Spatiotemporal dynamics of plant diversity in response to farmers’ evolved settlements in Shanghai

The expansion of the Shanghai metropolitan region has caused a substantial amount of farmland to become urbanized. Most farmers have lost their land and have been relocated from villages to new collective settlements, resulting in dramatic changes in the landscape pattern. This study explores the effects of this transformation on the spatiotemporal dynamics of plant diversity. We randomly sampled 22 plots comprising 294 subplots within two crossed transects that pass through 5 traditional villages and 17 new settlements. The results show that resettlement has exerted significant effects on plant species diversity, both temporally and spatially. Temporally, the Gleason index (GI) of total species over time could be ordered as 1990s > 2000s > 1980s, while Shannon’s diversity index (SHDI) was ordered as 2000s > 1990s > 1980s. Spatially, the GI of total species decreased from the urban center to the exurbs or from the inside to the outside of the built-up areas. SHDI was highest in suburbs or ecotones. Furthermore, the GI of total species had significant correlations with those of indigenous species, exotic species, and planted species (r > 0.90, p < 0.01) as well as with the region and location of settlement (r < −0.48, p < 0.01). Both indigenous and exotic species had significant positive correlations with total species richness at 0.01 levels. Generally, compared with traditional settlements, new settlements displayed greater richness and diversity of plant species, primarily because of the exotic species present in new settlements. The farmers’ socio-economic status was found to be the primary cause of differences in species richness. To protect indigenous and wild species, it is necessary to take into account local knowledge in villages to encourage Chinese farmers to participate actively in community greening. A bridge should be built between traditional villages and modern settlements and between the past and future for farmers.     

Investigation of plant growth and flower performance on a semi-extensive green roof

Understanding of plant growth and flower performance is crucial for appropriate planting design. This study was aimed to understand characteristics of growth pattern and flower performance in green roof plants and how plant species diversity effect these characteristics. A semi-extensive green roof was installed in 2005 and 54 species plant species were planted in 10 cm and 20 cm of the substrate in Rotherham, UK. Thirty-two quadrats (50 cm × 50 cm) were set up through the combinations of plant species diversity (high and low), planting density (high and low). Percentage of coverage and height of each species were recorded at every month from February to November 2006 in these 32 quadrates. Flowering time of each species was studied every two weeks from February to November 2006. Flowering time was various from plants; some showed a very long flowering time, over five months whereas some finished flowering within two weeks. The growth characteristics of individual plant species over time were categorized into six patterns of coverage and vertical growth pattern. Spread of individual plants was larger in high diversity of plants than those in low diversity of plants. Number of flowering was higher and overall flowering term was longer in the quadrats of higher plant species diversity than those of lower plant diversity. However, these tendencies were affected strongly by the combination of species used. Therefore, it is important to be aware of individual plant growth characteristics such as plant size, growth pattern and flower performance for planting design.     

Fragmentation and recreational use affect tree regeneration in urban forests

The aim of this study was to test whether fragmentation or recreational use affect tree regeneration in urban forests, and to quantify these effects. We sampled tree saplings at different distances from edges in spruce (Picea abies) dominated forests, and at different distances from paths that represented different levels of wear. Generalized linear mixed models were used to test our hypotheses. We found that fragmentation favours the regeneration of deciduous trees in urban spruce dominated forests: distance from the edge had a pronounced effect on regeneration, at least up to 80 m into the forests. Saplings of Betula pendula, Populus tremula, other deciduous species and Pinus sylvestris benefited from edge conditions. Betula pubescens saplings, however, were most abundant in the interior and small Sorbus aucuparia saplings at 25–30 m from the edge. All species suffered from the direct effects of trampling, while varying responses of species to distance from the paths were observed up to 6 m, and possibly further. As trees essentially define the living conditions for other forest species, we suggest that the spatial extent of edge and trampling effects should be studied for different types of forests. This knowledge should then be used in urban forestry and planning to define the threshold value that will allow for at least some “intact” interior. We suggest a diameter larger than 160 m to support indigenous species in boreal spruce dominated forests.     

