Culture method and photosynthetic photon flux affect photosynthesis,growth and survival of Limonium ‘Misty Blue’ in vitro

Microcuttings (shoots each with two leaves) of Limonium ‘Misty Blue’ were cultivated in vitro for 28 days under photoautotrophic (sucrose-free culture medium; CO₂ and photosynthetic photon flux (PPF) enriched conditions), photomixotrophic (medium with 30 g l⁻¹ sucrose; CO₂ and PPF enriched conditions) and heterotrophic (medium with 30 g l⁻¹ sucrose; CO₂ non-enriched conditions) methods. Several growth variables were measured during and at the end of cultivation: shoot fresh and dry weight, percentage of shoot dry matter, root fresh weight, number of leaves, leaf area, chlorophyll and sugar content of leaves, stomatal density and size, net photosynthetic rate (NPR) and percent survival of plantlets ex vitro. Plantlets grown in photoautotrophic and photomixotrophic methods had more leaves, high chlorophyll and sugar contents, high NPR, and showed high percent survival. However, these plantlets possessed less number of stomata per square millimeter. In contrast, the plantlets grown by the heterotrophic method showed decreased values of these growth variables except for the number of stomata per square millimeter. These results indicate that CO₂ enrichment for plantlets in vitro at a relatively high PPF would promote photosynthesis and hence growth of chlorophyllous explants/plantlets in vitro. The resulting plantlets were acclimatized better and sooner on ex vitro transplantation.     

Inflorescence bud growth,development and abscission in shoots of bearing and disbudded ‘Bianca’ pistachio trees

Summary

Dry-matter accumulation patterns and anatomical aspects of development and abscission of inflorescence buds borne on shoots of fruiting (BF) and non-fruiting (BNF) branches of bearing trees and in non-bearing branches of disbudded (NBD) pistillate trees of pistachio (Pistacia vera L.) were studied from the end of May to mid September. In NBD trees, inflorescence-bud summer drop was negligible and, by the end of the growing season, dry-matter content in NBD buds was three times higher than in BF buds. The anatomical investigation showed that the inflorescence buds, irrespective of their being on shoots of fruiting or not-fruiting branches, undergo the same differentiation process, which is completed by the end of spring. In June and July, signs of degenerations are detectable in the conducting tissue of the buds that will abscise. The degeneration seems to precede and, presumably, trigger the onset of abscission layers, which may develop in different points of the inflorescence. It is suggested that the event triggering the onset of the abscission process precedes the phase of rapid embryo development and that it might be ascribed to the embryo in the phase following the first zygotic division.     

Effect of part-tree flower thinning on fruiting,vegetative growth and leaf photosynthesis in ‘Cox’s Orange Pippin’ apple

Flower clusters were removed at full bloom from ten year old ‘Cox’s Orange Pippin’ trees on M.9 rootstocks, over the whole tree, on alternate branches or on whole sides. Mean fruit weight per tree at harvest was linearly dependent on leaf area per fruit and on light interception per fruit, both relationships accounting for over 90% of the variance. These relationships did not differ between treatments, implying either a mobile pool of carbohydrate or photosynthetic adjustment within the tree to crop load. Measurements of leaf photosynthesis in July and September showed no statistically significant differences in photosynthetic rate of spur or extension shoot leaves on bearing or non-bearing branches. Although the treatments caused no overall effects on shoot growth or leaf area per tree, sides of trees without fruit had greater leaf area and shoot growth than did sides bearing fruit. Fruit mineral composition and percentage dry weight were not affected by treatment except where the treatments significantly altered fruit size. In the following spring, although the treatments did not affect the total number of flower buds produced, branches that were deflowered in the previous spring carried significantly more flower buds than did branches which had cropped.     

