bluuebunny/crossref_metadata_2025 huggingface dataset:
Diurnal Chilling Sensitivity and Desiccation in Seedlings of Tomato
Authors: King Ann I. , Reid Michael S.
Published: August 2022

Seedlings of six cultivars of tomato (Lycopersicon esculentum Mill.) showed differences in chilling sensitivity depending on the time during the diurnal light/dark cycle when they were placed at low temperature. In all cultivars, sensitivity was highest when the chilling exposure started at the end of a dark period, although the magnitude of the diurnal variation differed among the cultivars. When roots were removed prior to or just after chilling, injury also appeared earlier in seedlings whose chilling was started at the end of a dark period. Seedlings chilled starting at different times during the diurnal cycle had similar stomatal conductance values during chilling. It appears that diurnal changes in chilling sensitivity are not due to altered root function during or following chilling exposure, nor to variations in desiccation during the chilling period resulting from diurnal differences in stomatal conductance.
Self Incompatibility in 19 Native Blueberry Selections
Authors: Garvey E.J. , Lyrene P.M.
Published: August 2022

Nineteen native blueberry (Vaccinium ashei Reade) clones selected from several areas in northern Florida and southeastern Georgia were self- and cross-pollinated in a greenhouse. Fruit set for the 19 clones averaged 15% after self-pollination and 58% after cross-pollination. Viable seeds per berry averaged four for self-pollination and 11 for cross-pollination. Average berry weight was 0.7 g for self-pollination and 1.1 g for cross-pollination, and average interval from flowering to ripening was 106 days for selfing and 92 days for crossing. Following self-pollination, pollen germinated and pollen tubes grew down the style as rapidly as after cross-pollination.
Influence of Phony Disease of Peach on Stem Hydraulic Conductivity and Leaf Xylem Pressure Potential
Authors: Evert Dean R.
Published: August 2022

Stem hydraulic conductivity of peach [Prunus persica (L.) Batsch] was lower in trees with phony disease than in healthy trees. This lower conductivity occurred in 1- to 4-year stems, in five cultivars, in two pruning systems, and from June through October. Leaf xylem pressure potential was lower in trees with phony disease than in healthy trees in each of the five cultivars tested and from June through September. The reduction in pressure potential in diseased trees exceeded any variations in pressure potential with cultivar or month. The area of functional xylem stained by dye was visibly smaller in stems from diseased trees than in healthy trees. These results were all consistent with the theory that symptoms of phony disease of peach are caused by xylem blockage.
Plant Growth Analysis of Field-grown Cowpeas
Authors: Fernandez George C.J. , Miller J. Creighton
Published: August 2022

Plant growth aspects of field-grown cowpea [Vigna unguiculata (L.) Walp.] were investigated under four N regimes: No N, rhizobial inoculation (cowpea “EL” inoculum), 100 kg fertilizer N/ha (NO3-N) at planting, and inoculation + 50 kg fertilizer N/ha at flowering. Five indeterminate cultivars, Brown Crowder, California Blackeye No. 5, Mississippi Silver, Tennessee White Crowder, and Lady, and one determinate cultivar, Bush Purple Hull, were compared. Plant growth variables were measured biweekly starting at the 4th week. Dry matter and leaf area per plant reached maximum at 56 days after planting in all five indeterminate cultivars, and 1 week later in the determinate cultivar. Large-seeded cultivars, California Blackeye No. 5, Mississippi Silver, Brown Crowder, and Tennessee White Crowder, generally produced larger leaves throughout the season than did ‘Bush Purple Hull’ and ‘Lady’. The relative growth rate (RGR) declined linearly with harvest time, irrespective of N treatment. The RGR of ‘Bush Purple Hull’ was lower than that of the indeterminate cultivars throughout the growth period. The net assimilation rate (NAR) of the indeterminate cultivars declined slowly from maximum values at 4 weeks and became negative during pod development. However, ‘Bush Purple Hull’ NAR increased during pod development, but declined very rapidly during late pod development. The leaf area ratio (LAR) declined curvilinearly with time in all N treatments and cultivars. The LAR values were lowest for the determinate cultivar, and the differences among indeterminate cultivars were not significant. Total dry matter, leaf area per plant, and average leaf size of inoculated and N-fertilized plants were greater than the uninoculated and unfertilized control. Nitrogen treatments did not affect physiological components RGR, NAR, and LAR.
Variation in Tree Size, Yield, Cropping Efficiency, and Alternate Bearing Among ‘Kerman’ Pistachio Trees
Authors: Johnson R.S. , Weinbaum S.A.
Published: August 2022

The pistachio (Pistacia vera L.) industry in California is based largely on a single pistillate (i.e., nut-producing) cultivar (Kerman) supported by seedling rootstocks of P. atlantica Desf. Data were collected and analyzed for tree growth and productivity of 113 mature ‘Kerman’ trees/P. atlantica seedlings over two cycles of alternate bearing. Tree size as estimated by trunk cross-sectional area varied 4-fold among the trees analyzed; tree yields, averaged over 4 years, varied 8-fold within the plot, and cropping efficiency (yield/cm2 of trunk cross-sectional area) varied 3-fold among the trees within the orchard. The severity of alternate bearing also was calculated. Eight superior trees were identified within the orchard that not only had higher average yields and cropping efficiencies, but also exhibited much more regular cropping patterns (i.e., reduced severity of alternate bearing) than adjacent trees and the orchard as a whole.
Influence of Orchard Floor Management on Vole and Pocket Gopher Populations and Damage in Apple Orchards
Authors: Sullivan Thomas P. , Hogue Eugene J.
Published: August 2022

