bluuebunny/crossref_metadata_2025 huggingface dataset:
An Agrometeorological Model for Assessing the Effect of Heat Stress During the Flowering and Early Fruit Set on Avocado Yields
Authors: Lomas J.
Published: August 2022

An agrometeorological model was developed for assessing the effect of heat stress during flowering and early fruit set on avocado (Persea americana Mill) yields. This model accounted for heat stress only and was considered to occur when the daily maximum temperature was ≥33°C. In addition to the daily maximum temperature, the model considered the duration of such temperatures in days, as well as the timing of the occurrences of such temperatures in relation to the flowering and early fruit set of ‘Fuerte’ avocado. The specifications of the climatic data inputs are based on experimental results in the temperature range of 33° to 43°C extrapolated linearly. A series of weighting factors were used for the duration of heat spells in days. In the temperature range of 33° to 35° the weighting was n − 1; for the 36° to 38° range, 1.4n; and for the 39° to 43°C range, 2.0n. Weighting factors for the timing of the occurrence of heat spells follow closely the near-normal percentage distribution curve of open flowers. At bud burst in March, the weighting is 0.4, increasing to 1.3 at early fruit set by mid-May and decreasing rapidly to 0.3 by the end of June. The functional relationship between the model heat stress output and the yield of avocado for an irrigated, high-yielding plantation shows fairly good correlation, r2 = 0.42 to 0.51, depending on the statistical method used. The agreement between the heat stress index and the yield of avocados is closely related only during those years when the plantation is subject to heat stress indexes greater than 10. Testing the model on independent data commenced in 1985 and includes a yield memory term.
Effects of Growth Regulator Sprays and Notching on Growth and Branching of ‘Starkrimson Delicious’ Apple Trees
Authors: Greene Duane W. , Miller Paul
Published: August 2022

A block of 2-year-old ‘Starkrimson Delicious’ apple (Malus domestica Borkh.) trees growing in Somerville, Victoria, Australia were treated with 0 to 500 ppm BA when terminal growth was 2 cm. BA application initially increased the rate of lateral shoot growth. However, the growth rate rapidly slowed and extension growth on the lateral shoots stopped earlier than on untreated trees. There was a linear increase in the number of lateral shoots and a linear reduction in the length of these lateral shoots as the concentration of BA was increased. BA forced more lateral shoots to grow at the tip of the branch than at the base, although shoots at the base of the limbs grew longer. A reduced concentration of BA was required to stimulate spurs to grow out into lateral shoots on the vigorous, more upright central leader. Lateral shoots were longer on the central leader than on the scaffold branches, indicating tree and/or branch vigor may be a major factor in producing good scaffold limb development following BA application. Notching forced more spurs to form lateral shoots on the central leader, and these shoots grew longer than those on the scaffold limbs. Notching increased the number of buds developing into lateral shoots following BA application. May and Baker 25-105 increased the number of lateral shoots on a tree. This result occurred both on untreated trees and on those that previously received 400 ppm BA. Reducing the number of lateral shoots by pinching apices of shoots soon after BA application was the most effective method to increase the length of BA-induced lateral shoots. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine (BA) (2-chloroethyl)phosphonic acid (ethephon), butanedioic acid mono(2,2-diemthylhydrazide) (daminozide), propyl 3-t-butylphenoxyacetate (May and Baker 25-105).
Physiological and Growth Responses of Mature Peach Trees to Postharvest Water Stress
Authors: Larson K.D. , DeJong T.M. , Johnson R.S.
Published: August 2022

Peach trees (Prunus persica L. Batsch cv. Regina) were subjected to three levels of postharvest irrigation between 15 June and 15 Oct. 1983. Wet-treatment (control) trees were irrigated at 3-week intervals, medium-treatment trees received one, and dry-treatment trees received no postharvest irrigations. Significant differences in seasonal patterns of stomatal conductance were found among all treatments, with conductance varying in proportion to irrigation level. Wet-treatment pre-dawn water potential (ψw) remained nearly constant at −0.3 MPa throughout the postharvest season, whereas the dry-treatment readings became more negative as the season progressed. Differences in mid-day ψw were less distinct, but generally reflected pre-dawn water status. The seasonal increase in trunk radius of the dry-treatment trees was reduced by 33% relative to either wet or medium treatments. The amount of daily trunk radial shrinkage was inversely proportional to irrigation level. Dormant pruning weights were 13% less in dry treatments than wet treatments. Return bloom of dry-treatment trees in Spring 1984 was 30% and 40% greater than medium- and wet-treatment return bloom, respectively. Dry-treatment fruit set was 70% greater than medium- or wet-treatment fruit set. Following fruit thinning, there were no significant differences among treatments for fruit yield or fruit size, but fruit maturity was slightly delayed in the dry treatment.
Seasonal Plant Shading, Growth, and Fruiting in ‘Earliglow’ Strawberry
Authors: Ferree David C. , Stang Elden J.
Published: August 2022

