Control of chlorophyll formation and sprouting of tubers by oil dipping in five potato cultivars of Pakistan

Five potato cultivars of autumn crop, dipped in corn oil, were observed for 90 days at room temperature under natural light. Chlorophyll formation took place in minute quantities in treated tubers of ‘Désirée’ and ‘Prima’, and a little more in ‘Primura’, ‘Montana’ and ‘Multa’, whereas all control tubers became completely green after 90 days. Sugars were significantly lower and starch higher in treated tubers than in controls. No sprout-development was observed in treated tubers of all cultivars, but 50–70% control tubers had sprouted during this period. Peeling-losses were minimum in treated tubers and were 67.5–85.4% in controls. The oil-dipped potato tubers of all cultivars could safely be stored for 60 days without quality deterioration under ordinary conditions of temperature and light.     

The effect of hydrogen cyanamide (Dormex) on flowering and cropping of different apple cultivars under tropical conditions of sub-optimal winter chilling

The effects of pre-bud-break application of 1.5% hydrogen cyanamide (3% Dormex) on the flowering and cropping of 12 apple cultivars were determined over the years 1988/89 to 1991/92 in tropical Zimbabwe, at a site with less than 300 h of winter chilling below 7.2 °C per year. Control trees, other than those of ‘Mutsu’ and ‘Goldjon’ which were indistinguishable from the treated trees, showed varying degrees of delayed flowering and low yield in comparison with the cyanamide-treated trees. The latter, irrespective of cultivar, attained full bloom within 4–5 weeks of the common date of treatment, so that blossoming of the different cultivars, as well as that of the different trees of each cultivar, was synchronized, and all cropped heavily in relation to tree size. Very satisfactory yields of ‘Mollies Delicious’, ‘Canvada’, ‘Drakenstein’, ‘Golden Delicious’, ‘NJ46’, ‘Marjorie Pye’, ‘Spartan’, ‘Starking’, ‘Granny Smith’ and ‘Ohinemuri’ were thus obtained by the use of cyanamide in an environment otherwise unsuitable for them, especially for the later cultivars on this list.     

Hardy framework influence (1969–1983) on yield, tree size and yield efficiency of ‘Wellspur’ and ‘Goldspur’ apple

Cumulative yield, trunk cross-sectional area, and yield efficiency were measured between 1969 and 1983 in an experimental planting (established in 1964 and top-worked in 1965) of ‘Wellspur’ and ‘Goldspur’ apple top-worked on frameworks of 19 cold-hardy cultivars (‘Alnarp 2’, ‘Antonovka’, ‘Beacon’, ‘Canada Baldwin’, ‘Delcon’, ‘Dr. Bill’, ‘Duchess’, ‘Haralson’, ‘Hawkeye Greening’, ‘Heyer 12’, ‘Heyer 20’, ‘J. Luke Seedling’, ‘McIntosh’, ‘Minnesota 447’, ‘Ottawa 271’, ‘Ottawa 292’, ‘Red Astrachan’, ‘Robusta 5’, ‘Yellow Transparent’) that were grafted on domestic seedling roots. There were significant differences in yield, trunk diameter and yield efficiency related to the interstock. ‘Duchess’ and ‘Heyer 12’ ranked highest in yield efficiency and lowest in tree size. ‘Red Astrachan’ ranked lowest in efficiency and largest in tree size. ‘McIntosh’ also tended to be low in efficiency. No severe winter temperatures occurred to test differential cold hardiness.     