Removal of all vegetation with herbicides over the total orchard floor or only in tree rows significantly reduced montane vole (Microtus montanus Peale), meadow vole (M. pennsylvanicus Ord), and northern pocket gopher (Thomomys talpoides Richardson) populations and damage. Herbicide treatments in four test orchards were carried out during May, July, and Sept. 1983 to 1985. Average overwinter abundance of voles was reduced 53% to 99% on treatment areas. Several vole populations went to extinction in the third year of herbicide treatment. Incidence of tree damage was 40.6% and 9.6% with feeding intensities of 17.2 cm2 and 0.4 cm2 of bark and tissues removed per tree on control and treatment blocks, respectively, during a peak year in abundance of voles. Pocket gopher populations and damage were significantly lower in treatment than control blocks. Deer mouse (Peromyscus maniculatus Wagner) and yellow pine chipmunk (Eutamias amoenus J.A. Allen) populations generally increased on treated areas. Use of herbicides to control orchard floor vegetation is an effective means of rodent damage control.
Effect of High CO2 Atmospheres on Stored Zucchini Squash
Authors: Mencarelli Fabio
Published: August 2022

Zucchini squash (Cucurbita pepo L. cv. Romanesco) were stored 19 days at 5°C in 21% ± 1% O2 plus 0.0%, 2.5%, 5.0%, or 10.0% CO2 and then stored an additional 4 days at 13° in air. High CO2 levels inhibited the rate of CO2 production and reduced the development of chilling injury symptoms at all three maturities (16, 20, and 22 cm fruit). There was a high negative correlation between CO2 levels and reduction of chilling injury. At the end of the 23-day storage period, 82% of the 22-cm squash held in 10% CO2 appeared salable, but they had a slight off-flavor and were soft; 79% of the fruit held in 5% CO2 were salable, firm, and free of off-flavors; samples from 2.5% CO2 and air were unacceptable because of decay and pitting. The percentage of unsalable fruit increased from 16- to 20-cm squash. Carbon dioxide concentrations around 5% may be useful for storing zucchini squash at about 5°, a temperature that normally causes chilling injury in zucchini.
Root and Air Temperature Effects on the Elemental Composition of Tomato
Authors: Papadopoulos Athanasios P. , Tiessen Herman
Published: August 2022

Four cultivars of greenhouse tomato (Lycopersicon esculentum Mill.) were grown in the greenhouse and two cultivars were grown in growth chambers in order to study the effects of root and air temperature on the elemental composition (N, P, K, Ca, and Mg) of leaf tissue. Most of the variation observed in the nutrient composition of leaves was due to air temperature and the cultivar used; only few root temperature effects were significant. Low air temperatures (24°/14°C, 24°/8°, 19°/14°; day/night) resulted in higher N concentrations in the leaf tissue, whereas root temperature had little effect on N. Response to air temperature was similar for P or for N. However, response to high root temperature (27° and 24° in the greenhouse and the growth chamber, respectively) was greater for P than for N. Air and root temperatures had little effect on K concentration in tomato leaves. Consistently high Ca and Mg levels resulted with low air temperatures (24°/8°, 19°/14°, 13°/8°), whereas root temperature had no effect on accumulation of these two nutrients. The incidence of blossom-end-rot in the fruit of all cultivars used in the study was associated with low Ca and Mg levels in the leaf tissue.
Micropropagation of Cherry Rootstocks: II. Invigoration and Enhanced Rooting of ‘46-1 Mazzard’ by Co-culture with ‘Colt’
Authors: Ranjit Makunda , Kester D.E.
Published: August 2022

Shoot invigoration and rooting potential of hard-to-root ‘46-1 Mazzard’ sweet cherry (Prunus avium L) was progressively increased during six consecutive subcultures when cocultured with easy-to-root ‘Colt’ (P. avium × P. pseudocerasus). Similar results were produced with gibberellic acid at a concentration range of 0.1 to 0.25 mg·liter−1, but rooting depended on transfer to a GA3-free medium. It is suggested that the invigoration and enhanced rooting involved rejuvenation of the mature ‘46-1 Mazzard’ to a more juvenile phase.
Screening Peaches in Vitro for Resistance to Xanthomonas campestris pv. pruni
Authors: Hammerschlag F.A.
Published: August 2022

A wick bioassay was developed to screen peach [Prunus persica (L.) Batsch] shoot cultures for resistance to bacterial spot [Xanthomonas campestris pv. pruni (E. F. Sm.) Dows)]. Three weeks after inoculation, the number of colony forming units (CFU) from 1-cm stem sections excised from highly susceptible cultivars was significantly greater than CFU from several resistant cultivars. Neither growth regulators nor the length of time that shoots were maintained in vitro prior to inoculation significantly influenced the response of these cultivars to bacterial leaf spot. This technique should be useful in screening for somaclonal variants obtained from peach cell cultures.
Plant Spatial Arrangement and Density Effects on Small- and Medium-vined Processing Tomatoes
Authors: Frost D.J. , Kretchman D.W.
Published: August 2022

‘Heinz 2653’ and ‘Heinz 722’ tomatoes (Lycopersicon esculentum Mill.) were grown at four plant populations (21,530, 28,700, 43,050, and 57,400 plants/ha) in both single and twin rows. Plant density had no influence on ripe fruit yields of ‘H-2653’. The twin-row configuration did result in increased yields from ‘H-2653’, but not ‘H-722’. Density had no influence on yield of ‘H-722’ in 1984, but yield was reduced at the highest density of the twin-row configuration in 1983. Shoot dry matter, ripe fruit yields, and total yields per hectare of ‘H-2653’ were higher from the twin rows than from the single rows. There were no yield advantages for ‘H-722’ in twin-row arrangements. The ‘H-2653’ yield increases in twin rows were due to an increase in number of ripe fruit per plant. As population pressures increased, the number of ripe fruit per plant, ripe fruit size, and clusters per plant decreased. Plants grown in twin rows covered a greater percentage of their allotted space than those in single rows, regardless of cultivar. As the population density increased, the canopy coverage also increased. Plants at high densities and those in twin-row arrangements intercepted more light than those at low density and single-row plantings.
Liming Reactions in Sphagnum Peat-based Growing Media
Authors: Williams Barbara J. , Peterson John C. , Utzinger James D.
Published: August 2022

