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- Author or Editor: J. B. Thompson x
Abstract
Feeding injury by pecan aphids on fully expanded pecan [Carya illinoensis (Wangenh) K. Koch] seedling foliage reduced net CO2 exchange within 2 weeks of infestation and was dependent upon aphid density and species. Increasing aphid population levels resulted in increasing reductions in net photosynthesis. Carbon exchange rates after a buildup and subsequent rapid decline of either Monellia caryella (Fitch) or Monelliopsis pecanis (Bissell) populations resulted in a 50% reduction in net photosynthesis and 25% reduction in dark respiration. This effect can persist at least 12 weeks after the cessation of aphid infestation. Such leaves exhibit aphid-induced clogging of the phloem with callose and other substances. Such clogging may be associated with the commonly observed aphid population decline in pecan orchards. Observations indicate that the influence of aphid feeding on leaf photosynthetic physiology may impair pecan productivity.
Vegetable Soybean Cultivars belonging to MG III thru V were evaluated for their Seed Yield Efficiency (SYE) and Resistance to Heliothis Zea.
This study was conducted in 1968 and 1969. Each entry was planted in a single row plot. Each plot was 5.0 m long and 0.75 m apart in a randomized complete block design with 4 replications.. All entries were evaluated for Seed Yield Efficiency by computing the ratio of seed dry matter wt. to non-seed dry matter wt. and their resistance as the percentage of damage pods.
Preliminary data indicated that cultivars kim and Oakland (MG III), Kingston and Jefferson (MG IV), Pershing and PI 416.467 (MG V) were very high in SYE while Fuji (MG III), Sanga (MG IV) and PI 417.266 (MG V) were observed to have high level of resistance to Heliothis Zea.
We hope that these cultivars could be used as parents for the development of Breeding Program in Vegetable Soybean.
Four cultivars of pecan [Carya illinoinensis (Wangenh.) K. Koch] were studied for 3 years to determine if variations in yield influence fatty acid composition of kernels. Trees used in the study are part of the U.S. Dept. of Agriculture, Agricultural Research Service Historical Block, a test orchard planted in randomized block design with four blocks, having one single-tree replication per block and containing 36 cultivars. Four trees of each of four cultivars (`Cheyenne', `Mohawk', `Pawnee', and `Osage') were used in this test. Trees were in their 5th to 7th leaf from grafting and showed patterns of increasing yield over time for each cultivar. `Osage' was earliest to mature nuts each year and produced nuts with the lowest linoleic acid content. `Cheyenne' was latest to mature nuts and had nuts with the highest linoleic acid content. Oleic acid composition varied with yield in `Osage' and `Pawnee': as yield (kilogram/square decimeter trunk area) increased, oleic acid content decreased. Kernel color, as determined by a Hunter LabScan 5100 Spectrocolorimeter, varied in relation to fatty acid composition for `Osage' and `Pawnee': as oleic acid content increased, kernel lightness decreased. High oleic acid content and light kernel color are associated with high-quality pecans. The pattern of decreasing oleic acid content associated with increasing kernel lightness raises questions concerning the role kernel color evaluation should play in selecting high-quality pecan cultivars.
Abstract
Butanedioic acid mono-(2,2-dimethylhydrazide) (daminozide) increased the red color and anthocyanin content of fresh and processed sweet cherries (Prunus avium L.). Daminozide had no effect on the USDA color grade for processed dark sweet cherries but reduced the USDA character of processed dark sweet cherries and increased drained weight losses regardless of cultivar. The use of daminozide on light sweet cherries resulted in reduced USDA color grade for the processed product. A 2-week delay in harvest also increased red color and anthocyanin content of sweet cherries, and increased the USDA color grade of the processed ‘Bing’, ‘Chinook’, and ‘Rainier’ cherries. In addition, it reduced the USDA character grade of processed ‘Chinook’ but not of ‘Bing’ and ‘Rainier’ sweet cherries.
Twenty-four half-sib sweetpotato families were field tested for freedom from injury by sweetpotato weevil and other soil inhabiting, injurious insects (WDS). Three pairs of adult male and female weevils were applied to the crown of each plant at the beginning of storage root enlargement. Naturally occurring numbers of WDS were high enough for considerable injury from those insects. WDS injury free roots ranged from 19% in Centennial, the suceptible control, to 57% in Regal, the resistant control. The highest family mean for percent non-injured by WDS was 55%. Weevil injury free roots ranged from 67% in Centennial to 90% in Regal with 3 families producing mean weevil non-injured roots of 89%. The genetic correlation between weevil injury free and WDS injury free roots was 0.69 ± 0.28. That estimate is preliminary and based on data from one environment. Evaluations will be repeated in 1994 for estimates of GXE to derive genetic correlation estimates with less environmental interactions.
