hand harvest. Hand-harvested fruit were 29 to 37% firmer than machine-harvested fruit. When held for 7-11 days at 15.5°C, machine-harvested fruit had more than twice the amount of soft and unmarketable fruit than hand-harvested fruit. Pruning rabbiteye blueberry plants increased the harvesting efficiency of the machine.

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Blair Buckley III and Katharine C. Pee

An investigation was conducted in 1993 and 1994 to examine the effect of row spacing on yield and pod maturity distribution of machine-harvested, green-mature southernpeas [Vigna unguiculata (L.) Walp]. `Texas Pinkeye Purple Hull' was planted at row spacings of 53, 89, and 107 cm single drilled and 107 cm double drilled. Marketable yield increased linearly as row spacing decreased. A double drill on a standard 107-cm row spacing did not result in higher yield than a single drill. Marketable yield from the double-drilled, 107-cm row spacing was less than yield from the 53-cm spacing. The seeding rate per hectare for the two treatments was the same. In 1993, the mature pod percentage at harvest increased linearly as row spacing decreased. Row spacings as narrow as 53 cm can be used to increase yield of machine-harvested, green-mature southernpeas.

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Desmond R. Layne and J.A. Flore

The influence of increasing levels of trunk damage on vegetative and reproductive capacity of 3- to 5-year-old `Montmorency' sour cherry (Prunus cerasus L.) trees was determined for three seasons. Removal of or damage to bark up to halfway around the trunk circumference minimally affected growth and productivity. The total wound callus produced per tree was related to wound size. Wound repair was variable depending on the type or extent of injury. Removal of damaged bark greatly reduced wound repair. Girdling 75% or 100% of the trunk circumference resulted in no tree mortality at one site and 17% and 50% mortality, respectively, at another. Differentiated phloem in wound callus of trees with 100% bark removal and survival 4 years following injury indicated that vascular reconnection occurred across wounds.

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Yaying Wu, Brian A. Kahn, Niels O. Maness, John B. Solie, Richard W. Whitney, and Kenneth E. Conway

Okra [Abelmoschus esculentus (L.) Moench] was grown at various highly dense (HD) plant populations for destructive harvest, and compared with control plants grown at spacings of 90 × 23 cm and harvested repeatedly by hand. Our objectives were to identify a HD plant arrangement and an optimum harvest timing to maximize marketable fruit yield per hectare with a single destructive harvest, and to evaluate the potential for regrowth of cut plants followed by one or more subsequent harvests. Within HD treatments, marketable fruit weight per hectare tended to increase as the plant population density increased. Spacings of 30 × 30 cm and wider were not dense enough for the destructive harvest system due to a low marketable yield potential. Wide spacings did favor regrowth of cut plants in two experiments, but total marketable yields were still highest with the highest plant populations tested. Delaying destructive harvest until many overmature fruit were present did not consistently affect marketable fruit yield, but always decreased the proportion (by weight) of marketable fruit to total harvested fruit. Overall, percentages of marketable yield obtained by destructive harvests of plots with HD plant populations were low relative to the cumulative marketable yield from control plots. The lack of concentrated fruit set in okra remains a limiting factor for destructive harvest. However, the labor-saving potential of this system should stimulate further research.

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Diego Barranco, Octavio Arquero, Carlos Navarro, and Hava F. Rapoport

Open access

Gregory A. Lang and George C. Martin

Abstract

Fruit-bearing olive (Olea europaea L.) shoots were exposed to more than 100 ethylene (C2H4) treatments to determine if C2H4-induced abscission varied between leaves and fruits in response to manipulation of treatment concentration, duration, and total amount of exogenous C2H4. Nearly three-quarters of the treatments induced greater fruit abscission than leaf abscission on a percentage basis. The potential for optimization of C2H4-induced fruit abscission relative to leaf abscission was examined by calculating the fruit-to-Ieaf (F:L) abscission ratio. Of the treatments inducing at least 75% fruit abscission, the dose range of 150 to 370 μmol C2H4 gave ratios up to 13.3; however, results were highly variable and closely dependent on the interaction of concentration and duration. Response surfaces were created to depict this interaction. Desirable levels of fruit abscission occurred at durations > 30 hr and concentrations > 2 to 3 μl·liter−1. However, excessive leaf abscission occurred at durations of 24 to 48 hr, depending on concentration. Acceptable F:L ratios were found for about 30% of the surface, with the highest ratios occurring for treatments of 3 to 5 μl·liter−1 for 28 to 34 hr.

Open access

G. A. Lang and G. C. Martin

Abstract

A laboratory system was developed to study olive (Olea europaea L.) organ abscission (21). An improvement of the use of ethylene-releasing compounds in this system is described to provide a model for field abscission responses and characterization of ethylene release. Olive fruit began the separation process as early as 7 to 13 hr after treatment with CGA-15281 (CGA), but not until 19 to 25 hr after treatment with ethephon (ET). CGA is characterized by an immediate, substantial breakdown to ethylene, whereas ET reaches its maximum ethylene release at 12 to 18 hr after application. Ethylene release was much greater from CGA than from equimolar concentrations of ET throughout the abscission initiation period. The relation of ethylene release characteristics to control of olive fruit and leaf abscission is discussed, with the suggestion that fruit respond more rapidly to, and at shorter durations of applied ethylene than do leaves.

Open access

Dennis J. Werner and S. Honma

Abstract

Fruit detachment force (FDF) in pepper (Capsicum annuum L.) was measured using mature fruit for the parental, F1, and F2 populations from the cross MSU 160 × MSU 249. Fruit detachment force was controlled by a low number of effective factors (k = 1-2) behaving mainly in an additive manner. Correlation coefficients between fruit detachment force and fruit length, width, and weight calculated from F2 data were positive and significant at the 1% level.

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Michael D. McCullough, James E. Motes, and Brian A. Kahn

Two problems associated with machine harvesting of peppers (Capsicum annuum L.) are plant lodging during growth and uprooting. Factorial combinations of four bedding treatments and two N rates were compared for effects on lodging, uprooting, and fruit yield of chile and paprika-type peppers in Fort Cobb and Bixby, Okla. Bedding treatments were 1) no bed (T1); 2) no bed with 5 cm of soil hilled to the plant bases (T2); 3) bedded preplant, but bed not sustained (i.e., allowed to erode) during the growing season (T3); and 4) bedded preplant and bed sustained during the growing season (T4). All plots received preplant N at 45 kg·ha–1. In 1992, one-half of the plots were sidedressed with 45 kg N/ha. In 1993, one-half of the plots were sidedressed with N at 45 and 90 kg·ha–1 for paprika and chile, respectively. The higher N rates consistently produced larger and higher-yielding chile plants and generally increased yield and stem and leaf weights of paprika plants. The force required to uproot plants was not significantly affected by N rates. Plant lodging was significantly worse at the higher N rates in only one of five studies. Bedding treatments did not have a consistent influence on fruit yield. The force required to uproot plants was greater with T2 and 4 compared to T1 and 3 in three of four studies. Plant lodging was not influenced by the bedding treatments.