Seasonal variation in the onset and duration of flower development in ‘Royal Gala’ apple buds

Summary

The formation of bud scales, transition leaves, true leaves, bracts and flower primordia were observed in buds removed from non-flowering sites on one year old shoots of apple ‘Royal Gala’. Buds were sampled from trees in Hawke's Bay, New Zealand (latitude 398S) during six successive seasons. The onset of flower development varied between seasons from 72 to 99.d after full bloom. Floral development was poorly synchronized within the populations of sampled buds, lasting 22 to 50.d. Differences in the onset and duration of flower development could not be related to seasonal differences in heat accumulation from full bloom. There was significant variation between seasons in the minimum number of appendages observed within buds that exhibited doming, which indicates floral development. In the 1998/99 season, doming was observed in buds that had only 15.7 appendages, whereas in the 1999/2000 season the minimum number of appendages within a bud that had initiated flowers was 17.5. When the data from all seasons were considered, the rate of appendage formation within developing buds was not consistently related to heat accumulation.     

The effect of boron upon leaf development and growth of the apple cultivar ‘Cox’s Orange Pippin’

One-year-old ‘Cox’s Orange Pippin’ trees planted in pots in sand culture in the spring of 1970 were (during the growing seasons of 1970–72) watered with nutrient solutions containing 0, 0.12, 0.23, 1.2, 3.5 or 7.0 mg boron per litre.

With increasing boron supply, the boron concentration of the leaves increased, the growth of current year’s shoots and to some extent of other plant parts increased, and summer leaf-fall and the occurrence of necrotic leaf spots (‘Cox spots’) decreased. The percentage of healthy leaves was greatest when boron in leaf dry matter was about 30 ppm.

In 1972 the trees with highest boron supply suffered from incipient boron toxicity and increased incidence of ‘Cox disease’ flowering was delayed, and the percentage of dead buds was increased. In the latter part of the summer the leaves curled upwards, turned purple and became brittle.     

The effects of low temperatures on the vegetative growth and flowering of the primocane fruiting raspberry ‘Autumn Bliss’

Summary

The effects of low temperatures on subsequent vegetative growth and flowering in the raspberry ‘AutumnBliss’ were investigated. In the first experiment, a number of lifting dates were used to determine the seasonal pattern of dormancy and the effect of natural chilling on plant development. In the second, different durations of artificial chilling(0, 2, 4, 6, 8 and 10 weeks at 0?C) were combined with two lifting dates to investigate the effect of natural and artificial chilling. In these experiments, plants which received little chilling grew slowly and failed to develop beyond short rosettes of leaves but as chilling increased, the rate of vegetative growth increased. This coincided with a decline in the time toflowering. These two responses, however, were distinct. In a third experiment, the effect of vernalization of actively growing canes was tested in an attempt to separate the effects of cold on time to flowering, and on the removalof dormancy. The plants responded significantly to cold treatment and flowering was advanced, indicating a distinct vernalizing effect     

Effect of intermittent as compared to continuous CO2 enrichment on growth and flowering of Chrysanthemum × morifolium Ramat. and Saintpaulia ionantha H. Wendl

Plants of three cultivars of Saintpaulia ionantha and Chrysanthemum × morifolium were grown until flowering at 335 (normal) or 900 μl l⁻¹ CO₂ (high). Continuous high CO₂ concentration increased the final dry weights from 76 to 123% in Saintpaulia and from 15 to 32% in Chrysanthemum compared to the normal concentration. Changing the CO₂ concentration from normal to high (intermittent) in intervals of 1 h resulted in dry weights intermediate to that of constant normal or constant high CO₂ concentrations in both species. Morning and evening enrichment gave the same effect as 1-h intermittent enrichment in Saintpaulia. High CO₂ concentration given every other day gave the same effect as 1 h intermittent CO₂ in Chrysanthemum. Increased dry weights were accompanied by more and larger leaves in Saintpaulia, and mainly by thicker and longer stem and more lateral breaks in Chrysanthemum.Time to flowering was significantly reduced by CO₂ enrichment in Saintpaulia, but was generally not affected in Chrysanthemum. Number of flowers and flowerbuds was increased by CO₂ application in both species. Constant high CO₂ concentration generally had effects superior to that of the intermittent treatments.     

