bluuebunny/crossref_metadata_2025 huggingface dataset:
LEAF GAS-EXCHANGE, WATER RELATIONS, AND IONIC RESPONSES OF SAPODILLA TO SALINITY
Authors: Mickelbart Michael V.
Published: April 2024

The influence of root zone salinity on leaf gas-exchange, water relations, and ion absorption of sapodilla [Manilkara zapota (L.) Royen] plants was studied in sand culture under greenhouse conditions to investigate the mechanisms of stress damage. Treatments consisting of a complete nutrient solution diluted to 1 dSm-1 (control), or the control solution salinized to 12 or 20 dSm-1 were administered from 16 Nov. 1991 until 29 Jan. 1992. The plants were arranged in a completely randomized design with six replications. Net photosynthesis of the plants receiving saline solutions began to decline within two weeks, and by 8 weeks was ca. 70 or 30% of that of control plants for the 12 or 20 dSm-1 treatments, respectively. Salinity reduced apparent quantum yield (based on light response curves), photosynthetic CO2 use efficiency (based on CO2 response curves), leaf osmotic potential, and pre-dawn xylem potential of sapodilla plants. Dark respiration and sensitivity to photoinhibitory damage (based on chlorophyll fluorescence) were not influenced by salinity. Exposure to salinity also increased leaf tissue Na+ and Cl- concentrations, and the Na+/K+ ratio.
EFFECTS OF COLD STORAGE AND RECONDITIONING ON ASCORBIC ACID, SOLUBLE PROTEIN, SUGARS CONTENT, AND ULTRA-STRUCTURE OF AMYLOPLAST MEMBRANES OF `YUKON GOLD' TUBERS.
Authors: Okeyo James A. , Kushad Mosbah M.
Published: April 2024

Yukon Gold, a yellow-fleshed potato cultivar, was grown in Southwest Virginia and analyzed for ascorbic acid, soluble protein, and sugars (glucose, fructose, and sucrose) at harvest, after 6 weeks storage at 3 C, and following 2 weeks reconditioning at 25 C. Scanning and transmission electron micrographs were taken at each of the three stages to determine the effect of cold storage and reconditioning on the ultrastructure of amyloplast membrane. At harvest the tubers contained 154.0 mg/100 g ascorbic acid, 45.4 mg/g soluble protein, and 4.1 mg/100 g total sugar on dry weight basis. Cold storage resulted in more than 2.5 fold increase in ascorbic acid, between 4 and 9 fold increase in sugars, and a significant increase in soluble protein content. Reconditioning, however, decreased ascorbic acid, soluble protein and sugars. The ultrastructure of the amyloplast membranes remained intact throughout the storage period.
INVOLVEMENT OF CORK CELLS IN DEVELOPMENT OF EPICUTICULAR WAX FILAMENTS
Authors: Jenks Matthew A. , Ashworth Edward N.
Published: April 2024

Chemically-induced near-isogenic (bm) mutants of Sorghum bicolor with altered epicuticular wax (EW) provide a model system for elucidating ultrastructural mechanisms associated with EW production. Light and scanning electron microscopy reveal that tubular EW filaments are deposited over rounded papillae on the surface of modified epidermal cells--cork cells. Transmission electron microscopy reveals that wildtype cork cell apical walls are sinusoidal, multi-layered, and possess an osmiophilic apical cap forming an intermediate layer between the inner and outer walls. Highly vesiculated cytoplasmic extensions appear directly beneath papillae. Whether osmiophilic globules within cork cell cytoplasm serve as precursors for EW is still unclear. Unique nearisogenic mutants bm-21, bm-22, and bm-38 with little papillar EW production have alterations in cork cell apical cap and vacuole development. Specific Sorghum bm gene mutations alter development of EW crystal morphology and cork cell ultrastructure.
BIOMASS ACCUMULATION PATTERNS IN A COMMERCIAL `EARLY BLACK' CRANBERRY PLANTING
Authors: DeMoranville Carolyn J.
Published: April 2024

Dry weight accumulations (area basis) in new shoots, old leaves, woody stems, roots, and fruit of `Early Black' cranberry were determined seasonally for 1987 to 1989. The planting received 335 kg/ha of 10N-8.7P-8.3K per season, New shoot tissue accumulated dry mass at a rapid rate from late May until, late July, and again 1n the late summer (stem lignification). Root biomass was variable, declining and increasing in a cyclic pattern. Apparently, cranberry roots are short-lived. At times of declining biomass, many decaying roots were found in the samples. The pattern of biomass accumulation in roots was opposite that of shoots with shoot:root varying during the season from 0.12 to 0.55. Over the entire season, root biomass accounted for >60% of the total biomass per unit area of cranberry bog. At this location, fruit made up 10% of standing biomass at harvest. Changing fertilizer dose affected new shoot weight and length and fruit production, but the effect on root biomass was not significant in the 3 years of the study.
COMPENSATION OF RED RASPBERRY TO PRIMARY BUD REMOVAL
Authors: Moore Patrick P.
Published: April 2024

To determine the impact of loss of primary buds on yield of red raspberry (Rubus idaeus L.), all primary buds on a cane were removed for two of the four canes on a hill for six Pacific Northwest raspberry cultivars at Puyallup, WA in February, 1991 and for five cultivars in February, 1992. Each cane was harvested individually and compared to non-treated canes in the same hill. Each cultivar was represented by two hills each year. In each year, there was no effect of treatment for total yield, fruit weight, length of season, or date of 5, 50 and 95 percent harvest.
OPTIMIZING SUNLIGHT INTERCEPTION IN PECAN ORCHARDS
Authors: Wood Bruce W. , Burcaw Jeffrey W. , Poole Michael W. , Burnette Mark T.
Published: April 2024

The relative intolerance of pecan trees to low light environments suggests a need for the development of sunlight management strategies that optimize orchard productivity. Current strategies exhibit little emphasis on integrating sunlight interception, tree growth, and orchard design within this context. Therefore, there is a myriad of geometrical variation among commercial orchards and an associated difference in productivity.

