EFFECT OF SOME CHEMICAL THINNING COMPOUNDS ON FRUIT QUALITY OF TABLE

By DALIA MOHAMED HUSSEIN MOHAMED

B.Sc. (Pomology),Fac.Agric.,Cairo Univ.,2006 THESIS

Submitted In Partial of the Requirements of the Degree of MASTER OF SCIENCE

In Agricultural Sciences

(Pomology)

Department of Pomology

Faculty of Agriculture Cairo University

EGYPT 2017

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ABSTRACT

This investigation was conducted during two successive seasons (2009-2010) on two cultivars (Manzanillo and Eggizi Shami) in a private orchard in the Alex. desert road. The aim of this study is to investigate the effect of some chemical thinning agents GA3 (100,150 and 200 p.p.m), NAA (100,150 and 200 p.p.m) and Urea (4,6,8 and 10%) sprayed at full bloom, five days after full bloom, ten days after full bloom and fifteen days after full bloom on initial fruit set (twenty one days after full bloom), final fruit set (forty five days after full bloom), sixty days after full bloom and at harvest date. The effect of these treatments on fruit characteristics (fruit length, diameter and weight) and oil content of Manzanillo and Eggizi Shami olive cvs. was also studied. The results showed that used chemical thinning agents reduced fruit set significantly and improved fruit quality and oil content compared with control (sprayed with water only). Urea spray was the most effective in reducing fruit set compared with GA3 and NAA. The highest concentration was more effective than the lower one in each chemical component. Fruiting of Manzanillo cv. was significantly lower than Eggizi Shami cv. GA3 of studied showed moderate effect in reducing fruit set (between Urea and NAA). The most effective date in reducing fruiting was at full bloom, while the lowest was at fifteen day after full bloom. It could be recommended that spraying with Urea or NAA at moderate concentration (4% and 150 p.p.m) was effective in reducing fruit set and improving fruit quality and oil content in both cultivars of study.

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INTRODUCTION

Olive (olea europaea L.) is a species of the oldest cultivated fruits since its fossilized leaves dating to around 37,000 years ago have been discovered on the Aegean island of santorini.

The olive is belonged to the family oleaceae, which comprises of 22 genera and the genera Olea is one of them with 35 species (Heywood, 1978).The domesticated olives belong to the genus olea, species europaea, sub species sativa and number of the cultivated species is estimated more than 2500 cultivars.

Olive cultivation plays an important role in the economy of many countries in the Mediterranean basin, it isn‟t only increase the land value where the soil is unsuitable for other crops, but also contributes to soil conservation and helps to overcome environmental problems (Dennis, 1977)

Its fruit is of major agricultural importance in the Mediterranean region as the source of . The world production of olive, as shown in Table (1), was 20,344,342 tons. The major producer countries are Spain , Italy, Greece, Turkey, Morocco, Syria, Tunisia, Egypt, Algeria, Portugal and others, (FAO, 2013). Table1 : Countries and production with ton of olive trees. (FAO, 2013): Production Percent Country (Tons) (%) Spain 7,875,800 38.7 Italy 3,022,886 14.9 Greece 2,000,000 9.8 Turkey 1,676,000 8.2 Morocco 1,181,675 5.8 Syria 1,000,000 4.9 Tunisia 963,000 4.7 Egypt 510,000 2.5 Algeria 395,000 1.9 Portugal 350,900 1.7 Total 20,344,342 100

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Table 2 : Egyptian Governorates area and production of olives (Ministry of Agriculture and Land Reclamation, 2013): New land Old land Total Fruiting Total Fruiting Prod. Prod. Governorate area area area area (Ton) (Ton) (Fed.) (Fed.) (Fed.) (Fed.) N. Sinai 43,468 24,864 56,839 - - - Noubaria 37,739 19,440 143,856 - - - Matruh 28,960 21,867 56,286 - - - S. Sinai 13,860 9,661 14,714 - - - Ismailia 13,523 7,283 48,111 6,048 5,623 37,146 Fayoum 10,671 10,671 49,268 4,220 4,219 19,479 Cairo 9,908 5,720 3,844 - - - (Others) 30,261 23,882 114,135 4,085 3,795 19,392 Total 188,390 123,388 487,053 14,353 13,637 76,017