Day and night temperatures,daily light integral,and CO2 enrichment affect growth and flower development of Campanula carpatica ‘Blue Clips’

Campanula carpatica Jacq. ‘Blue Clips’ plants were grown in a greenhouse under nine combinations of day and night temperatures created by moving plants every 12 h among three day/night temperatures (15, 20, and 25°C). At each temperature, there were three daily light integrals (DLI; 4.2, 10.8, and 15.8 mol m⁻² per day, averaged over the experimental period) created with varying supplemental light, and ambient (≈400 μmol mol⁻¹) and enriched (≈600 μmol mol⁻¹) CO₂ concentrations. Time to flower was closely related to average daily temperature (ADT), and was not significantly affected by the day or night temperatures delivered to achieve a specific ADT. Time to flower was not largely affected by DLI or CO₂ enrichment. As plant ADT increased between 15 and 25°C, flower diameter decreased about 1 mm per degree and was not related to the difference between day and night temperatures (DIF). Flower diameter was smallest and least sensitive to changes in temperature at lower DLI and at ambient CO₂ levels. There were 10 less flower buds and 0.3 g less dry mass per plant at first flower for every 1° increase in plant ADT at high and medium DLIs. Flower bud number and dry mass were relatively low and less sensitive to changes in ADT at low DLI, and increased slightly with CO₂ enrichment at medium and high but not at low DLI. Plant height was not related to ADT, but increased linearly as DIF increased from −6 to 12°C at all DLIs, but the response was stronger under low DLI than high and medium DLIs. Flower bud number and dry mass were correlated closely with the ratio of DLI to daily thermal time (base temperature of 0°C). Flower bud number and dry mass were highest when C. carpatica plants were grown at 15°C with a DLI of 10–15 mol m⁻² per day.     

The impact of photoperiod and irradiance on flowering of several herbaceous ornamentals

Forty-one herbaceous species were grown under short-days (8 h photoperiod, ambient irradiance averaged 12–13.2 and 6.4–8.3 mol m⁻² day⁻¹ for Experiments I and II, respectively) with or without supplemental high-pressure sodium lighting (+50, 100, or 150 μmol m⁻² s⁻¹); or under long-days delivered using natural day lengths and irradiance with night interruption lighting (2200–0200 h at 2 μmol m⁻² s⁻¹ from incandescent lamps) or under ambient daylight plus supplemental irradiance during the day and as a day extension to 18 h (0800–0200 h) with supplemental high pressure sodium lighting (+50, 100, or 150 μmol m⁻² s⁻¹) to identify the impact of photoperiod and irradiance on flowering of each species. Days to first open flower, leaf number below first flower, and mean dry weight gain per day (MDWG) were measured when the first flower opened. Twenty-seven species were photoperiodic with examples of five photoperiodic response groups represented: obligate short-day (2), facultative short-day (5), obligate long-day (16), facultative long-day (4); 13 were day neutral (no photoperiod response in flowering). One species, Salvia sclarea L., did not flower. A facultative irradiance response was observed with 10 species; 28 species were irradiance indifferent; 2 had delayed flowering as irradiance increased. Photoperiod affected MDWG of 30 species. Increasing irradiance affected MDWG with 14 species. Photoperiod interacted with irradiance to affect MDWG of 11 species. Cobaea scandens had the greatest MDWG (0.40 g day⁻¹) while Amaranthus hybridus had the least MDWG (0.01 g day⁻¹) across photoperiod and irradiance levels.     

