Abstract
Bush-type snap beans (Phaseolus vulgaris L.) were seeded by a no-tillage method into standing wheat (Triticum aestivum L.) stubble of 8, 15, 23, 30, and 38 cm in height to evaluate the effects of stubble height on pod mechanical harvest efficiency, plant morphology, and shoot component yield. Basal internode elongation, stem plus leaf yields, pod yields, efficiency of mechanical pod harvest (MH), and height of basal pod set were related in a positive linear or curvilinear fashion to wheat stubble height. Quantity of pods missed during MH was related negatively to height of basal pod set. Harvest efficiency was maximized with 15-30-cm stubble heights, and these notillage systems yielded MH pod levels that equaled or exceeded those of a conventional tillage (plow, disk 2 times) system. Superior MH efficiency was attributed to increased basal internode length and mechanical support of the shoots by the wheat stubble.
Abstract
Three year old lemon trees [C. limon (L.) Burm f.] were selectively pruned to form a 3- to 4-scaffold branch structure for limb shaker harvesting. Yield was reduced 16 kg per tree and trunk circumference 10 cm above the bud union was reduced 5.3 cm per tree over a 6-year period. Training was completed with minimal production loss.
in the north-temperate United States: reliable productivity, excellent yields, late-midseason ripening, medium-large fruit, uniform size, light-blue fruit color, and easy fruit removal force making it suitable for mechanical harvest. ‘Talisman’ is
Pectin metabolism was analyzed in tabasco pepper (Capsicum frutescens L.) to determine the metabolic process associated with the ease of fruit detachment from the calyx. The ease of fruit detachment (deciduous fruit) is a desirable trait in peppers that facilitates mechanical harvest. Two genotypes that differ in the fruit detachment force were used: `Easy Pick' (EZ), which requires a low force, and `Hard Pick' (HP), which requires higher force. Pectin dissolution in water from fresh-ripe EZ tissue was 20 times higher than from HP tissue. EDTA-soluble uronide from inactivated EZ cell wall, however, was only 1.8 times higher. Pectin dissolution was inversely correlated to the fruit detachment force and followed a sigmoidal curve during fruit ripening. Size-exclusion chromatography of EDTA-soluble polyuronides indicated that pectin was degraded in ripe fruit tissue from both genotypes. The degree of depolymerization, however, was more extensive in EZ fruit. Consequently, the ease of fruit detachment was attributed to pectin ultra-degradation. Total pectin content in dry tissue and ethanol/acetone-extracted cell wall was similar in both genotypes. Pectin content in dry tissue was maintained throughout ripening, while extracted cell wall pectin increased slightly. In contrast, the degree of pectin esterification of extracted cell wall decreased only in ripe EZ fruit. These results suggest that pectin de-esterification may have a role in the enhanced pectin depolymerization and consequently in the ease of fruit detachment of the EZ genotype.
Research was conducted to develop a cultural system that would permit a destructive mechanical okra [Abelmoschus esculentus (L.) Moench] harvest. This paper reports on studies to determine the responses of okra plant architecture to various highly dense (HD) plant populations, and to consider the implications of those responses for destructive mechanical harvest. Growing okra in plant arrangements more densely planted than the control (which was spaced at 90 × 23 cm) did not affect overall plant heights. The position of the first bloom or fruit attachment and of the first marketable fruit attachment tended to become higher on the stem as plant population density increased, especially when comparing plants from the 15 × 15 cm spacing to control plants. The number of marketable fruit per plant was usually unaffected by plant population. Branch number and defruited dry weight per plant decreased as plant population density increased. Plant architecture did not affect the ability of an experimental mechanical harvester to recover marketable fruit from three different okra cultivars grown in a HD arrangement. The lack of concentrated marketable fruit set, rather than plant architecture, was the main limiting factor to the success of densely planted okra for destructive harvest.
