Evaluation of Vegetative Growth Parameters of Almond Varieties (Prunus Amygdalus L.) at Holleta, Central Highlands of Ethiopia

The study's goal was to evaluate almond cultivars' vegetative growth performance and adaptability under Holetta conditions. The trial was carried out at the Holetta Agricultural Research Center with four almond varieties arranged in RCBD and three times replicated. Ferraduel had the highest tree height of 129.58 cm in the first growing season of 2011, followed by Desmayo (108.75 cm), Ferragnes (96.17 cm), and Marcona (95.56 cm). The Ferraduel variety has the highest recorded height except in 2014 and 2015. Annual growth differed significantly between years, with 2015 recording the most (42.7 cm) and 2013 following closely after (32.8 cm). The cross-sectional area of a tree trunk increased in general as the growth season progressed. In 2011, Marcona had the lowest TCSA (2.04 cm 2 ), whereas Ferragnes (86.58 cm 2 ) had a much lower TCSA in 2016. The exponential canopy stretch was somewhat limited from 2012 to 2013. The growing season 2016 has the most main branches, followed by the growing season 2013, with the values of 3.44 and 3.14, respectively. While the 2014 growing season had the fewest major branches, followed by the 2015 growing season with values of 2.19 and 2.58, respectively. Across all growing seasons, the Desmayo variety exhibited the highest branching height. With increasing tree height, TCSA and canopy stretch grow linearly. It also shows non-linear positive correlations of 0.43 and 0.35 with yearly growth rate and branching height, respectively.

vegetative growth performance and adaptability of almond cultivars.

Materials and methods Experimental site description
The research was carried out at the Holeta Agricultural Research Center (HARC), which is located at an elevation of 2400 m a.s.l., at N 9° 3' and E 38° 29'. The area has a mean annual rainfall of 1041.4 mm and relative humidity of 58.7 percent. The major rainy season lasts from June to September, accounting for 70% of the total rainfall, with the remaining 30% falling between February and April. The average annual maximum and lowest temperatures are 21.7 O C and 6.7 O C, respectively (EIAR, 2017). The soil type in the area is primarily Nitosol, which has an average organic matter content of 1.8 percent, a nitrogen content of 0.17 %, a phosphorus content of 4.55 ppm, the potassium content of 1.12 Meq/100 g of soil, and a pH of 5.24 (Gemechu, 2007).

Methodology and field management
In 2011, four almond cultivars were brought from Spain and established at the Holeta Agricultural Research Center: Marcona, Desmayo, Ferragnes, and Ferraduel. The experiment was set up with three replications in a completely randomized block design (RCBD). Four plants were planted in each plot, with a 4 m x 4 m spacing between plants and rows. All necessary field management procedures were carried out, including manure and fertilizer application, irrigation water supply, pruning and training, weeding, and pest and disease control.

Data collection
Every year, data for growth metrics were collected for each variety at the commencement of the dormancy break (September-October).Among them; Tree height (cm): was taken by measuring the height of the tallest branch from the ground using height meter. Annual shoot growth (cm): was determined by measuring the lengths of one season-grown bud stick from the North, South, East, and West directions, and the average length of four bud sticks was used for this study. Tree trunk cross-sectional area (TCSA) (cm 2 ): The tree trunk diameter was measured 10 cm above the graft union to calculate TCSA using the equation (Westwood et al., 1963).

= 4
Where, = 3.14, D is the diameter measured 10 cm above the graft union. Canopy stretch (width) (m): was the mean measurement of the spreading of branches from North to South and from East to West directions and calculated as follows (Liu et al., 2021). ℎ ℎ = + !" 2 Where DNS is the North-South width and DEW is the East-West width. Number of main branches: was the number of primary branches arose from the main stem. Branching height (cm): was measured from ground level to the point of the first main scaffold branch emerged.

Data analysis
The parameters were subjected to an analysis of variance (ANOVA) using SAS 9.3 statistical software, and treatment means were computed using the Least Significant Difference Test at a 5% probability level (Gomez and Gomez, 1984).

Result and discussion Tree height
The interaction of variety and year produced a highly significant change in tree height (P < 0.0001) ( Table 1). There is also a noticeable difference between kinds and years. Ferraduel had the tallest tree height of 129.58 cm in the first growing season of 2011, followed by Desmayo (108.75 cm), Ferragnes (96.17 cm), and Marcona (95.56 cm). With the exception of 2014 and 2015, the Ferraduel variety had the maximum recorded height. Even if the longest tree height does not differ significantly between 2014 and 2015, the Ferraduel variety's limited growth may be attributed to tree pruning in 2013. Except for 2015, there is no statistically significant difference in pruning between cultivars Ferraduel and Desmayo, and the same is true for Marcona and Ferragnes. With the exception of 2012 and 2013 (with values of 186.5 cm and 189.9 cm, respectively), statistically significant differences in variable years were noted. The record for the greatest height was set in 2016 with a measurement of 460.7 cm. In all species, the size of the tree determined reproductive performance. Larger trees were more capable of acquiring and storing minerals and carbohydrates, and they produced more fruit (Carbone et al., 2013). The highest value of growth parameters discovered in plants from early planting may be connected to higher temperatures that prevail during the growth phase, hastening plant vegetative growth (Rahman et al., 2014).

Annual shoot growth
The annual growth rate of almond varieties combined with the growing season showed a highly significant difference (P < 0.0001) ( Table 1). The length of new bud sticks was not taken in the first two growing seasons (2011 and 2012) since there was no clear delimit for one season growth and no significant difference between them. However, there was a large disparity between years, with 2015 (42.7 cm) being the highest and 2013 being the lowest (32.8 cm). Changes in environmental circumstances (temperature) and field management could be to cause (irrigation and cultivation). Except for Ferraduel, which has the highest yearly growth rate of 21.8 cm, there is no statistically significant difference amongst varieties. For a long time, heavy or severe pruning was thought to promote vigorous vegetative growth over flower bud development (Marshall, 1931). According to Paul et al. (2017), the vegetative development changed depending on the environmental conditions.