Comparison of non-destructive LAI determination methods and optimization of sampling schemes in an open Populus euphratica ecosystem

Populus euphratica (P. euphratica) grows in the water-limited Tarim River Basin in spatially heterogeneous open ecosystems; thus, efforts to quantify the leaf area index (LAI) with optical instruments developed for homogeneous closed canopies have a high probability of failure. In this study, we explored methods for designing an acceptable sampling scheme to quantify the tree LAI for open P. euphratica canopies in arid areas. Field data were collected from three 30 m × 30 m plots and one 100 m × 100 m plot. We compared three indirect methods, i.e. i) allometry, ii) LAI-2000 canopy analyser, iii) Tracing Radiation and Architecture of Canopies (TRAC), and a new semi-direct method combining leaf density and crown volume (SDDV) method for quantifying the isolated tree and canopy LAI of a P. euphratica forest. We also analysed the effects of random and grid sampling designs on the accuracy of the LAI estimates obtained with the LAI-2000. The results showed that the allometric method is applicable to isolated trees with regular shapes; however, because the LAI of P. euphratica was calculated from an allometric equation based on the basal area (at 1.3 m), the allometric equation is prone to failure if the basal area is beyond a specific range. Because there are no significant differences in the plot size between the allometric and the SDDV method predictions, the proposed SDDV method can be used as an alternative for field measurements. The combination of LAI-2000 and TRAC is found to be more reliable than TRAC only, and the field view of the LAI-2000 sensor and the clumping index are important factors for sparse vegetation LAI retrieval. The results from sampling optimization showed that for the LAI-2000 instrument, the best sampling method is grid sampling, and the sampling interval should not be less than 20 m. For random sampling scheme, the number of sampling points in a 100 m × 100 m plot should be greater than 86 with a coefficients of variation of 15% and an allowable error (AE) of 0.15 m² m⁻², respectively.     

Comparison of the use of zeolite and perlite as substrate for crisp-head lettuce

This research was carried out to assess the effects of zeolite and perlite on growth and nutrient status of lettuce plants and the amount of waste elements. The trials were done in a PE covered tunnel during autumn and spring seasons. Plant material was Lactuca sativa var. capitata, and the cultivars Bombola and Brogan were used for autumn and spring seasons, respectively. Five different growing media based on perlite and clinoptilolite, a kind of zeolite, mixed at different ratios (1 + 0, 3 + 1, 1 + 1, 1 + 3, 0 + 1, v/v) were tested. It was concluded that the use of zeolite led to increased plant growth, higher N and K contents in plant tissues and to reduced K leaching.     

Long-term remediation of compacted urban soils by physical fracturing and incorporation of compost

On the Cornell University campus a long-term study has measured the impacts of a soil remediation strategy on plant growth and soil quality using the Cornell Soil Health Test. The Scoop & Dump (S&D) process of soil remediation consists of physically fracturing compacted urban soils, incorporating large quantities (33% by volume) of compost with the use of a backhoe, and annually top dressing with mulch. This study was designed to investigate the impact of this remediation technique for the amelioration of compaction and degradation of soils in the urbanized environment.The study finds that over a 12-year period remediated soils exhibit improved (reduced) bulk density (R² = 0.50) (P < .0001) (n = 30), increased active carbon (R² = 0.61) (P < .0001) (n = 30) and increased potentially mineralizable nitrogen (R² = 0.61) (P < .0001) (n = 30). When S&D soils were compared to unamended (Unam) soils, improvements were found in aggregate stability (S&D = 72.41%, Unam = 34.90%, P < .0001, n = 30), available water holding capacity (S&D = 0.22%, Unam = 0.15%, P < .0001, n = 30), total organic matter (S&D = 8.43%, Unam = 3.23%, P < .0001, n = 30), potentially mineralizable nitrogen (S&D = 27.53 mg/kg, Unam = 3.11 mg/kg, P = 0.0005, n = 30), active carbon (S&D = 1022.47 mg/kg, Unam = 361.60 mg/kg, P < .0001, n = 30), and reduction in bulk density (S&D = 0.89 g/cm³, Unam = 1.47 g/cm³, P < .0001, n = 30). Application of the S&D process provides an alternative to using specified soils and has potential for improving long term soil quality using locally sourced materials and simple methods.     

