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Previously published research suggests that the yield and water-use efficiency of C-3 plants can be enhanced through foliar-applied methanol. Potatoes (Solanum tuberosum L. cv. Russet Burbank) grown in Oregon at Klamath Falls, Madras, and Ontario were subjected to repeated foliar methanol treatments during the 1993 season. Methanol was applied at 20%, 40%, and 80% concentration with Triton X-100 sticker-spreader at 0.1%, and methanol was applied at 20% and 40% without Triton X-100. Methanol had no effect on tuber yield, size distribution, grade, or specific gravity at any location. Tuber stem-end fry color showed no methanol response at the two locations where it was measured. Soil water potential (measured at Madras and Ontario) showed no difference in water-use efficiency between methanol-treated and nontreated potato plants.
An apparatus was designed to deliver low-dose UV-C light to the surface of fruit on a processing line and tested for its control of postharvest decay. It consisted of a row of UV-C emitting lamps mounted on a frame above a conveyer belt that transported the fruit. The dosage of the UV-C light delivered to the fruit surface was regulated by varying the speed of the conveyor belt. Postharvest decay after 28 days storage of `Empire' apples was reduced 52% relative to the untreated checks when the fruit were conveyed at 6.2 m·min−1 (1.38 kJ·m−2 dose) under the UV-C apparatus. Factors affecting the practical application of UV-C irradiation of fruit for controlling postharvest decay are discussed.
Abstract
Flowering, fruit set, fruit size, and bearing potential are the main components of tree fruit and nut yield. The contributions of the individual components to yield and their interrelationships must be clearly defined in research addressing tree fruit productivity. Researchers have been inconsistent in terminology and procedures used to evaluate treatment effects on the major yield components. Although the relative effect of a treatment may be evident within an individual study, standardized measuring and reporting procedures are necessary if one wishes to compare results within the same species from various investigators, locations, and disciplines.
Wooden fruit bins are a source of diapausing codling moth and postharvest pathogenic fungi. The redistribution of codling moths within bins is a problem where codling moth populations are being controlled by areawide codling moth sterile release programs, mating disruption programs, or both. Laboratory and fumigation chamber trials were carried out to determine the impact of relatively low levels of carbon dioxide on late-instar codling moth (Cydia pomonella L.) and two postharvest fruit pathogens, Penicillium expansum Link ex Thom and Botrytis cinerea Pers. ex Fr. Fumigation of diapausing codling moth with 40% CO2 in laboratory trials resulted in over 60% mortality after only 6 days of exposure and mortality increased with time of exposure. Significant mortality (68%) of diapausing codling moth larvae occurred after 14 days of exposure in the laboratory to 13% CO2 and a mean of 88% mortality was recorded after fumigation for 20 days. A significant number of P. expansum (46%) spores failed to germinate after laboratory exposure to 13% CO2 for 12 and 18 days respectively. Close to 100% of the P. expansum spores failed to germinate by day 20. When diapausing codling moth larvae and spores from both plant pathogens were placed in wooden fruit bins and fumigated for 21 days at 13% CO2, 75% of the diapausing codling moths died and 80% of the P. expansum spores failed to germinate. No effect on B. cinerea was observed.
Lychnophora pinaster, known as arnica, is a medicinal plant of the Cerrado ecosystem in Brazil. It is widely used in the form of alcoholic extract for its anti-inflammatory and anesthetic and healing effects on sprains, bruises, and inflammation. Owing to the great difficulty of propagation, it is listed by the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis in the category of plants vulnerable to extinction. Micropropagation offers a solution to this problem by allowing the preservation and expansion of germplasm. The objective of this research was to establish a protocol for in vitro propagation of arnica. The best medium for germination of arnica embryos and plantlet growth was a quarter strength semisolid Murashige and Skoog medium (MS/4) containing 0.75% (w/v) sucrose. For shoot induction, the best results were obtained on MS/4 with 2.76 μm of benzylaminopurine. Maximum shoot elongation before rooting occurred in the presence of 8.67 μm of gibberellic acid for 19 d. Microshoots were successfully rooted in the presence of 10.7 μm of naphthalene acetic acid for 15 d. After rooted plantlets were acclimatized in a greenhouse for 20 d, the survival rate was 100% when planted in a soil from the area of occurrence of the species, whereas 0% survived when planted in Plantmax.
