Flower Bud Density Research Articles

Flower and leaf bud density manipulation affects fruit set, leaf-to-fruit ratio, and yield in southern highbush ‘Misty’ blueberry

This study examined the influence of the different flower bud-to-leaf bud ratios on flowering, fruit set, leaf-to-fruit ratio, fruit quality, yield, and new flower bud production in southern highbush ‘Misty’ (Vaccinium corymbosum L. hybrid) blueberry. The flower bud-to-leaf bud (FB: LB) manipulations were as follows: in 2019, 1FB: 0LB, 1FB: 1LB, 1FB: 2LB, 1FB: 3LB, 1FB: 4LB, 1FB: 5LB, 2FB: 1LB, 2FB: 2LB, 2FB: 3LB, 2FB: 4LB, and 2FB: 5LB; and in 2020, 2FB: 1LB, 2FB: 2LB, 2FB: 3LB, 2FB: 4LB, 2FB: 5LB, 4FB: 2LB, 4FB: 3LB, 4FB: 4LB, 4FB: 5LB, and 4FB: 6LB. The highest fruit-setting rate was observed with 1FB: 1LB (96.7 %) followed by 2FB: 3LB (88.8 %) in 2019, when the leaf-to-fruit ratios were 4.8±1.0 and 6.2±0.9, respectively. A 100 % fruit set was recorded for 2FB: 2LB followed by 4FB: 3LB (95.6 %) in 2020 with 1.1±0.4 and 0.4±0.2 leaf-to-fruit ratios, respectively. In contrast, all fruit quality parameters, including berry weight, size, and yield were highest for the 2FB: 3LB with a leaf-to fruit ratio of 6.2±0.9 and the 2FB: 4LB with a leaf-to fruit ratio of 2.9±0.6 in 2019 and 2020, respectively. Consequently, the two flower buds with three to four leaf buds per bearing shoot (2FB: 3LB or 2FB: 4LB) can be implemented in ‘Misty’ blueberry to enhance the productivity of blueberry plants.

Genotype-environment interaction on the density of peach buds cultivated in a humid subtropical climate

Abstract Studies on the interaction of genetic and environmental effects on floral morphogenesis in peach trees grown in humid subtropical climate provide important information related to adaptation and for assisting in the selection of new cultivars. This study aimed to verify the genetic and environmental effects and to identify peach tree genotypes with greater shoot length, vegetative bud, flower bud density adaptability and stability under humid subtropical climate conditions. Twelve peach tree genotypes were evaluated over a period of eight years, during the growing season (2006/07 to 2013/14) in Pato Branco-PR, Brazil. Data were collected for shoot length (SL), flower bud density (FBD) and vegetative bud density (VBD), as well as temperature, humidity and precipitation. For the analysis of adaptability and stability we used GEE Biplot methodology. SL was influenced by the temperature and relative humidity. Increased exposure time to temperatures below 20 °C and above 30 °C, high thermal amplitude and relative humidity of less than 50% reduced shoot growth. VBD and FBD were predominantly controlled by the genetic factor. For VBD, the genotypes ‘Cascata 1055’ and ‘Conserva 681’ were the most adapted. For FBD, the genotypes ‘Cascata 1055’, ‘BRS Bonão’, ‘Conserva 681’, ‘Cascata 967’ and ‘BRS Kampai’ presented better adaptability. The genotypes more adapted to the FBD can be recommended for cultivation in the humid subtropical climate, since they also present greater stability in the production of fruits, independently of the meteorological conditions that occur during the vegetative and reproductive season.