Carbon sequestration of four urban parks in Rome

Urban parks form the largest proportion of public green spaces contributing to both physical and mental well-being of people living in urban areas. CO₂ sequestration capability of the vegetation developing in parks of four historical residences (Villa Pamphjli, Villa Ada Savoia, Villa Borghese and Villa Torlonia) in Rome and its economic value were analyzed. Villa Pamphjli and Villa Ada Savoia having a larger vegetation extension (165.04 ha and 134.33 ha, respectively), also had a larger total yearly CO₂ sequestration per hectare (CS) (780 MgCO₂ ha⁻¹ year⁻¹ and 998 MgCO₂ ha⁻¹ year⁻¹, respectively) than Villa Borghese (664 MgCO₂ ha⁻¹ year⁻¹) and Villa Torlonia (755 MgCO₂ ha⁻¹ year⁻¹), which had a lower vegetation extension (56.72 ha and 9.70 ha, respectively). CS was significantly correlated with leaf area index (LAI). The calculated CS for the four parks (3197 MgCO₂ ha⁻¹ year⁻¹), corresponding to 3.6% of the total greenhouse gas emissions of Rome for 2010, resulted in an annual economic value of $ 23537 /ha.     

An adaptive approach to intensive green roofs in the Mediterranean climatic region

The present study aims to introduce an adaptive approach to intensive green roofs by evaluating suitable, lightweight substrates and by determining the effect of their depth on the growth and physiological status of Pittosporum tobira L. and Olea europaea L. The two-year study was conducted in outdoor containers (1.2 m × 1.2 m) while treatments included the use of two depths (30 cm and 40 cm) and three different substrates: (a) pumice (Pum) mixed with peat (P) and zeolite (Z) in a volumetric proportion of 65:30:5 (Pum₆₅:P₃₀:Z₅), (b) pumice mixed with compost (C) and zeolite in a volumetric proportion of 65:30:5 (Pum₆₅:C₃₀:Z₅) and (c) sandy loam soil (S) mixed with perlite (Per) and zeolite in a volumetric proportion of 30:65:5 (S₃₀:Per₆₅:Z₅). Each experimental plot was planted with four plants of P. tobira and one plant of O. europaea var. Koroneiki. Measurements included determination of the physical and chemical characteristics of the substrates while plant growth and physiological status were determined through plant growth index, trunk perimeter for olive trees, SPAD measurements and chlorophyll_a+b content. Both the plant species exhibited better growth and higher chlorophyll content in the compost-amended substrate (Pum₆₅:C₃₀:Z₅) due to its higher nutrient content. The 40 cm depth substrate provided minimal improvement in the growth of both the plants at the end of the first year while in the second year the deeper substrate positively influenced the growth of olive trees.     

The overlooked carbon loss due to decayed wood in urban trees

Decayed wood is a common issue in urban trees that deteriorates tree vitality over time, yet its effect on biomass yield therefore stored carbon has been overlooked. We mapped the occurrence and calculated the extent of decayed wood in standing Ulmus procera, Platanus × acerifolia and Corymbia maculata trees. The main stem of 43 trees was measured every metre from the ground to the top by two skilled arborists. All trees were micro-drilled in two to four axes at three points along the stem (0.3 m, 1.3 m, 2.3 m), and at the tree’s live crown. A total of 300 drilling profiles were assessed for decay. Simple linear regression analysis tested the correlation of decayed wood (cm²) against a vitality index and stem DBH. Decay was more frequent and extensive in U. procera, than P. acerifolia and least in C. maculata. Decay was found to be distributed in three different ways in the three different genera. For U. procera, decay did appear to be distributed as a column from the base to the live crown; whereas, decay was distributed as a cone-shape in P. acerifolia and was less likely to be located beyond 2.3 m. In C. maculata decay was distributed as pockets of variable shape and size. The vitality index showed a weak but not significant correlation with the proportion of decayed wood for P. acerifolia and C. maculata but not for U. procera. However, in U. procera, a strong and significant relationship was found between DBH and stem volume loss (R² = 0.8006, P = 0.0046, n = 15). The actual volume loss ranged from 0.17 to 0.75 m³, equivalent to 5%–25% of the stem volume. The carbon loss due to decayed wood for all species ranged between 69–110 kg per tree. Based on model’s calculation, the stem volume of U. procera trees with DBH ≥ 40 cm needs to be discounted by a factor of 13% due to decayed wood regardless of the vitality index. Decayed wood reduces significantly the tree’s standing volume and needs to be considered to better assess the carbon storage potential of urban forests.     