We have developed a mathematical model incorporating computer simulations of pecan tree growth in a wide variety of orchard situations. Variables include tree shape, intertree spacings, geometrical pattern within the orchard, geographical coordinates, and time and day of year. This model predicts the extent of shading during the daily interval of maximum photosynthesis for any combination of these variables. It can also be used by the orchardist to establish orchards in which trees receive maximum levels of sunlight within specific windows of time; for example, during the period of nut filling or during the accumulation of dormant season assimilate reserves.
THINNING DATES INFLUENCE SIZE OF `ROYAL GALA' APPLES
Authors: Call Robert E. , Kilby Michael W.
Published: April 2024

A thinning-timing study of apple, (Malus domestica Borkh. cv. `Royal Gala'), grown on M7a rootstock, was initiated during the Spring of 1992 to determine the optimum and last effective thinning date to affect `Royal Gala' apple size. Trees planted in 1987 in sandy-loam soil and trained on a three tier Ebro trellis system were used in this study. Thinning-timing treatments were begun at full bloom and continued weekly for four weeks making a total of five thinning dates and an non-thinned control. Each treatment's flowers and/or fruits were hand thinned to 15 - 20 centimeters between fruit on tree limbs. Measurements of the diameter of marked apples from each treatment were made weekly during the growing season to plot growth curves. Results show a significant difference of larger fruit size and weight of second and third thinning treatment dates as compared to the other treatment dates and the control.
BROILER AND LAYER POULTRY MANURE AS FERTILIZERS FOR LETTUCE, CABBAGE, AND STRAWBERRY
Authors: Rubeiz I.G. , Farran M.T. , Sabra A.S. , Al-Assir I.A.
Published: April 2024

Floor litter from broiler chickens (BCM), 8 weeks old, and from laying hens (LHM), 1 year old, were evaluated as nitrogen fertilizers. Lettuce cv. Paris Island cos was transplanted to a greenhouse that had received 6 months earlier 18t/ha BCM (19% H2O, 5.5% N), 28t/ha LHM (22% H2O, 3.7%N), or NH4NO3 at 100kg N/ha during the season. Yields were comparable among all treatments. Cabbage cv. Cosmos Royal was grown under 2.4 or 4.8t/ha BCM (2.3% H2O, 4.5% N, 2.2% P), 3 or 6t/ha LHM (3.4% H2O, 3.8% N, 3.4% P), or (NH4)2SO4 at 100kg N/ha. Comparable yields were achieved among all treatments. Strawberry cv. Douglas was grown under 11t/ha BCM (7.7% H2O, 4.9% N, 1.6% P), 13t/ha LHM (5.6% H2O, 3.9% N, 1.7% P) or (NH4)2SO4 at 100kg N/ha. Highest yields, over a 3 month-period, were under BCM followed by LHM, (NH4)2SO4 and the control. Poultry manure is equally effective to mineral N fertilizers on head forming crops, and superior to mineral N on long season strawberry. BCM is recommended over LHM when both are available.
RELEASE OF NITRATE - N FROM TROPICAL SOILS TREATED WITH FERTILIZERS
Authors: Hamilton Mark D. , Cruz Frank J. , McConnell James
Published: April 2024

The passage of nitrate nitrogen through three Guam soils was investigated using six different fertilizers. Controlled release and water soluble forms were applied to soils in polycarbonate pots 11cm in diameter. Controls received no fertilizer application. Soil types used were Yigo silty clay and Guam cobbly clay loam, from northern Guam, and Akina silty clay from southern Guam. All pots were exposed to ambient temperature and humidity but were shielded from direct sunlight and rain. All were kept near field capacity by daily applications of distilled water. Leachate was collected weekly for three months and measured using an ion selective electrode. Initial results suggest that nitrate levels were primarily affected by soil type rather than the type of fertilizer applied. Nitrate was invariably highest in Yigo silty clay, lowest in the Akina silty clay and intermediate in the Guam cobbly clay pots. Patterns of nitrate release were similar in the Yigo silty clay and Guam cobbly clay soils with peak values at the fourth and fifth week, 700ppm and 450 ppm respectively, then falling to 300ppm and 150ppm respectively by the sixth week. However, Akina silty clay soils gradually increased in nitrate to 120 ppm in the last two weeks of the experiment.
BRIDGE SPECIES FOR INTROGRESSION OF WILD GERMPLASM IN SWEET POTATO BREEDING.
Authors: Gisella Orjeda , Carey E. , Lawrence M.
Published: April 2024

The species of section Batatas represent the primary potential source of wild germplasm for sweet potato breeding. Their wide distribution and adaptation make their use desirable, but their direct use is constrained by their ploidy level (2x, and 4x, in contrast with cultivated I. batatas which is 6x) and lack of storage root production.

We investigated 4x clones of interspecific origin (6x I. batatas 2x I. trifida) as bridges to introgress genes from several wild species of the section Batatas to I. batatas. Six 2x wild species from different origins were reciprocally crossed to the 4x clones. The crosses were successful only when the diploid wild species were used as females (2x × 4x) indicating unilateral interspecific incompatibility. The unsuccessful types of crosses (4x × 2x) were repeated using wild hybrid males containing I. trifida in their parentage. This time only those crosses involving a hybrid having I. trifida as its female parent produced seeds. Progenies from the successful 2x × 4x crosses were diploid instead of the expected triploid. Triploid progenies were obtained only in the 4x × (2x hybrid) crosses. Some triploid progenies produced 2n pollen in varying frequencies. These results show different levels of crossing barriers among Ipomoea species and give us alternative pathways for overcoming them. I. trifida was identified as a possible bridge species.
VARIATION IN YIELD AND RAPD MARKERS AMONG IPOMOEA BATATAS cv. JEWEL CLONES
Authors: Villordon Arthur O. , LaBonte Don R.
Published: April 2024

Sweetpotato clonal propagation is achieved through sprouts obtained from roots saved from the previous crop. Recommended cultural practices dictate replacing seedstock with foundation seed on a continual basis to maintain the original attributes of the variety. Theoretically, cultivar purity is maintained within and among foundation programs. However, mutations are common in sweetpotato and not all of these off-types may be detected through visual selection. The existence of genetic variation in quantifiable traits, i.e., yield, among foundation stocks may indicate that current maintenance practices need to be improved.