A comparative study of young ‘Thompson Seedless’ grapevines (Vitis vinifera L.) under drip and furrow irrigation. II. Growth, water use efficiency and nitrogen partitioning

The response of 3-year-old grapevines (Vitis vinifera L. cultivar ‘Thompson Seedless’) to furrow and drip irrigation was quantified in terms of water status, growth, and water use efficiency (WUE). Drip irrigation was applied daily according to best estimates of vineyard evapotranspiration while furrow irrigations were applied when 50% of the plant available soilwater content had been depleted. Drip and furrow irrigated vines showed similar water status (midday leaf water potential, Ψ₁) and shoot growth patterns throughout the season. Dry weight partitioning was not significantly different between treatments but root mass was somewhat larger for the furrow than drip irrigated vines. Nitrogen concentrations of the fruit and roots were significantly (P < 0.05) less for the drip irrigated vines when compared with the furrow treatment. Similar WUE (kg water kg⁻¹ fresh fruit wt.) were obtained for both treatments indicating that furrow irrigation was as efficient as drip irrigation under the conditions of this study. The data indicate that drip irrigation may increase the potential for control of vine growth by making vines more dependent on irrigation and N fertilization than furrow irrigation.     

In vitro propagation of Symphytum species

Methods are described for the in vitro propagation of Symphytum × uplandicum Nyman from bud, root and stem explants. Highest shoot numbers were produced from root explants > 4 mm in diameter, cultured vertically with their distal cut surface on the medium. The most suitable medium for shoot production was Murashige and Skoog's (MS) with 0.3 mg l⁻¹ 6-benzylaminopurine (BAP). These shoots developed roots on MS medium without hormones and were successfully transplanted into pots. Subculturing shoots onto MS medium containing BAP, kinetin (K), 6-λ,λ-(dimethylallylamino)-purine or gibberellic acid (GA₃) at 0.5, 1.0, 5.0, 10.0 or 30.0 mg l⁻¹ failed to stimulate outgrowth of axillary buds in culture. In vitro propagation from root explants was also achieved with S. asperum Lepech., S. officinale L. and S. × uplandicum cultivars ‘Bocking 1’, ‘Bocking 2’, ‘Bocking 4’ and ‘Bocking 17’, but not with S. bohemicum, S. grandiflorum DC, S. tuberosum L. or S. × uplandicum ‘Bocking 7’ and ‘Variegatum’.     

A comparative study of young ‘Thompson Seedless’ grapevines under drip and furrow irrigation. I. Root and soil water distributions

Soilwater distribution, soilwater extraction, and root distributions were determined for young grapevines (Vitis vinifera L. cultivar ‘Thompson Seedless’) grown under drip and furrow irrigation near Fresno, CA, USA. Soilwater content and extraction was determined to a depth of 0.9 m by neutron scattering from an array of nine access tubes installed throughout one-quarter of the soil volume available to each vine. Root distribution was determined from root intersections with vertical planes established parallel and perpendicular to the vine row. Drip irrigation was applied daily according to estimated evapotranspiration, and furrow irrigation was managed according to 50% depletion of the plant available soil water. Drip and furrow irrigated vines showed similar water status and shoot growth patterns. There was a confined soil wetted zone beneath the emitter discharge that largely coincided with a confined and shallow root system of drip irrigated vines. In contrast, furrow irrigated vines had a deeper and more widespread root system. Differences between water applied and soilwater content 3 days after irrigation suggested large water losses by evaporation during that period for furrow irrigated vines. Consumptive use of furrow irrigated vines was 12.5% greater than drip irrigated vines, but similar irrigation efficiencies were obtained for both irrigation systems when soilwater status was carefully monitored. Water applications for both irrigation systems were less than 50% of the longterm mean for irrigation deliveries to farms in the area. Thus, the results indicate that a significant potential for water savings exists in the San Joaquin Valley by means of irrigation management. It is concluded that relatively high and similar irrigation efficiency can be obtained with both drip and furrow irrigation of young grapevines in arid and semiarid regions when careful management is used.     

Growth and yield response of ‘Correll’ peach trees to fumigation with DBCP

A study was conducted to evaluate the effect of the nematicidal soil-fumigant DBCP (1,2-dibromo-3-chloropropane) on a peach (Prunus persica L. Batsch.) orchard planted on a site with high potential for “short life”. ‘Correll’ peach trees on ‘Lovell’ rootstock were planted on a Ruston fine sandy loam soil (Typic Paleudult, fine loamy, siliceous, thermic) on which 2 generations of peach trees had been grown. Increased tree growth and yield occurred when DBCP was applied twice (pre-plant and 1 year post-planting). After 4 years, there were no differences in the nematode populations or foliar nutrient content as a result of fumigation with DBCP.     