Ozone forming potential of tropical plant species of the Vidarbha region of Maharashtra state of India

Volatile organic compounds (VOC) are emitted by many plants. In this study, sixty common plant species of the Vidarbha region of Maharashtra, India were examined for VOC (isoprene and monoterpene) emissions. Plant species VOC emission rates ranged from undetectable to 75.2 μg g^?1 h^?1. Dalbergia sissoo exhibited a maximum VOC emission rate of 75.2 μg g^?1 h^?1. Ozone forming potentials (OFP) of the sixty plant species were also estimated using the method of Benjamin and Winer (1998). Maximum ozone forming potential of 77 g O₃ (tree)^?1 d^?1 was observed in the case of Mangifera indica. Out of 60 species, 26 species (43.3%) had low OFP (less than 1 g O₃ (tree)^?1 d^?1), 18 species (30%) had medium OFP (less than 1–10 g O₃ (tree)^?1 d^?1) and 16 species (26.7%) had high OFP (more than 10 g O₃ (tree)^?1 d^?1).     

In vitro production of Prunus necrotic ringspot virus-free begonias through chemo- and thermotherapy

Prunus necrotic ringspot virus (PNRSV)-free Begonia spp. plants were raised from petioles of virus-infected plants using in vitro techniques. The petioles were grown on MS medium supplemented with 0.2 mg/l NAA and 0.2 mg/l BAP (pH 5.8). For rooting, half-strength MS medium without any plant growth regulators was used. On rooting medium, shoots were subjected to chemotherapy (virazole, 2-thiouracil or 6-azauracil) and thermotherapy (38 °C for 16 h light period and 22 °C for 8 h dark period) separately or in combination. Regenerated plants (treated with chemo- and thermotherapy) were indexed for PNRSV by DAS-ELISA and RT-PCR. An amplified product of 785 bp was obtained by RT-PCR in PNRSV-infected plants. Virazole at a concentration of 20 mg/l was found to be more effective (30 and 20% of PNRSV-free plants as indexed by ELISA and RT-PCR, respectively) in comparison to the other chemicals. Thermotherapy for 25 days gave 35 and 25% PNRSV-free plants as indexed by DAS-ELISA and RT-PCR, respectively. A combination of both treatments gave a good number of PNRSV-free plants (67.5 and 57.5% as indexed by DAS-ELISA and RT-PCR, respectively). At higher concentrations all three chemicals were found to be toxic. Thermotherapy for more than 25 days caused browning of leaves and shoots died.     

The influence of systemic inducing agents on horse chestnut leaf miner (Cameraria ohridella) severity in white flowering horse chestnut (Aesculus hoppicastanum L.)

Two separate trials during 2010 and 2011 were conducted using field grown white flowering horse chestnut trees (Aesculus hippocastanum L.) to asssess the insecticidal efficacy of three systemic inducing agents (SIR), namely (Messanger (active substance (a.s.) Harpin protein), Phoenix (a.s. Potassium phosphite) and Rigel (a.s. Salicylic acid derivative) applied to coincide with the appearance of each adult generation of the insect pest, horse chestnut leaf miner (Cameraria ohridella Deschka and Dimic; HCLM). A conventional synthetic insecticide (deltamethrin) used within the UK for HCLM control was included for comparison. A marked impact of SIR inducing agent and frequency of application on HCLM severity was recorded. The effectiveness of each SIR inducing agent on mean number of HCLM mines per leaf and percent HCLM larvae/pupae mortality increased when applied at increasing frequencies i.e. three sprays provided greater control than two sprays while two sprays provided greater control than one spray. The synthetic insecticide deltamethrin provided the greatest degree of HCLM control with two foliar sprays providing 100% HCLM control. Efficacy of SIR inducing agents based on reduction of HCLM mines per leaf after three sprays averaged across both the 2010 and 2011 growing seasons was in the order potassium phosphite > salicylic acid derivative > harpin protein > water control where leaf mining activity was reduced by 35–64%. Enhancement of leaf phenolic content was indicated as a means by which SIR agents reduced leaf mining activity. Results show commercially available SIR inducing agents exist that provide potentially acceptable degrees of HCLM control provided at least two sprays are applied during a growing season.     

