Showing papers in "Journal of Horticultural Science in 1988"

Chemical control of tree vigour and the promotion of flowering and fruiting in mango (Mangifera indica L.) using paclobutrazol

Abstract: SummarySoil application of paclobutrazol reduced internodal length, shoot length and height increments of one to eight year old veneer grafts of three mango cultivars on seedling rootstocks. Soil applications of growth retardant caused precocious flowering in young grafts and promoted flowering in bearing trees. Axillary flowering and cauliflory were observed in treated trees and flowering was advanced. Soil-treated trees given 10 g a.i. per tree flowered six to eight weeks earlier than control trees. In cv. Banganapalli, early-flowered shoots which had failed to set fruits, flowered again at the same time as control trees. Post-harvest applications may be more advantageous than a pre-bloom application, with a longer lag time. There was a significant increase in yield per tree which was even more significant when tree vigour was allowed for. Fruit size and quality were not affected by the treatment. An application rate of 10 g a.i. per tree gave the desired effects for at least two years in five year old ...

Meristem culture and micropropagation of a variety of ginger (Zingiber officinale Rosc.) with a high yield of oleoresin

Abstract: SummaryMeristems of ginger with or without leaf primordia were induced to form shoots on three-quarter strength Murashige-Skoog’s (MS) medium containing sucrose 6%, coconut milk (CM) 20%, ascorbic acid (AA) 100 mg l−1, glutamine (GL) 400 mg l−1, activated charcoal (AC) 250 mg l−1, 6-benzylaminopurine (BAP) 0.5 mg l−1, indolebutyric acid (IBA) 0.4 mg l−1 and agar 0.8%. Meristem-derived shoots exhibited consistent multiplication on three-quarter strength MS medium containing sucrose (3%), AA (100 mg l−1), AC (100 mg l−1), BAP (4–5 mg l−1) and agar (0.8%). Liquid media (agitated or static) were less effective than a solid (agar-gelled) medium for micropropagation. Kinetin and naphthalene acetic acid (NAA) incorporated at various levels (0.01–0.8 mg l−1) with or without added BAP and IBA neither improved plantlet formation nor enhanced shoot multiplication. The in vitro plants were successfully established in vivo and the rhizome yield was comparable with that of plants grown by conventional methods.

Effect of temperature on growth and flowering of litchi (Litchi chinensis Sonn.) cultivars

Abstract: SummaryModerate day/night temperatures (20/15° v. 15/10°C) increased vegetative growth and reduced flowering in the seven litchi cvs Tai So, Bengal, Souey Tung, Kwai May Pink, Kwai May Red, Salathiel and Wai Chee. At higher temperatures (25/20° and 30/25°C), vegetative growth was promoted further and flowering eliminated. Temperature also influenced the type of inflorescence formed. More leaves were formed on the panicles of trees growing at 20/15° than at 15/10°C. All terminal shoots on all cultivars produced panicles at 15/10°C. The relative order for the amount of flowering at 20/15°C was: ‘Wai Chee’>‘Salathiel’>‘Kwai May Pink’>‘Tai So’>‘Bengal’>‘Souey Tung’>‘Kwai May Red’. Cultivars which were vigorous at high temperatures produced fewer panicles at 20/15°C and fewer leafless panicles at 15/10°C. Only small differences were observed in the leaf water potential and the nutrient status of the shoots at different temperatures. Vigour and flowering of the cultivars in the glasshouse generally reflected fi...

Nitrogen fertilization under saline conditions in tomato and cucumber plants

Abstract: SummaryTomato (Lycopersicon esculentum, Mill.) and cucumber (Cucumis sativus, L.) seedlings were grown in a growth chamber in 4 litre containers filled with nutrient solutions. Four experiments were conducted with four NaCl levels factorially combined with four N levels. The concentrations of NaCl were 4, 25, 50, and 100 mmol l−1 and 4, 16, 32, and 64 mmol l−1 in the tomato and cucumber experiments respectively. The N levels in allexperiments were 2, 6, 10 and 15 mmol l−1 added as NO3− or as NH4+ + NO3− (2:1). Salinity had a statistically significant negative effect on all responses considered, although the effect was N source-dependent. Addition of N enhanced development of shoot and root dry weights of both species. The optimum N concentration in the nutrient solution varied between 6 and 10 mmol l−1, although the most appropriate N fertilizer varied with species. Leaf Cl− concentration decreased in both species when NO3− was used as the N source, whereas it increased in the comparative tissues of plant...