The olive tree produces more flowers and sets more fruits than can be sustained by the available raw materials. This condition of heavy crop results in limb breakage; small fruit of less value, late maturity and poor quality; reduced vegetative growth; and ultimately depressed prices. The year following excessive production the return crop may be so depressed that harvest would not be economical. Use of (NAA) at(150 p.p.m) as a foliar spray effectively reduces crop size and helps to ensure larger individual fruit size the current year and return cropping the next year. Martin et al., (1980). The present study aimed to investigate: 1- The effect of some chemical thinning compounds (GA3 , NAA and Urea) used at full bloom, + five days after full bloom, + ten days after full bloom and fifteen days after full bloom on fruit set of Manzanillo and Eggizi Shami olive cvs.

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2- The effect of previous chemical thinning compounds on fruit physical characteristics in both studied cvs. 3- The effect of chemical thinning compounds on fruit oil content of both studied cvs. REVIEW OF LITERATURE

1- Problems of olive production Olive (Olea europaea L.) shows alternate bearing, with unreliable cropping patterns and inconsistent fruit size and quality every year. Olive trees are prone to bear fruit in alternate cycles (Krueger et al., 2004; Lavee, 1996). The heavy crop loads of “on” seasons give rise to fruit of very poor quality while in “off” seasons, the increase in fruit size does not make up for the loss in yield (Krueger et al., 2004). The thinning of olive fruit in intensively irrigated orchards is a prerequisite for obtaining more suitable fruits heavy cropping years (on years). Olive growers are advised to do fruit thinning during “on” year crop to reduce the occurrence of alternate bearing ( Abu-Zahra and Al-Dmoor, 2013).

In many countries, thinning NAA is used to minimize alternate bearing behavior in olives (Barone et al., 2013). Decreasing the crop load early in “on” seasons increases fruit quality in the year of application, and also increases the crop load in the subsequent season, thereby reducing the negative effects of yield alternation (Dag et al., 2009). Application of NAA at 100 - 150 p.p.m. at 15 days after full bloom (DAFB) has been used to chemically thin olives in various countries (Lavee, 2006). 2- Alternate bearing. Alternate bearing is a widespread phenomenon in many fruit trees and a major problem facing olive growers. Alternate bearing causes substantial fluctuation in income for olive farmers, as the heavy crop loads of “on” season give rise to very poor fruit quality, small fruit size in several oil cvs. (Dag et al., 2009) and table olive cultivars (Hartmann, 1952; Martin et al., 1980., Krueger et al., 2004., El-Sharony., 2012).

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Fruit size is the limiting factor, as too small fruit do not qualify as table olives (Lavee, 2006), thus resulting in a significant loss of income, whereas the increase of fruit size in an “off‟‟ year does not make up for the loss in yield (Krueger et al., 2002). That said, not only does alternate bearing create challenges regarding operating and utilizing storage and processing facilities, but also with the planning of labour and other horticultural farming practices (Morselise and Goldschmidt, 1982). Olives are valued based on fruit size. Heavy crops have preponderance of small fruit that are expensive to pick and of little value. Further, olives are alternate bearing; light crops invariably follow heavy crops. Fruit thinning has been shown to reduce crop load, improving size of the remaining fruit and to minimize alternate bearing (Ferguson et al., 1994). Chemical thinning has certain advantages over hand or mechanical thinning: low thinning cost, greater size of olives, earlier maturation and better quality and decrease in biennial bearing (Loonnis, 2008).