Effect of stage of harvesting and seed treatment on germination,seedling emergence and growth in Corchorus olitorius ‘Oniyaya’

Fruits of Corchorus olitorius L. were harvested at three different developmental stages on the basis of colour (yellow, yellow with brown patches or completely brown). Seed germination (total and rate) and seedling emergence from soil varied with the fruit colour. Steeping the seeds in water at 97°C for 5 s and seed-coat scarification using sandpaper significantly improved seed germination and seedling emergence. Stage of harvesting also affected the shoot lengths and degree of uniformity in shoot lengths of 5-week-old seedlings.     

Preliminary studies on the use of (2RS, 3RS)-paclobutrazol for fruitlet thinning and growth control of ‘Conference’ pear

Summary

Single foliar sprays of paclobutrazol (PP333) at 300, 1000 or 3000 mg H applied at three different stages from full bloom to petal-fall in a year of average initial sets . and fruit size were equally effective in thinning ‘Conference’ pear, increasing the proportion of large fruits at harvest, but decreasing their absolute numbers. Sprays applied nine days after petal-fall reduced initial sets less effectively and, applied 21 days after petal-fall, were ineffective. Thinning was completed within 25 days after petal-fall. Shoot extension was initially retarded at all three concentrations, but later increased, so that the total growth made during the season was not reduced. Single foliar sprays at 300 or 1000 mg l^?1 applied at 70% full bloom in a year of heavy set and small fruit size increased the numbers of large fruits in the >55 mm size category by 66% and decreased those of fruits <55 mm by a similar amount. The increase in the yield of fruits >55 mm and decrease of unsaleable <45 mm fruits was equivalent to about 3 and 2 t ha^?1 respectively from a total average yield of about 17.5 t ha^?1. In the same experiment, similar sprays counteracted the stimulation in the production of small fruits by sprays of gibberellic acid (GA) applied on the same day, but did not increase the harvest of large fruits. Sprays of paclobutrazol at 30 or 100 mg l^?1 applied two weeks after petal-fall and then on three successive occasions at two-week intervals inhibited total extension growth per shoot during the season without affecting initial or final sets, fruit size or flower bud production. Single sprays applied at 100 mg l?1 in July reduced total extension per shoot almost as effectively as the repeated sprays. For more effective control of ‘Conference’ shoot growth, paclobutrazol may have to be sprayed later in the season than commercially recommended. Applied as a blossom thinner, paclobutrazol may increase the yield of large fruits only in years of heavy set and small fruit size, requiring that applications be delayed until set can be judged.     

Influence of rootstock on vegetative growth,fruit yield and quality in ‘Cuore di Bue’, an heirloom tomato

Summary

Heirloom tomatoes (Solanum lycopersicum L.) such as ‘Cuore di Bue’ are highly appreciated by consumers for their outstanding quality and flavour. Nowadays, they are often grafted onto vigorous rootstocks in order to overcome several soil-borne diseases. The present study was conducted in 2007 and 2008 in Southern Italy. Plants of ‘Cuore di Bue’, an heirloom ‘oxheart’ tomato, were grown in a greenhouse either as non-grafted plants, or grafted onto two inter-specific (S. lycopersicum S. habrochaites) rootstocks (‘Beaufort F₁’ and ‘Maxifort F₁’) in order to evaluate their effects on vegetative growth, marketable yield, fruit quality, and the sensory properties of ‘Cuore di Bue’ tomato fruit. Growth analysis revealed that ‘Maxifort F₁’ enhanced plant growth, particularly in terms of leaf area and leaf fresh weight. Grafted plants had higher leaf area ratios (by 13%) and higher leaf dry weight fractions (by 18%) compared to non-grafted ‘Cuore di Bue’ plants. Marketable yields increased by 20 – 25% in grafted plants in both years. However, total soluble solids (TSS) contents, titratable acidity (TA), and TSS/TA ratios were not significantly affected by grafting.Vitamin C contents decreased by 14 – 20% in both years in the fruit of plants grafted onto either rootstock. The sensory profiles of fruit were not modified by grafting, although taste panelists expressed a higher preference for purchasing fruit from plants grafted onto ‘Maxifort F₁’. These results confirm that, when using the appropriate rootstock/scion combination, grafting can improve plant growth and the marketable yield of heirloom tomato fruit without reducing the sensory quality of the fruit or its biochemical parameters. However, grafting can reduce vitamin C contents and, thus, nutritional quality.     