The effect of different day/night temperature regimes on growth, development and yield of glasshouse tomatoes

Abstract: SummaryThe response of glasshouse grown tomatoes, cv. Counter, to day/night temperature regimes was examined in two consecutive years. In both years three day/night temperature regimes, with the same average 24-hour temperature, were applied in duplicate, i.e. high/low, equal, and low/high. Differences in temperature were maintained from three days after planting (4 December 1984 and 3 February 1986) until 13 May 1985 and 1 May 1986, respectively. Plant development (increase in number of trusses) was not affected.by the temperature regime. Growth in length of the stem was strongly reduced by a lower day temperature. In the first experiment the crop at the low day temperature treatment was damaged by leaf scorch, most likely caused by low transpiration. Consequently, early yield was lower for this treatment. In the second experiment no leaf scorch occurred and no significant differences in early yield were found. Final yield and average fruit weight, until 1 July for both experiments, were higher at the hi...

Role of pectolytic enzymes in the development of woolliness in peaches

Abstract: SummaryThe role of pectolytic enzymes in the development of woolliness in peaches (Prunus persica, cv. Peregrine), stored at different temperatures, was studied. All peaches became woolly during a ripening period of 12 days at 10°C following storage at 2°C, whereas 75% of those stored at –0.6°C developed this disorder. Only 6% of fruit showed symptoms of woolliness after 48 h at 23°C prior to storage. The sugar content, as well as the viscosity of soluble pectin, of peaches stored after the delay period reached a maximum during the 15th day of cold storage, after which it decreased until the end of the ripening period. In peaches stored immediately, however, the maximum sugar content and viscosity was reached during the ripening period. Pectinesterase (PE) activity fluctuated between the different treatments and its possible role in the development of woolliness is not clear. The polygalacturonase (PG) activity of those peaches which became woolly after being stored directly at either temperature was mark...

Production of volatile aroma substances by ‘Golden Delicious’ apple fruits after storage for various times in different CO2 and O2 concentrations

Abstract: Summary‘Golden Delicious’ apple fruits were stored for 3–9 months at 11 combinations of CO2/O2 concentrations at 1°C. The production of volatiles by the stored fruits was measured by gas chromatography during a post-storage shelf-life period at 20°C. The reduction in the production of volatiles largely resembled the general inhibition of ripening under the various controlled-atmosphere (CA) conditions. With increasing CO2- and decreasing O2-concentrations, aroma volatile production was reduced, especially if both gas treatments were simultaneously applied. However, there was neither a simple additive or synergistic, nor a linear relationship between changes in storage atmosphere composition and aroma volatile production. Decreasing the O2 concentration to 3% had little effect on volatile production, but a further decrease to 1% significantly reduced it. At O2 concentrations above 3%, higher CO2 concentration became decisive in diminishing volatile production. After an extended storage, a clear residual CA...

Some maturity indices for tamarillo and pepino fruits.

Abstract: SummaryColour, firmness, juice content and °Brix levels were identified as maturity indices for tamarillo and pepino. The fruits were classified into three stages of maturity on the basis of colour. There were green (immature), purple (mature) and red (ripe) for tamarillos, and green (immature), pale-green (mature) and golden-yellow (ripe) for pepinos which corresponded with the stages at which they might be used for cooking, in salad or as dessert respectively. Purple tamarillos were considered to be at optimum maturity for harvesting and marketing when purple, because they then continued to ripen after harvest and became softer and juicier. Pepinos failed to exhibit similar changes but they were best for dessert when golden-yellow with a firmness as resistance to pressure of 2 kg cm-2, a minimum of 40% juice and 9 °Brix. Post-harvest dipping in ethephon increased the colour, °Brix and improved the flavour of both fruits, but enhanced the production of CO2 and ethylene in pepinos only.

Antibacterial activity of French tarragon (Artemisia dracunculus Linn.) essential oil and its constituents during ontogeny

Abstract: SummarySteam distillation of the essential oil from French tarragon (Artemisia dracunculus L) yields a mixture of almost fifty different components. A set of ten bacterial species was exposed to the whole oil and several of its constituents, and the level of bacterial inhibition determined. Among the bacteria tested were several of public health significance, including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus faecalis and Yersinia enterocolitica. The most inhibitory compounds present in French tarragon essential oil were anisaldehyde, paracymene, eugenol, limonene, linalool, menthol, cis-ocimene, alpha-phellandrene, alpha-pinene and beta-pinene. The.antimicrobial activity of whole oil was also assessed at different stages during plant ontogeny.