3- Solving of alternate bearing. Excessive crops must be reduced early in the “on” season to overcome biennial bearing and to obtain adequate fruit quality. Fruit thinning can rectify or ameliorate an established alternate bearing cycle and is also a management technique used to increase fruit size (Link, 2000). Hartmann et al.,(1980) found that there are different cultural methods are commonly applied in the world in order to decrease the severity of alternation and improve the fruit quality in olive as well in many fruit species showing alternation. These methods can be summarized as breeding, fertilization, pruning, girdling, thinning, using of plant growth regulators and applying convenient harvest (Hartmann et al., 1980, Morselise and Goldscihmodt, 1982, Poli, 1987, El- Sharony, 2012). -Thinning. 4-Types of thinning.

a. Hand thinning: Stino et al., (2010) studied the effects of manual thinning by removing 25 and 50% of the fruit set and foliar application of Pix (Mepiquat

6 chloride MC: N, N-dimethyl piperidiniurn chloride) at 500, 1000, 1500 and 2000 p.p.m (during the on‟ season) were assessed as tools to enhance fruiting of and Manzanillo olive cultivars in the off season. Data clarified that manual thinning by removing 50% of the fruit set was the most effective treatment in increasing flowering density, sex ratio setting and yield. The attained effect was assumed to be due to reducing the number of fruits in the 'on' year which lead to increasing stored nutrients and assimilates in the on' year and or due to decreasing the inhibitory effect of seeds on floral bud induction and differentiation leading to better flowering and fruiting in the 'off year.

Elizabeth, (2013) said that Fruit thinning by hand is effective, but it isn‟t practical due to high labor costs , However, for a few trees in the home garden, it may be an acceptable alternative. For maximum benefit, thinning should be completed 3 weeks after full bloom. Later thinning contributes less to larger fruit size and does not reduce alternate bearing. The following points should be observed by the home producer when hand thinning .

b. Chemical thinning.

- Chemical compounds used in chemical thinning a. Naphthalene acetic acid (NAA) Chemical thinning has certain advantages over hand or mechanical thinning: low thinning cost, greater size of olives, earlier maturation and better quality and decrease in biennial bearing (Loonnis, 2008).

It has important role in fruit formation, abscission cell elongation, apical dominance, photoperiod and geotropism (Haidry et al., 1997). Application of NAA (100 and 150) mg/l 15 days after full bloom has been used to chemically thin olives in various countries (Lavee, 2006).

Elizabeth, (2013) noticed that NAA is absorbed into the leaves and fruit and is then translocated to the fruit stems. An abscission layer forms during the first two weeks after NAA application, causing fruit drop. Only fruit are removed, and the leaf-to-fruit ratio is changed. Therefore, chemical

7 thinning is potentially more effective in mitigating the effects of alternate bearing than pruning. Pruning plus chemical thinning is recommended for crop control in 'Manzanillo'; however, chemical thinning is not recommended for 'Sevillano'cv.

Using the concentration of (200 p.p.m) NAA at FB+5 days resulting in a strong reduction in fruit set and increase in fruit size and return bloom. Treatments later than FB+15 and with concentrations of (200 p.p.m) and higher should be avoided (Barone et al., 2013). b. Gibbrellic acid (GA3)

Abd El-Naby et al., (2012) studied spraying the olive trees with GA3 at (75 p.p.m) on first December impact on reducing the density of flowering, fruit set, decreased the yield of 2009 season as compared with most GA3 concentrations, while control gave the highest yield. On the contrary, in 2010 season GA3 at (75 p.p.m) on first December gave the highest yield, while control gave the lowest yield. In 2011 season, the control gave the highest yield while the lowest yield was observed when trees were sprayed with GA3 at (75 p.p.m) at mid-January. Spraying the olive trees with GA3 at (75 p.p.m) on first December reduced the alternate bearing index (ABI) in comparison with other GA3 concentrations (0, 25, 50 p.p.m) in different times. Spraying olive trees with GA3 at (75 p.p.m) on first December led to an increase in vegetative growth and to improve in fruit characteristics and increase the oil percentage. Abd El-Razek et al., (2013) found that using GA3 treatments (50 & 100 mg/L) produced lower yield than those of salicylic acid and benzyl adenine. Nafea and Abdulfatah, (2014) found that olive cultivation can be successfully carried out in Iraq, Ashrasie, is one of the most common olive, which is mainly used for green pickles, as foliar application on the trees, (GA3) (75, 100 and 125) mg/l, (NAA) (50, 100) mg/l in addition of control was done after 15 days after fruit set for two seasons 2009-2010, 2010-2011, fruit harvested at mid- October. The effect of growth regulators (GA3 and NAA) was not uniform in different treatments. However, GA3 (100 and 125)