The effects of high CO2 pre-storage treatments and rate of establishment of controlled atmosphere conditions on bitter pit and bruise susceptibility of ‘Bramley’s Seedling’ apples

Summary

Bitter pit incidence in Bramley apples that were cooled prior to either slow (three weeks) or rapid (one day) establishment of controlled atmosphere (CA) conditions (9% CO₂, 12% O₂) was 14.7 and 3.2% respectively. Bruise susceptibility was also reduced by rapid CA establishment although the rate of fruit softening was unaffected. The control of bitter pit by pre-storage treatment with 15–25% CO₂ for one to three weeks was no better than by rapid establishment of CA, although bruise susceptibility was further reduced by some treatments. Some pre-storage treatments caused injury to the apple skin and flesh (brownheart). The extent to which fruits were injured was dependent on CO₂ concentration and the duration of CO₂ treatment. There was some evidence that early picked fruit not cooled prior to CO₂ treatment was more severely injured both internally and externally by CO₂ than that harvested later and cooled prior to treatment.     

Effects of the application of ‘cash’ on the growth,fruit yield,and nutrient status of tomato (Solanum lycopersicum L.) grown in reclaimed saline soil

Summary

The effects of ‘cash’ [a novel 2:5:1 (w/w/w) mixture of calcium sulphate, ground sunflower heads, and humic acid] as a soil amendment on the growth, fruit yield, and leaf nutrient status of tomato (Solanum lycopersicum L.) grown on reclaimed saline soil (EC = 9.4 dS m^–1) were investigated. A glasshouse experiment was performed in a completely randomised design with six treatments (0, 10, 20, 30, 40, or 50 g ‘cash’ kg^–1 soil) each with four replicates. The results indicated that ‘cash’ increased both the shoot dry weight (DW) plant^–1 and the root DW plant^–1, the free proline contents of leaves, and leaf chlorophyll contents. The use of ‘cash’ also increased the number of fruit plant^–1, fruit yield pot^–1, and fruit vitamin C contents, although total soluble solids (TSS) contents were not affected. The contents of nitrogen (N), potassium (K), and calcium (Ca), and the Ca:Na ratios of leaf tissues increased with all application rates of ‘cash’. Leaf phosphorus (P) contents showed no response to any applied level of ‘cash’. Leaf sodium (Na) contents declined gradually with an increase in the level of ‘cash’ applied to the soil. We concluded that ‘cash’ has a pronounced positive effect on the growth and fruit yield of tomato plants grown in reclaimed saline soil. ‘Cash’ therefore has the potential to be used as a soil amendment for vegetable crops such as tomato to overcome the adverse effects of salinity in newly-reclaimed soils.     

Effects of farmyard manure on soil organic carbon stock,the pattern of fertility build-up,and plant growth in ‘Mallika’ mango (Mangifera indica L.)