Tree trunk cross-sectional area
The interaction effect of variety and year indicated a highly significant difference (P < 0.0001) in tree trunk crosssectional area (fig 1). The cross sectional area of a tree trunk expanded in general as the growth season progressed. In 2011, Marcona had the lowest TCSA (2.04 cm 2 ), but Ferragnes have had a much lower TCSA (86.58 cm 2 ) in 2016 ( Figure 1). TCSA showed an exponential trend throughout growing seasons for all varieties (Figure 1). The most frequent measurement of a tree's size and, consequently, its fruit-bearing capacity is the trunk cross sectional area (Wright et al., 2006). The width of a tree trunk's trunk is an important indicator of its strength. The widening of the trunk could be owing to the root system's high absorption, which aids in the production of organisms to expand the crown, which, in turn, aids in the formation of many xylem and phloem elements (Kiprijanovski et al., 2009). TCSA and the number of fruits per plant were influenced by both the training strategy and the rootstock.

Canopy stretch (m)
On canopy stretch, the combined effect of variety and year is highly significant (P < 0.0001) (fig 2). In the first year of planting, there was no significant difference between the varieties Marcona (34.38 cm) and Ferragnes (35.00 cm), and the same is true for Ferraduel (45.21 cm) and Desmayo (46.25 cm). The exponential canopy stretch was somewhat limited from 2012 to 2013 (Figure 2). This could be owing to growth restrictions imposed by the environment. Plant growth is influenced by the origin of the planting materials (Yudohartono and Ismail, 2013). The canopy pattern varies from plant to plant and can be categorized into several groups. Large trees are more productive than trees with smaller diameters, according to Molina et al. (2011). Fruit yield is determined by the volume of the crown rather than the width of the stem, with larger trees producing more fruit. Weather conditions, as well as the volume of the tree crown, are important factors in fruit production. Differences in canopy spread could be caused by environmental factors such moisture content and soil temperature, as well as soil and disease factors that affect plant emergence and survival (Nigam, 1992).

Number of main branches
The number of main branches is unaffected by the combined effect of variety and year (P < 0.05) (Table 1). However, the effects of year and variety separately (Figure 3 and 4) show a highly significant difference (P < 0.0001). The planting season 2016 has by far the most major branches, followed by the growth season 2013 with Advances in Life Science and Technology www.iiste.org ISSN 2224-7181 (Paper) ISSN 2225-062X (Online) Vol.91, 2022 values of 3.44 and 3.14, respectively. Pruning in 2013 may be to cause for the low number of major branches (Figure 3). The Feraduel variety had the most main branches, followed by Marcona and Desmayo, with values of 3.21, 2.92, and 2.83, respectively. Although the branches are not the plant's direct reproductive structures (i.e., they do not photosynthesize), they are important because they allow the leaves to spread out in space, letting water and nutrients flow from the soil to the leaves easier (Paoletti et al., 2021). Unit leaf biomass, as well as large branching, ensure that the greatest branches are sustained by the same stem, and other secondary branches are supported by each branch head, and so on, up to the shoots, which are producers empowered to achieve more diversity in reproductive structures (Rosati et al., 2013).

Figure 4. Distribution of number of main branches for varieties
Branching height (cm) There was a highly significant difference in branching height (P < 0.0001) for the interaction impact of year and variety (Table 1). Even though it was not statistically different from Ferraduel (46.58), Desmayo (48.67) had the highest branching height in the first growing season of 2011. Throughout all growth seasons, the Desmayo cultivar has the highest branching height. In 2013, the branching height of Marecona and Ferragnes types decreased, probably as a result of pruning, which encourages new scaffold branch growth. By enhancing cytokinin transfer from rootstock to scion, grafting height can influence branching height and stimulate lateral bud growth (Karlidag and Esitken, 2012). The number of lateral branches has a big influence on the tree's optimal structure. Furthermore, fruit tree fertility and fruit development are influenced by the height, orientation, and angle of lateral branches with the stem (Yldrm and Kankaya, 2004). As demonstrated in Table 2, tree height exhibited a high positive linear correlation with trunk cross-sectional area (0.97 ~ 1) and canopy stretch (0.95 ~ 1). This indicates that as tree height increases, TCSA and canopy stretch increase with it. It also displays non-linear positive correlations of 0.43 and 0.35 with yearly growth rate and branching height, respectively. Annual growth rate had a positive correlation with TCSA, canopy stretch, and branching height, with values of 0.48, 0.56, and 0.41, respectively. The number of primary branches was negatively correlated with all other characteristics except height and TCSA. However, the number of main branches has a correlation value of ~ 0, indicating that there is no linear link between the variables.
The highly significant positive relationship between desirable traits will help a plant breeder because it may aid in the simultaneous enhancement of both characters (Shiva et al., 2017). In vegetative growth, plant height, canopy volume, and intermodal length were all positively correlated (Shiva et al., 2017). According to the findings Pandey et al., (2007), there were also significant positive associations between vegetative characteristics and yield. 0.35* 0.41** 0.34** -0.09 0.51*** 1.00 ***, **, *, ns = Correlation is significant at the 0.1%, 1% and 5% level, respectively

Conclusions
All vegetative growth parameters are affected by year and variety interaction, with the exception of the number of main branches. Tree height, trunk cross sectional area, and canopy stretch all showed an exponential graph as the