Spagnum peat, perlite, vermiculite, and six media formulated (by volume) from these constituents (2:1, 1:1, 1:2 peat: perlite; 2:1, 1:1, 1:2 peat: vermiculite) were limed with 0, 0.9, 1.8, 2.7. 3.6, 5.4, 7.2, and 9.0 kg∙m−3 dolomite [CaMg(CO3)2]. Media were wet to container capacity with distilled/deionized (d/d) water, incubated at 25° ±3°C, and pH determined at day 0, 2, 5, 7, 14, 28, 56, and 84. Liming reactions in mixes could not be predicted from reactions occurring in sphagnum peat, perlite, and vermiculite constituents alone. Although sphagnum peat made the major contribution to liming reactions, both perlite and vermiculite were found to contribute to liming responses of media in which they were incorporated. The major portion of pH change due to incorporation of pulverized dolomite in peat-based media occurred within 2 days. Change in pH was complete within 14 days.
Effect of Two Polymeric Coatings on Fruit Quality of ‘Bartlett’ and ‘d’Anjou’ Pears
Authors: Meheriuk M. , Lau O.L.
Published: August 2022

‘Bartlett’ and ‘d’Anjou’ pears (Pyrus communis L.) coated with either Pro-long or Nutri-Save, two proprietary fruit-coating materials, were firmer, higher in titratable acidity, and greener in skin color than noncoated fruit stored in air at 0°C. Coated fruit were, in most instances, comparable to noncoated fruit stored in controlled atmospheres (CA). The incidence of core breakdown in ‘Bartlett’ pears and superficial scald in ‘d’Anjou’ pears were lower in coated fruit than in noncoated fruit kept in air storage. The incidence of scald in CA-stored noncoated fruit was usually comparable to and sometimes lower than in the air-stored coated fruit. Normal fruit ripening, however, was adversely affected by the coating compounds, particularly in ‘Bartlett’ pears. Coated ‘Bartlett’ pears tended to develop a blotchy appearance of green interspersed with yellow when held at ripening temperatures.
Phytoalexin Production Potential of Grape Berries
Authors: Creasy L.L. , Coffee M.
Published: August 2022

The capacity to synthesize the stilbene resveratrol in response to UV irradiation is used as a measure of the phytoalexin production potential of grape berry skin. Greenhouse-grown berries after set, but before maturation, had high phytoalexin potential, whereas buds, flowers, and mature fruits had low potential. Stilbenes were not synthesized in the fleshly part of fruit and were found erratically in small amounts in noninduced berry skin. In field samples, ‘Concord’, ‘Cabernet Sauvigon’, and ‘Catawba’ had high resveratrol production potential whereas ‘White Riesling’, ‘Chancellor’, and ‘Cayuga White’ had low potential. The phytoalexin production potential decreased in all cultivars after late August, independent of their maturity.
Water Relations and Net CO2 Assimilation of Peach Leaves of Different Ages
Authors: Andersen P.C. , Brodbeck B.V.
Published: August 2022

Net CO2 assimilation rate (A) and plant water relations of peach [Prunus persica (L.) Batsch cv. Flordaking] leaves were monitored during development under field conditions. Leaf conductance to water vapor (gl) and transpiration rate (E) of unfolding and expanding leaves approached maximum values before maximum A values were achieved. Net CO2 assimilation rate and water use efficiency (WUE) were greatest for recently expanded leaves and gradually declined with age after full expansion. Leaf water potential (ψw) was similar for all leaf ages under field conditions. Leaf dry weight/cm2 and chlorophyll/cm2 increased with leaf age after expansion. Diurnal patterns of gl, E, and ψw were similar for expanded spring- and summer-flush leaves. Midday ψw of −2.4 MPa (ψp = about 0.3 MPa) did not reduce gl. Expanding shoots had higher osmotic potentials (ψπ) and thus maintained lower turgor potentials (ψp) than fully expanded shoots. Shoot and leaf elongation rates were related exponentially to ψp and were reduced drastically below ψp 1.0 and 0.7 MPa, respectively. The bulk modulus of elasticity (є) increased linearly with ψp, but there were no significant differences in є of expanding and nonexpanding shoots. As leaf water deficits developed, shoot and leaf expansion were inhibited prior to gl or A. Thus, a moderate level of water stress can reduce the rate of vegetative growth of peach trees without concomitant reductions in carbon assimilation.
Endosperm Type, Inbred Background, and Leakage of Seed Electrolytes During Imbibition in Sweet Corn
Authors: Schmidt D.H. , Tracy W.F.
Published: August 2022