Growth, yield and vase life of rose as influenced by different cultivars under protected condition of Eastern Himalayas

An investigation was carried out to evaluate the performance of four exotic rose cultivars (Sphinix Gold, Upper Class, Bordeaux andAvalanche) under protected condition in sub-tropical hills of Nagaland. High coefficient of variation both at genotypic and phenotypic level couple with high heritability and genetic advance for thorn density per inch. The genotypic correlation coefficient studies reveal that plant height at first flower flush was positively and significantly correlated with plant spread EW/NS direction, thorn density per inch and diameter of flower bud.Significant positive association of total number of petals per flower was revealed with plant spread EW/NS direction. Length of the sprouted bud was similarly a significant positive correlation with diameter of flower bud and thorn density per inch, length of the sprouted bud and days taken to bud sprouting. Phenotypic correlations of plant height at first flower flush with number of branches per plant, thorn density per inch. Similarly a significant positive correlation was observed between diameter of flower and length of the sprouted bud. Significant positive correlation also existed between number of flower per plant and number of petal per flower. Since there is a highly positive association among this component character, the selection of this particular character for improvement of any cultivars shall automatically influence other character in desirable direction. Among the cultivars studied the Sphinix Gold,Upper Class and Bordeaux are suitable for commercial cultivation under Nagaland condition.

Estimation of genetic parameters and prediction of breeding values in an autotetraploid blueberry breeding population with extensive pedigree data

The strategy for breeding blueberries has been based on phenotypic selection without accounting for pedigree correlation information. A central premise of classical quantitative genetics is that through knowledge of the relationships among individuals in a population, we can make inferences about breeding values (BVs), estimate genetic parameters, and support phenotypic selection. Genetic evaluations using best linear unbiased prediction (BLUP) and restricted maximum likelihood (REML) are founded on pedigree information and have been the standard method used in livestock and forest breeding. Despite theoretical and practical benefits, their application in blueberry breeding programs remains unexploited. The objective of this study was to evaluate the use of REML/BLUP in the University of Florida blueberry breeding program in order to estimate genetic parameters and predict BVs of primary selection traits. To do this, we collected phenotypic data for eight selectable traits (yield, flower bud density, fruit weight, fruit firmness, fruit diameter, fruit soluble solids, fruit pH, and fruit scar diameter) from 1996 individuals. The highest narrow-sense heritabilities were found for fruit weight, scar diameter, and yield. The majority of genetic correlations between traits were under 0.20. The largest genetic gain was achieved when selections from early stages were used as parents and the top 5% of the population was selected. Compared to traditional phenotypic selection, our results are evidencing of the importance of implementing REML/BLUP to estimate genetic parameters that help and support the breeding strategy and maximize genetic gains.

Drones for butterfly conservation: larval habitat assessment with an unmanned aerial vehicle

Evidence-based nature conservation focuses on ecological facts and the incorporation of knowledge on the ecology of species, including its entire life cycle. In butterflies, imagos and its larvae often demand specific and diverging micro-habitat structures and resources. In consequence, ecological requirements of the imaginal and pre-imaginal stage have to be taken into consideration to conduct effective conservation management. Here we analyse ecological pre-requisites of imagos and larvae for two lycaenid butterfly species, the common blue Polyommatus icarus and the adonis blue Polyommatus bellargus. Both butterfly species occur in calcareous grasslands and mainly depend on two plant species at our study site, the horseshoe vetch Hippocrepis comosa and bird’s-foot trefoil Lotus corniculatus. These plant species serve as nectar sources and larval host plants for the two butterfly species. First, we assessed the occurrence of imagines and larvae of the two butterfly species and recorded various micro-habitat characteristics, like the number of flower buds of the two main host plants, the surrounding vegetation height, percentage of bare soil, availability of shadow, and the distance to and geographic direction of thickets at respective sites. In a second step we took high resolution aerial pictures from our study area using an unmanned aerial vehicle (drone). Based on these aerial pictures and the information on the larvae´s habitat preference from our field observations, we trained a habitat suitability model to identify micro-habitat structures suitable for larvae of the two butterfly species. We found that abundance of imagos is positively correlated with flower bud density of the two host plants. Low vegetation height and high proportion of bare soil (but not flower bud density) positively influence egg oviposition. The calculated habitat suitability models predict the occurrence of high quality larval habitats with high prediction power (AUC = 0.72). This combined data set consisting of field observations, high resolution aerial pictures taken from an unmanned aerial vehicle, and models underline that (1) species with complex life cycles may request more than one habitat niche, depending its stage of development, and (2) high resolution aerial pictures taken from drones provide valuable background data to generate habitat suitability models—even on a micro scale but covering larger parts of a landscape.