‘Earliglow’ strawberry (Fragaria × ananassa Duch.) plants were covered with 60% shade cloth in Wisconsin and Ohio during each of the following developmental phases: 1) check, no shade; 2) the runnering period after plant establishment; 3) flower initiation period in Fall 1983; 4) early growing season (from mulch-off until first flowering); 5) the fruiting period, 1984; and 6) constant shade. ‘Earliglow’ has a photosynthetic light response curve typical of a C, plant. Leaf dry weight per plant was decreased at both locations by constant shading during the fruiting period, just prior to plant sampling. Crown dry weight was reduced by constant shading. Leaf nutrient element contents of K, Ca, Mg, B, and Fe varied by location, but were not appreciably affected by shading treatments. Shading during the active runnering period resulted in increased total yield the following spring by 12% in Wisconsin and 17% in Ohio. In Wisconsin, increased total yield was the result of increased number of fruit in midseason harvests. Berry size was increased for constant shading or shading during fruiting, but yield was offset by lower fruit numbers. Usable fruit in Ohio on plants shaded during runnering was increased by 20% compared to the unshaded control. Constant shade resulted in an 18% and 46% reduction in total yield in Wisconsin and Ohio, respectively. Shading during the fruiting period resulted in yield reductions in both Ohio (13%) and Wisconsin (27%). Yield reductions were also noted in Ohio when shading occurred during early spring (21%), just prior to fruiting, or during flower formation (24%) the previous fall. Shading during the spring growth and fruiting period delayed fruit maturity and peak harvest 5 to 7 days.
Zinc Complexation in the Phloem of Blight-affected Citrus
Authors: Taylor K.C. , Albrigo L.G. , Chase C.D.
Published: August 2022

Extracts from Zn-accumulating phloem tissue of blight-affected trees had higher Zn-binding capacity than extracts from healthy trees. A 4-kDa, highly anionic, zinc-binding fraction was isolated from the phloem of predecline and decline stage ‘Valencia’ sweet orange [Citrus sinensis (L.) Osbeck] and ‘Marsh’ grapefruit (C. paradisi Macf.) trees grown on blight-susceptible rootstocks. Diethylaminoethyl (DEAE) Sephadex chromatography revealed the Zn-binding fraction contained at least four different anionic species. Two of the four species were present in healthy as well as predecline- and decline-stage trees. The other two species were found in only the predecline and decline trees. All Zn-binding factors were similar to the poly(γ-glutamyl-cysteinyl) glycine peptides in terms of size, anionic character, pH and temperature stability, capacity to bind other metals, and spectrophotometric properties.
Fecundity of Crosses Between Tetraploid and Hexaploid Vaccinium
Authors: Lyrene P.M.
Published: August 2022

The purpose of this study was to compare the relative fecundity of tetraploid × hexaploid and hexaploid × tetraploid crosses in blueberry. Four types of crosses were made using cultivars and advanced breeding lines consisting largely of V. ashei Reade (6×) and V. corymbosum L. (4×). Fruit set, number of developed seeds per ripe berry, and number of seedlings per pollinated flower were determined. Tetraploid × hexaploid crosses averaged as high in percent fruit set as tetraploid × tetraploid crosses, but seed number per ripe fruit was only 29% as high and seedling number per pollinated flower only 35% as high. Hexaploid × tetraploid crosses, by contrast, set only 48% as much fruit as hexaploid × hexaploid crosses. Despite reduced fruit set, hexaploid × tetraploid crosses averaged almost as high in number of seedlings produced per pollinated flower as the reciprocal cross. In both types of cross, the success rate strongly depended on the particular genotypes used in crossing. The overall success rate from crosses between tetraploid and hexaploid clones was 2.32 seedlings per pollinated flower, which is high enough to allow production of large pentaploid populations for use in breeding.
Anthocyanin, Aglycone, and Aglycone–sugar Content in the Fruits of Temperate North American Species of Four Sections in Vaccinium
Authors: Ballington James R. , Kirkman William B. , Ballinger Walter E. , Maness Eleanor P.
Published: August 2022

HPLC analysis of the fruits of species of Vaccinium sections Herpothamnus (V. crassifolium and V. sempervirens), Pyxothamnus (V. ovatum), Polycodium (V. stamineum), and Oxycoccoides (V. erythrocarpum), determined that species in these sections fall into two distinct groups. Species in Herpothamnus and Pyxothamnus contained the 3-monoarabinosides, 3-monogalactosides, and 3-monoglucosides of cyanidin, dephinidin, malvidin, peonidin, and petunidin. Differences in anthocyanins (ACY), aglycones, and aglycone-sugars were not useful in distinguishing among species in Herpothamnus. However, differences in aglycones and aglycone-sugars were useful in distinguishing between Herpothamnus and Pyxothamnus. Species in Polycodium and Oxycoccoides contained more than 90% cyanidins, no delphinidins, and small percentages of peonidins and malvidins. Vaccinium stamineum also contained no petunidins. These two sections were similar in ACY and aglycones, but did vary in percent galactose and arabinose. Potential crossabilities, along with overall similarities in ACY among these and other sections, support a fairly recent origin of North American sections of the genus Vaccinium.
Carbon Metabolism in Scions of Colorado Blue Spruce: I. Needle Starch
Authors: Beeson Richard C. , Proebsting William M.
Published: August 2022

Needle starch metabolism was studied during graft development of Colorado blue spruce (Picea pungens Englemann ‘Hoopsi’) scions on Norway spruce [Picea abies (L.) Karst] rootstocks. Starch accumulated during the initial stages of union formation, but the rate of accumulation slowed over time. Peak starch content in developing greenhouse grafts was ≈30% and, in lath house grafts, ≈50% of that in 3-year-old grafts forced in the greenhouse. Prior to budbreak, starch content declined rapidly, stabilizing at pre-grafting levels during shoot elongation. Grafts with misaligned unions accumulated starch during the first week, but the starch content then declined. Preventing photosynthesis in scions during union formation prevented starch accumulation, but did not affect graft success or subsequent scion growth. We concluded that neither starch accumulation nor current photosynthesis in the scion were required during union development.
Carbon Metabolism in Scions of Colorado Blue Spruce: II. Carbon Storage Compounds
Authors: Beeson Richard C. , Proebsting William M.
Published: August 2022