Endosperm mutants of maize often exhibit poor seed quality, as indicated by poor germination and seedling vigor. The measurement of seed leachate electrolyte conductivity (SLEC) is a rapid method of evaluating seed quality. Generally, high SLEC indicates poor seed quality. Other endosperm types in addition to sugary (su) are becoming important in the sweet corn industry. To facilitate the conversion of inbreds to new endosperm types and maintain acceptable levels of seed quality, it would be useful to determine the relationship between endosperm type and SLEC. The objective of this study was to determine the effects of inbred background, endosperm type, and inbred × endosperm interactions on SLEC and to determine the relationship between seed weight and SLEC. Ten seed weight and SLEC of six near-isogenic lines differing for 10 endosperm types were measured. Ten combinations of the following endosperms were used; sugary (su), waxy (wx), sugary-2 (su2), dull (du), and shrunken-2 (sh2). Significant differences in SLEC were found among endosperm types: sh2 had the highest SLEC (186.1 dS·m−1) and Su su2 the lowest (62.9 dS·m−1). Over endosperm types, 10-seed weight and SLEC were negatively correlated (r = 0.84**). This negative relationship may be due to damage suffered by the pericarp during the collapse of the endosperm of the lighter endosperm types. Significant differences in SLEC also were found among inbreds. Values ranged from 162.3 dS·m−1 to 55.7 dS·m−1. Among inbreds, SLEC and 10-seed weight was positively correlated (r = 0.82*). Endosperm by inbred interactions had significant effects on SLEC. This interaction is of importance to those converting inbreds to different endosperm types and should be considered when choosing seed parents for hybrid production.
Comparison of Two Recurrent Selection Procedures For Yield in Two Pickling Cucumber Populations
Authors: Nienhuis J. , Lower R.L.
Published: August 2022

A “gynoecious synthetic” (GS) population, developed by random mating of 50 adapted Cucumis sativus L. cultivars and breeding lines, and a “hardwickii semi-exotic” (HSE) population, developed by open-pollinating an F2 population derived from a cross between a Cucumis sativus var. hardwickii (R.) Alef. accession LJ 90430 and a gynoecious inbred line GY 14, were subjected simultaneously to S1 line (S1 and reciprocal full-sib (RFS) recurrent selection. S1 selection resulted in increased fruit number per plant in the GS and HSE populations, and in the GS × HSE population hybrid. In contrast, RFS selection did not result in increased fruit number per plant in the GS and HSE populations or their hybrid. The contrasting responses to S1 compared to RFS selection suggests that additive gene effects were more important than nonadditive effects in the expression of fruit number per plant. Correlated responses to selection resulted in increased number of days to harvest in the GS population, and in reduced percentages of gynoecious plants and pistillate flowers in the HSE population. No change in fruit firmness, and a reduction in length : diameter ratio of fruit only in the GS × HSE population hybrid developed through S1 selection, suggests that selection for increased fruit number per plant should not adversely affect these fruit quality characteristics in either the GS or HSE populations.
Winter Root Temperature Effects on Vegetative Budbreak, Spur Development, and Flowering of ‘Delicious’ Apple
Authors: Young Eric
Published: August 2022

Effects of continuous root temperatures > 15°C on vegetative budbreak, shoot and spur development, and flowering were studied during the first 3 years of growth in ‘Delicious’ apple trees (Malus domestica Borkh.) on MM.106, M.7a, and M.9 rootstocks. Sixteen trees of each rootstock-scion combination were potted and placed on an outside container area with overhead irrigation. Root-zone temperature was maintained at > 15° throughout the winter in half the trees, while the other half were at ambient temperature. Vegetative budbreak and spur development were reduced significantly and flowering was increased during the first 2 years by warm winter root temperatures. Flowering the third year was increased on MM.106 trees due to enhanced spur development the first 2 years. Flower bud to vegetative bud ratio was reduced on ambient-root trees in the second and third year and root : shoot ratio was increased, indicating that root chilling during dormancy favored vegetative growth, particularly root growth.
Influence of Strip Tillage on Yield, Diseases, and Nematodes of Tomatoes
Authors: McKeown A.W. , Cerkauskas R.F. , Potter J.W.
Published: August 2022

Strip tillage into killed rye (Secale cereale L.) and oats (Avena sativa L.) cover crops was evaluated as a production system for machine-harvested processing tomatoes (Lycopersicon esculentum Mill.). No effect of tillage on yield was found for 2 out of 3 years. Yield was reduced in the third year in strip-tilled rye plots due to low transplant vigor and possibly low-temperature injury. Populations of plant parasitic nematodes were stimulated by rye and strip tillage. Bacterial diseases were increased by strip tillage in one season. Long-term evaluation of conservation-oriented systems is required to determine effects on yield, nematodes, and diseases.
Influence of Plant Growth Regulators on Transition of Bermudagrass Putting Green Overseeded with Perennial Ryegrass
Authors: Mazur A.R.
Published: August 2022

Field studies were conducted for 3 years on putting green turf to determine the influence of the plant growth regulators (PGR) pronamide (PRON), ethephon (ETHR), mefluidide (MEFL), and maleic hydrazide (MH) on the transition from overseeded perennial ryegrass (Lolium perenne L. ‘Yorktown II’) turf to hybrid bermudagrass [Cynodon dactylon (L.) pers. × C. transvaalensis Burtt-Davy ‘Tifgreen’] in the spring. All PGR treatments were effective in increasing bermudagrass coverage over untreated grass; however, all reduced turf quality to some degree, with the exception of ETHR. The high PGR rates generally had lower turfgrass quality than the low rates. The March and early April application had the greatest bermudagrass coverage in 1982 and 1985, whereas the early March treatment generally had lower turfgrass quality than later applications. PRON at 0.28 kg·ha−1 applied as a single application in 1985 had higher initial bermudagrass coverage than when applied as split application, but split application maintained higher turfgrass quality than the single application. The split application of MEFL at 0.56 kg·ha−1 provided greater bermudagrass coverage than the single application when applied 6 Mar. or 3 Apr.; however, the split application resulted in lower quality than obtained from a single application applied on 6 Mar. in 1985. PRON at 0.28 kg·ha−1 and higher rates reduced growth and corresponding mowing requirements. Chemical names used: 1,2-dihydro-3,6-pyridazinedione (maleic hydrazide); N-(2,4-dimethyl-5-[([trifluoromethyl]-suIfonyl)amino]phenyl) acetamide (mefluidide); 2-chloroethyIphosphonic acid (ethephon); and 3,5-dichloro-(N-1,1-dimethyl-2-propynyI) benzamide (pronamide).
Paclobutrazol Suppresses Shoot Growth and Influences Nut Quality and Yield of Young Pecan Trees
Authors: Wood Bruce W.
Published: August 2022