Characterization of the vineyard byotyp collection of peach as step in prebreeding process

In this research, morphological characterization of vineyard peach collection was conducted. In 78 accessions thirty qualitative traits of tree, flower, leaf, fruit and stone were analysed by using UPOV and ECPGR descriptors. Most of the studied traits showed a high degree of variability. The lowest variability obtained for the leaf traits, and highest for skin and flesh colour. Not only were the accessions sorted into a large number of categories by the most of their properties, but also there was a significant level of variability in the collection, reflecting in the fact that the traits were recombinant in a different way. Principal component analysis (PCA) and a dendrogram were performed to determine relationships among accessions and to obtain information on the usefulness of those characters for the discrimination. The PCA revealed that the first 4 principal components were able to represent 43.1% of total variance. Traits with high discriminating values comprised internal and external fruit colour, flower type and colour, flower bud density and stone shape. The cluster analysis showed that the accessions were placed in three main clusters. The greatest impact on the separation in clusters had fruit over colour and extent of fruit over colour. Moreover, the collection can also comprise some accessions with the preferred recombination of properties that might be interesting for further studies in breeding.

Morphological properties of fruit bearing shoots of apricot cultivars

Morphological properties of fruit bearing shoots: length, number of flower buds and vegetative buds and their ratio were studied in 20 apricot cultivars during a two-year period. Control cultivar for comparison was ?Hungarian Best? (?Magyar kajszi?), clone 235. Fruit bearing shoots of apricot were classified into three groups: shoots, sylleptic shoots and spurs. The average length of shoots ranged from 68.8 to 85.0 cm; of sylleptic shoots from 6.9 to 27.0 cm; and of spurs from 1.4 to 4.1 cm. Flower buds/vegetative buds ratio was higher in spurs and sylleptic shoots (2,5 on average), compared to shoots (1,8 on average). Most of the studied apricot cultivars are characterized by higher flower bud density compared to control cultivar (?Hungarian Best?), indicating their higher yield potential. For all studied traits statistically significant differences between cultivars were found. The great variability was found in length of shoots, number of flower buds, and number of vegetative buds, while small coefficients of variation were found in thickness of shoots and length of internodes. Based on the obtained results, recommendations for pruning can be made. Cultivars with a higher number of flower buds (per 1 m in length and in relation to vegetative buds) such as: ?Lenova?, ?Tomcot?, ?Veecot?, ?Ninfa?, ?Sophia?, ?Silvercot? and ?Goldrich? require severe pruning. On the other hand, cultivars with lower flower bud density e.g. ?Hungarian Best?, ?Cegledy Arany? and ?Bella d?Imola? can be pruned slightly.

Gypsum Rate Evaluation for Wild Lowbush Blueberry (Vaccinium angustifolium Ait.) Soils

Four rates of gypsum (CaSO4·2H2O) were compared at two commercial wild lowbush blueberry fields (Addison and Belfast, ME) to determine the most suitable rate for increasing blueberry nutrient uptake under Maine soil conditions. Gypsum treatments (1,121, 2,242, 3,363, or 4,484 kg·ha−1) were compared to diammonium phosphate (DAP; 448 kg·ha−1) and a control. Gypsum and diammonium phosphate were applied pre-emergent in May 2009 to 0.9 m × 15 m plots arranged in a randomized complete block design with six blocks in each field. Composite leaf and soil samples were collected in July 2009 and analyzed for nutrient concentrations. Within each treatment plot, stems from four randomly placed 0.023 m2 quadrats were collected in October 2009 for stem length, branching, and flower bud measurements. Soil Ca and S concentrations were increased by gypsum at both fields. Gypsum increased leaf N and P concentrations only at the field that was deficient in these nutrients (Addison). Diammonium phosphate increased leaf N and P concentrations compared to the controls at both fields. Gypsum at 2,242 kg·ha−1 or higher corrected P deficiency; but only the 3,363 kg·ha−1 and 4,484 kg·ha−1 rates corrected leaf N deficiency. At Belfast, diammonium phosphate did not increase flower bud density or yield. At the deficient Addison field, a lower rate of gypsum (3,363 kg·ha−1) than that recommended for Canadian soils (4,000 kg/ha) was effective in correcting leaf N and P deficiency. Flower bud density and yield were raised by diammonium phosphate but not by any of the gypsum treatments.