Yield tests and RAPD analysis were conducted among Jewel clones obtained from eight sources. Significant differences in yield among clones were observed during the 1992 season. The yield tests were conducted in two locations in Louisiana. Concomitantly, genomic DNA was isolated from each clone using a modified cTAB procedure and assayed against twenty primers. Eight primers which produced distinct, reproducible bands were identified and used for polymorphism analysis. At least one primer (OPA-06) demonstrated putative RAPD marker variation. Two-primer assays also revealed differences in RAPD markers. The results indicate the potential usefulness of RAPD markers in sweetpotato breeding, particularly in cultivar maintenance.
APPLICATION OF DIBA TO DETECT TMV AIO CMV IN PEPPER PLANTS
Authors: Yong Liu
Published: April 2024

Dot Immunobinding Assay(DIBA) is a very specific method in the detection of TMV and CMV in pepper plants. There is no positive reaction in the detection of CMV with TMV--Antiserum and of TMV with CMIV--Antiserum respectively. The maximum reacting dilutions of crude sap of TMV and CMV are 5120 and 2560, respectively. The comparison of three blocking systems in TMV and CMV detection showed that both TBST+3%BSA and TBST+3%Casein systems are better than TBST system. The sensitivity of detection of sap extracts of infected pepper leaves with TMV or CMV by DIBA is more than that of by Immuno Sorbant Election Microscopy.
PLANT GROWTH REGULATORS IN THE FORCING SOLUTION INFLUENCE PROTEIN EXPRESSION OF FORCED SOFTWOOD GROWTH
Authors: Yane Guochen , Read Paul E.
Published: April 2024

Plant growth regulators (PGR) in the forcing solution have been demonstrated to influence the bud break and shoot elongation for a wide range of woody plant species (Yang and Read, 1989). However, it was not clear how PGR in the forcing solution modified the breaking of bud dormancy at the molecular level, in terms of protein expression. Dormant stems of spirea and privet were forced in forcing solution containing 200 mg 8-hydroxyquinoline citrate per liter and 2% sucrose, plus different concentrations of BA, IBA or GA3. New softwood growth was harvested for protein analysis. The preliminary results suggest that total protein expression was stimulated by adding BA or GA3 to the forcing solution for spirea and privet. The protein expression was not well correlated with the concentration of IBA in the forcing solution. However, a slight increase of total protein expression was noticed when a higher concentration of IBA was added to the forcing solution for privet. Results of this research will be discussed in relation to development of a better understanding of the physiology of bud dormancy.
IDENTIFICATION OF THE SOURCE AND STRUCTURE OF A FUNGISTATIC SUBSTANCE IN SPHAGNUM MOSS
Authors: Hess Charles E.
Published: April 2024

Horticulturalists have used sphagnum moss as a germination medium for years. It has a high moisture holding capacity, provides good aeration, and seedlings germinated in sphagnum moss have a lower incidence of “damping off”, a syndrome characterized by the rapid death of large numbers of seedlings caused by several fungi including Pythium, Rhizoctonia, and Fusarium. Substances have been extracted from sphagnum which inhibit the growth of the fungi associated with damping off. The primary source of the fungistatic substances are bacteria which grow in association with sphagnum moss. Although there are variations in the species of bacteria found in sphagnum moss collected from different geographical areas, they all appear to be in the genus Pseudomonas. One of the fungistatic substances has been identified as the seven carbon ring compound known as tropolone.
TEMPERATURE AFFECTS PLANT GROWTH AND SULFUR UTILIZATION IN ONION (Allium cepa)
Authors: Randle William M. , Bussard M.L. , Warnock D.F.
Published: April 2024

`Willamette Sweet' onions were grown at 10, 17, 24 and 31 C in controlled environment chambers to determine the effect of temperature on plant growth and sulfur utilization in non- and bulb-inducing photoperiods. Plants were first grown for 11 weeks at a 10 hour (non-bulbing) photoperiod and then for 4 weeks at a 16 hour (bulbing) photoperiod. Plants were fertilized weekly 200 ppm 20-20-20 soluble fertilizer containing 7 percent sulfur. Plants had greatest and least growth at 24 and 10 C, respectively in the 10 hour photoperiod while bulb maturation was greatest at 30 C in the 16 hour photoperiod. Leaf sulfur concentration increased linearly in plants grown from 10 to 30 C in the 10 hour photoperiod. Bulb sulfur concentration in plants grown at 30 C was twice that of plants grown at 20 or 15 C in the 16 hour photoperiod.
GROWTH ANALYSIS OF UV-B IRRADIATED CUCUMBER SEEDLINGS AS INFLUENCED BY PAR SOURCE AND CULTIVAR
Authors: Krizek Donald T. , Mirecki Roman M. , Kramer George F.
Published: April 2024