Paclobutrazol (PBZ) was applied in one or more formulations as a basal trunk drench (0, 19, 38, 76, 152 mg·cm−2 trunk cross-sectional area) or orchard floor application (0, 52, 104, and 208 mg·cm−2 trunk cross-sectional area) to 3- and 10-year-old pecan [Carya illinoensis (Wangenh.)C. Koch] trees. Vegetative growth was highly sensitive to PBZ for at least 3 to 4 years after a single treatment. There were no differences due to formulation for any of the parameters evaluated. Shoot growth and production of in-shell nuts were negatively related in a curvilinear manner to PBZ rate. Nut size increased the first two seasons after treatment, and yield efficiency increased curvilinearly with PBZ rate. Excessive vigor of Iammas shoots coincided with the cessation of vegetative growth inhibition by PBZ. There was a differential cultivar response in nut yield for 3-year-oid ‘Cheyenne’ and ‘Desirable’ trees; however, there was no cultivar differences in 10-year-old trees of ‘Shoshoni’, ‘Desirable’, and ‘Cape Fear’. Use of PBZ appears to allow for the manipulation of tree size of young pecan trees. Chemical names used: β-[(4-chlorophenyl)-ethyl] -α-(1, l-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Fall Ethephon Application Increases Peach Flower Bud Resistance To Low-temperature Stress
Authors: Durner Edward F. , Gianfagna Thomas J.
Published: August 2022

Eight-year-old ‘Cresthaven’ peach (Prunus persica L. Batsch.) were sprayed to runoff in mid-October with ethephon and Dormex, two potential bloom-delaying compounds. Flower buds were evaluated for differences in hardiness after field exposure to < −23°C for 4 hr in Jan. 1987. Buds treated with ethephon were significantly hardier than control buds or buds treated with Dormex. Controlled freezing tests just before bloom, continuing through full bloom, indicated the same difference. In addition, ethephon-treated buds had an estimated LT50 of −1.6° at full bloom compared to an estimated LT50 <0°, but greater than −0.5° for controls. Ethephon-treated buds also attained full bloom ≈7 days later than control buds. Yield also was enhanced by ethephon compared to all other treatments. Results confirm the bloom-delaying phenomenon associated with fall ethephon application and also indicate that ethephon increases the intrinsic hardiness of peach flower buds when applied in the fall. Chemical names used: (2-chloroethyl) phosphonic acid (ethephon); calcium cyanamid (Dormex).
Fruiting Affects Photosynthesis and Senescence of Pecan Leaves
Authors: Wood Bruce W.
Published: August 2022

Seasonal measurements of net photosynthesis (Pn), stomatal conductance (Cs), and endogenous senescence-related chemicals were made on pecan [Carya illinoensis (Wang.) C. Koch] trees growing in the orchard environment. Leaves from terminal shoots of mature, 75-year-old ‘Moneymaker’ trees in the “on” alternately bearing phase maintained 10% to 40% higher Pn rates than did those of “off” phase trees. These “on” leaves also maintained higher levels of chlorophyll, protein, amino acids, and RNA, but less K. than “off” leaves. The presence of developing fruit suppressed the rate of late summer and autumnal leaf senescence, with “on” trees retaining their leaves in a higher state of vigor than those of “off” trees. Pn and Cs rates between leaflets of adjacent fruiting and nonfruiting shoots of 7-year-old ‘Desirable’ trees were also 10% to 15% higher for the fruiting shoots throughout the season. Pn and Cs rates were influenced such that gas exchange of leaves increased as sink demand increased. These data provide evidence that this sink-demand associated stimulus operates in a localized rather than a generalized manner and that it retards the rate of leaf senescence.
Effect of Water Deficit on Vegetative Growth and Fruit Development in Jojoba
Authors: Nerd A. , Benzioni A.
Published: August 2022

The effect of water deficit on shoot growth and fruit development in jojoba was studied in 8-year-old jojoba [Simmondsia chinensis (Link) Schneider] plants. In both fruiting and defruited nonirrigated plants, shoot growth, which started at the beginning of April, stopped in June when the xylem water potential (ψx) measured at dawn fell to a value below the osmotic pressure at the point of turgor loss. Osmotic adjustment during the summer enabled some resumption of growth in the autumn at low ψx values. Irrigated plants grew throughout the warm season only if defruited: competition for assimilates evidently inhibits growth during the period of fruit filling. Fruit growth was not affected by water deficit, since fruit are apparently highly resistant to water loss.
Early Flowering in Lettuce as Influenced by a Second Flowering Time Gene and Seasonal Variation
Authors: Ryder Edward J.
Published: August 2022

Variation in flowering times within genotype classes of the Early Flowering (Efef) gene in lettuce (Lactuca sativa L.) suggested that more than one gene may govern flowering time. Segregation from crosses between earlier and later plants in the early class indicated a second discrete flowering time gene. This gene was confirmed in F3 family analyses and in subsequent progeny comparisons. The first gene is renamed Early flowering-1 (Ef-lef-1) and the second is named Early flowering-2 (Ef-2ef-2). The consequences of the presence of the second gene in cultivars and in the backcross breeding procedure are discussed. Flowering time is influenced by daylength and temperature.
Effectiveness of NAA and Paclobutrazol for Control of Regrowth of Trunk Suckers on ‘Okanagan Riesling’ Grapevines
Authors: Reynolds Andrew G.
Published: August 2022