The study evaluated the roles of storage carbohydrates and neutral lipids in the success of Colorado blue spruce (Picea pungens Englemann ‘Hoopsi’) grafts. These scions do not require photosynthesis nor receive photosynthates from the rootstock during union development. Carbohydrate and neutral lipid contents, along with respiration and scion water relations, were measured during union development. Stored carbon compounds were sufficient to supply the needs of the scion during the 9 weeks of union development. Estimates of carbohydrate use indicated that decreases in sugar content (bark and needle) were insufficient to account for more than 25% of the estimated respiration. The results indicate that the quantity of carbon storage compounds is not a factor in graft success. We propose that neutral lipids may be the major carbon reserve of the scion during graft formation.
Plant Population Influences Growth and Yields of Bell Pepper
Authors: Stoffella Peter J. , Bryan Herbert H.
Published: August 2022

Bell peppers (Capsicum annuum L. cv. Early Calwonder) were plug-mix seeded at 13-, 25-, 38-, and 51-cm within-row spacings in two rows on raised beds and thinned to one, two, or three plants per hill upon emergence. The experiments were conducted on commercial pepper fields located in southern Florida during the Winter 1983 and Spring 1984 seasons. Populations ranged from 21,527 to 258,328 plants/ha. Plant growth characteristics were measured at anthesis and just before the final harvest in each experiment. Root and shoot weights, shoot : root ratios, and stem diameters generally decreased and plant heights generally increased in response to higher plant populations. The lower shoot : root ratios at higher plant populations indicated that plants were producing more root mass in proportion to shoot mass than plants at lower populations. Number of primary and secondary branches per plant in the two experiments averaged 2.7 and 5.3, respectively, and were generally not influenced by plant populations. Marketable fruit yields/ha increased linearly in response to higher plant populations. Marketable fruit number and weight per plant decreased with higher plant populations, whereas fruit size (g/fruit) was unaffected. This observation suggested that the higher marketable yields/ha at higher plant populations were attributed to more plants with a lower number of similarly sized fruits per plant. The 25-cm within-row spacing with two plants per hill resulted in 81,109 plants/ha, the optimum marketable pepper fruit yield.
Electrophoretic Characterization of Diploid Plums of the Southeastern United States
Authors: Byrne David H. , Littleton Thomas G.
Published: August 2022

Twenty-nine Japanese-type plum clones were assayed for isozymic variability for eight enzyme systems. Glutamate dehydrogenase (GDH), leucine amino-peptidase (LAP), malate dehydrogenase (MDH), phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), and peroxidase (PX) showed variability among the plums surveyed. 6-phosphogluconate dehydrogenase (6PGD) and triosephosphate isomerase (TPI) were not variable. Isozymic characterization uniquely identified 38% of the clones. The remainder separated into groups of two to three clones that were distinguishable using vegetative morphological characteristics. Reported parentage of five out of nine plums examined was not consistent with their isozymic genotypes.
Growth and Fruiting of ‘Delicious’ Apple Trees as Affected by Severity and Season of Pruning
Authors: Barden John A. , DelValle Terry B. G. , Myers Stephen C.
Published: August 2022

Individual scaffold limbs on 5-year-old ‘Red Prince Delicious’ apple (Malus domestica Borkh.) trees on five rootstocks were unpruned or pruned in Aug. 1981 or Feb. 1982 using three severities at each time. Responses to summer and dormant pruning were similar; no significant interactions occurred. In Dec. 1982, branch circumference was inversely related to pruning severity. Compared to the control, all pruning severities decreased shoot number and increased mean shoot length in 1982; only the most severe pruning suppressed total shoot growth. Flowering and fruiting in 1983 were inversely related to pruning severity.
Mulch Surface Color Affects Yield of Fresh-market Tomatoes
Authors: Decoteau Dennis R. , Kasperbauer Michael J. , Hunt Patrick G.
Published: August 2022

The influence of polyethylene mulch surface color on the plant light environment and tomato (Lycopersicon esculentum Mill) production was investigated. White- or silver-painted mulches reflected more total light, and a lower ratio of far-red relative to red light, than mulches painted black or red. Soil temperatures were warmer under the black and red mulches. Mulch color also affected the yield and growth of tomato. Tomato plants grown with red mulch generally had the greatest early marketable yields and produced the least amount of foliage. Plants grown with a white or silver-colored mulch had lower early marketable yields but produced more foliage. These results suggest that mulch surface color can induce changes in the plant microclimate (e.g., spectral balance and quantity of light, root zone temperatures) that can act through natural regulatory systems within the growing plant and affect tomato plant growth and fruit production.
Water Deficits and Rooting Volume Modify Peach Tree Growth and Water Relations
Authors: Proebsting L. , Jerie P. H. , Irvine J.
Published: August 2022