A growth analysis was made of UV-B sensitive (`Poinsett') and insensitive (`Ashley') cultivars of Cucumis sativus L. grown in growth chambers at 600 μmol m-2 s-1 of photosynthetically active radiation (PAR) provided by red- and far-red-deficient metal halide (MH) or blue- and UV-A- deficient high pressure sodium/deluxe (HPS/DX) lamps. Plants were irradiated 6 h daily with 0.2 (-UV-B) or 18.2 (+UV-B) kJ m-2 d-1 of biologically effective UV-B for 15 days from time of seeding. In general, plants given +UV-B vs. -UV-B treatment showed lower specific leaf area (SLA) and leaf area ratio (LAR), higher specific leaf mass (SLM), mean relative growth rate (MRGR), and net assimilation rate (NAR), and no difference in leaf mass ratio (LMR). Plants grown under HPS/DX lamps vs. MH lamps had higher SLM and NAR, lower SLA, LAR, and LMR, and no difference in MRGR. Cultivar affected only LMR. PAR source and/or cultivar did not affect plant response to UV-B radiation.
FLORIDA CITRUS ROOTSTOCKS
Authors: Wutscher Heinz
Published: April 2024

The best indicator of trends in citrus rootstocks in Florida is the statistics of registered trees in nurseries collected by the Bureau of Citrus Budwood Registration of the Florida Department of Agriculture and Consumer Services. In 1992, 45.8% of these trees were on Swingle citrumelo (Citrus paradisi Macf. × Poncirus trifoliata [L.] Raf.), 27.9% on Carrizo citrange (C. sinensis [L.] Osbeck × P. trifoliata), 14.8% on Cleopatra mandarin (C. reticulata Blanco), 4.8% on miscellaneous rootstocks (mostly numbered citrumelos and Rangpur × Troyer (C. reticulata hybrid × [C. sinensis × P. trifoliata]), 3.2% on sour orange (C. aurantium L.), 1.9% on Volkamer lemon (C. volkameriana Wester), and 1.2% on rough lemon (C. limon [L.] Burm. f.). There are no official statistics on the rootstocks of existing, mature citrus groves; estimates are 35% on Carrizo, 25% on rough lemon, 20% on sour orange, and 15% on Cleopatra. Very few groves are planted now because of overproduction and depressed prices. In rootstock tests under way, Benton citrange (C. sinensis × P. trifoliata), pummelo × trifoliate orange (C. maxima × P. trifoliata), and Changsha mandarin × trifoliate orange (C. reticulata X P. trifoliata) hybrids look promising.
LIPID PEROXIDATION AND PLANT TISSUE DISORDERS
Authors: Novacky Anton
Published: April 2024

Increased solute leakage resulting from ozone injury, senescence, wounding and virus or bacteria-induced hypersensitive reaction [HR] have been related to membrane lipid peroxidation [LPX]. The genesis of LPX in various situations may derive from several different processes: a) the direct addition of O2 to unsaturated fatty acids forming hydroperoxide in an enzymatic reaction catalyzed by lipoxygenase, an enzyme widely distributed in plant seed, root, and leaf tissue or b) peroxidation by active oxygen species [AO], e.g. O2 and H2O2, that are generated during normal cellular metabolic activities. Increased production of AO could occur as the result of a metabolic change or a reduction in the amount or activities of antioxidants, i.e. ascorbic acid, vitamin E, and glutathione, and the detoxifying enzymes catalase and superoxide dismutase. The HR against plant pathogenic bacteria and viruses will be used as case histories to discuss the genesis of lipid peroxidation.
SUSTAINABILITY OF VEGETABLE GERMPLASM - HAVE WE BEEN TOO EFFICIENT FOR OUR OWN GOOD: THE CIP CASE.
Authors: Collins Wanda W.
Published: April 2024

Valuable vegetable genetic resources exist in potentially precarious survival situations in developing countries. This germplasm is often in the hands of local farmers who do not have the resources to maintain material with no immediate and apparent benefit to them. Concerns have been raised about the breeding activities of international agricultural research centers whose efforts are linked with national agricultural research system (NARS) efforts to introduce improved cultivars directly to these farmers. Critics have maintained that the introduction and availability of improved vegetable genotypes have endangered the survival of important land-races, other locally adapted materials, and even wild species. Are these concerns justified? The International Potato Center (CIP) has been involved in potato cultivar improvement for 20 years. The impacts of their improvement program on NARS, local farmers and survival of important native germplasm will be examined.
SANITATION OF LIGHTLY PROCESSED FRUITS AND VEGETABLES
Authors: Hurst William C.
Published: April 2024

Fresh produce processing (lightly processed fruits and vegetables) is a new, emerging industry offering nutritious, convenient products with fresh-like qualities. The two real-life challenges facing produce processors are sanitation and temperature management. Safety considerations exist because of the potential for hazardous bacteria to grow at refrigerated temperatures. Even with refrigeration, product shelf-life is minimal. Sanitary guidelines must be developed to encompass both processing plants and employees. Research is needed in three areas--modified atmospheric packaging, product surface discolorations, and pest control to ensure that products remain competitive in the marketplace. Educational programs must be developed to combat complacency among employees concerning sanitary habits and temperature abuse during processing, storage and distribution of fresh-cut products to customer markets.
CULTIVAR CHARACTERISTICS--LIGHTLY PROCESSED FRUITS AND VEGETABLES
Authors: Romig William
Published: April 2024

To date, fruit and vegetable varieties have not been developed with the lightly processed segment of the market in mind. Cultivars have been developed for the processed industry and for fresh market. However, manufacturers of lightly processed foods have relied on their ability to select from pre-existing varieties which are best suited to their process. Occasionally, varieties have been developed with a lightly processed product in mind, but the variety was not developed with the process in mind but with the desired consumer attributes. In most cases, the manufacturer of lightly Processed fruits and vegetables is using the same variety and harvested lot for bulk produce and lightly processed products, in which case the breeders priorities for bulk produce may not be the same as for lightly processed foods. For example, the breeder will target yield, disease resistance, sensory, and perhaps shelf life for whole produce. However, he/she tends not to be concerned with sensory attributes of pre-cut products or the shelf life of the variety prior to or post processing. The value added to pre-cut or lightly processed foods and potential market size will eventually determine if the development of varieties exhibiting specific attributes for this market segment is warranted. Positive Business analysis may dictate the development of varieties with specific geometric dimensions, resistance to specific postharvest disorders, reduced levels of substrates or key enzymes controlling sensory attributes or shelf life characteristics, etc. using a few key examples, the author will illustrate how characteristics desired in lightly processed are driving the development of new varieties.
EFFECTS OF BRASSICA RESIDUES ON ASPARAGUS DECLINE SYNDROME AND PLANT GROWTH
Authors: Elson Marshall K. , Kelly John F. , Price Hugh C.
Published: April 2024