Irrigation of greenhouse-grown cucumbers

Abstract: SummaryThe potential evapotranspiration (ETP) of heated greenhouse-grown cucumber was measured over two experimental seasons (1982–3 and 1983–4) using plants grown in drainage lysimeters. The crop ETP at planting in November was 0.2 of evaporation from a United States Weather Bureau Class A screened pan (Epan) located outside the greenhouse, and increased gradually to 1.1 × Epan at the conclusion of the experiment in May. Over the whole growing period the average water requirement was equivalent to 0.7 × Epan. The crop ETP ranged between 0.6 and 5.7 mm d−1 with a whole-season irrigation requirement corresponding to 5040 m3 ha−1. Water applications at 0.6 × ETP reduced yield significantly. The highest yield was obtained with the 1.0 × ETP treatment. Soil salt concentration below the dripper increased as the amount of water applied decreased, while mid-way between irrigation lines, salt concentration increased as the amount of water supplied increased. The highest salt accumulation occurred in the surface 0...

Russeting (cuticle cracking) in glasshouse tomatoes in relation to fruit growth

Abstract: SummaryRelationships between the occurrence of russeting (cuticle cracking) and fruit diameter, relative growth rate (RGR) and the period from fruit set to harvest were investigated in a glasshouse experiment. Fruits were visually and microscopically examined for the presence of cracks and graded from 0 (no symptoms) to 4 (severe symptoms). Cracks occurred on fruits six to seven weeks after fruit set in the last phase of fruit growth. The extent of russeting increased with increase in the period from occurrence to harvest. Russeting was most marked at higher RGR and long periods from fruit set to harvest. The percentage of russeted fruits varied from 10 to 80% over the total production period. More russeting was apparent in plants carrying a low fruit load. It is suggested that this variation is the result of a complex of factors related both to fruit growth and fruit load and to the tensile strength and extensibility of the epidermis.

Effect of overhead shading on yield and fruit quality of kiwifruit (Actinidia deliciosa)

Abstract: SummaryKiwifruit vines (cv. Hayward) were shaded from early spring until fruit harvest at levels of 100% (control), 70% or 45% full sun. Although shoot growth during the early part of the season was not significantly affected by the shading, the percentage bud burst was reduced and the time of full bloom appeared to be slightly delayed. The mean fresh weight of individual fruits was significantly reduced by shading, and fruit on shaded vines reached commercial harvest maturity of 6.2% soluble solids two to three days later than those on unshaded vines. During cool storage, fruit from vines grown under 45% full sun were slightly but consistently less firm and had lower soluble solids concentrations than unshaded fruit. No differences in the starch or total sugar contents were found between shaded or unshaded fruit, either at harvest or after cool storage. Shading vines did not affect either the colour (HunterLab values) or the chlorophyll concentration of fruit. Possible implications of these results for c...

Comparative studies on the postharvest physiology of fruit from different species of Annona (custard apple)

Abstract: SummaryFruit of three Annona species, viz. cherimoya (A. cherimola Mill), sugar apple (A. squamosa L.) and custard apple (atemoya, Annona X) were ripened in ethylene-free air and under propylene. Differences were found in patterns of respiration, ethylene production and fruit firmness changes during ripening. Cherimoya and custard apple fruits showed two successive rises in respiration rate whereas sugar apple fruits showed only one. Ethylene production showed one main peak but the onset of rapid ethylene production occurred after the beginning of the respiration climacteric in all three species. Custard apple fruit had acceptable eating quality (as judged by sensory assessments and chemical analyses of pulp) for up to four days after first detectable softening, when ripened at 20°C in ethylene-free air or under propylene. Fruit ripened in ethylene-free air had better ripe fruit quality than fruit ripened under propylene.

Relative salt tolerance of pistachio cultivars

Abstract: SummaryThe effects of four soil NaCl levels (0, 1 600, 3 200, and 4 800 μg g−1) on the growth, chemical composition and plant water relationships of pistachio cvs Badami, Fandoghi and Kale-ghoochi were studied in an arid calcareous soil in a glasshouse experiment. Fandoghi was less tolerant to NaCl salinity probably because of higher uptake and/or transport of CI and Na ions, lesser osmoregulatory ability, and greater reductions in the top and root dry weights with respect to the CI concentration in the soil saturation extract. The 50% reduction in the top and root dry weights were obtained, respectively, at an electrical conductivity of the saturation extract (ECe) of 9.3 and 10.0 mmhos cm−1 for ‘Badami’, 7.9 and 7.9 mmhos cm−1 for ‘Fandoghi’ and 9.6 and 10.0 mmhos cm−1 for ‘Kaleghoochi’. Growth of tops and roots was stopped, respectively, at ECe values of 18.7 and 20.6 mmhos cm−1 for ‘Badami’; 15.9 and 15.5 mmhos cm−1 for ‘Fandoghi’, and 19.2 and 20.4 mmhos cm−1 for ‘Kale-ghoochi’.