Seasonal rooting behaviour of cuttings of plum cultivars as influenced by IBA treatments

The response to IBA treatments in different planting seasons of four plum cultivars, as measured by rooting and field establishment, was investigated during 1986 and 1987. Among the four cultivars, ‘Santa Rosa’ gave the largest rooting percentage, number of primary and secondary roots per cutting, length and diameter of roots and field survival. The European cultivars ‘Greengage’ and ‘Early Transparent Gage’ showed poor rooting and field establishment. The cuttings planted during summer under mist gave better rooting and field establishment than dormant season- or autumn-planted cuttings. Similarly, IBA treatment of cuttings with 2000 mg l⁻¹ during summer and 3000 mg l⁻¹ during dormant and autumn seasons gave the largest rooting and survival percentages, high numbers of primary and secondary roots per cutting, and greater length and diameter of primary roots.     

Identification and investigation of relationships of mandarin types using isozyme analysis

Sixteen enzyme systems with 19 loci were used to discriminate 19 mandarin cultivars and hybrids. Variability was observed at 12 loci, and all but 3 mandarin types could be discriminated, 2 of which were probably identical. Relatedness within the tangelo and tangor groups was high, probably reflecting their recent origin. Relatedness within the common mandarin group was low, reflecting their multiple origins and long cultivation. Exceptions were cultivars ‘Algerian’ and ‘Beauty of Glen Retreat’, which differed at only 1 locus. Relatedness between the groups was generally low, with the least relatedness between the tangelos and the other groups, probably owing to their grapefruit parent. The ‘Ellendale’ cultivars formed a particularly cohesive group, but with 2 isozyme genotypes, differing at 2 loci, both marketed as ‘Ellendale’. Three of the ‘Ellendale’-type cultivars probably arose by self-pollination of ‘Ellendale’, the rest either by self-pollination or by mutation.     

Characterization for yield, fruit quality, and molecular profiles of lemon genotypes tolerant to ‘mal secco’ disease

‘Mal secco’ is a serious disease of lemon and other citrus species, reduces lemon production, and limits the use of susceptible cultivars especially in the Mediterranean countries, against which there is no effective management system to control the disease. The objective of this study was to determine yield efficiency, tree and fruit characters, and molecular profiles of the selected promising genotypes in lemon breeding program to develop ‘mal secco’ tolerant lemon cultivars. After 4 years of evaluation, ‘Tuzcu 894’, a progeny of ‘Finike Yerli Yuvarlak’ and ‘Kutdiken’, was designated as promising genotype with high yield, fruit weight, juice content and low seed number contrary to ‘Kutdiken’ as control. ‘Tuzcu 8911’ was suitable for dense planting having the highest yield in CV. In addition, these two promising genotypes survived after many years being subjected to artificial and natural P. tracheiphila infections and harsh winter temperatures, which were attractive to the citrus industry. Molecular analysis, as assessed with 11 inter-simple sequence repeats (ISSR) primers, indicated that ‘Tuzcu 09 Aklimon’ and its selections, ‘Tuzcu 896’, ‘Tuzcu 897’ and ‘Tuzcu 898’, were distinct from the other genotypes with similarity value of 0.82. Genetic variation among the other lemon genotypes was low and some of the genotypes were identical. It was concluded that variations in the agronomical characters are mainly due to mutations.     