An elite group of 38 strawberry accessions representing all subspecies of the beach strawberry [Fragaria chiloensis (L.) Miller] and the scarlet strawberry (F. virginiana Miller) was planted in a replicated design at five locations across the United States, and evaluated for plant vigor, flowering date, runner density, fruit set, fruit appearance, and foliar disease resistance. Considerable genotyp× location interaction was observed for many of these traits. However, a few genotypes were impressive at all locations including PI 551735 (FRA 368) with its unusually large, early fruit, and PIs 612486 (NC 95-19-1), 612493 (Frederick 9), and 612499 (RH 30), which were very vigorous and had unusually good fruit color. Genotypes that were superior at individual locations included PIs 551527 (FRA 110) and 551728 (Pigeon Pt.) in Maryland for their large fruit, and PI 612490 (Scotts Creek) in Oregon which had extremely large fruit, superior color, firmness, and flavor. The PIs 612495 (LH 50-4), 612498 (RH 23), and 612499 (RH 30) performed well as day neutrals at multiple sites.
Annual legume ground covers were evaluated in pecan (Carya illinoinensis) orchards to supply nitrogen and increase beneficial arthropods. Treatments were established at two sites, each with 5 ha of a `Dixie' crimson clover (Trifolium incarnatum) /hairy, vetch (Vicia villosa) mixture and 5 ha of grass sod. Data indicated that the legume mixture supplied over 100 kg·ha-1 N to the pecan trees. Beneficial arthropods were greater in orchards with legume ground covers than in orchards with a grass groundcover. Lady beetles and green lacewings were the most important spring predators, and green lacewings were the most important fall predator. The Species distribution on the ground covers differed from that in the canopy. Coleomegilla maculata lengi, Hippodamia convergens and Coccinella septempunctata were the most abundant lady beetle species in the legume ground covers, and Olla v-nigrum, Cycloneda munda, and Hippodamia convergens were the most abundant species in the pecan canopies. Beneficial arthropods appeared to suppress injurious pecan aphids.
Thirty-two tomato (Lycopersicon esculentum Mill.) or L. pimpinellifolium (L.) Mill. accessions were inoculated with race T2 of Xanthomonas campestris pv. vesicatoria (Xcv) in a field experiment at Wooster, Ohio, in 1995. Plants from accessions which segregated for race T2 resistance in greenhouse tests were selected and these are designated by hyphenated extensions below. The eight most resistant accessions from 1995 and PI 262173 were retested in 1996. Lycopersicon esculentum accession PI 114490-1-1 had virtually no Xcv symptoms either year. Lycopersicon pimpinellifolium accessions LA 442-1-Bk and PI 128216-T2 expressed a high level of resistance in 1995, but only partial resistance in 1996. Accessions with partial resistance for both seasons were PI 79532-S1, PI 155372-S1, PI 126428, PI 271385, PI 195002, PI 262173, Hawaii 7998, and Hawaii 7983. PI 79532-S1 is a L. pimpinellifolium accession and the remaining seven are L. esculentum. Twenty accessions tested in 1995 for T2 plus 10 other accessions were also tested for race T1 resistance in Presidente Prudente, Sao Paulo, Brazil, in 1993. Hawaii 7983, PI 155372-S1, PI 114490, PI 114490-S1, and PI 262173 had greater resistance to T1 than the susceptible control, `Solar Set'. Comparisons with earlier experiments, in which accessions were inoculated with race T1 or T3, indicated that the most consistent source of resistance to all three races was PI 114490 or selections derived from it.
Particle bombardment using the Bio-Rad PDS-1000/HE system is being investigated as a means to develop a stable transformation system for the bulb onion. Donor materials for bombardments included sterile meristems and radicals from newly germinated seeds, callus of Allium cepa `TG1015', `Sunlite', and `Buffalo', A. fistulosum `Heshiko', and suspension-cultured cell lines with confirmed regeneration capability, as well as regenerated plants of an F1 interspecific hybrid. Transient expression assays using the B-glucuronidase (GUS) reporter gene system were used to optimize the conditions for transformation. Various promoters combined with the GUS coding sequence were tested. Results indicate genotype specificity for promoter expression. Some tissue continued to exhibit GUS activity after several months in culture, indicating potential for achieving stable transformation of onion.