Three levels of NAA (0, 10,000, and 20,000 ppm) and paclobutrazol (PP333; 0, 250, 500 ppm) were applied in latex paint to suckered vine trunks of ‘Okanagan Riesling’ (Vitis spp.). NAA reduced suckers/vine and percentage of sucker regrowth in each of three seasons. Cluster weight, berries/cluster, and berry weight were increased with NAA in each season, whereas vine size, °Brix, and total acidity (TA) showed a similar trend 1 year following application and thereafter. PP333 reduced sucker number and regrowth, but not as effectively as NAA, and its effects were shorter-lived. No yield components were influenced by PP333 except berry weight, which varied linearly in 1984 and 1986 and quadratically with concentration in 1985. PP333 increased °Brix and TA linearly 1 year following application. Both chemicals tended to reduce pH in 1984 and 1985, but NAA increased pH in 1986 relative to concentration. Chemical names used: 1-naphthaleneacetic acid (NAA); β-1[(4-chorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Improving Grapevine Budbreak and Yields by Evaporative Cooling
Authors: Nir G. , Klein I. , Lavee S. , Spieler G. , Barak U.
Published: August 2022

The effect of evaporative cooling on budbreak and yield of Vitis vinifera L. (‘Perlette’ and ‘Thompson Seedless’) vines grown in the southern Jordan Valley in Israel was investigated. Overhead microsprinklers were operated from 0600 to 1800 hr daily during the autumn and winter months, either alone or in combination with cyanamide sprays after pruning. Evaporative cooling decreased the temperature of buds exposed to direct sunlight from 30° to 16°C and that of shaded buds from 25° to 13°. Evaporative cooling induced an early uniform budbreak. However, when evaporative cooling was combined with cyanamide spray, its effect was evident only during the initial phase of bud emergence. In 1985 cyanamide spray and evaporative cooling alone increased yield of ‘Perlette’ by 6% and 6% to 24%, respectively, and by 17% to 46% when both treatments were combined. In 1986 prolonged evaporative cooling increased the yield of ‘Perlette’ by 25% but, in combination with cyanamide, by only 11.6% over the unwetted cyanamide-treated control. In both years, evaporative cooling with or without cyanamide advanced fruit maturation.
Variability of Rubber and Plant Growth Characteristics Among Single-plant Selections from a Diverse Guayule Breeding Population
Authors: Thompson Anson E. , Ray Dennis T. , Livingston Margaret , Dierig David A.
Published: August 2022

Single plant selections from a diverse guayule (Parthenium argentatum Gray) breeding population were evaluated for rubber and resin concentration, rubber and resin yield, and 12 growth characteristics. Thirty-seven superior selections (≈9% of the total of 421 single plant selections) exhibit combinations of satisfactory biomass production, high rubber yield, and strong regeneration and survival after harvesting by clipping the branches at a height of 0.10 m. Rubber concentration (%) was not highly correlated with the 12 plant characteristics measured. In contrast, rubber yield (g/plant) was highly correlated with plant dry weight and other plant characters related to biomass production. Twelve of the 37 superior selections had yields >125 g of rubber per plant, and the rubber concentration of seven of these 12 plants exceeded the mean (7.1%) of the 37 superior selections. Selection for high rubber concentration and yield with strong top regrowth after clipping appears to be feasible, and should expedite the development of a multiple harvesting system and rapid commercialization of guayule as a new domestic source of natural rubber.
Adventitious Root Initiation in De-bladed Petioles from the Juvenile and Mature Phases of English Ivy
Authors: Geneve Robert L. , Hackett Wesley P. , Swanson Bert T.
Published: August 2022

An in vitro system has been developed to study adventitious root initiation in the juvenile and mature phases of English ivy (Hedera helix L.). The system uses de-bladed petiole explants cultured in a defined liquid medium. Adventitious roots are visible macroscopically after 18 days. Juvenile petiole explants show a dose-response to auxin application with optimal root initiation at 100 μM NAA or IAA. With optimal auxin concentration, root initials form in juvenile petiole explants directly from cortical parenchyma cells, which involves induction (1–6 days), meristem organization (6–9 days), and root elongation stages (9–18 days). Sucrose is required for outgrowth of root primordia but not for initiation of primordia. Mature petiole explants respond to auxin with random cell divisions in cortical parenchyma cells; root initials form at a low frequency from callus resulting from this cortical cell division. Distribution of 14C at various times after administration of 14C-labeled NAA is similar in juvenile and mature petioles. Because of their difference in rooting potential, coupled with similarity in anatomical organization, distribution of 14C from NAA, and identical genotype, juvenile and mature petioles provide an excellent experimental system for analyzing the morphogenetic, physiological, and genetic basis of rooting potential. Chemical names used: 1-napthaleneacetic acid (NAA); 1H-indoIe-3-acetic acid (IAA).
Evaluation of DRIS for Judging the Nutritional Status of Hazelnuts
Authors: Alkoshab Othman , Righetti Timothy L. , Dixon A.R.
Published: August 2022