developing mechanical harvesting equipment that can substitute for the increasing shortage of hand labor is growing, especially for specialty crops such as blueberries. Research into mechanical harvesting of blueberries has been ongoing since the 1950s with
In the southwestern U.S. growing region, which includes southern New Mexico, west Texas, and southeastern Arizona, mechanical harvest of chile peppers (Capsicum annuum) is increasing because of the high cost of hand labor. Mechanical harvesters have been developed, but there is limited information on the performance of chile cultivars when machine harvested. Four red chile pepper cultivars (New Mexico 6-4, Sonora, B-18, and B-58) were grown in a farmer's field near Las Cruces, N.M., and harvested in October 2000 using a double-helix-type harvester. Ethephon was applied 3 weeks before harvest at 1.5 pt/acre (1.75 L·ha-1) to promote uniform ripening. Ethephon caused fruit of `B-18' and `B-58' to drop before harvest, thereby affecting yield results. Treatment with ethylene-releasing compounds is not recommended for these cultivars. `Sonora' and `New Mexico 6-4'dropped much less fruit than `B-18' and `B-58' after the ethephon treatment. Dry weight marketable yield ranged from 1419 to 2589 lb/acre (1590.5 to 2901.8 kg·ha-1), and total yield potential (discounting dropped fruit) ranged from about 2500 to 3100 lb/acre (2802.1 to 3474.6 kg·ha-1), depending on cultivar. Harvest efficiencies of 73% to 83% were observed among the cultivars. Trash content of the harvested chile varied from 25% to 42% of dry weight. Trash was predominantly diseased and off-color fruit, leaves, and small stems. Trash content was highest for `Sonora'. `New Mexico 6-4' had the greatest marketable yield and harvest efficiency among the cultivars evaluated in this study.
Abstract
Six gynoecious inbred lines of cucumber (Cucumis sativus L.) were evaluated for parthenocarpic yield by using 2 diallel analysis programs. A complete diallel of F1 and half-diallel of F2 generations, including parents, was used to study the genetics of parthenocarpic yield. Highly significant differences for GCA and SCA effects were found for all yield characters, suggesting that both additive and non-additive gene action were important. Reciprocal differences or maternal effects were not significant for any of the yield characters. Diallel analysis suggested that recessive genes were acting in the direction of higher yields. Accordingly, the development of a parthenocarpic hybrid cultivar with high yield potential would require that both parents possess genotypes with high yield potentials. Heritability estimates varied from nearly 0 to 32% for 3 different yield measurements with number of fruits on the main stem most heritable. Significant ratios for heterosis and heterobeltiosis were obtained for all yield measurements. However, only fruit number on the main stem was affected by an inbreeding depression. Breeding improvement programs for parthenocarpy might include recurrent selection for fruit number on the main stem of gynoecious seed parent lines combined with backcrossing of the gene for hermaphroditic expression into gynoecious parthenocarpic lines for pollen parents.
Abstract
The top cross method was used to judge the performance of 17 hermaphroditic lines (pollen parents) for parthenocarpic yield and associated characters of cucumber (Cucumis sativus L.). Hybrid yields of 3 to 6 parthenocarpic fruits per plant were observed with 68 to 99.5% gynoecious expression. Four hermaphroditic lines were judged outstanding based on their hybrid performance for the necessary high percent of gynoecious expression combined with high yield. Significant correlations were detected between days-to-flower and nodal position of first-pistillate flower, and between the latter and yield. Heritabilities were 64%, 63%, and 73% for days-to-flower, nodal position of the first-pistillate flower, and gynoecious expression, respectively. The heritability for yield (number of fruit/plant) of parthenocarpic fruits was 20%. Accordingly, plant breeders might enhance selection gains for associated characters, but realize somewhat less success for yield (fruit number).
Abstract
The parthenocarpic yield and associated traits of 20 gynoecious hybrids of pickling cucumber (Cucumis sativus L.) were measured by crossing 4 gynoecious with 5 hermaphroditic lines. The experimental hybrids were grown in the field and harvested for the once-over harvest system. Additive genetic variance was greater than non-additive for yield and associated characters, except gynoecious expression where non-additive was more important. The GCA for harvest-time, gynoecious expression, and yield of the female parents was greater than that of the male parents in this population. The converse was true for flowering-time. The dominance estimates indicated complete dominance for early flowering and over-dominance for gynoecious expression. The remaining characters appeared to be under the control of genes with additive effects and partial dominance. Narrow sense heritabilities of half-sibs (males and females) for fruit no. and fruit wt/plant were 53 to 60% and 32 to 65%, respectively. The genotypic and phenotypic correlations for flowering-time and nodal position of first-pistillate flower were high as was nodal position of first-pistillate flower with parthenocarpic yield.