To compare the effects of water deficits and restricted root volume, 1- and 2-year-old peach trees (Prunus persica L.) with roots divided among four 2.5-Iiter pots were irrigated daily with 30% (deficit irrigation) or 100% (non-deficit) replacement of water used the day before. The water was applied to one, two, or all four pots during the period of rapid terminal growth. After 7 weeks, all trees received 100% replacement of water used the previous day. After terminal growth ended, the root : shoot ratio of the 2-year-old trees was adjusted by 1) tripling available soil volume, 2) removing two-thirds of lateral branches, 3) both 1 and 2, 4) treatment 3 defoliated, or 5) left unchanged. Deficit irrigation reduced midday leaf water potential, leaf conductance, and terminal growth equally, regardless of irrigated soil volume, whereas in non-deficit irrigated trees these factors were proportional to the irrigated soil volume. After deficit irrigation ended, terminal growth resumed at rates above those of the trees with non-deficit irrigation applied to all four pots and proportional to the severity of growth reduction during deficit irrigation. Pruning and defoliation increased leaf conductance within 3 days. Increased soil volume increased leaf conductance after 4 weeks. Deficit irrigation nearly eliminated flowering for the following year. Tripling the soil volume overcame the effect of deficit irrigation on flowering, but pruning did not. Defoliation inhibited flowering. The effect of restricted irrigated soil volume was similar to that of deficit irrigation. Increasing root : shoot ratios by adjusting the soil volume or by pruning the shoot always increased leaf conductance.
Nitrogen Level and Time of Mechanized Summer Shearing Influence Long-term Performance of a High-density ‘Redskin’ Peach Orchard
Authors: Walsh Christopher S. , Allnutt Francis J. , Miller Anita N. , Thompson Arthur H.
Published: August 2022

‘Redskin’ peach (Prunus persica Batsch.) trees, planted at a high-density spacing (3 × 5 m), were fertilized annually with urea at rates of 45, 90, or 135 kg·ha−1. Trees were trained to a trapezoidal hedge by annual, mechanized, summer pruning. Within each fertilizer plot, subplots of five summer-pruning treatments were applied. Single pruning treatments were made at 120 days after full bloom (DAFB) and 150 DAFB. Paired pruning treatments were applied 30 + 60 DAFB, 60 + 120 DAFB, and 60 + 150 DAFB. Pruning at 120 DAFB alone, and in combination with pruning at 60 DAFB, decreased trunk cross-sectional area (TCA), fruit soluble solids content, and weight, while increasing the percentage of surface that was red. Pruning at 30 DAFB followed by a second pruning at 60 DAFB decreased leaf Ca concentration in comparison to pruning treatments applied later in the season. Increasing N fertilization also decreased leaf Ca. Year, N level, and pruning treatments gave a statistical interaction on mean fruit weight and yield.
Nitrogen Concentration and Photosynthetic Photon Flux in Greenhouse Tomato Production: I. Growth and Development
Authors: Larouche Régis , Gosselin André , Vézina Louis-Philippe
Published: August 2022

Tomato plants (Lycopersicon esculentum Mill. cv. Vedettos) were grown in growth chambers under two photosynthetic photon flux (PPF; 125 and 250 μmol·s−1·m−2, high-pressure sodium lamps) conditions for 18 hr and four N fertilization regimes (5, 10, 15, and 20 meq·liter−1) to characterize the ratio of vegetative to reproductive growth. At the lower PPF, vegetative growth was limited and did not respond to N increments in the nutrient solution. At 125 μmol·s−1·m−2, maximum yields were obtained at the lowest N fertilization level. At 250 μmol·s−1·m−2, maximum leaf dry weight and yields were obtained at intermediate N fertilization levels (10 and 15 meq·liter−1). Light levels did not alter the nitrate content of stem sap (but high PPF resulted in nitrate accumulation in leaves) but, at low PPF, nitrate accumulated in leaves at 20 meq N/liter. Nitrate in stem sap varied only slightly with N increments in the nutrient solution. The ratio of fruit fresh weight to leaf fresh weight decreased as N increased in the nutrient solution.
Soil pH and Extractable Elements under Blight-affected and Healthy Citrus Trees on Six Florida Soils
Authors: Wutscher Heinz K.
Published: August 2022

Citrus trees affected with blight, a disease of unknown cause, were associated with soils having higher pH and Ca levels than soils under healthy trees. A detailed study of soil samples taken in 5-cm increments to a depth of 45 cm under healthy and blight-affected trees from five sites showed that pH, determined separately for each increment, showed significantly lower mean pH values under healthy trees. Double-acid (0.05 N HCI and 0.025 N H2SO4) extracts of soil under blighted trees contained more Ca at all five sites. Higher P and K were associated with blight in three of six and four of six comparisons, respectively. In one of five sites, Mn and Zn were higher and Fe lower under blighted trees. The soil under trees in very early stages of blight in the heavily affected part of a block compared with soil under trees in the healthy part of the block was higher in pH and Ca. Soil where lime was incorporated deeply by mixing or deposition of dredged calcareous subsoil on the surface was associated with the most severe incidence of blight.
Pecan Nut and Kernel Characteristics Show Genotype–Environment Interactions
Authors: Thompson T. E. , Young E. F. , McIlrath W. O. , Petersen H. D. , Sibbett G. S.
Published: August 2022

Results are presented for performance of pecan [Carya illinoinensis (Wangenh.) C. Koch] clones at six established National Pecan Advanced Clone Testing System (NPACTS) sites for 16 nut quality factors from 1980 through 1985. Total nut weight and percent kernel were significantly greater at Tulare, Calif. than at any other location, with ≈80% of the clones averaging 6.5 g/nut or more and ≈90% averaging at least 54.5% kernel. Nut weight was smallest at El Paso, Texas. Daily mean temperatures during nut expansion may be a major factor determining nut weight response. Low nut density was characteristic of more clones at Baton Rouge, La. than at any other location. Kernel color was lightest at El Paso and darkest at Baton Rouge, with darker color appearing to be related to high field moisture conditions before harvest. Nut weight was not related to kernel percentage, color, or percent kernel covered with fuzz (packing material); thus, large nuts are not necessarily of lower quality and can be selected in an effective breeding program. Amount of nut “packing material” retained in the sutures of kernel halves after shelling was generally not related to other traits, except that material retained in ventral grooves increased with nut and kernel weight. Depth and width of dorsal grooves were not related to retention of packing material and can be disregarded in future pecan nut evaluation systems. Many other expected character relationships were verified and the overall NPACTS nut evaluation system will be revised based on these results.
Plant Analysis for Nitrogen Fertilization of Asparagus
Authors: Gardner B. R. , Roth R. L.
Published: August 2022