Direct and apparent residual effects of prohexadione - calcium applied to young cropping sweet cherry trees

The same young cropping 'Regina' sweet cherry trees were foliar treated with prohexadione-calcium (Pro- Ca) in two consecutive years at a concentration of [ 125, 125 x 2, 250 ]-(A) and [ 250, 375, 500 ]-(B) mg ProCa l<sup>-1</sup>, respectively. The following year some trees from A-treatments were left untreated to observe carry-over effects (C). None of A-treatments influenced tree trunk, shoot extension and internode growth, whereas B-treatments reduced shoot extension and internode length, simultaneously increasing flower bud density, particularly by 500 mg ProCa l<sup>-1</sup>. There were no carry-over effects produced by C-trees, except some retardation in shoot extension. None of the treatments influenced the tree cropping level. Fruit diameter was reduced by A-treatments, but fruit shape (L/D ratio) and mass were reduced by treatments B, and such reduction was also exhibited by C-trees (residual effects).

LONG-TERM EFFECT OF WATER DEFICIT IRRIGATION ON CHERRY VIGOR AND PRECOCITY

Different post-harvest regulated deficit irrigation treatments were established in a young and vigorous commercial ‘Bing’ cherry (Prunus avium L.) orchard planted in dry shallow soil with drip irrigation. The treatments given over a three-year period were as follows: T1= 100%, T2= 75% and T3= 50% of full ETc. The available water remaining percentage (%AWr) and midday stem water potential (SWP) were measured during the water-deficit period. During the three-year period average SWP was -0.68, -0.83 and -1.04 MPa while %AWr was 89.9, 71.7 and 41.4 for T1, T2 and T3 respectively. SWP was highly correlated with %AWr (r2= 0.89). After three years trunk growth decreased by 6% (T2) and 10% (T3). Shoot length for T3 was 27% lower, flower bud density and yield efficiency were 85% and 57% higher when compared to T1. Seasonal shoot length was highly correlated with flower bud density on productive branches (r2= -0.76). Average fruit weight was not affected while double fruits were not substantially affected by treatments. An accurately adjusted post-harvest water deficit can be used to control vigor and promote early production of cherries, while saving significant amounts of water.

Role of Paclobutrazol and Ethephon in Reproductive Growth of 'Allahabad Safeda' Guava (Psidium guajava L.) Plants at Different Spacing

A study on 4-year 'Allahabad Safeda' guava plants was made to assess the influence of Paclobutrazol (PP 333), [(2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4 triazol-1-yl) pentan-3-ol], a gibberellin-inhibitor, and Ethephon [(2-chloroethyl) phosphonic acid], a vegetative growth inhibitor and a ripening promoter, on reproductive growth of plants. Treatments in the form of foliar application at 500 and 1000 ppm were applied consecutively during March 2007 and 2008 on plants at 6m x 2m, 6m x 3m, 6m x 4m and 6m x 5m spacing. Maximum flowering and fruit set was recorded in paclobutrazol treated plants in both rainy and winter crops. Ethephon reduced flower bud density (FBD) and fruit set during both the cropping seasons. However, Ethephon treated plants exhibited slightly higher fruit retention. Ethephon advances fruit maturity by upto a week during rainy season and two weeks during winter season. Paclobutrazol treated plants exhibited significantly higher fruit number, fruit yield, yield efficiency, fruiting density compared to Ethephon treated and control plants. Reproductive growth of plants at wider spacing of 6m x 5m and 6m x 4m significantly improved compared to closer spacings of 6m x 2m and 6m x 3m during both cropping seasons. Plants at wider spacing responded better to Paclobutrazol applications with respect to flowering and fruiting.