Restorative potential,fascination, and extent for designed digital landscape models

Few studies have investigated whether manipulating objective measures related to fascination and extent affect respondents’ ratings of restorative potential (RP) and estimations of fascination and extent. The following study addresses this need. We manipulated or measured variables in 27 color digital landscape model views. Tree height represented a measure of fascination. Three measures related to extent: The number of organized plant groups represented coherence. Shannon’s Information Entropy bit values represented plant species complexity. The visible view polygon area in each model represented scope. We included 65 respondents’ RP ratings for the digital model views in analyses, along with estimations of fascination (n = 48), extent (n = 43), coherence (n = 38), complexity (n = 44), and scope (n = 35). Collinearity diagnostics indicated dependency between respondents’ estimations of fascination, extent, and complexity, and between estimations of coherence and scope. A strong, inverse correlation occurred between respondents’ RP ratings and the view polygon area. Repeated measures ANOVA test results suggest that respondents’ RP ratings increased as mean designed tree height increased. RP ratings for model views depicting scattered and formally arranged plants were significantly higher than views of clustered plants. Moreover, the decrease in RP ratings between scattered and clustered scenes was greater when plants represented three bits of entropy instead of two. Chief among the implications stemming from this study is that increasingly taller trees and groundcover plants may have increasingly greater restorative potential.     

A liquid 2,4-D pulse increased shoot and root regeneration from leaf explants of adult Prunus rootstocks

Regeneration of adult plant material is one of the main limitations for successful Prunus rootstock transformation. Results herein show that a liquid pulse (90 min) of 2,4-dichlorophenoxyacetic acid (2,4-D) (1.7 μM), applied to leaf explants, greatly improved shoot regeneration in Marianna 2624 (Prunus cerasifera × munsoniana) and Myrobalan 605 AD (P. cerasifera); and induced roots in Adafuel (Prunus × amigdalo-persica) when placed in regeneration medium. Whole leaves and basal leaf explants of Marianna 2624 regenerated shoots in a higher proportion of explants after the pulse (up to 58.9% in whole leaves) than medium or tip leaf segments, whereas the leaf tip was the explant that showed less regeneration. In the regeneration medium, in the presence of BAP, NAA was more effective than 2,4-D. The application of an auxin pulse is a simple method that could enhance adult plant regeneration in commercial rootstocks.     

Improved efficiency of somatic embryogenesis from zygotic embryos in Hyoscyamus niger by seed water-soaking

We describe an efficient procedure to obtain somatic embryos from mature zygotic embryos of Hyoscyamus niger (black henbane). It has several advantages over previous regeneration methods, which are: the use of mature seeds, an average 80% somatic embryogenesis rate and a high (eight-fold higher than the control) plant regeneration frequency. The critical step in this protocol was soaking of the seeds in sterile distilled water for 16 h, prior to excision and culture of zygotic embryos, on MS basal medium supplemented with 2% sucrose, 2 g/l myo-inositol, 0.5 g/l 2-(N-morpholino) ethanesulfonic acid and 1 mg/l α-naphthalene acetic acid (NAA). The regenerated somatic seedlings were fertile and were morphologically uniform. This procedure is simple, rapid and effective for high frequency of plant regeneration via somatic embryogenesis. Moreover, this new method should facilitate the development of strategies to routinely transform recalcitrant plant species, including henbane.     