This study was initiated to establish critical N plant tissue levels for asparagus (Asparagus officinalis L.) during the fern growing season. Tissue samples for chemical analysis were taken from asparagus plants over three growing seasons. The experiment consisted of nine treatments with five levels of water ranging from 750 to 4200 mm·ha−1 and five levels of N fertilizer ranging from 100 to 655 kg N/ha. Only the cladophylls were sampled during the fern growing season beginning in mid-April and monthly through mid-September. Total N concentration at various sampling dates and spear yield were highly correlated. Total N concentration indicated the N status of the asparagus plant. Minimum or critical levels of total N were established for the fern growing season in the desert regions of Arizona.
Response of Carrot Seeds to Heat Treatments
Authors: Strandberg J. O. , White J. M.
Published: August 2022

Tolerance of carrot seeds (Daucus carota L.) to heat treatments that could eradicate seedborne pathogens was investigated. Germination and emergence of seedlings from seeds treated in hot water at 35, 40, 45, 50, or 55C from 4 to 20 min were not affected, but seeds treated at 60C for 8 min or more were affected adversely. At 45 and 50C, treatment durations as long as 48 min did not affect emergence, but >20 min at 55C reduced emergence. Similar results were obtained when seeds were treated at the same temperatures in water containing 1.1% sodium hypochlorite (NaOCI). Emergence of seeds treated in hot water or 1.1% NaOCl and planted within 5 days generally was similar to that of treated seeds stored for 90 days at 20C in 60% RH before planting. Any existing differences were small and not clearly related to temperature–duration treatment combinations. Percent emergence from seeds of 19 out of 25 hybrid cultivars treated at 50C for 15 min was reduced by an average of 2.9%, but differences for untreated seeds ranged from −13.3% to +4.8%. Emergence from hot water-treated seeds was reduced after 6 weeks of storage at 70% and 80% RH, but not at 20% to 60% RH. Prolonged treatment and the higher temperatures were particularly effective in reducing populations of seedborne Alternaria dauci.
Carbon Dioxide-induced Brown Stain Development as Related to Phenolic Metabolism in Iceberg Lettuce
Authors: Ke Dangyang , Saltveit Mikal E.
Published: August 2022

Controlled atmospheres containing air + 11% CO2 caused tissue injury and induced phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activity in iceberg lettuce (Lactuca sativa L.) midrib tissue. Injury symptoms included brown stain (browning of epidermal tissue) and sunken epidermal areas (pitting) a few millimeters in diameter. Pitting occurred in high-CO2 atmospheres at 5C with no increase in phenolic content, but browning did not develop until the tissue had been transferred to air at 25C. Browning developed within several hours of transfer to air and the degree of browning was correlated with the soluble phenolic content. The oxidation of soluble phenolic compounds to brown substances by polyphenol oxidase (PPO, EC 1.10.3.2) could account for tissue browning. Lignification was associated with cell wall thickening in discolored tissue and was accompanied by an increase in ionically bound and soluble peroxidase (POD, EC 1.11.1.7) activities. Exposure of tissue to elevated CO2 increased ionically bound indoleacetic acid (IAA) oxidase activity, but reduced soluble IAA oxidase activity. Application of an aqueous solution of 1.0 mm IAA to the tissue before treatment did not significantly reduce browning. Lettuce tissue exposed to 1.5% O2 + 11% CO2 had reduced PAL activity and lower soluble phenolic content than lettuce exposed to air + 11% CO2. Depending on the sensitivity of the lettuce tissue to CO2 injury, low-O2 atmospheres either reduced or slightly retarded browning induced by 11% CO2.
Maturation and Germination of Mango Somatic Embryos
Authors: DeWald Stephen G. , Litz Richard E. , Moore Gloria A.
Published: August 2022

Maturation and germination of mango (Mangifera indica L.) somatic embryos were achieved by sequential transfer of heart-shaped somatic embryos on a series of media based on the B-5 formulation. Precocious germination and other developmental abnormalities were controlled by incorporating 3 μm abscisic acid (ABA) and 6% (w/v) sucrose in the medium. Other factors, including the substitution of Gelrite (0.175%) for agar, the use of solid rather than liquid medium, and the culture of somatic embryos in darkness until physiological maturity also affected normal growth and development. Coconut water (20%, v/v) was also essential for mango somatic embryogeny. Germinated mango somatic embryos were successfully established in planting medium and they have continued to grow in a greenhouse.
Effects of Dwarfing Rootstocks and Interstems on the Free Amino Acid and Protein Levels in Apple Roots1
Authors: Lasheen Aly M. , Lockard Raymond G.
Published: August 2022