Origin and genetic diversity of Tunisian grapes as revealed by microsatellite markers

Ten SSR loci, previously developed for grapevine, were analyzed to evaluate the genetic variability, cultivar relatedness, and parentage in a collection of 61 autochthonous Vitis vinifera cultivars from Tunisia.The number of alleles per locus ranged from 6 to 11, while the number of genotype patterns varied between 10 and 21. The expected heterozygosity varied between 0.621 and 0.855 and the observed heterozygosity was higher than 0.9 at 4 loci (VVMD28, VVMD5, VVIP31 and VVS2) indicating that the SSRs were highly informative.Cluster analysis using unweighted pair group method with arithmetic averaging (UPGMA) suggested 14 groups among studied cultivars and 53 grapevine denominations out of 61 were unequivocally distinguished, with all accessions showing at least one-specific combination of alleles.On the other hand, in order to overcome the existing confusion in Tunisian grapevine nomenclature, of the analyzed homonymous pairs of cultivars, only ‘Balta 2’ and ‘Balta 3’ have shown identical allelic profiles, consistent with their being the same genotype. Hence, nomenclature distinction is meaningless and only one denomination should be retained.Due to the high overall power of exclusion (Q) (greater than 99.99%) and to the absence of null alleles, the set of microsatellite loci used is appropriate to determine parentage in Tunisian grapevines beyond any reasonable doubt. The analysis of fingerprints indicated that the Tunisian grape vines have evolved through out crossing between five possible parents: Balta 1, Beldi Baddar, Beldi Rafraf, Beldi Local Rafraf and Khedhiri 3.     

Cross-pollination improves ‘Orri’ mandarin fruit yield

‘Orri’, a selection of ‘Orha’ mandarin [Temple (Citrus temple hort. ex Y. Tanaka) × Dancy (Citrus tangerina hort. ex Tanaka)], is a new high-quality Israeli mandarin which, in the last decade, has become one of the leading varieties in Israel. ‘Orri’ has an excellent taste, the rind is deep orange in color and easily removed, and it contains few or no seeds. However, ‘Orri’ grown in Israel suffers from inadequate yield and no published studies have yet addressed this problem. In the present study we determined that ‘Orri’ productivity depended on conditions being favorable to cross-pollination. Under cross-pollination conditions a positive correlation (R² = 0.97) was found between yield per tree and number of fruits per tree, and more than 90% of the fruits exceeded 60 mm: the most profitable size range. These data suggest that the number of fruits per tree, and not fruit size, is the limiting factor for yield improvement in ‘Orri’ orchards. Studying seed set showed that ‘Michal’ mandarin (Citrus reticulata Blanco) is a compatible pollenizer for ‘Orri’ flowers: the number of seeds per ‘Orri’ fruit increased as the distance from ‘Michal’ trees decreased. The present study demonstrated that cross-pollination of ‘Orri’ resulted in yield improvement, yet at the price of increased seed set.     

The inhibition of flower bud differentiation in ‘Crimson Gold’ nectarine with GA3 as an alternative to hand thinning

The reduction of flower bud density by gibberellin sprays, to adjust the cropping level, is a novel approach to fruit thinning of peach and nectarine. A linear reduction in the number of flowers developed per unit of shoot length was found following the spray application of increasing concentrations of GA₃, in the nectarine cultivar ‘Crimson Gold’. These reductions in flower number led to reductions in yield at harvest, and increases in mean fruit weight. Flowering was slightly delayed by the GA₃ treatments, but no differences in ripening were detected at harvest, this depending rather on fruit size. The yield obtained by the application of 200 mg l⁻¹ GA₃ corresponded to that obtained with a very good thinning level, as established by hand thinning. No secondary effects on vegetative growth followed either the application of GA₃ or the reductions in crop load by means of hand thinning. Decreasing crop-loads have resulted in an increase in fruit size and an advance of fruit ripening, measured by greater levels of soluble solids and lower flesh firmness. A good commercial quality fruit size was obtained for crop-loads of 300 fruits per tree or less.     