Optimising the organic components of topsoil mixtures for urban grassland

In order to optimise the organic components of topsoil mixtures for urban grassland, we conducted two pot experiments, each with seven topsoil mixtures and perennial ryegrass (Lolium perenne) as the experimental crop. The mineral base material of the topsoil mixtures was a blend of crushed bedrock (0–2 mm), sand and agricultural topsoil. The organic components comprised three types of organic waste-based products (WBP), namely sewage sludge (SS), water sludge (WS) and garden-park compost (GPC), which were added in varying ratios to a total amount of 0.3 m³ WBP m^?3. In both experiments, mineral nitrogen (N) availability was the key limiting factor for plant growth. Plant growth increased with increasing amounts of the N-rich SS, whereas WS and/or GPC alone resulted in sparse biomass production. Topsoil mixtures with 0.1 m³ m^?3 each of SS, WS, GPC or with 0.1 m³ SS m^?3 and 0.2 m³ WS m^?3 resulted in favourable growth patterns and acceptable soil chemical properties. Topsoil mixtures containing ≤0.1 m³ SS m^?3 can therefore be recommended for the establishment of urban grassland. With >0.1 m³ SS m^?3, N and phosphorus (P) were applied in excess, causing intensive plant growth and strongly increased readily available phosphorus (P-AL) content in topsoil. We therefore suggest revision of the current Norwegian regulations, which permit inclusion of 0.3 m³ SS m^?3 in topsoil mixtures for urban greening.     

Shoot induction and plant regeneration from receptacle tissues of Lilium longiflorum

An efficient system has been developed for the in vitro plant regeneration of Lilium longiflorum Thunb. by culturing receptacle sections from flower buds. The sections were cultured on one-half MS medium plus 30 g l⁻¹ sucrose, 8 g l⁻¹ agar, 5.4 μM NAA or 4.9 μM IBA plus 2.2 μM BAP. A section size of 3–4 mm was found to be optimal. After 60 days an average of 41 shoots were formed per explant. More vigorous shoots were obtained by subculturing on hormone-free medium with 20 g l⁻¹ sucrose. Rooting occurred on one-half MS medium with 1.1 μM NAA. Rooted plants were hardened-off in a greenhouse for two months, and normal flowering plants were produced.     

The rootstock effects on plant adaptability,production, fruit quality,and nutrition in the peach (cv. ‘Suncrest’)

In clayey and calcareous soils without a stable irrigation and fertilization system, the type of rootstock can particularly affect both the vegetative and productive properties of ‘Suncrest’ peach (Prunus persica L. Batsch) plants, and the qualitative and nutritional attributes of their fruit. The GF677 rootstock (P. persica × Prunus amygdalus) promoted the highest vegetative development, followed by Julior (Prunus insistitia). The ‘Suncrest’ on Ishtara [(Prunus cerasifera × P. persica) × (P. cerasifera × Prunus salicina)] and Barrier1 (P. persica × Prunus davidiana) had lower, but similar, plant vigour, but the latter rootstock differed in its higher production of pruned wood. The lowest adaptability to these cultivation conditions was observed for ‘Suncrest’ grafted onto Citation (P. persica × P. salicina), which showed the lowest plant development and production. For the plant yield, the ‘Suncrest’ grafted onto GF677, Julior, Ishtara, and Barrier1 were all similar. The fruit yield and both the canopy volume and pruned wood of ‘Suncrest’ grafted onto Ishtara showed a particular relationship, giving the best indices of yield efficiency and plant physiological equilibrium. Moreover, the same rootstock promoted the largest fruit size, while the smallest fruit were found on GF677 rootstock. The fruit from the Citation ‘Suncrest’ ripened 3 days early, while those from Barrier1 had a late fruit ripening. Firmness, soluble solids and the soluble solids to total acidity ratio were only affected slightly by the different rootstocks, while the total acidity of the fruit varied significantly according to rootstock; the fruit from ‘Suncrest’ grafted onto Barrier1, Julior, and Citation had the highest total acidities. The rootstock effects on the nutritional attributes of the fruit were relevant. The ‘Suncrest’ on Julior and GF677, followed by Ishtara, produced fruit with the greatest antioxidant activities and total phenolic contents. The ‘Suncrest’ on Citation and, especially, Barrier1 had reduced nutritional values of the fruit. The variations in antioxidant activities and total phenolic contents showed a positive correlation.