The levels of total free amino acids, arginine, aspartic acid, glutamic acid, serine and protein were determined in the roots of apple plants grafted with (a) rootstocks of MM 111, MM 106 or EM IX or (b) rootstock MM 111 plus interstems 1, 3, 5, or 7 inches long of ‘Red Delicious’ (RD), MM 106 or EM IX; all scions were RD. The levels of free amino acids and protein in the rootstocks were not related to their dwarfing effect. The level of free amino acids was very low in MM 106. The levels of free amino acids in the roots of plants with MM 106 interstem increased as the interstem was increased in length. Plants with EM IX interstem had high and nearly equal levels of free amino acids in the roots when the interstem was 3, 5, or 7 inches long, but there was a much lower level in the roots of plants with a 1-inch interstem. The levels of protein in the roots of plants with MM 106 or EM IX interstem showed smaller differences but followed the same pattern as that of free amino acids. Among control plants free amino acids and protein were lower in roots of plants with 2 grafts than in those with 1 graft, and free amino acids were lower in the roots of those with 5- and 7-inch interstems than in those with 1- and 3-inch interstems. The levels of individual amino acids were variable, but the levels of aspartic acid and serine followed a pattern similar to that of total free amino acids.
Pollination and Erratic Bearing in ‘Italian’ Prune1
Authors: Thompson M. M. , Liu L. J.
Published: August 2022

Erratic fruitfulness, reputedly characteristic of ‘Italian’ prune in many areas, was pronounced in this 2-year study. Supplemental pollination with self-pollen and with pollen of 2 other cultivars did not increase fruit set over that of open-pollination in any orchard regardless of whether yield was high or low. Controlled self- and cross-pollinations established that ‘Italian’ is self-fertile. The lack of differences in fruit set on caged trees with and without bees as well as the failure to increase set with supplemental self-pollinations demonstrated that bees are not necessary to transfer the self-fertile pollen. It was concluded that inadequate pollination, in terms of quantity or quality, is not responsible for the sporadic poor yields of this cultivar.
Effect of Flooding on Ethylene Concentration in Horticultural Plants1
Authors: Kawase Makoto
Published: August 2022

Ethylene concentrations in leafless softwood cuttings of Malus robusta and Ligustrum obtusifolium and in leafy cuttings of Chrysanthemum morifolium increased in non-submerged controls steeped upright in water 2.5 cm deep for 20 hr. Increase in ethylene concn was greater in submerged cuttings than in controls.

Ethylene concn in fruits of Malus pumila ‘Red Gold’ and ‘Jonathan’ increased during 24 hr submersion. In Lycopersicon esculentum, however, submersion decreased ethylene concn in both young and mature fruits. Ethylene concn in bulbs of Tulipa fosteriana ‘Red Emperor’ increased in those submerged and the control, but with no significant difference between them. In bulbs of Tulipa gesneriana ‘Peach Blossom’ and tubers of Solanum tuberosum ‘Katahdin’, no ethylene gas was detected either before or after submersion.

Flooding the bases of intact plants of Chrysanthemum morifolium, Helianthus annuus, Lycopersicon esculentum, and Raphanus sativus for 24 hr increased ethylene concn in submerged stems and roots, while it did not change ethylene concn in controls. When roots and basal stems of Chrysanthemum morifolium and Helianthus annuus plants were flooded, ethylene concn in non-flooded stems adjacent to flooded stems also increased. When the bases of intact Lycopersicon esculentum plants were flooded, ethylene concn was greater in the lower half of the submerged portion than in the upper half.
Cold Injury to Red Raspberries and the Effect of Premature Defoliation and Mite Damage1
Authors: Doughty C. C. , Crandall P. C. , Shanks C. H.
Published: August 2022

Defoliated and undefoliated red raspberry canes were subjected to freezing temperatures in December, January, and February and lateral buds were examined for injury. Raspberry plants injured by 2-spotted spider mite were also evaluated for freeze injury. Freezing tests showed that the pith in the basal portion of the buds was most susceptible to freeze damage followed in order by the pith of the cane, the vascular tissue in the base of the buds and the floral primordia. Defoliation and mite injury increased the susceptibility of the bud tissues to freeze injury and reduced starch and sugar reserves. Severe mite defoliation reduced the number of live dormant primary buds and primary laterals the following year.
Influence of Gibberellic Acid on Early Patch Budding of Pecan Seedlings1
Authors: Taylor R. M.
Published: August 2022

A lanolin - potassium gibberellin (GA3) mixture when applied to the trunks of pecan seedlings, beginning 7-10 days after emergence and continuing at 10-14 day intervals for a total of 4 treatments, resulted in sufficient trunk growth for successful patch budding to be accomplished by the end of the third month of growth.
Effect of Container Type and Expanded Polyethylene Mulch on Soil Temperature, Root Growth, and Survival of Dwarf Yaupon Holly1
Authors: Pertuit Alton J.
Published: August 2022

We evaluated effects of plastic and polystyrene containers, double-walled combinations of them and expanded polyethylene disc mulches on soil temp, root growth, and winter survival of Dwarf Yaupon Holly (Ilex vomitoria, Ait. cv. Nana). All container treatments resulted in greater plant survival than did single, plastic pots. Double plastic pots resulted in the greatest amount of root growth. Regardless of container type or combination, mulching increased root growth. The influence of containers and mulch on soil temp, as affected by ambient temp, was determined under controlled conditions. Some treatments insulated the soil, influencing the rate of temp change and the hr required for the soil to freeze and thaw.
Acceleration of Filbert Nut Drop by (2-Chloroethyl)phosphonic Acid1,2
Authors: Lagerstedt H. B.
Published: August 2022

Concentrations of 750 to 1,000 ppm of (2-chlorethyl)phosphonic acid (ethephon) will accelerate filbert nut drop by 2-3 weeks without causing excessive premature foliage drop, reduction in nut quality, or plant injury. When ethephon was applied in dilute and concentrate air-carrier sprays at 250, 500, and 750 ppm, responses were found to be a function of concn regardless of total amount of material applied. Results from 4-year trials indicate that over 90% nut drop can usually be attained approximately 3 weeks after treatment. Treatment should be applied as nuts start changing color from green to brown and begin their normal abscission from the base of the husk. Ethephon accelerates maturation of the filbert husk and causes its early release.
Effect of Daylength, Light Intensity, and Temperature On Growth and Flowering in Roses1
Authors: Moe Roar
Published: August 2022

Increasing daylength inhibited budbreak, while high temp hastened it. The initiation of flowering was promoted by high light intensity and long days. The effect of daylength was temp dependent. At low temp rose shoots differentiated more leaves before flower initiation with short days than with long days, while at high temp there was no significant difference.