Asparagus Decline Syndrome is caused by Fusarium oxysporum f.sp. asparagi (FOA) and Fusarium moniliforme (FM). Resistant asparagus varieties have not been found and chemicals are often ineffective against Fusarium spp. Cabbage (Brassica oleracea) residue has been shown to reduce Fusarium infection in cabbage. However, canola (Brassica napus) also reduces yields in wheat.

Seven Brassicas were selected for testing in the greenhouse and field (Kale, Turnip, Glacier Canola, Global Canola, Yellow Mustard, Dwarf Essex Canola, Humus Canola). Brassica residue added to soil reduced root growth of asparagus, wheat, cress, cucumber, and cabbage seedlings upto 4 weeks. Brassicas grown in the field reduced FOA populations and the incidence of Fusarium infection, but did not inhibit plant growth. Extraction of Brassica residue did not yield any non-volatile Fusarium-inhibitory compounds.
USE OF REFLECTIVE MULCHES FOR CONTROL OF MOSAIC VIRUS DISEASE AND REDUCTION IN APHID VECTOR IN SUMMER SQUASH
Authors: Brown J.E. , Henshaw M.D. , Dangler J.M. , Woods F.M.
Published: April 2024

Silver reflective plastic mulches were compared with conventional bare ground culture for the reduction of aphids, and mosaic virus diseases as follows: Cucumber Mosaic, Watermelon Mosaic I and II, Zucchini Yellows Mosaic, and Squash Mosaic. Silver plastic mulch produced higher marketable yields than the bare ground treatments. Other colors (white, yellow, and black plastic with yellow edges) of plastic mulch treatments were intermediate in their effects on aphid population and virus disease reduction. Silver reflective mulch alone and silver reflective mulch with insecticide were superior to other colors of plastic mulch in reducing aphid populations. Silver reflective plastic mulch, with or without insecticide, resulted in 10-13 days delay in the onset of the above mentioned mosaic disease.
CULTURAL PRACTICES INFLUENCE DILL PRODUCTIVITY IN THE SOUTHEASTERN UNITED STATES
Authors: Miller Thelma , Bandele Owusu , Javius Marion , Udoh Oscar , Belvitt Byron
Published: April 2024

The effects of planting density and N fertilizer rate on fresh yield of `Long Island Mammoth' dill (Anethum graveolens L.) were evaluated using a split plot design. Planting density (one versus two row beds) was the main plot treatment and N rate, the subplot treatment. High, medium and low N rates were 0, 56 and 112 kg/ha in 1990, but 28, 56 and 112 kg/ha in 1992, respectively. P and K were applied at rates of 59 and 111 kg/ha, respectively. In 1990 yields increased as N rate increased. In 1992 the medium N rate produced greater yields than did the high rate, but yields from plots receiving the low N rate did not differ from those receiving other treatments. Planting density did not significantly affect yield in either year. In a second study four, cultivars (`Bouquet', `Crown', `Long Island Mammoth' and `Tetra') were evaluated in 1990 using a randomized complete block design with N applied at 56 kg/ha. `Dukat' and `Fernleaf were added in 1992. Cultivar yields differed only in 1992 when `Long Island Mammoth' outyielded `Crown' and `Fernleaf'.
WATER APPLICATION SCHEDULING BY PAN EVAPORATION FOR DRIP-IRRIGATED TOMATO
Authors: Locascio S.J. , Smajstrla A.G.
Published: April 2024

Tomatoes (Lycopersicon esculentum Mill.) were grown on an Arredondo fine sandy soil to evaluate the effects of water quantity scheduled by pan evaporation using drip irrigation and polyethylene mulch in a three year study. Water was applied at 0, 0.25, 0.50, 0.75, and 1.0 times pan evaporation in one application per day. The response to irrigation varied with rainfall during the three seasons. In an extremely dry season, fruit yields were doubled by irrigation. Total fruit yields were highest with irrigation quantities of 0.75 and 1.0 times pan and significantly lower with 0.25 and 0.50 times pan water quantity. In an extremely wet season, fruit yields were not influenced by water quantities from 0 to 1.0 times pan. In a third season that was wet from the middle to the end of the season, irrigation more than doubled the marketable yield. However, yield increased only from 65.9 Mt·ha-1 with 0.25 times pan to 74.1 Mt·ha-1 with 0.75 times pan. Tomato leaf N concentrations were reduced slightly with each increase in water quantity applied even though N was applied with drip irrigation.
GA3 DELAYS MATURITY AND INCREASES FIRMNESS OF PEACH FRUITS.
Authors: Ward Daniel L. , Taylor Bradley H.
Published: April 2024

Two experiments were conducted in 1992 to examine the effects of GA3 concentration and date of GA3 application on peach fruit maturation and quality. Concentrations of 0, 24, 48 and 72 mg/l GA3 were applied on 28 June. GA3 at 48 mg/1 was applied on 25 May, 10 June, 28 June and 18 July. Mature `Canadian Harmony' trees were used in a randomized complete block design with 8 blocks. All concentrations of GA3 applied 28 June delayed the weighted average harvest date by ≈2 days. There was a linear increase in concentration of maturity with increasing GA3 concentrations. There was no detectable date of application effect on fruit maturation. There was a small (16%) increase in fruit firmness that was linearly related to increasing GA3concentration. Fruit firmness was greater with earlier dates of GA3 application.
INFLUENCE OF LONG-TERM ROOT PRUNING ON APPLE TREE ROOT DISTRIBUTION
Authors: Ferree David C.
Published: April 2024