The effects of pre- and post-harvest development on mushroom tyrosinase.

Abstract: SummaryTyrosinase activity and the content of phenols in the skin and flesh of mushroom sporophores were assayed during pre- and post-harvest development. Skin tissue has more non-latent tyrosinase activity and phenols than the flesh. Latent tyrosinase from both tissues can be activated by trypsin or sodium dodecyl sulphate (SDS). Trypsin activation of skin tryosinase is significantly greater than by SDS, while SDS activates the flesh enzyme to a significantly greater extent. The degree of activation (the proportion of non-latent to fully activated activity) increases only during post-harvest development. The phenol content of the mushroom tissues is greater in the low-quality strain D649 than in the high quality U3. The relationships between tyrosinase activity and phenol level with mushroom quality are discussed.

Development of an in-vitro rooting bioassay using juvenile-phase stem cuttings of Persea americana Mill.

Abstract: SummaryA rooting test was developed with shoot cuttings taken from aseptically germinated avocado seed. The rooting required treatments in two steps: (1) three days in a medium containing indole-3-butyric acid (IBA) (25 mg l−1) and (2) four to eight weeks in an auxin-free medium. Rooting was accomplished with both media containing 0.3× strength Murashige and Skoog salts, 3% sucrose, 0.4 mg l−1 thiamine hydrochloride, 100 mg l−1 i-inositol, and 0.8% ‘TC’ agar. The auxin-free medium also contained 1 gl−1 activated charcoal.

Primocane (autumn)-fruiting raspberries: a review with particular reference to progress in breeding

Abstract: SummaryThe characteristics of primocane-fruiting (PF) raspberries (developmental cycle, ripening season, yield) and the effects on these of changes in the environment (day-length, length of growing season, temperature, nutrition, growth regulator applications) are described. Economic aspects are discussed in relation to extending the season, reduction in establishment and production costs compared with summer-cropping raspberries, and mechanical harvesting. Progress in breeding new PF varieties in North America and Europe and current and potential future prospects for growing PF raspberries are discussed.

Physiological changes associated with the development of woolliness in ‘Peregrine’ peaches during low-temperature storage

Abstract: SummaryThe effects of different durations of storage and temperature on the development of woolliness in peaches (Prunus persica cv. Peregrine) were studied. All peaches became woolly during ripening for 12 days at 10°C following storage at 2°C but only 75% of those stored at –0.6°C developed this disorder. Firmness and the respiration rate of woolly peaches decreased sharply at the onset of woolliness while peaches which subsequently became woolly had a lower ethylene content throughout the storage and ripening periods. When peaches were held for 2 days at 23°C before storage at either temperatures, few fruit developed symptoms of woolliness. Although the amount of extractable juice remained high in fruit stored without pre-treatment at 23°C, the quantity fell rapidly during the ripening of peaches which became woolly.

Control of shoot growth of peach and nectarine trees with paclobutrazol

Abstract: SummaryExperiments were carried-out on ‘Crimson Gold’ nectarine and ‘Redhaven’ peach to investigate effects of paclobutrazol on tree growth. This growth regulator strongly inhibits vegetative growth of these cultivars by reducing the number and length of internodes per shoot. Soil applications in early spring reduced shoot extension growth in ‘Crimson Gold’ trees, the effect increasing linearly with the amount applied. Autumn applications to the soil were less effective in this cultivar, but a significant inhibition of shoot growth has been observed in ‘Redhaven’. Foliar sprays also controlled shoot growth when concentrations of 250 ppm were applied on four occasions. No differences in yield were observed, although increases of mean fruit weight were found when paclobutrazol was applied to the soil in early spring. In the year after applying paclobutrazol, the trees previously treated grew more than the untreated controls.