The Diagnosis and Recommendation Integrated System (DRIS), which uses nutrient element concentration ratios as indicators of nutrient deficiency, was used to evaluate current sufficiency ranges for hazelnut trees. Reference values that were derived from published and unpublished field data were used to calculate DRIS indices for N, P, K, Ca, Mg, Mn, Fe, Cu, B, and Zn. A nutritional imbalance index (NII) was computed as the sum of DRIS indices irrespective of sign, and a threshold NII value (mean NII + 1 SD), above which severe imbalances are expected, was established. DRIS diagnoses were then compared with the sufficiency range approach to determine if relative deficiencies or excesses associated with severely imbalanced trees would have been routinely detected in 624 mineral analyses of hazelnut leaves. A previously published field trial was also reevaluated. DRIS diagnosis generally agreed with the diagnoses made by the sufficiency range method, especially if sufficiency ranges for some elements were made more narrow. However, some nutrients were never identified by DRIS as a major relative deficiency or excess in any of the trees judged severely imbalanced, based on the sum of DRIS indices. Nitrogen and Mg deficiencies were not detected unless lower NII thresholds were used. Unfortunately, lowering NII thresholds enough to detect N and Mg deficiencies identified some high-yielding trees as severely imbalanced. DRIS will not detect all deficiencies or excesses. Therefore, DRIS is best viewed as a supplement to sufficiency range diagnoses that provides additional information when severe imbalances are detected.
Nitrate Monitoring for Pumpkin Production on Dryland and Irrigated Soils
Authors: Swiader John M. , Sullivan Joseph G. , Grunau John A. , Freiji Fadi
Published: August 2022

Field experiments were conducted in 1985 and 1986 to determine in-season indexes for petiole NO3-N in dryland-grown and irrigated pumpkins (Cucurbita moschata Poir.). The level of NO3-N in petioles of recently mature leaves was a good indicator of the seasonal N status for pumpkins on irrigated sand, and to a lesser degree for pumpkins on dryland loam. Petiole NO3-N concentrations decreased with time and with decreasing N rate at both sites, with the rate and extent of decrease considerably greater on the irrigated sand. The optimum time of sampling was at about initial fruit set or early fruiting. Critical (10% yield reduction) and minimum sufficiency (lowest concentration before yield reduction) levels for petiole NO3-N at early fruiting were estimated at 6300 and 8000 μg·g−1, respectively, in dryland and 4000 and 6700 μg·g−1, respectively, for irrigated plantings. Deficiency symptoms were associated with NO3-N concentrations <1500 μg·g−1. Soil NO3-N levels proved unsatisfactory as a NO3-N index in dryland soil, but meaningful relationships (R2 = 0.31) were obtained between fruit yield and soil NO3-N on irrigated sand. Fertilizer N requirements for 90% and 100% of marketable yield were estimated at 44 and 158 kg N/ha for dryland and 125 and 225 kg N/ha for irrigated pumpkins, respectively. However, N fertilizer rates of 202 and 269 kg N/ha delayed harvest 9 days on irrigated sand and 15 days on dryland loam, compared to lower N rates.
Influence of Orientation and Position of Fruiting Laterals on Canopy Light Penetration, Yield, and Fruit Quality of ‘Granny Smith’ Apple
Authors: Tustin D. Stuart , Hirst Peter M. , Warrington Ian J.
Published: August 2022

Fruiting laterals were tagged within the inner and outer canopy zones of the basal, mid, and upper tiers of dormant, mature central-leader ‘Granny Smith’ apple (Malus domestica Borkh.) trees and were classified into pendant (>120°), horizontal (30°-120°), and vertical (0°-30°) types. Transmission of photosynthetic photon flux (PPF) to spur sites on tagged laterals was measured in mid-season and fruits from these sites were harvested at commercial maturity for assessment of fresh weight, soluble solids concentration (SSC), starch pattern index, and background color. Pendant laterals produced fewer, smaller, and greener fruit per flowering spur than horizontal or vertical laterals. Fruit fresh weight and soluble solids concentration increased with increasing height in the canopy and were higher in the outer compared with the inner horizontal canopy position. Background color followed a trend opposite to that of fresh weight and soluble solids concentration, with fruit from the lower inner canopy regions being greenest. Both fresh weight and SSC showed highly positive correlations with the percentage transmission of PPF. Fruit set showed a positive correlation with PPF, although the relationship was weaker than that for fresh weight or SSC. PPF penetration was lower to pendant laterals than to horizontal and vertical laterals and declined from upper to lower and from outer to inner canopy positions. Pendant fruiting laterals received < 15% of PPF, irrespective of location within the canopy.
Influence of Pruning and Urea Sprays on Growth and Fruiting of Spur-bound ‘Delicious’ Apple Trees
Authors: Ferree David C. , Forshey C.G.
Published: August 2022

Spur quality and leaf nutritional levels were determined in various canopy sections of mature spur-bound ‘Delicious’-type apple (Malus domestica Borkh.) trees and then various pruning and foliar urea treatments were applied to alter growth and improve fruit size. Fruit size declined from the top to the bottom of the canopy of mature spur-bound ‘Starkrimson Delicious’ trees with a similar pattern in the following criteria: leaf area/spur, spur specific leaf weight, and spur bud diameter. Spur leaf area was higher in the top center and east sections than in the top south. Spur bud diameter in the bottom third of the canopy was highest in the north and east sections, lowest in the central section, and intermediate in the south and west sections. Concentrations of leaf Mn, Zn, B, Al, and Na tended to increase from the top to the bottom of the canopy. Four urea sprays (6 g urea/liter) during the cell division period of fruit growth had little influence on spur quality, but fruit weight was increased 3 successive years. Spur pruning of 25-year-old ‘Starkrimson Delicious’ trees was not sufficient to increase shoot growth or improve spur quality, but heading back into 2-year-old wood plus spur pruning increased shoot number by 38%. Spur and heading-back pruning increased the number of shoots and total shoot leaf area of 13-year-old ‘Red Chief Delicious’ trees, and the combination of both pruning types led to the greatest increase. Heading-back of the younger trees increased leaf area of both shoots and spurs and spur pruning also increased leaf area/spur. Heading-back pruning increased average fruit weight, and the increase was positively correlated with total leaf area, shoot leaf area, and number of shoot leaves/mm of branch circumference.
Responses of Parthenocarpic Cucumbers to Low-oxygen Storage
Authors: Kanellis Angelos K. , Morris Leonard L. , Saltveit Mikal E.
Published: August 2022

