الفهرس 
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Abstract
Citrus are the most important fruit crops in the world after grapes. In Egypt, citrus are the prevalent fruit crop and its acreage ranked the first fruit crops.
This study was carried out during three successive seasons of 2019, 2020 and 2021 on 25 years old Balady mandarin trees budded on sour orange root stock and planted at 5 x 5 m apart.
The selected trees grown on the experimental orchard of Faculty of Agriculture, Assuit University Egypt. where the soil has a clay texture and well draing, surface irrigation was used , therefore , this study aimed to examine the effect of spraying potassium, micro nutrient and see weed extracts on yield and fruit quality of Balady mandarin.
Fourty eight healthy trees, uniform in vigor as possible were chosen. The chosen trees were divided into eight different treatments including the control, the treatments were as follows.
1- Control (spraying water only)
2- Liquid potassium 2%
3- Micronutrients 3%.
4- Seaweed extracts 2%.
5- Potassium 2% + Micronutrients 3%.
6- Potassium 2% + seaweed extracts 2%.
7- Micronutrients 3% + sea weed 2%
8- Potassium 2% + Micronutrients 3% + seaweed extracts 2%.
The selected trees received four sprays from each treatment at full bloom, just after fruit setting, first week of July and September.
Treatments were arranged in a randomized complete block design with three replications per treatment, two trees each.
The following parameters were measured during the three seasons.
1- Yield weight
2- Fruit number/tree
3- Fruit weight
4- Pulp weight (g)
5- Fruit volume (cm3)
6- Juice volume
7- Fruit length (L.) (cm)
8- Fruit diameter (D) (cm)
9- Fruit shape parameter
10- Total Soluble Solids % (TSS%)
11- Total acidity percentage
12- Vitamins C (mg/100 ml)
13- Total sugars
1-Yeild and its components:
The fruits were harvested at maturity stage and directly transferred to the laboratory of pomology Department.
1.1- Yield weight (Kg/tree):
All the studied treatments significantly increased yield weight during the three studied seasons. The best treatments concerning yield weight during the three season of study were spraying with potassium at 2% + micronutrients at 3% + seaweed extracts at 2%.
On the other side, the control tree produced the least value of yield weight during the three studied seasons.
1.2- Fruit number/tree:
The results took the same trend of yield weight (kg/tree). Hence, spraying with potassium at 2% + micronutrients at 3% + seaweed extracts at 2%, micronutrients at 2% + seaweed extracts at 2%, potassium at 2% + micronutrients and the potassium at 2% + seaweed extracts at 2% recorded the highest number of fruit/tree.
2- Fruit Physical characteristics:
2.1- Fruit weight:
All the treatments significantly increased the average fruit weight. The best treatments in this respect were potassium at 2% + micronutrients at 3% + seaweed extracts at 2%, micronutrients at 3% + seaweed extracts at 2%, potassium + seaweed and then potassium + micronutrients.
2.2- Pulp weight (g):
The results of pulp weight (g) took the same trend of fruit weight where the same superior treatments recorded the best results.
2.3- Peel weight (g):
There were no significant differences between all the treatments. During the 3rd season, micronutrients, potassium, micronutrients + seaweed and seaweed recorded the highest values.
2.4- Fruit volume (cm3):
The treatments significantly increased fruit volume (cm3) comparing with the control. The best treatments in this respect were potassium + micronutrients + seaweed extracts, micronutrients + seaweed extracts, potassium + micronutrients.
2.5- Juice volume (cm3):
The best results obtained from the trees sprayed with micronutrients followed by seaweed extracts and then micronutrients + seaweed extracts.
2.6- Fruit dimensions:
2.6.1- Fruit length (L.) (cm):
The treatment significantly increased the average fruit length during the three seasons of study. The superior treatments this respect were potassium + micronutrients + seaweed extracts followed by micronutrients, and then seaweed micronutrients + seaweed.
2.6.2- Fruit diameter (D) (cm):
Seaweed extracts, potassium + micronutrients + seaweed, potassium and then potassium + seaweed represented the highest values with no significant differences between them.
2.6.3- Fruit shape parameter:
During the three seasons of study and the combined analysis of the three seasons these were no significant differences between the treatments concerning the fruit shape parameter (L/D) ratio).
3- Fruit chemical characteristics:
3.1- Total Soluble Solids % (TSS%):
All the treatments during the 1st and 2nd season of study significantly increased the percentage of total soluble solids while in the 3rd season most of the treatments did not significantly affected the TSS% comparing with the control.
3.2- Total acidity percentage:
The beset treatments on decreasing the percentage of acidity were potassium + seaweed extracts and potassium and micronutrients.
3.3- Vitamins C (mg/100 ml):
Most of the treatments significantly led to an increase of V.C content in mandarin fruits. The best treatment in this respect was potassium + micronutrients + seaweed extracts which recorded 5.63 (mg/100 ml). While the control gave only 4.63 (mg/100 ml).
3.4- Total sugars:
All the treatments, with an exception of some treatments in the 3rd season, significantly increased the percentage of total sugars. Three seasons average data suggested that all the treatments significantly increased the percentage of total sugars. The best treatments in this respect were potassium + micronutrients + sea weed and potassium then potassium + micronutrients. The percentage of total sugars associated with the previous treatments were 10.99, 10.65 and 10.41%, respectively. Total sugars percentage of the control recorded the lowest value (8.80%).
According to previous results it could be concluded that spraying Balady mandarin trees with liquid potassium 2% + micronutrients 3% + seaweed extracts 2% four sprays at full bloom, just after fruit set, first week of July and September to improve yield and fruit quality.