# Evaluation of the Effect of Biostimulation on the Yielding of Golden Delicious Apple Trees
## 3 Results and Discussion
In 2008, 2019, 2011 and 2015, the trees of the studied apple variety had more than 150 apples per tree while in 2010 and 2017 they had less than 130. [PERSON] et al. (2003) report that applications of preparations based on seaweed extracts contribute to earlier flowering, better fruit set and fruit emergence of many crops [24]. Biostimulant formulations based on seaweed extracts enhance plant growth [25; 26; 27; 28; 29], and have positive effects on flowering parameters [30; 31; 32; 33]. Apple trees of the Golden Delicious variety had very good yields throughout the study cycle which were at a minimum level of 67.0 t \(\times\) ha\({}^{-1}\). The fruit yield of the studied variety ranged from 20.1 to 30.9 kg \(\times\) tree\({}^{-1}\) tj. from 67.1 to 102. 9 t \(\times\) ha\({}^{-1}\). Significantly the highest yield was obtained in 2015 and significantly the lowest in 2010. In 2008, 2009, 2011, 2012, 2015 and 2016 the total yield exceeded the threshold of 90 t \(\times\) ha\({}^{-1}\), regardless of the fertilization program which accounts for 60% of the entire research cycle. The percentage of fruits with a diameter of more than 7.5 cm ranged from 20.4 to 91.4% and differed significantly between the studied years. There were no significant differences in the percentage of large fruits with a diameter of more than 7.5 cm in the years 2009, 2012-2016. The values of this parameter in the mentioned years oscillated from 86.5 to 91.4%. In 2017 the share of large fruits in the total yield was at the level of 20.4%, regardless of the method of fertilization applied to Golden Delicious apple trees. In the study by [PERSON] and [PERSON] [34], it was proven that apple trees of the Elise, Sampion and Novamac cultivars on which the Goemar BM 86(r) biostimulant was applied, foliard had a higher total yield and a higher average weight and diameter of a single apple. The positive effect of the technology with biostimulation based on seaweed extracts on the percentage number of large fruits, i.e., with a diameter of more than 7.5 cm and on the marketable  
a, b,\(\sim\), \(\sim\), \(\sim\), \(\sim\), \(\sim\), \(\sim\), \(\sim\), \(\sim\) & \(\pm\) 4.9 & \(\pm\) 3.3 a & \(\pm\)yield in each year of the study was shown by [PERSON] et al. [4] where apple trees of the 'Szampion' variety were evaluated. The commercial yield ranged from 16.1 to 90.7 t \(\times\) ha\({}^{-1}\). A large scatter in the evaluation of this parameter was shown between the years of study. In 70% of the study years, the marketable yield was above 70.0 t \(\times\) ha\({}^{-1}\) and was significantly higher than in other years. Such a trend was observed in 2009, 2011-2016. 2017 had significantly the lowest commercial yield which reached the lowest level during the study period. Fruit weight ranged from 175.0 to 218.0 g regardless of the fertilization technology used. Significantly the heaviest apples were obtained in 2009, 2015 and 2016, the weight of a single fruit was at least 200.0 g. Apples with weight above 170.0 g were obtained in 2008, 2010 and 2017. The year 2010 was the least favorable for horticultural production. [35] showed that pear trees treated with the biostimulant Goemar BM(r) yielded more abundantly with pears having a larger diameter and weight of a single fruit. An increase in the quality of grape berries in the study of [36] was obtained after the application of a mixture of seaweed extract together with lime and magnesium. A positive effect on the apple weight after the application of such biostimulants was also demonstrated by [37] while [38] showed no effect of Goemar BM 86 formulation based on marine algae extract on the average weight of single fruit and total yield in apple crops. The yield volume of apple trees of the Golden Delicious variety during the 10 years of the study varied regardless of the combination used, from 64.6 t \(\times\) ha\({}^{-1}\) (2010-Biostimulation) to 111.6 t \(\times\) ha\({}^{-1}\) (2015-Control).