`Melrose'/M.26 apple trees were root pruned annually for 8 yrs at full bloom on 2 sides to a depth of 25-35 cm. Spacial distribution was determined by counting roots on the exposed wall (2m × 2.5m area) of a trench and classifying them into 4 size classes. Root pruning caused a reduction in the total number of roots and the ratio of large to small roots in the 0-30 cm soil depth on the side of the tree that had been root pruned. Total number of roots declined in root pruned trees 60 and 90 cm from the trunk in the sample taken perpendicular to the root pruning cut, but not on the side parallel to the root pruning cut. Root number in all 4 size classes declined with depth and exhibited significant linear and quadratic patterns.
EFFECT OF PRIMOCANE SUPPRESSION ON YIELD AND COLD HARDINESS OF `MARION ' BLACKBERRY
Authors: Bell Neil C. , Strik Bernadine C. , Martin Lloyd
Published: April 2024

Primocanes were either not cut, or cut at ground level from plants on a single occasion at one month intervals from late April to late July, 1991 and 1992. For each treatment, the coldhardiness of primocane tissues was evaluated on four dates from early November to early February. One-node samples were frozen and an LT50 developed for tissues by estimating browning on a 1-5 scale. Data on yield and its components were collected the year after primocane suppression treatments. In 1991, although yield per cane declined linearly with later primocane suppression date, yield per plant was highest for the April suppressed plants. Hardiness of all tissues generally increased from November to January and then decreased. Plants with primocanes suppressed in June and July were significantly hardier than those suppressed earlier. Growing point tissues were the least hardy of those tested. Phloem and cambial tissues were approximately 4 ° C hardier than the growing point, while the bud base and pith were 12 ° C and 17 ° C hardier, respectively. Data for 1992 will also be presented.
NITROGEN NUTRITION AND GROWTH ANALYSIS OF POINSETTIA
Authors: Rose Mary Ann , White John
Published: April 2024

Objectives of several experiments were 1) to characterize shoot N uptake and recovery efficiency in relation to the growth and development of `Celebrate 2' and `Lilo' poinsettias, and 2) to minimize N use in crop production by manipulating the concentration and timing of N application. `Lilo' had significantly greater shoot N uptake and recovery efficiency than `Celebrate 2', but the pattern of uptake over the production cycle was similar between cultivars. In the first several weeks after potting, N uptake and recovery efficiency were low. Maximum uptake and recovery efficiency occurred between 6 and 8 weeks after potting. After 8 weeks, and throughout bract development, N uptake decreased

`Celebrate 2' poinsettias were supplied with either a constant 200 mg·N·l-1 (control), or a variable concentration of N that increased or decreased corresponding to N uptake patterns observed in previous experiments. The N uptake curves for these two treatments were similar, and at final harvest (anthesis), there were no significant dry weight, leaf area, or quality differences. By matching the N supply to the N uptake curve, N recovery efficiency increased from 38% to 58%, and 41% less total N was applied compared to the control. The allocation of N and dry weight to leaf, stem, and bract tissue was also similar between treatments.
THE USE OF PLANT GROWTH REGULATORS TO CONTROL EASTERN BLACK NIGHTSHADE (SOLANUM PTYCANTHUM) BERRIES.
Authors: Masiunas John B. , Crotser Michael P.
Published: April 2024

Eastern black nightshade berries interfere with harvest, stain fruit, and are an undesirable contaminate in processing vegetables. The problem may be reduced if flowering, berry production, and maturity could be regulated. Greenhouse experiments evaluated the effect of commercially available plant growth regulators on eastern black nightshade growth and reproduction. Nightshade were seeded in 10 cm plastic pots and allowed to grow until the reproductive stage. Chlormequat-chloride, ethephon, gibberellic acid, dikegulac sodium, and paclobutazol were applied at standard rates in 90 L ha-1 of spray solution using a moving nozzle spray chamber. Nightshade growth, flowering, and berry production were evaluated 3 wk after treatment. Gibberellic acid and ethephon caused leaf chlorosis. Ethephon increased the percentage of ripe berries and decreased the number of flowers per plant.
EFFECTS OF SPACING AND IRRIGATION REGIME ON THE PRODUCTION OF WATERMELONS FOR SEED CONSUMPTION
Authors: Nerson Haim , Burger Yosef
Published: April 2024

Two field experiments were conducted at Newe Ya'ar (northern Israel) to examine the effects of spacing and irrigation on the production of watermelons for seed consumption. Increasing population from 3000 to 12000 plants/ha significantly increased fruit number per unit area and only slightly decreased mean fruit weight. Increasing the water supply from dryland farming to weekly irrigation significantly increased mean fruit weight but had only a small effect on fruit number. Seed yield positively correlated with fruit number per unit area and to a lesser extent with fruit yield. In 1991, maximal seed yield (1.33 kg/10 m2) was obtained in the higher population density (10,000 plants/ha) supplied with one irrigation (800 m3 /ha) at fruit set. In 1992, maximal seed yield (1.24 kg/10 m2) was obtained in the highest population density (12,000 plants/ha) supplied with weekly irrigation. Mean seed weight was not affected significantly by spacing or irrigation regime, nor by fruit size or fruit number per unit area. Yellow Malali, derived by selection in a commercial field, had twice the seed yield as the commercial cultivar Malali.
WHEN DOES PHOTOSYNTHESIS LIMIT YIELD OF PEACH?
Authors: Catania M. , Flore J. A.
Published: April 2024

