Budbreak Number Research Articles

MORPHOLOGICAL CHARACTERISTIC OF VIERUL LOCAL GRAPE (Vitis spp.) CUTTING SEEDS ON PODZOLIC SOIL USING VARIOUS CONCENTRATION OF AUXIN SOAK

The development of grapes (Vitis vinifera) has obstacle among others are limited optimal land and difficult nurseries. Suboptimal land use for grape cuttings can use red yellow podzolic soil (ultisol). Podzolic soil has an acidic pH and low macro and micro nutrient uptake but can still be used as a growing medium. Vierul local grapes are a type of grape that has begun to be developed as root stock in nurseries but needs to be improved for its root success using a synthetic phytohormones bath of napthaline acetic acid (NAA). The purpose of this study was to determine the morphological character of vierul local grape cuttings at various concentrations of NAAsoaking in podzolic soil growing medium. This research has been carried out in a screen house from August to December 2021. This study used a non-factorial completely randomized design (CRD) with 3 treatments and 3 replications as block consisting of F0, F1, F2, F4 following by 0, 2, 4, 6 g L-1 respectively. The morphological characteristics observed is number of bud break, time of leaves appear, number of leaves, tendril length and percentage of live cuttings. The results of the study were analyzed using ANOVA at the 5% level and continued using the DMRT at the 5% level. The result showed that soaking of NAA at a concentration of 0 g L-1 (F0) had the best result for the variable number of bud break and number of leaves. Concentration of 6 g L-1 (F3) had the best result for variable length of the tendril while for the variable when the leaves appear, NAA soaking has no significant effect. The percentage of live cuttings is still low because it is influenced by the quality (material) of cuttings, the age of woodstock, growing media and water availability.

Axillary Budbreak in a Cut Rose Crop as Influenced by Light Intensity and Red:far-red Ratio at Bud Level

When flower-bearing shoots in cut rose (Rosa ×hybrida) are harvested, a varying number of repressed axillary buds on the shoot remainder start to grow into new shoots (budbreak). Earlier experiments indicated that light reaching the bud affected the number of budbreaks. In all these studies, whole plants were illuminated with different light intensities or light spectra. The aim of this article is to disentangle the effects of light intensity and light spectrum, in this case red:far-red ratio, at the level of the buds on budbreak in a rose crop. Three experiments were conducted in which light intensity and red:far-red ratio at the level of the buds were independently varied, whereas intensity and red:far-red ratio of incident light on the crop were not changed. Light intensity and red:far-red ratio at the position of the buds were quantified and related to budbreak on the shoot remainders. Removal of vertical shoots increased light intensity and red:far-red ratio as well as budbreak (1.9 budbreaks per shoot remainder compared with 0.4 budbreaks when five vertical shoots were present). No vertical shoots and red light-absorbing shading paper over the plant base mimicked the effect of vertical shoots with respect to light intensity and red:far-red ratio, but budbreak (1.0 budbreaks) was intermediate compared with treatments with and without shoots. This suggested that the presence of shoots exerts an inhibiting effect on budbreak through both effects on light at the bud and correlative inhibition. When plants had no vertical shoots and light intensity and red:far-red ratio at bud level were changed by neutral and red light-absorbing shading paper, there was a positive effect of light intensity on budbreak (0.3 more budbreaks per shoot remainder) and no effect of red:far-red ratio. Combinations of high and low light intensity with high and low red:far-red ratio on axillary buds showed that there was a positive effect of light intensity on budbreak (0.5 more budbreaks per shoot remainder) and no effect of red:far-red ratio. Our study reveals that when light intensity and red:far-red ratio received by the plant are similar but differ at bud level, budbreak was affected by light intensity and not by red:far-red ratio.

Budbreak Number in Apple Seedlings as Selection Criterion for Improved Adaptability to Mild Winter Climates

Absence or long delay of budbreak, also known as prolonged dormancy, is the most important symptom during incomplete dormancy. Budbreak number was evaluated to quantify seedling response to chilling and selection on excised and intact 1-year-old apple (Malus ×domestica Borkh.) seedlings under controlled and natural environmental conditions. Indices based on: 1) the number and distribution of budbreak (prolonged dormancy grade = PDG); 2) the number of buds breaking, including shoot length with increased budbreak as part of the calculation (prolonged dormancy index = PDI); and 3) budbreak number per 100-cm shoot (NB) were tested in association with budbreak time (TB). The indices expressed the effects of cold treatments that induce earlier and higher numbers of budbreak. PDI and NB, but not PDG, identified families with increased budbreak. Seedlings with high PDG and NB were also associated with families in which high chill requiring parents were used, indicating that TB as pre-selection criterion may fail to identify seedlings with increased budbreak. Response to pre-selection for increased budbreak using PDG could be verified with the PDS and NB indices in seedlings and seedling clones. The NB of intact 1-year-old shoots under natural conditions is recommended as a pre-selection criterion against prolonged dormancy in suboptimal winter conditions.

Selection for Increased Budbreak in Apple

Significant response to selection for budbreak number (NB) based on data recorded on 1-year-old shoots of young apple (Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.) seedlings (Expt. I) and branches from adult seedling trees (Expt. II) has been demonstrated in clonally propagated seedling trees. Between family variation for NB was low and masked by year × family interaction effects. Realized heritability for NB was estimated as 40% to 60%. Correlated response in uniformity and position of budbreak, and in the number and length of side shoots, was found. Association between the time of budbreak (TB) and NB, according to midparent and cross groupings, and according to the parental means, indicate a positive genetic correlation between these traits. Where data on adult trees were used as a measure of selection response and tested on young clonal trees, significant response and genetic variation was shown, confirming the presence of utilizable genetic variance and that this procedure may be successfully applied as an early screening method for increased budbreak in adult trees. Combined selection utilizing genetic variance between crosses as well as within crosses is proposed as the best procedure to increase the frequency of seedlings with increased budbreak and to improve adaptation to low winter chilling conditions.