Light penetration, growth, and fruit productivity in ‘Fuji’ apple trees trained to four growing systems

The study was conducted to document the range in soil nutrients, trunk and shoot growth, leaf characteristics and nutrient content, flower bud characteristics, yield, fruit quality, disease occurrence, light penetration, and shoot bark color in a 15-year-old ‘Fuji’ apple ( Malus × domestica Borkh.) orchard on M.26 rootstocks trained to four growing systems. SS trees naturally growing had greater width and volume than the LT lightly heading, MLT heavily heading, and S trees thinning and bending. LT trees had more upward terminal shoots at old branches, large numbers of lateral shoots, and longer total shoot length. Leaf [N], [P], and [K] were the lowest for the MLT trees. SS and S trees had greater flower bud density and fruit yield, but LT trees had poor fruit color and less soluble solids and firmness. Percent light penetration into the canopy was the highest with the S system but not different from MLT or SS. The lowest was for the LT system, however, it was not statistically different from MLT or SS.

Significance of Flower Bud Density for Cultivar Evaluation in Almond

Flower bud density, spur density, and number of flower buds per spur were evaluated in 57 almond cultivars and selections during 3 consecutive years to establish their repeatability as well as their potential to ensure a sustainable commercial production. These three traits showed a high variability with significant differences between genotypes and years as well as a significant interaction of genotype and year. The effect of location and the interaction of location and genotype were not significant for bud density, but they were for spur density and number of flower buds per spur. Variability of flower bud density is mostly related to the number of flower buds per spur as indicated by the higher repeatability of spur density than that of the other two traits. A high flower bud density is essential for a sustainable production, because a high number of flowers may compensate frost damage. Early selection for a high flower bud density can be done indirectly through selection for a high spur density but requires its evaluation over several years.

Effects of Fertilizer Rate on Growth and Fruiting of Containerized Southern Highbush Blueberry

The effects of fertilizer rate and composition on growth and fruiting of ‘Misty’ and ‘Star’ southern highbush blueberry were evaluated in a containerized production system using pine bark medium. Two fertilizer analyses (12N–1.8P–46.6K and 12N–5.2P–9.9K) and three fertilizer rates were used. Plant growth and fruiting were unaffected by fertilizer analysis. Growth and fruit yield of ‘Star’ increased linearly with increasing fertilizer rate. For ‘Misty’, plant growth and yield were reduced at the highest fertilizer rate as a result of a high incidence of blueberry stem blight associated with that treatment. Flower bud density was highest for the ‘Misty’ plants receiving the high fertilizer rate and this may have resulted in excessive fruit set leading to stress-induced blueberry stem blight. Optimum fertilizer rates for young southern highbush blueberry plants grown in containerized pine bark systems appear to be cultivar-specific and similar to fertilizer requirements in soil culture.

Studying on the frost damage of some peach and nectarine varieties

To be able to grow stone fruit species, the peach and the nectarine varieties, yield stability is very relevant. However, the climate is suitable in Hungary for growing stone fruits. We have to calculate with damage. Important winter damage and spring frost damage occur in every second year on the Great Pplains. To reveal the frost tolerance of cultivars and to clarify the differences among growing areas is the most important point of peach and nectarine production.We, made our experiments in the winter of 2005 (January-February), at Pallag, Zsombó, Siófok, Sóskút and Szatymaz. These former places are determinant in peach and nectarine growing in Hungarian respects.In our experiments we analyzed 10-10 fruit shoot from 82 varieties, and we measured the frost damage and the flower bud density.The minimum and the maximum frost damage values (%) at the different growing places were 7.6-38.7 at Siófok, 6.5-31.3 at Sóskút, 34.3-100 at Szatymaz, 83.7-99.6 at Pallag and 51.9-99.6 at Zsombó. There were expressive differences between the same cultivars depending on the growing area.The frost damage of „Suncrest” variety was 7.6% at Siófok, 8.2% at Sóskút but it was 69.8% at Szatymaz. The „Maystar” variety had 17.6% at Siófok, 12.4% at Sóskút and 87.2% frost damage at Szatymaz. In case of „Redhaven” variety the frost damage values were 16.8% at Sóskút, 54.6% at Szatymaz. We collected fruit shoots from three different heights in case of „Cresthaven” variety. In case of 1 meter height the frost damage was 74.6%, at 2 meter height 44.7%, and 25.2% at 3 meter.We experienced also big differences in flower bud density (flower bud/10 cm) of varieties. The following cultivars had the highest flower bud density (6-7 bud/10 cm): „Suncrest”, „Meystar, „Maria Luisa” and the „Maria Bianca”, „Redhaven”, „Michellini” had the lowest flower bud density (2-3 bud/10 cm).After our experiments we established that there were very expressive differences among the frost damage of peach and nectarine varieties from different climatic conditions and there are also big variance between the frost damage values of those fruit shoots, what were collected from different heights, but from the same variety. It conspicuous very good among our items, that difference of the flower bud density is very big among the varieties.To be able to grow peach and nectarine successfully, the suitable variety (low frost damage value, high flower bud density) and the suitable growing are is determinant.