Summary

A field experiment was conducted on mango (Mangifera indica L.) to study the effects of farmyard manure (FYM) on soil organic carbon (SOC) content and on the build-up of fertility over three growing seasons (2006–2007, 2007–2008, and 2008–2009) at Bhubaneswar, Orissa, India. Five treatments, including the application of FYM at 5.0 kg plant^–1, 7.5 kg plant^–1, or 10.0 kg plant^–1, the recommended dose of a chemical fertiliser (RDF; N:P:K=75:20:60), and a non-fertilised control, were evaluated in a randomised block design. The results indicated that SOC contents increased significantly in the FYM-treated plots. The highest SOC density (554 g m^–2) and stock (5.55 Mg ha^–1) were recorded in the treatment with FYM at 10 kg plant^–1. The rate of increase in SOC density was highest (193 g m^–2 year^–1) with FYM at 10 kg plant^–1, and lowest in the untreated control (15 g m^–2 year^–1). Regular addition of FYM had a positive effect on the build-up of soil fertility. However, the greatest increases in soil N, P, K contents were in the 7.5 kg plant^–1 FYM treatment (means = 319.9, 19.1, and 270.8 kg ha^–1 for N, P, K, respectively). Farmyard manure significantly influenced the growth parameters of mango trees over the three seasons. There was a positive and linear relationship between increasing rates of application of FYM and trunk cross-sectional area.     

The effects of Apogee® on shoot growth,secondary flowering,fire blight,fruit quality,yield and return bloom in ‘Bartlett’ pear growing in California

Summary

Apogee^® sprays were applied to mature ‘Bartlett’ pear (Pyrus communis L.) trees as single or multiple sprays during the growing seasons of 1999 to 2003 at concentrations of 420 g ha^–1 (125 mg ^–1) or 840 g ha^–1 (250 mg^–1): both reduced vegetative shoot growth. Two sprays of 840 g ha^–1 applied 3–3.5 weeks apart were most effective and reduced shoot growth by approximately 40%. An application made 2 d after fall bloom was ineffective and led to more vegetative shoot growth. Single sprays of Apogee^® made within 9–28 d after full bloom (DAFB) were equally effective in reducing vegetative shoot growth. Bourse shoot growth was reduced 43% by 3 April, 2001 (8 DAFB) treatment of 840 g ha^–1 when bourse and vegetative shoots ranged from 2.5 to 7.5 cm in length. Subsequent single applications of 840 g ha^–1 Apogee^® (on April 12 or 23, 2001) did not reduce bourse shoot growth significantly. Vegetative shoot growth was also reduced by 12% (9 d after treatment) and by 38% (approximately one month after treatment) by 840 g ha^–1 Apogee^® applied on 3 April, 2001, (8 DAFB). In 2002, bourse shoot growth was controlled most effectively by split applications (840 + 420 g ha^–1 or 840 2 g ha^–1, 9 April and 24 May) and by 840 g ha^–1 Apogee^®, applied at 2.5 to 7.5 cm shoot growth (9 April). These split applications, as well as girdling, decreased shoot strikes in 2002, the year after treatment. Split applications of 840 g ha^–1 Apogee^® made in April to early May were most effective in controlling both vegetative and bourse shoot growth in most years, although single applications of Apogee^® were effective in some years. Subsequent flushes of shoots tended to be controlled by split applications with the second application timed to the emergence of new shoots. Apogee^® was not consistently effective in reducing the incidence of Type I or Type V secondary flowers in these trials. Single or multiple sprays of Apogee^® had no measurable or consistent effect on return bloom, fruit size or shape, firmness, percentage soluble solids, or yield per tree over the period of these experiments. Apogee^® appears to have promise as a shoot growth control agent in ‘Bartlett’ pear growing in California, USA, without deleterious effects.     

The long-term effects of pre-planting soil fumigation on the growth and cropping of cvs Laxton’s Fortune and Cox’s Orange Pippin on M.2 rootstock,planted on land affected with a replant disease of apple

Soil fumigation of land affected by apple replant disease, using chloropicrin at 281 1 ha^-1 before planting-out, caused increases in shoot numbers, trunk girth and of 35% in total crop accumulated over 10 years for cv Cox’s Orange Pippin on M.2 rootstock. Chloropicrin at 1121 ha^-1 gave rise to a smaller response, and DD at 5621 ha^-1 was ineffective. Cv Laxton’s Fortune on M.2 showed little response to any treatment.