Parthenocarpic cucumber fruit (Cucumis sativus L. cv. Deliva) of marketable maturity (10 to 14 days after anthesis) were held at 12.5° or 20°C in reduced O2 levels for 5 or 18 days before transfer to air. Carbon dioxide production at reduced O2 levels was generally less than in air; however, at O2 levels < 0.5%, anaerobic respiration resulted in increased rates of CO2 production. Upon transfer to air after 18 days, all samples from reduced O2 showed increased CO2 production rates that equalled or exceeded that of the air controls. Except at 0.0% and 0.25% O2 levels, ethylene production was increased in reduced O2. After transfer to air, ethylene production increased and the increase was inversely related to the previous O2 level. Ethanol and acetaldehyde production were measureable for fruit held in 1% O2 after 18 days at 12.5° and showed dramatic increases at lower O2 levels. Low-O2 injury (pitting) developed on most fruit held at 0.0% O2 and on many fruit held at 0.25% O2. Only minima! commercial benefits are likely to be realized from storage of 1 to 3 weeks in 0.5% to 2.0% O2 at 12.5°.
Postharvest Characteristics of Geraldton Wax Flowers
Authors: Joyce Daryl C.
Published: August 2022

Abscission of flowers of Geraldton wax (Chamelaucium uncinatum Schau., Myrtaceae) exposed to ethylene was prevented by pulsing with silver thiosulfate. Both a short pulse (15 min, 4.0 mm Ag+) at 25°C and an overnight pulse (0.5 mm Ag+) at 2° were effective treatments. Silver thiosulfate did not improve the vase-life of flowers held in air. Gamma irradiation (60Co source), an insect control measure, resulted in a reduction in vase-life; even at doses as low as 0.05 kGy. Vase-life of Geraldton wax flowers was not affected by prior storage for up to 2 weeks at 0° to 2°. Iprodione pretreatment (1 g·liter−1, 30-sec dip) for Botrytis cinerea Pers. control improved the vase-life of flowers stored for 2 weeks. A preservative solution containing sucrose (1% to 3% w/v) and 8-hydroxyquinoline sulfate (200 mg·liter−1) increased the vase-life of Geraldton wax flowers. Higher sucrose levels (>5% w/v) may cause desiccation of foliage and excessive nectar secretion from floral nectaries. Chemical name used: 3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide (iprodione).
Sixteen-year Performance of Five Nucellar and Old-budline ‘Valencia’ Oranges
Authors: Rouse Robert E. , Maxwell Norman P.
Published: August 2022

Sixteen-year mean and cumulative yields are reported for nucellar sweet orange [Citrus sinensis (L.) Osbeck] ‘Olinda Valencia’, ‘Campbell Valencia’, ‘Cutter Valencia’, ‘Frost Valencia’; one Texas Agricultural Experiment Station (TAES) nucellar ‘Valencia’ selection, and old-budline ‘Valencia’ on sour orange (C. aurantium L.) rootstock. Yields for individual years were consistent among the highest with ‘Olinda Valencia’ and ‘Campbell Valencia’, and lowest with ‘Frost Valencia’ and old-budline. Cumulative yields were comparable for ‘Olinda Valencia’ and ‘Campbell Valencia’. Tree canopy volumes were greatest for the TAES nucellar selection and smallest for old-budline, which was not significantly different than ‘Frost Valencia’ or ‘Olinda Valencia’. Based on yield per unit of canopy, ‘Olinda Valencia’ had the highest yield efficiency and lowest coefficient of variation among years. Internal fruit quality data (°Brix, acid, °Brix : acid ratio, and percentage juice) did not differ among cultivars.
Is the P Gene in Common Bean Located in Linkage Group VII?
Authors: Bassett Mark J. , Awuma Kafui
Published: August 2022

Linkage tests in common bean (Phaseolus vulgaris L.) were made between black-seeded lines carrying the marker genes round leaf (rnd) and stipelless lanceolate leaf (sl) and the white-seeded lines ‘Miami’ and ‘Inepuisable’ and an induced mutant for white seed, 3-254. The crosses ‘Miami’ × ‘Inepuisable’ and ‘Miami’ × 3-254 were made to test for allelism of the white seed genes in these lines. ‘Miami’ was found to be allelic to ‘Inepuisable’ and 3-254 at the white seed locus (presumed to be P). Furthermore, there was no indication of linkage between the white seed locus and the markers rnd and sl. These results contradict expectations of linkage of P with rnd and sl based on previously published linkage maps and indicate that the present map position of P is incorrect.
Effects of External Ethylene on the Production of Endogenous Ethylene in Olive Leaf Tissue
Authors: Goren Raphael , Nishijima Chic , Martin George C.
Published: August 2022

Olive (Olea europaea L.) leaves are characterized by their ability to respond to exogenous ethylene by a 100- to 400-fold enhanced ethylene production irrespective of leaf age or time of year when sampled. The autoenhancement of ethylene production from intact or detached leaves is positively correlated with the concentration of external ethylene. A lag time of 72 to 120 hr occurred before the autoenhancement of ethylene production could be observed. An autoinhibition of ethylene production was usually observed during the first 24 to 48 hr. The effect was, however, much less pronounced. This autoinhibition of ethylene production apparently does not involve wound ethylene. Olive fruit normally produce only negligible amounts of ethylene, and the enhanced ethylene evolution, which was observed after the fruits were exposed to exogenous ethylene, was found to be exogenous ethylene that was trapped by the fruit tissue during its exposure to ethylene. In leaves, however, autoenhancement of ethylene production evidently is a physiological response that may induce a senescing process in the leaves rather than abscission.