Fruit bearing shoot characteristics of apricot and sweet cherry cultivars in Hungary

: Our study was carried out on 23 apricot and 9 sweet cherry cultivars in February 2005. Fruiting laterals were classified into four groups (0-10 cm, 10-20 cm, 20-40 cm and >40 cm) and then the density and setting of flower buds were evaluated and expressed as bud/cm. The flower bud density of four types of fruit bearing shoots and the changes in the frost resistance were studied. Shoots were collected from a young orchard in Gone (apricot), Siófok (sweet cherry) and Nagykutas (sweet cherry). There were significant differences among the cultivars in the density of flower buds. The number of flower buds/cm shoot length ranged between 0.91 and 2.20 in the average of the different fruit bearing shoot types on apricot. Based on the results, the bud density of shorter shoots is generally higher on apricot, but this is not valid for all cultivars. For cvs. Magyarkajszi and Ceglédi bíborkajszi, the highest flower bud density was detected on shoots of medium length (10-40 cm). There were fivefold and almost twofold (1.85) differences in bud density among cultivars on shoots shorter than 10 cm length and longer than 40 cm length, respectively. The ratio of the bud densities of the different types of shoots also ranged between wide boundaries. For cvs. Bayoto, Toyesi and Toyiba this ratio was 2.5-3.5, while for cv. Magyarkajszi it was 1.3.
 In the average of fruit bearing shoots on sweet cherry, cv. Bigarreau Burlat (1.10 bud/cm) and cv. Germersdorfi 45 (0.61 bud/cm) had the largest and the lowest flower bud density, respectively. Among the fruit bearing shoots, the largest flower bud density was in the group of 0-10 cm fruiting laterals. Among cultivars, cv. Bigarreau Burlat had the largest bud density. In the groups of n- i 0 cm, 10-20 cm, 20-30 cm and 30-40 cm fruiting laterals, the lowest flower bud density was for cv. Linda, cv. Germersdorfi 45, cv. Ferrovia and cv. Sunburst, respectively. On cvs. Van and Bigarreau Burlat, large numbers of double-set flower buds were observed on the fruit bearing shoots longer than 20 cm. Fruit setting differed on the different types of fruit bearing shoots, with the lowest value measured on above 40 cm shoots. The highest fruit setting was observed on cv. Katalin, while the lowest value was measured on cv. Germersdorfi 3.

Variable success of biological control of Lythrum salicaria in British Columbia

Purple loosestrife, Lythrum salicaria , has invaded North American wetlands over the last 200 years. A biological control project was started in British Columbia, Canada, in 1993 with the introduction of Galerucella calmariensis , a leaf-feeding beetle of European origin. To evaluate the success of the biological control project in the Lower Mainland of British Columbia, we monitored the defoliation levels of Lythrum at 10 release sites of the control agent, identified factors associated with among-site variability in defoliation levels, and determined the effect of defoliation on the performance and abundance of Lythrum . In tidal areas, the beetles could not establish due to tidal disturbances. The control agent established at all non-tidal sites, but defoliation levels varied considerably. Defoliation levels were negatively associated with predation on Galerucella eggs, suggesting that general predators may be able to prevent or delay successful biological control of Lythrum . Eggs on Lythrum stems surrounded by water experienced lower predation rates than eggs on stems on land, indicating that standing water acts as a partial refuge against predators for Galerucella eggs. Flower-bud density, length of inflorescence, and plant biomass per m 2 were all negatively related with the intensity of beetle feeding, and stem height was marginally reduced with increased beetle grazing. Dry biomass per m 2 of Lythrum appeared to decline drastically only at sites where beetle grazing was intense.