Terbacil (100 ppm) was applied to mature Redhaven (Prunus persica L. Batsch), once, or twice in different combinations during stage I, II, or III of fruit development or after harvest to determine the effect of photosynthetic inhibition on abscission, fruit size, yield, and shoot growth of the current seasons crop, and winter hardiness, tree carbohydrate status, and return bloom and fruit set the following year. Following application all trees were thinned to the same level in the middle of stage II. Field determinations indicated terbacil inhibited photosynthesis to 0-20% of the control within 24 h, and that leaves recovered to 85-95% within 7-10 days. Fruit thinning was related to the time of application, however, there were no significant differences in crop load at harvest. Fruit size, yield and maturity were inversely related to the time of application. Cold hardiness of the shoots was reduced significantly by Nov. 30 for all applications. Carbohydrate and 1993 fruit set analysis are incomplete at this time. This study indicates that stress early in the season has a greater effect on the current season crop than a similar stress later in the season.
ESTIMATION OF STRAWBERRY LEAF CHLOROPHYLL CONTENT AND PHOTOSYNTHETIC ACTIVITY USING REFLECTANCE AND FLUORESCENCE MEASUREMENTS IN THE FIELD
Authors: Chen Chuhe , Cameron J. Scott , Klauer Stephen F. , Foote Paul W.
Published: April 2024

Portable spectroscopy and fluorescence instruments were used to establish a nondestructive method for estimating chlorophyll (Chl) content and photosynthetic activity in strawberry leaves. 25 genotypes of Fragaria chiloensis were selected as experimental material from a large, replicated field collection. Gas exchange, Chl content, leaf reflectance spectra and induction kinetics of fluorescence from dark-adapted leaves were measured in newly expanded mature leaves.

Negative correlation coefficients between reflectance measurements at 510-650 nm and 690-700 nm and Chl a, b and total Chl were highly significant and reached their peak values around 570 nm (r = -0.80**, total Chl). Multiple regression analysis showed that combining the reflectance measurements at 520 nm with 570 nm significantly improved the model's correlation coefficient (r = 0.86***, total Chl). Reflectance at 520 and 570 seems to represent signals from different components in the photosynthetic apparatus. Combining certain fluorescence parameters with reflectance measurements significantly improved the correlation with Chl a, b and total Chl (r = 0.91***, total Chl). The regression model combining reflectance and fluorescence measurements offers a useful, nondestructive method to simultaneously assess leaf Chl content and induction kinetics of fluorescence using portable spectroscopy and fluorescence instruments. Fluorescence parameters Fv/Fm and Ft combined to show a moderate relationship (r = 0.66**) with CO2 assimilation rate.
VARIATION IN MALE FERTILITY OF PELARGONIUM XDOMESTICUM
Authors: Stuart Mary , Haniford Glenn , Jourdan Pablo
Published: April 2024

Poor seed set in P. xdomesticum hinders development of new and improved cultivars. Crossing data has indicated differences among selections in male fertility. A study was undertaken to examine the amount of male fertility in the species as evidenced by pollen staining and pollen germination and development. Eight P. xdomesticum selections were crossed as males onto two selections used as females. Styles were harvested 2 hours after pollination and examined using fluorescence microscopy to determine the number of germinated pollen grains on the stigma and the number of pollen tubes produced in the style. Pollen from the 8 selections was tested for viability by staining with fluorescein diacetate (FDA) and examined using fluorescence microscopy. The males varied in pollen viability from 69% pollen staining producing 16 pollen tubes to 18% saining producing 3 tubes. The most fertile males produce enough pollen tubes to effect fertilization of all of the ovules in a P. xdomesticum ovary.
TRANSMISSION OF CITRUS TRISTEZA VIRUS RESISTANCE FROM CITRUS BREEDING LINE US119
Authors: Hearn C. Jack , Garnsey Stephen M. , Barrett Herbert C.
Published: April 2024

Citrus rootstocks resistant to decline induced by citrus tristeza (CTV) have been developed using resistance found in Poncirus trifoliata (L.) Raf. A breeding line with resistance to CTV infection, US119 [Citrus paradisi Macf. cv. Duncan × P. trifoliata (L.) Raf. × C. sinensis cv. Succory], was developed and crossed with `Ambersweet' orange [C. reticulata Blanco × (C. paradisi × C. reticulata) × C. sinensis] to develop scions resistant to CTV infection. Fifty-one progeny were tested for CTV resistance by grafting each to rough lemon [C. limon (L.) Burm. f.] seedlings infected with CTV. These propagations were assayed repeatedly by ELISA. Seventeen progeny consistently tested negative for CTV (resistant), 24 were consistently positive (susceptible), and 10 gave weak or inconsistent reactions. These results confirm the feasibility of developing CTV-resistant scions by use of US119 to solve the stem pitting disease caused by CTV.
LOW-VOLUME APPLICATION OF ETHEPHON: SURFACTANT EFFECTS ON SPRAY DROPLET/DEPOSIT INTERACTION WITH LEAF SURFACES
Authors: Bukovac M.J. , Whitmoyer R.E. , Brazee R.D. , Reichard D.L.
Published: April 2024

Ethephon is applied to cherry trees as an aqueous spray to facilitate harvesting. Surfactants may be added to improve retention and coverage. We studied the effects of spray volume and surfactant on ethephon deposit formation on sweet cherry leaves using SEM and dispersive x-ray analysis. Cherry leaf surfaces have little epicuticular wax fine-structure hence are readily wetted; contact angle for upper and lower surfaces was 70-82° and 89-92°, respectively. Gum on the upper surface increased wetting dramatically. Droplets (0.24μl) with ethephon at concn (x = 400 mg l-1, 5x, 10x, 20x, 40x) simulating spray volumes of x (full retention) to l/40x resulted in deposits on the lower surface in the form of an annulus at high, and as discrete masses at low spray volumes. On the abaxial surface, the ethephon ppt as discrete masses over veins or anticlinal walls. Surfactant (0.1% Silwet L-77) increased deposit area with lesser effects as spray volume was decreased.
RASPBERRY BUSHY DWARF VIRUS IN RED RASPBERRY BREEDING PLOTS
Authors: Stahler Margaret M. , Lawrence Francis J. , Martin Robert R.
Published: April 2024