Rate of shoot growth was stimulated by long day and high temp. The final length of shoots at flowering was significantly longer with 16-hr days than shorter days, while increasing temp and light intensity decreased shoot length. Growth of the uppermost internodes, especially the neck, was most sensitive to daylength, temp, and light intensity.

The number of days from cut back until flowering was decreased by increasing daylength, temp, and light intensity. The great fluctuation in number of days from cut to cut in greenhouse roses in the course of the year was due to change in light intensity, daylength, and temp.
Effect of Butylated Hydroxytoluene (BHT) on Apple Scald1
Authors: Gough Robert E. , Shutak V. G. , Olney C. E. , Day H.
Published: August 2022

‘Cortland’ and ‘Delicious’ apples were treated with 2 concn of butylated hydroxytoluene (BHT) and 3 levels of diphenylamine (DPA) at 3 temp levels over a 2-year period. On ‘Cortland’ apples, BHT at 10,000 ppm reduced scald as effectively as 2,000 or 4,000 ppm DPA. BHT also reduced scald on ‘Delicious’. BHT residue analyses indicated that most of the BHT remained in the peel of the apple, but the residue was greatly reduced in cold storage within 72 hr after treatment.
Extension of Vase-Life of Cut Flowers by Use of Isoascorbate - Containing Preservative Solutions1,2
Authors: Parups E. V. , Chan A. P.
Published: August 2022

A floral preservative solution containing iso-ascorbic acid, 100 ppm, sucrose, 4%, and 8-hydroxyquinoline sulfate, 50 ppm, extended cut rose life and was equal to other preservative formulations for carnations and snapdragons. Biochemical and other changes in rose petals resulting from the use of this preservative solution are described.
The Influence of Flower Removal on Growth and Seed Yield of Phaseolus vulgaris L.1
Authors: Wien H. C. , Sandsted R. F. , Wallace D. H.
Published: August 2022

Dry beans (Phaseolus vulgaris cvs. Red Kidney and Great Northern) were grown in the cool season in the lowland tropics at Los Banos, Philippines. Manual removal of flowers for 11 days from first bloom resulted in increased wt of vegetative parts and no change in rate of total dry wt gain. New branches, roots, and leaves provided efficient alternate sinks for assimilates, so that leaf area was increased and maintained longer, and more branches formed. Although temporary flower removal increased pod set compared to control plants, pod and seed abortion prevented a significant yield increase. This resulted in lower ratios of seed wt to total dry wt, and decreased pod wt production per unit leaf area.
A Characterization of the “After-Rest” Period of Flower Buds of Two Peach Cultivars of Different Chilling Requirements1
Authors: Couvillon G. A. , Hendershott C. H.
Published: August 2022

The “after-rest” and “post-rest” quiescent periods of flower buds of 2 peach cultivars of different chilling requirements were characterized by a period of reduced inhibition during which the degree of inhibition decreased each succeeding week. Buds within this reduced period of inhibition appeared to be quiescent since they broke and grew during 2 weeks in a greenhouse. However, during this period the buds responded to GA3 and chilling temp. The “post-rest” quiescent period was not reached until mid-February, at which time the buds no longer responded to GA3 or additional chilling and bud break occurred within 72 to 84 hours after exposure to the greenhouse environment.

The degree of inhibition of buds of the 2 cultivars varied throughout this study. ‘Redhaven’ buds were more inhibited than buds of ‘Redskin’ throughout the period studied.
Single Harvest Yields of Strawberries in Relation to Cultivar and Time of Harvest1
Authors: Barritt Bruce H.
Published: August 2022

The suitability of 8 strawberry (Fragaria × ananassa Duch.) cultivars and selections for mechanical harvesting was evaluated by manual harvest at specified intervals during 2 ripening seasons. Single harvests 5, 8, 12 or 15 days after the date the majority of primary fruits were ripe significantly reduced marketable yields below the total yield of the conventional (several harvests throughout the ripening period) type. Highest single yields occurred on days 5 and 8. ‘WSU 1142’3 produced the highest marketable yields in single harvests. These equalled 75% for day 8 in 1971 and 69% for day 5 in 1972 of the conventional harvest marketable yield. ‘Shuksan’ and ‘Hood’ also produced high single harvest yields while ‘Northwest’, ‘WSU 1165’ and ‘Rainier’ had low yields. The incidence of Botrytis fruit rot increased and mean fruit size decreased as single harvest was delayed.
Placental Tissue and Ovule Development in ‘Lodi’ Apple1,2
Authors: Simons Roy K.
Published: August 2022

The ‘Lodi’ apple has heavy bearing characteristics. This study shows it to have profuse numbers of ovules compared with other commercial cultivars. The principal morphological difference between ‘Lodi’ and other cultivars is that ‘Lodi’ contains numerous smaller seeds attached to the placental tissue, not only at the proximal end, but extending all the way to the distal end.
Ethephon [l,2-14C(2-chloroethyl)phosphonic Acid] in Peach Fruits. II. Metabolism1
Authors: Lavee S. , Martin George C.
Published: August 2022