Harvest-pruning and trellising of ‘Sultana’ vines. I. Effects on yield and vegetative growth

Yield reductions averaging 10% are reported from 2 experiments in which ‘Sultana’ vines were continuously harvest-pruned for 11 and 9 years respectively. Over the period of the study there was no evidence of the yield reduction increasing with time.Differences between treatments in bunch number, berry weight and total soluble solids did not account for the reduction in yield. However, berry number per bunch was consistently, if not always significantly, lower on treated vines. Harvest-pruned vines had lower pruning-weights than the control vines.Increases in trellis width from 0.30 to 0.45 m to 0.90 m generally led to increases in yield caused by increases in bunch number. A 0.30 m wide T-trellis, with foliage wires added to support the shoots vertically to a height of 2 m, also gave yield increases over the standard 0.30 m trellis in most seasons. Harvest-pruned vines on the 0.90 m wide trellis gave similar yields to control vines on the standard 0.30 m trellis.     

Defining urban forestry – A comparative perspective of North America and Europe

Urban forestry is generally defined as the art, science and technology of managing trees and forest resources in and around urban community ecosystems for the physiological, sociological, economic, and aesthetic benefits trees provide society. First mentioned in the United States as early as in 1894, the concept underwent a revival during the 1960s as a comprehensive and interdisciplinary approach to the specific challenges related to growing trees in urban environments. Later, urban forestry evoked the interest of scientists and practitioners in other parts of the world. However, harmonization of urban forestry terminology has been complicated by, for example, the involvement of different disciplines and translation difficulties. In many European languages, for example, the direct translation of ‘urban forestry’ relates more to forest ecosystems than to street and park trees. Efforts in North America and Europe defining ‘urban forest’, ‘urban forestry’ and related terms are introduced. A comparative analysis of selected urban forestry terminology in both parts of the world shows that urban forestry has a longer history in North America, based on traditions of shade tree management. Moreover, urban forestry has become more institutionalized in North America. Urban forestry in Europe has built strongly on a century-long tradition of ‘town forestry’. In both parts of the world, definitions of urban forestry and urban forest have become more comprehensive, including all tree stands and individual trees in and around urban areas. Agreement also exists on the multifunctional and multidisciplinary character of urban forestry. These similarities offer opportunities for international harmonization of terminology.     

Assessment of urban forestry research and research needs in Nordic and Baltic countries

A review of research and research needs in urban forestry was carried out in Denmark, Estonia, Finland, Latvia, Norway and Sweden during 2005. A questionnaire addressing post-2000 and ongoing research was sent to 146 researchers and generated 76 completed questionnaires. Universities were found to lead urban forestry research, while municipalities headed funding organisations in terms of number of projects funded. Planning, ecological and management aspects were the most common research themes, but socially oriented research also played an important role. The research needs questionnaire was sent to 192 key research actors (assignors, users and researchers), resulting in 63 completed needs assessments. The research themes of ‘urban forest management’, ‘social and cultural values’ and ‘urban forest and green planning’ were prioritised for future research. Comparison of ongoing research and research needs showed discrepancies, as ongoing research does not always cover the same themes identified as primary research needs. Priorities for future research as identified by the research community respective those assigning and using research also differed. Economic assessment of benefits, for example, scored much higher as a need among researchers than other respondents. In terms of present weaknesses in the research ‘infrastructure’, research actors emphasised lack of funding, fragmentation of research and insufficient critical mass. The region's urban forestry research can be enhanced and made more meaningful by strengthening national and international networking within the research community, across disciplines, as well as between researchers and those commissioning and using research.     

Response of pepper and eggplant to continuous light in relation to leaf chlorosis and activities of antioxidative enzymes

Activities of the oxygen radical-scavenging enzymes were determined in leaves of ‘Kyomidori’ pepper (Capsicum annuum L.) and ‘Senryo’ eggplant (Solanum melongena L.) seedlings under two photoperiod treatments; 12 h light/12 h dark (12/12 h) or with continuous light (24/0 h) for six days. Growing eggplant under continuous light resulted in leaf chlorosis after four days and a sharp decline in the chlorophyll content. In eggplants grown under 24/0 h photoperiod, the activities of antioxidative enzymes; superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) rapidly increased from day two. This was an indication of photooxidative damage. In contrast, leaf chlorosis did not occur in pepper plants grown under continuous light, while the chlorophyll content was even higher in the 24/0 h than in the 12/12 h photoperiod. Continuous light did not enhance the activities of SOD and POD in leaves of pepper. However, the CAT activity increased faster and was significantly higher in pepper than in eggplants grown under continuous illumination. Pepper plants did not appear to suffer from photooxidative damage and thus grew normally under continuous illumination.     