Influence of flower bud density, flower bud drop and fruit set on apricot productivity

Flower bud density, flower bud drop and fruit set were studied for nine apricot cultivars in order to understand the influence of these variables on apricot biology and productivity. Cultivars in southern Spain were chosen as representatives of different flowering times and productivity. Results indicate differences among cultivars in the studied parameters. Low flower bud production, high flower bud drop and low fruit set were often recorded in mid- to late flowering cultivars. These traits subsequently led to poor yields. Early blooming varieties, which are frequently good producers, generally showed the highest flower bud density, medium flower bud drop and high percentage of fruit set. The influence of the cultivar was more determinant than the seasonal effect on fruit yield. This information should be useful to breeders for choosing the best parents for productivity.

Effect of Foliar Copper and/or Iron Application on Growth and Yield of Lowbush Blueberry

In a commercial lowbush blueberry (Vaccinium angustifolium Ait.) field with low leaf Cu (<7 ppm) and Fe (<50 ppm) concentrations, nine 1.8 m × 15 m treatment plots were established in a randomized complete block design with 6 blocks. Copper Keylate® (Stoller Enterprises, Inc.) containing 5% Cu was used as a foliar spray in a volume of 626 L·ha-1. In a similar volume, the Stoller Enterprises Inc. product Fe Keylate®, containing 5% Fe (5% chelated Iron), was used to provide Fe. Ammonium sulfate (0.7%) was added to the solutions to enhance uptake. Treatment plots received either Cu Keylate® at 0.6 kg·ha-1 Cu or Fe Keylate® at 0.6 kg·ha-1 or a combination of both nutrients in one spray. Treatments included a 19 June prune - or crop-year application of Cu, Fe, or Cu + Fe, and a prune-year Cu + Fe June 7 and June 19. A plot receiving no treatment served as a control. Leaf Cu and Fe concentrations were raised to above satisfactory leaf concentrations (Cu >7 ppm, Fe >50 ppm) by their respective treatments. Concentrations were significantly higher for each element when they were applied together. Two applications were not better than only one. No carry-over effect was seen in the crop year. Crop-year applications of Cu and Fe were effective in raising their respective concentrations. Stem density, length, number of branches or branch length was not affected by treatments at the end of the prune year. Flower bud density and average number of flower buds per stem were not meaningfully affected by prune year Cu or Fe treatments. Berry yield was not influenced by any treatment suggesting that the Cu and Fe standards are too high.

Bud-, flower- and fruit-density in stone fruits

In 164 varieties of five stone fruit species, counts of flower buds, flowers and fruits set have been performed, regularly, between 1982 and 2002. The critical number and sample size has been determined for the purpose to estimate the yielding potential of peach plantations. For a rapid test, 10 shoots per variety are recommended. In sour cherry and peach varieties, the number and ratio of leaf and flower buds has been assessed on bearing shoots of different length.
 The typical flower bud density of 129 peach varieties varies, as a rule, between 0.13 and 1.10 bud/cm. Three groups of flower-bud-densities could be distinguished: low (0-0.40 bud/cm), intermediate (0.41-0.60 bud/cm), high (more than 0.60 bud/cm). About 62% of varieties belong to the intermediate group. Negative correlation has been found between flower density and relative fruit set, whereas positive correlation between flower density and fruit yield.
 The results are utilised in the description and choice of varieties, moreover, in choosing of optimal pruning policies. Varieties of high flower bud densities are recommended to be preferred for growing sites with frequent late frosts. Abundantly yielding varieties of low vegetative vigour are to be pruned more severely than those characterised by low yields, vigorous growth and low flower density. Sour cherry varieties, which are inclined to grow "whips" ought to be stimulated to grow longer shoots (40-50 cm per year), than varieties woid of that tendency (30-40 cm).