Red raspberry (Rubus ideas L.) selection fields in Oregon were screened to determine the incidence and prevalence of Raspberry Bushy Dwarf Virus (RBDV), a pollen-borne virus, using enzyme-linked immunosorbent assay (ELISA). In total, 365 genotypes were tested from three different fields which contained both junebearing (JB) and primocane fruiting (PF) clones. Positive RBDV infected genotypes were 29% JB and 65% PF; 30% JB and 72% PF; 42% JB and 64% PR in the 1991, 1989-90, and 1985-89 established fields, respectively. Examination of all pedigrees of RBDV positive and negative JB selections were very similar containing both susceptible and resistant cultivar parents, especially `Willamette,' considered immune. The PF selection pedigrees were very different from the JB pedigrees with the resistance status of the cultivar parents largely unknown. RBDV resistant genotypes from these selection plots could be useful parents in breeding programs.
CHARACTERIZATION OF BLACKBERRY PYRENES
Authors: TAKEDA FUMIOMI
Published: April 2024

Pyrene (the pit of a druplet) size is a factor contributing to blackberry fruit quality. Large pyrene size, based on weight, length, or volume, and “seediness” is undesirable in processed blackberry products. Several of the recently released eastern thornless and erect Arkansas blackberries can be alternative sources of quality fruits for processors. The purpose of this study was to compare pyrenes of blackberries from the Oregon (O), Arkansas (A), and eastern USDA (E) breeding programs. Pyrene size (length) ranged from 2.5 mm in `Darrow' to 4.0 mm in `Black Satin' and `Merton Tnornless'. Pyrenes of A blackberries generally were ellipsoidal and smaller than E blackberries which were “clam” shaped. Pyrenes of E blackberries such as `Black Satin' and `Chester' had a thick endocarp and were much thicker and wider than A and O blackberries. In contrast, several O blackberries including 'Marion' had flat pyrenes with a soft, thin endocarp. The results of this study indicate that the pyrene thickness trait is a major factor contributing to seediness.
OPTIMAL SPACIAL ORIENTATION OF TREE CROPS BASED ON MAXIMIZING SUNLIGHT INTERCEPTION DURING CRITICAL GROWTH AND DEVELOPMENTAL WINDOWS
Authors: Wood Bruce W. , Burcaw Jeffrey , Poole Michael W. , Burnette Mark T.
Published: April 2024

Tree crops are often planted at particular geometrical and spacing patterns with little or no quantitatively based data on how the arrangements influence sunlight interception and productivity.

We have developed a mathematical model describing intertree shading derived from computer simulations of tree growth and light extinction through the canopy. Variables include tree shape, intertree spacings, orchard geometry, geographical coordinates, season, and time of day. This model predicts the extent of intertree shading during the daily interval of maximum photosynthesis for any combination of these conditions and indicates that optimal orchard design is unique for each latitude and tree crop. It can be used by the orchardist to establish orchards in which trees receive maximum levels of sunlight within specific windows of time; for example, during the period of fruit development or during the accumulation of dormant season assimilate reserves.
DEBATES--A TOOL TO HELP STUDENTS THINK ABOUT HORTICULTURAL ISSUES
Authors: Coons Janice
Published: April 2024

Routine methods of teaching often do not challenge a student's ability to think creatively and independently. In many horticulture classes the emphasis is on learning of facts, principles, and techniques, rather than the consideration of controversial issues such as chemical usage. I have used student debates as a tool to discuss various horticultural issues which are controversial. Possible debate topics, methods for the presentation of the debates, and ways to evaluate the debates will be presented. The use of debates in horticulture classes will be considered from the perspective of both students and the instructor. Both strengths and weaknesses of student debates as a learning experience in horticulture classrooms will be presented.
IMPORTANCE OF HORTICULTURE INSTRUCTION IN SECONDARY AGRICULTURAL EDUCATION PROGRAMS IN NEBRASKA
Authors: Frederick Craig , Fitzgerald Jay B. , Blezek Allen G. , Dillon Roy D.
Published: April 2024

A survey was used to identify specific elements of the horticulture curriculum included in Nebraska Secondary Agricultural Education programs as perceived by nurserymen, garden center operators, and Nebraska secondary agricultural education teachers. A comparison of Nebraska nurserymen's and Nebraska secondary agricultural education teachers' rating of horticulture curriculum content was determined and specific skill areas were identified which are important for employment in the horticulture field.

The statistical comparisons of Nebraska Association of Nurserymen members' and Nebraska secondary agricultural education teachers' rating of skill areas and curriculum content for employment in the horticulture field in Nebraska will be discussed.
INTERIOR PLANTS IN A CLASSROOM IMPROVE AIR QUALITY AND THE LEARNING ENVIRONMENT
Authors: Goodwin Georgia K. , Lohr Virginia I.
Published: April 2024

Plants were added to a college computer lab to determine their effect on air quality and their influence on human psychological and physiological responses. Sixteen plants of varying size and color were added to a stark computer room that measured approximately 8 m × 13 m. Temperature, humidity, carbon dioxide, particulate matter, and human response were monitored in the presence and absence of plants.

The addition of plants enhanced the learning environment physically and psychologically. Relative humidity was slightly, but significantly, higher when plants were in the room than when they were absent. Particulate matter accumulation was found to be less than half as much in the presence of plants compared to accumulation in the absence of plants.