Performance and compatibility of ‘Muscat Gordo Blanco’ grape on eight rootstocks

In a soil not previously planted with vines, ‘Muscat Gordo Blanco’ (= ‘Gordo’) grafted on to 8 rootstocks did not significantly increase the 7-year cumulative yield compared to own-rooted (control) vines despite the increased vigour (pruning-weight) given by some rootstocks. ‘Gordo’ on 1613 rootstock had the maximum cumulative yield, but this was only 8% greater than control. Growth of vines on rootstocks 62–66 was the most vigorous as judged by trunk circumference.During the course of the trial a number of vines on ‘Salt Creek’ (‘Ramsey’) died and others declined markedly due to graft-incompatibility. Surviving vines yielded 40% less than control due to fewer and smaller bunches. They also had lower Brix and pruning-weight and smaller trunk circumference.Symptoms of Legno riccio virus were observed below the bud union on ‘du Lot’ and 420 A rootstocks, and yield of vines on ‘du Lot’ was lower than control. Due to their poor performance, grafting ‘Gordo’ on ‘Ramsey’ and ‘du Lot’ rootstocks is not recommended. In soil not previously planted with vines, ‘Gordo’ clones on their own roots are the most economical and best to use.     

Susceptibility of Raspberry Varieties to Infection by Aphid-Borne Viruses

Kennebec and Russet Rural potato vines were sprayed in the field ten days after full bloom (i.e. at blossom drop) with 0-375% solution of maleic hydrazide (MH-30) in water at the rate of 100 gallons per acre. Respiration measurements were made every 3J days during storage at 41° F. (5° C.) and 70° F. (21⁰ C.). Similar measurements were made during conditioning of tubers previously stored at 41⁰ F. The respiration rates of tubers from untreated and maleic hydrazide-treated plants were identical as long as no tubers sprouted.     

Optimum leaf area index in T-bar trained kiwifruit vines

Summary

The effect of leaf area index (LAI) on canopy growth, light interception, yield, fruit growth and quality and return bloom of kiwifruit were examined in 1990 and 1991. Different LAIs were obtained in the 1990 season with defoliation treatment made precociously at different intensities, in a diffuse way, uniformly in the whole canopy. At the end of canopy development LAIs of 3.6,3.3,3.1,2.6 and 1.8 were obtained and evaluated. The kiwifruit vines with a bud load of 680?700 and LAIs of 3.3 and 3.6 in 1990, showed an optimum and constant yield (>90 kg per vine), good average fruit weight (>100 g) and high fruit quality in both years, and also good return bloom the following season. The reduction of LAI to 2.6 and 1.8 drastically reduced, in the year of LAI imposition, both yield (?18.5% and ?30%, respectively) and mean fruit weight (?18.6% and ?29.1%, respectively) compared with vines with an LAI higher than 3.1. In the same treatments, the soluble solids concentration in the fruit was significantly decreased and a great reduction in numbers of fruiting shoots and numbers of fruits per fruiting shoot were observed in the year following the LAI imposition. In vines with the same bud load, fruit number and an LAI of 3.1, small variations in yield and fruit weight in the year of defoliation treatments were recorded, but in the following season the yield was significantly reduced (?14 kg per vine) due mainly to a decrease in the number of fruiting shoots (?14%). In kiwifruit vines with low LAI (2.6 and 1.8) nearly all fruits present in the canopy ripen, with no significant fruit drop. At low LAI, the sink strength of the fruit was greater and more extended so that vine growth and the plants reserves were restricted. Under the conditions of this experiment, an LAI higher than 3.3, corresponding to a leaf area-fruit ratio higher than 600 cm² per fruit, is necessary to obtain regular vine growth and yield, optimum fruit size and quality and return bloom the following season.