Physiological and anatomical features of the silvering disorder of Cucurbita

Abstract: SummaryLeaf silvering is a physiological disorder of marrows, Cucurbita pepo, exacerbated by drought. Silvered leaves had spaces between the upper epidermis and the mesophyll cells and within the mesophyll. The palisade cells were smaller and spongy mesophyll cells fewer. Completely silvered leaves contained 14% less chlorophyll per unit leaf blade area than green leaves. The rate of photosynthesis decreased as severity of silvering increased. The rate of photosynthesis was about 30% lower in the completely silvered than in the green leaves at saturating and above-saturating light and CO2. The results suggest that in silvered plants the CO2 absorption mechanism has been affected.

Plant density studies with banana (cv. Williams) in a subtropical climate. I. Vegetative morphology, phenology and plantation microclimate

Abstract: SummaryThe influence of plantation age and plant density on pseudostem size, canopy cover and vegetative growth characteristics of banana cv. Williams was investigated over four cropping cycles at Burgershall Research Station, in the subtropical Eastern Transvaal. Densities were 1000, 1250, 1666 and 2222 plants ha−1. Over all densities, pseudostem height, lamina area, numbers of functional leaves at flowering and LAI increased with plantation age up to the second ratoon (R2). This increase in canopy cover caused vegetative and total cycle intervals to be extended progressively from plant crop to R3. Within cycles, higher density had little effect on plant height or lamina length, but induced thinner plants with significantly narrower leaves than at low density. Peak ratoon LAI at flowering almost doubled between 1000 and 2222 plants ha−1. At 1000 plants ha−1, four cropping cycles were completed in the same period as three cycles at 2222 plants ha−1. Annual leaf emergence rate was significantly reduced by ...

Patterns of assimilate transport from leaves to fruit within a kiwifruit (Actinidia deliciosa) lateral

Abstract: SummaryKiwifruit leaves began to export 14C-assimilate when they were 49 to 64% fully expanded. The translocation was bidirectional, but within an intact lateral, assimilates flowed along pathways which linked the fruit on the nth node with its subtending leaf and, at least, with the leaves at nodes n+5 and n+8. However, after the lateral was pruned, the pattern of translocation was altered, so that all the distal leaves supplied each fruit.

Effects of herbicides and cultivation on the growth of Opuntia in plantations

Abstract: SummaryLandraces of the genus Opuntia (Cactaceae) are important in semi-arid regions of the Mediterranean area and in Mexico, Argentina, and Chile where they provide animal fodder, and fruits and vegetable material for human use. There is little literature on current cultivars or horticultural practices for use in these plantings. Opuntia plantations when not cultivated have a low productivity. Due to the great reduction in cactus growth by weeds and the tediousness in hand weeding spiny cactus germplasm collections, herbicides were evaluated for use in Opuntia plantings. Multiple combinations of eight herbicides (hexazinone, tebuthiuron, simazine, diuron, bromacil, oryzalin, oxyfluorfen, and metolachlor) and a mechanical cultivation treatment were examined for their effect on the biomass production and survival of Opuntia lindheimeri. The vegetative cover measured 7 months from planting ranged from 0.1% to 83%. Biomass was measured by complete harvest 14 months after planting and ranged from 511 kg ha−1 ...

The effects of storage and development on Agaricus bisporus proteases

Abstract: SummaryChanges in protein level and protease activity were compared in two tissues of the sporophore of Agaricus bisporus. The skin tissue (pilei pellis) contains on average 58% more protein and 88% more protease activity on a fresh-weight basis than the flesh tissue (pileus trama) of freshly harvested sporophores. The protein level of the tissue fell as the mushrooms grew and developed while in contact with their mycelium, but the protease activities showed no correlated trend. A large increase in proteolytic activity and a decrease in protein content was observed in the tissues of harvested mushrooms after 5 days’ storage at 18°C. The results are discussed in relation to mushroom quality during storage and the development of mushrooms before and after harvesting.

Anatomical changes including chloroplast structure in peach leaves under different light conditions

Abstract: SummaryTwo-year-old peach (Prunus persica Sieb, et Zucc. cv. Ohkubo) trees were shaded so as to receive approximately 50%, 25%, 10% of full daylight from the bud sprouting stage, and their growth was compared with that of unshaded control trees two months after treatment. Compared with those in the control group, average leaf area was increased 45%, 71% and 36% by 50%, 25% and 10% of full sun, respectively. Shade-grown leaves were thinner, flatter, and darker green than sun-grown ones; leaves grown in heavy shade (10% of full sun) had one or two poorly developed palisade layers; in contrast, sun-grown leaves had two or three layers of well developed palisade cells. Dry weight per fresh weight or per unit area of leaf was highest in sun-grown leaves and lowest in leaves grown in heavy shade. Stomatal density decreased with shading. Chlorophyll content per unit leaf area or per dry weight increased with shading. Shade-leaf chloroplasts (10% and 25% of full sun) were larger and rich in thylakoids, while sun-...