The acid methanol extract from the exocarp of l,2-l4C(2-chloroethyl)ohosphonic acid 14c-CEPA treated peach fruits contained 4 radioactive substances in addition to 14c-CEPA. In the petroleum ether extract 3 such substances were found. The total radioactivity of these substances, compared to the 14c-CEPA and its inherent contaminants recovered from the peach fruit exocarp, did not exceed 3%. Neither the petroleum ether nor acid methanol fractions contained a true metabolite of CEPA as a result of reactions involving living tissue. The nature of the radioactive fractions and their significance is discussed. Additional examinations were made on the stability of these fractions and their distribution in the fruit. Sugars were involved in the formation of one of the major radioactive fractions.
Variation in Thiocyanate Content of Radish Plants During Ontogeny1
Authors: Chong Calvin , Bible B.
Published: August 2022

Large differences occurred in thiocyanate (SCN−) content in roots and various tissues of the top of radish (Raphanus sativus L.) during ontogeny. In the root of ‘Burpee White’ and ‘Champion’, a decreasing content in SCN− occurred during rosette (vegetative) growth; thereafter, only small changes in SCN− content of roots were observed to flowering. In the foliage of both cultivars, a decreasing content in SCN− during growth of the rosette, as in the root, preceded large increases during reproductive growth. The highest amounts of SCN− in the foliage were found at early bolting. The SCN− content in vegetative and reproductive tissues decreased with age. Throughout ontogeny, the occurrence of large amounts of SCN− in young photosynthetic tissues, particularly in the emerging leaves, indicated that such tissues are probably major sites of synthesis or storage of SCN− precursors. Differences in the SCN− content of foliage and marketable roots of 14 radish cultivars were indicative of genetic control of thiocyanates in radishes.
Benomyl and Thiabendazole Treatments Reduce Decay of Apples in Polyethylene Consumer Bags1
Authors: Hardenburg R. E.
Published: August 2022

Adding 250 ppm benomyl or 500 ppm thiabendazole (TBZ) to contaminated dump-tank water in apple-packing plants reduced subsequent decay of fruit packed in polyethylene bags. In 9 tests with bagged apples (Malus domestica) stored in master containers for 3 months at 0°C plus 2 weeks at 21°C, decay averaged 6.0% in control lots, 3.9% with TBZ, and 1.8% with benomyl. Bags containing at least 1 decayed apple after this holding period averaged 44% for control lots, 27% with TBZ, and 19% with benomyl. However, 3 months at 0°C plus 2 weeks at 21°C was too long to store prepackaged apples in cartons, because of the high percentage of bags with decay. The fungicides also reduced decay during shorter storage of 2 weeks at 4.4°C plus 2 weeks at 21°C. Combination fungicide and scald-inhibitor treatments before bagging were effective. Without scald inhibitors about 33% of the apples scalded, while with scald inhibitors, alone or combined with fungicides, 10% scalded.
Magnesium Nutrition of White Rose Potato in Relation to Vegetative Growth and Minerals of Leaf and Root Tissues
Authors: Fong Kwok H. , Ulrich Albert
Published: August 2022

‘White Rose’ potato plants (Solanum tuberosum L.) grown outdoors in water cultures with 0 to 16 meq/1 Mg displayed deficiency symptoms 30 days after transplanting ranging from severe to none. Corresponding growth reduction was caused by Mg stress. Critical concentrations in plant tissues for Mg deficiency were 0.06% Mg, dry wt basis, for the petiole and 0.09% for the blade of recently matured leaves.

Magnesium stress lowered the Mg concentration of petioles and blades much more than that of the fibrous roots. It had no appreciable effect on K but it decreased Na in most plant parts. Magnesium stress increased Ca in the fibrous roots and petioles but decreased it in blades. It increased nitrate-N in all tissues, and increased PO4-P in the fibrous roots and petioles but decreased it in blades. All petioles, as a rule, were much higher in K, Na, NO3-N, and soluble PO4-P than the blades. Our results indicated that the minerals interacting with Mg depend on the plant part analyzed.
The Commercial Implications of Gibberellin A4A7 Plus Benzyladenine for Improving Shape and Yield of ‘Delicious’ Apples1
Authors: Unrath C. R.
Published: August 2022

Gibberellin A4A7 (GA4-7) and benzyladenine (BA) were applied to ‘Starkrimson Delicious’ apples from 1969 through 1972. In initial tests, GA4-7 + BA (50 to 200 ppm each) increased fruit length, fruit wt and length/diam ratio (L/D) but did not alter diam or fruit color. Firmness and seed numbers were reduced only at 200 ppm. At concn above 50 ppm flower initiation was substantially reduced. Concentrations of 25 ppm were as effective as 50 ppm but concentrations below 25 ppm were not effective. To be most effective, these materials must be applied between full bloom and petal fall. In general, a single application was more effective than split applications. Repeated annual applications of 50 ppm resulted in continued good response and no adverse effects. In one of the 4 years tested, fruit set but not commercial crop, was significantly reduced by applications of GA4-7 + BA. Air blast applications were as effective as hand gun applications even when the amount of spray mixture/acre was substantially reduced. The average fruit weight response in all experiments reported was 12 and 20% at 25 and 50 ppm, respectively. The improved fruit shape and increased fruit mass could justify the use of GA4-7 + BA in apple producing areas where post bloom temp conditions reduce “typiness”.