Mature ‘Valencia’ oranges when sprayed 2 months prior to harvest in the spring of 1969 with a 1 or 3% solution of Pinolene, a liquid polyterpene plastic film former, were greener at harvest, lost less wt, and had better appearance than control fruit after 9 weeks of storage. Fresh and fixed sections of peel from control and plastic-treated ‘Hamlin’ orange fruit from trees sprayed 2 months before harvest with a 1% solution of Pinolene were observed with a scanning-electron microscope after harvest. The surfaces of control fruit showed considerable variation with some areas having essentially no epicuticular wax platelets while other areas were completely covered. On sprayed fruit, plastic often partially masked the wax platelet edges. On control fruit, the openings to the outer stomatal chambers were usually unobstructed although the stomatal pores between the guard cells were often plugged. In most cases, the openings to the outer stomatal chambers of sprayed fruit were partially or completely obstructed with plastic.
Callus induction and regeneration of alkaligrass (Puccinellia distans) was developed in our laboratory for use in transformation studies of turfgrass. Particle bombardment of the embryogenic callus is being evaluated using a helium particle inflow gun constructed at Colorado State Univ., according to the design of Philippe et al. (Ohio State Univ., 1993). Its utility in delivering DNA to plant cells is being tested by measuring the frequency of transient gene expression of a reporter gene (GUS pBI121) in embryogenic callus of alkaligrass. Varying pressure of helium and the distance of the calli in the chamber are also being evaluated for efficiency in transformation.
The relative decline in fruit size from primary to secondary to tertiary positions on the inflorescence of large-fruited clones was much greater than for small-fruited clones. Large-fruited clones produced fruit with more achenes and larger achenes than did small-fruited clones. Fruit weight was positively correlated with total achenes per fruit, developed achenes per fruit, mean weight of total and developed achenes, and fruit weight per developed achene. These results lead to the conclusion that fruit size differences among strawberry clones are due to the combined effects of developed achene number, developed achene size, differential activity of achenes in producing growth hormones and differential sensitivity of receptacular tissue in responding to growth hormones.
Kentucky is one of seven states in the southeast evaluating 13 Asian pear cultivars for suitability to the region. The cultivars were planted on a (20′ × 10′) spacing in 1989 at three separate locations. Data on time of bloom, tree growth, fire blight susceptibility and fruit quality and yield were collected. This study demonstrates the variability seen in Asian pear cultivars in response to site. There was a significant site by cultivar interaction for fire blight. The Princeton site had significantly more fire blight than either Lexington or Quicksand. Four cultivars, Niitaka, Shin Li, Shinko and Shinseiki had low fire blight ratings which were not significantly different between the three sites. Asian pear growth rates were significantly different between the three sites, but cultivar growth rates were not. Tree growth rate showed a significant negative correlation to fire blight rating. That is infected trees did not grow much. Initial findings show Shinko, Shinseiki and Niitaka to have some tolerance to fire blight spread and to produce good yields of attractive fruit. However, Niitaka had a very tough skin with a tendency towards fruit cracking. The cultivar Shin Li which also had fire blight tolerance did not produce fruit or flowers.
Growth of fungi from the surface of excised peel taken from Florida citrus fruit interfered with controlled studies on pigment changes of the flavedo. Control of these fungi was not achieved even though whole fruits were dipped in various concentrations of sodium hypochlorite before removing discs of peel for incubation in culture on a defined medium (5). Normally, the presence of fungal growth was evident on all discs of excised peel after 3 to 5 days incubation at 30°C. Development of a technique to control these fungi was necessary to allow longer incubation of discs to observe pigment changes.
Applications of lead arsenate to ‘Temple’ oranges lowered the titratable acid content but not the soluble solids or percentage juice. The percentage total decay, peel injury, and creasing were not appreciably influenced by the lead arsenate sprays. Fruit from trees sprayed with lead arsenate passed legal maturity standards 15 to 20 days earlier than fruit from non-sprayed trees.
A Chatillion Fruit and Vegetable Testor (Model 516-1000 MRPFER) was modified and used to measure capping (plugging) percentage, capping force and pedicel breaking force of strawberry fruits. The resulting instrument (“capometer”) proved to be fast, accurate, portable and well adapted to field use. The correlation (significant at 1% level) between capping percentage obtained with the capometer and capping percentage obtained by hand proved the validity of the use of the capometer to measure the fruit detachment forces. Capping percentage and the force required to cap the fruit and to break the pedicel differed significantly among the cultivars tested.
Free phenolic constituents increase more than 2-fold in injured peel of oranges (Citrus sinensis Osbeck) cv. Valencia after 48 hr at 30°C and 96 to 98% relative humidity (rh). Concomitantly, conjugated phenolic compounds decrease to near depletion as a heavily lignified layer forms on injured cells. At 5°C all wound healing processes slow down. Infection of injured tissue by Penicillium digitatum Sacc. at 27°C inhibits lignin synthesis and the disappearance of conjugated phenolic compounds, but does not interfere with the usual increase in free phenolics. Mycelium of P. digitatum contributes little to the level of phenolic compounds of decayed fruit tissue. Extracts of free phenolic substances from healed tissue d) not exhibit fungistatic activity on P. digitatum spores, Lignin formation provides a mechanical barrier which retards or inhibits penetration of injured tissue by P. digitatum.
Diallel crosses were used to determine the inheritance patterns for capping percentage, capping force, and pedicel breaking force in Fragaria × ananassa Duch. cultivars. The diallel crosses were evaluated with the Jinks-Haymen formulae and these results were compared with the phenotypic evaluation of the parent cultivars. Capping percentage, capping force, and pedicel breaking force are different genetic traits but they were significantly correlated with each other. The pattern of inheritance for each trait was controlled by both additive and dominant genes. The overall direction of dominance for the respective traits was for higher capping percentage, lower capping force and lower pedicel breaking force. ‘Gorella’ exhibited extreme overdominance for low capping force. Because of the large environmental influence on these traits, progeny tests such as diallel crosses provide a better evaluation of the genetic potential of a cultivar than its phenotypic performance.
Healing of minor injuries to ‘Valencia’ orange (Citrus sinensis (L) osbeck) occurs rapidly at 30°C and 96-98% relative humidity. It is manifested by a marked increase in the activity of phenylalanine ammonia-lyase (PAL) and deposition of lignin. PAL activity is confined mainly to injured flavedo while uninjured peel and albedo tissues exhibit very little activity. Inoculation of injured flavedo, immediately after injury, with P. digitatum sacc. disrupts the increase in PAL activity. When acetone powder from decayed peel was mixed with that of healed injured fruit and enzyme preparation was made from the mixture, there was no apparent reduction in phenylalanine ammonia-lyase activity, except that cuased by dilution. The synthesis of both PAL and lignin in mature fruit is strongly inhibited by cycloheximide, but not by actinomycin D.