Abstract
‘Golden Delicious’ apples (Malus domestica Borkh.) from trickle-irrigated plots were more mature than sprinkle-irrigated apples. Trickle-irrigated apples were higher in yellow color, soluble solids, and pH. Titratable acidity and moisture were less in fresh and stored apples that were grown with trickle irrigation. Applesauce from trickle-irrigated apples was superior in consistency and developed less free liquor (weep) than sauce from sprinkle-irrigated apples. Drip losses were greater in frozen apple slices from sprinkle-irrigated apples. Canned or frozen apple slices were firmer when produced from apples that were sprinkle-irrigated. The color of apple products from trickle-irrigated apples was superior to the products from sprinkle-irrigated apples. These differences resulted from treatments where leaf water potential differed by only 1 to 2 bars, –14 and –12 bars with trickle and –12 and –11 bars with sprinklers in 1978 and 1979.
`Beauregard' storage roots which were discarded from the Mississippi sweetpotato foundation seed program because of the presence of flesh mutations were bedded in Spring 1991. After the plants were pulled from the roots, the roots were further examined, and the flesh mutations were characterized by size and frequency. The progency from the original roots were examined for flesh mutations for three generations in 1991, 1992, and 1993. The degree of mutation in the original root did not influence the degree of mutation in succeeding generations of storage roots. In 1992 and 1993, the degree of mutation in the third and fourth generation roots did not differ from that of storage roots grown from plants from the foundation seed plant beds.
`Beauregard' and `Centennial' were planted in plots of four different topsoil thicknesses (0, 3, 6, and 9 inches) to evaluate the effect of topsoil thickness on sweetpotato production. In 1994, the 0-inch topsoil treatment produced a greater total marketable yield for `Beauregard' than did the 6- and 9-inch topsoil for `Centennial'. The 0- and 9-inch topsoil produced a greater total marketable yield than did the 3- and 6-inch treatment. When averaged over 2 years, 1993 and 1994, there were no differences in total marketable yield in either `Beauregard' or `Centennial' due to topsoil thickness. Averaged over both years, topsoil thickness had no effect on weight, diameter, or length of `Beauregard' roots.
Commercial kiwifruit production often requires substantial inputs for successful pollination. Determining the length of time that female flowers can be successfully pollinated can aid management decisions concerning pollination enhancement. The purpose of this research was to determine the effective pollination period (EPP) for ‘AU Golden Sunshine’ and ‘AU Fitzgerald’. Either 30 (2013) or 32 (2014, 2015) flowers of ‘AU Golden Sunshine’ were hand pollinated each day for 1 to 5 (2013) days after anthesis (DAA) or 1 to 7 DAA (2014, 2015), and then isolated to prevent open pollination. Anthesis was considered the day the flower opened. Similarly, ‘AU Fitzgerald’ flowers were pollinated and then isolated 1 to 6 DAA in 2013 and 1 to 7 DAA in 2015. For ‘AU Golden Sunshine’ in 2013, fruit set was consistent over the 5-day period, but fruit weight, fruit size index, and seed number decreased between 1 and 3 and 4 and 5 DAA. In 2014, fruit set decreased between 1 and 6 and 7 DAA, whereas fruit weight, fruit size index, and seed number each decreased in a linear trend. In 2015, fruit set also decreased between 1 and 6 and 7 DAA, whereas all other responses decreased linearly. Based on fruit set in 2014 and 2015, the EPP for ‘AU Golden Sunshine’ was 6 DAA. The EPP for ‘AU Fitzgerald’, however, was more variable. In 2013, fruit weight, fruit size index and seed number decreased between 1 and 4 and 5 and 6 DAA, suggesting that the EPP was 4 DAA. In 2015, fruit set remained consistent over the 7-day period with fruit weight, fruit size index, and seed number decreasing linearly. Differences in temperature and the alternate bearing tendency of kiwifruit species likely contributed to the discrepancies between the years for the EPP. For each cultivar, reductions in fruit weight, size, and seed number were observed before an observed decrease in fruit set. Greater fruit weight, size, and seed number were observed when flowers were pollinated within the first few DAA, with results varying thereafter.