Genetic Variation in Chilling Requirement in Apple Progeny

Genetic variation in chilling requirement was investigated over three growth periods using clonal progenies of six apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] families derived from crosses of high and low chill requiring cultivars. Two quantitative measurements related to chilling requirement, viz., the time of initial budbreak (vegetative and reproductive) and the number of breaking buds over a specified time interval, were used as evaluation criteria. Genetic and environmental variances of the traits are presented as intra-class correlation coefficients for clones within and between families. For budbreak time, reproductive and vegetative, broad-sense heritability averaged around 75% and 69% respectively, indicating a high degree of genetic determination in this material. For budbreak number, moderate to low genetic determination was found with broad-sense heritabilities around 30%. Estimates of genetic components of variance between families were generally very low in comparison to the variance within families and predict potentially favorable responses to truncation selection on the traits within these progeny groups. Analysis of the data showed that distribution of budbreak time is typical of quantitative traits with means distributed closely around midparent values. Skewed distributions towards low budbreak number were obtained in varying degrees in all families.

Flower and Fruit Load Influence Blueberry Plant Development and CO2 Exchange Rate

Two southern highbush blueberry cultivars, `Sharpblue' and `Misty', were used to investigate the influence of varying flower bud density and fruit load on vegetative development, whole-plant canopy CO2 exchange rate (CER), and leaf CER. Plants were grown in pots and flower buds were removed so that initial flower bud density (fl ower bud number/total cane length) on a whole-plant basis ranged from 0.05–0.35 flower buds/cm. Vegetative budbreak number, leaf area, and leaf area: fruit ratio decreased with increasing flower bud density. In `Sharpblue', whole-plant canopy CER measured at fruit ripening decreased with increasing flower and fruit load and decreasing leaf area:fruit ratio, while leaf CER increased with increasing fruit load and decreasing leaf area:fruit ratio. In `Misty', whole-plant canopy CER measured 4 weeks after full bloom decreased with increasing flower and fruit load, but whole-plant canopy and leaf CER at fruit ripening were similar among the different fruit loads. Average fruit fresh and dry weights increased and the fruit development period decreased with increased leaf area:fruit ratio in both cultivars. These data suggest that carbohydrate source limitations from reduced leaf area development and whole-plant canopy CER lead to decreased fruit fresh and dry weights and delayed ripening in some southern highbush blueberry cultivars.

Study and Comparison of Different Methods of Nonsexual Propagation of F12/1 and Colt Rootstocks of Cherry

This research work was carried out for 2 years at Kelardasht-Mazandaran and Mardabad-Karaj Agricultural Research Stations to evaluate the rooting of selected and hybrid F12/l and Colt rootstocks under climatic conditions of Iran. Young F12/l and colt rootstocks (semi-hard wood and summer cuttings) available in Kelardasht Agricultural Research Station were used These rootstocks were also used for layering. Summer cuttings were taken in early July and, after wounding, were treated with IBA with 1000, 2000, and 3000 ppm and then put under mist. Three months later the rooted cuttings were evaluated on the basis of rooting percentage, number and the length of the main and the lateral roots and the length of the rooted section. The hardwood cuttings were prepared in two intervals (early Dec. and late March) and, when wounded, were treated with IBA with the same concentrations. Finally, the experiments were completed by horizontal layering of several rootstocks and covering them with soil. The results were used in a completely randomized block design in four treatments, and the averages were compared by Duncan test. The results indicate that the summer cuttings treated with 1000 ppm IBA have the highest rooting percentage in both rootstocks, while those treated with 2000 ppm gave the best results with regard to number and the length of the main root. The best result on the number and the length of the lateral roots are achieved in cuttings treated with 2000 ppm IBA. Number and the length of lateral roots in Colt and F12/l rootstocks are, respectively, high in cuttings treated with 2000 and 3000 ppm. IBA. In semi-hardwood cuttings, different concentrations of IBA were effective on callus formation and budbreak. Thus, there were more callus formation in high concentration and the number of budbreaks was reduced. Study on the layering method indicates that there are 6.1 and 3 rooted cuttings in every Colt and F12/l layered rootstocks respectively. The rooting percentage in the said rootstocks is 100% and 73.3%, respectively.

Overcoming rest at different growth stages with hydrogen cyanamide

Hydrogen cyanamide was effective in overcoming rest in red-osier dogwood ( Cornus sericea L.) at specific growth stages. The concentration of hydrogen cyanamide needed to overcome rest was dependent on the growth stage. From the onset of rest to maximum rest 1.0–2.0 M hydrogen cyanamide favored earlier and larger numbers of bud break. During the post-rest period 1.0 M hydrogen cyanamide was the best concentration to enhance faster and greater bud break. During the quiescent period, hydrogen cyanamide delayed the time and reduced the number of bud break. Hydrogen cyanamide had no effect on stem elongation. The growth that occurred when hydrogen cyanamide was applied at the onset of rest to maximum rest was short (rosette-like). Applications of hydrogen cyanamide after this stage of development produced elongated shoots similar to the growth of controls during normal spring growth. These studies suggest that the role of hydrogen cyanamide in breaking rest is to enhance early bud break and not shoot elongation.