Discrimination of zygotic and nucellar seedlings of five polyembryonic citrus rootstocks by isozyme analysis and seedling morphology

Abstract: SummaryIsozyme analysis using eight loci of six enzyme systems was used to distinguish zygotic from nucellar seedlings resulting from open pollination of five polyembryonic citrus rootstocks. Zygotic seedlings were detected by isozyme analysis in the rootstocks rough lemon (2.1%), trifoliata orange (2.6%), sweet orange (0.8%) and ‘Troyer’ citrange (0.8%). No zygotic seedlings of ‘Cleopatra’ mandarin were detected, but this may be due to the high proportion of homozygous loci. The zygotic seedlings had arisen by both self pollination and cross pollination of the maternal parent. There was some morphological variability amongst the zygotic seedlings but these characters could not be used to identify all of the zygotic seedlings detected by isozyme analysis.

Calcium deficiency of glasshouse cucumber as affected by environmental humidity and mineral nutrition

Abstract: SummaryThe effects of interactions between environmental humidity, calcium supply and electrical conductivity (EC) of the growing medium on calcium deficiency in cucumber leaves were investigated in two glasshouse experiments. A low or high humidity during the day was combined with either a low or a high humidity during the night. The 24 h average vapour pressure deficits achieved over the period from planting until calcium deficiency occurred varied from 0.44 to 0.88 kPa. Visible symptoms and the calcium content of the leaves were closely correlated with 24 h average vapour pressure deficit. The effect of humidity on calcium deficiency inceased with increasing EC and decreasing calcium supply. When calcium accounted for more than 47% of all cations in the root environment, the effect of humidity on calcium deficiency was negligible. It was concluded that deficiency symptoms gradually became apparent when the calcium content of the leaf margins fell below 500mmol kg−1 dry matter. At low vapour pressure de...

Thinning 'Golden Delicious' apples with naphthalene acetic acid in relation to spray concentration, volume and time of day.

Abstract: SummaryA trial was conducted at the Grove Research Station in the Huon Valley of Southern Tasmania in 1984/85 using naphthalene acetic acid as a thinner for mature ‘Golden Delicious’ trees. Sprays were applied at concentrations of 10 or 20 ppm NAA, at spray volumes of either 4 000 or 7 000 l ha-1 at 0800,1200,1600 or 2000 hours, 10 days after full bloom. Twenty ppm removed significantly more fruit than 10 ppm. Increasing the volume of spray from 4 000 to 7 000 l ha-1 also significantly increased fruit thinning. Spraying at 0800 hours removed more fruit than in the afternoon or evening. The relationship between fruit set and the timing of the spray between 0800 and 2000 hours was positive and linear. There was no significant interaction between concentration and timing of spray treatments for any of the variables recorded. Spraying with 7 000 l ha-1 in the early morning is recommended for thinning ‘Golden Delicious’.

Some physiological characteristics of fruits of jujube (Zizyphus spina-christi L., Willd.) at different stages of maturity

Abstract: SummaryJujube fruits (Z. spina-christi L., Willd.) of the three cvs Bambawi, Zaytoni and Mallasey were harvested at three stages of maturity and their physiological characteristics measured. Moisture content, titratable acidity, total chlorophyll and pectic substances decreased with fruit maturity. Total soluble solids, carotenoids and vitamin C contents increased as the fruit matured.

Synchrony of yield of melons as affected by plant type and density

Abstract: SummaryTwo closely related muskmelon hybrids, ‘Galia’ and ‘D72’, the former a widely grown vine-type cultivar and the latter an experimental hybrid derived from a birdsnest-type muskmelon plant introduction, were compared for synchrony of yield in plant density trials at Gainesville, Florida, U.S.A. and at Newe Ya’ar, Israel. Plant densities employed at the former location were 10, 20 and 30 thousand plants ha−1 and at the latter location 5, 10, 20 and 40 thousand plants ha−1. On a land-area basis, ‘D72’ and ‘Galia’ produced similar total yields but the fruits of ‘D72’ were smaller and more numerous than those of Galia. Yield was not significantly affected by density in Florida, but in Israel, fruit number and yield per unit land area increased as the density increased. Fruit size decreased with increased planting density. Synchrony of yield, that is, the concentration of yield over time, was calculated as a weighted numerical index and as the percentage of the total yield harvested during the peak three-...