8 mg/l in combination with NAA (50 and 100) mg/l gave maximum value of most physical characteristics, fruit set, yield and oil of olive trees cv. Ashrasie . Gibbrellic acid treatments increase the weight, length, width of olive fruits, stone weight and flesh weight than untreated ones, (Rotundo and Gioffre, 1984), improvement fruit weight and flesh: seed ratio, (Barut and Eris, 1995; Ramezani and Shekafandeh, 2009). c. Urea Lolaei et al., (2014) used three levels of boric acid (0, 50, and 100 mg/l) and of Urea (0, 500, and 1000 mg/l) sprayed on olive. The results showed that application of Urea mixed with boric acid significantly increased fruit weight and number at 0.01 probability level. The highest fruit number was produced using 100 mg/l of boric acid and 500 mg/l of urea and it was significantly different from the control. Spraying application of boric acid and Urea significantly increased B and N content of the leaves. The results of the study revealed that the treatment (boric acid at 100 mg/l and Urea at 500 mg/l) resulted in the highest oil content of olive. El-Sherkawy et al., (2010) studied the effect of Urea at (2% and 3%) on biennial bearing index, fruit quality and vegetative growth of Picual olive trees in both "On" and "Off" years. The obtained results indicated that Urea treatments reduced alternate bearing severity as compared with the control during the four seasons of study through thinning fruits of on-years (2006&2008) and increasing flowering and fruiting in off-years (2007&2009). In addition, the treatment produced fruits with good quality sincerity increased fruit weight, flesh/stone ratio, fruit dimensions and oil content. 5-Time of application Eris and Barut (1993) found that application of NAA (100 and 150 p.p.m) 10 days after full bloom and GA3 (25,50 and 100 p.p.m) at fruitlet to decrease the sevirity of alternation in Gemlik olive cv. by improving the yield. This was found with GA3 which increase fruit set but NAA decrease fruit set.

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Used various concentrations (2, 4 and 6%) of Urea as chemical thinner were applied to „‟cv. at full bloom (FB), FB+10, FB+20. Urea reduced fruit set significantly only when applied at FB+20, at fruitlet stage. Final fruit set was reduced by about 50% as compared to the control plants treated with 6% urea at FB+20. Crop load and fruit characteristics were affected by treatments (Barattà et al., 1990). Application of NAA at (100 and 150) mg/l 15 days after full bloom has been used to chemically thin olives in various countries (Lavee, 2006). 6- Effect of thinning compounds on physical characteristics Nafea and Abdulfatah, (2014) found that foliar application on trees (GA3) (75, 100 and 125) mg/l, NAA (50 and 100) mg/l in addition of control was done after 15 days after fruit set for two seasons 2009-2010, 2010-2011, fruit harvested at mid- October. The effect of growth regulators (GA3 and NAA) was not uniform in different treatments. However, GA3 (100 and 125) mg/l in combination with NAA (50 and 100) mg/l gave maximum value of most physical characteristics, fruit set, yield and oil of olive trees.

El Sherkawy et al., (2010) showed that spraying Ethrel (100, 200, 300 p.p.m) , NAA at ( 100 p.p.m, 150 p.p.m ) and Urea at 2% and 3% at 15 days after full bloom in on-years of biennial bearing cycle of Picual olive cv. reduce alternate bearing severity as compared with the control during the four seasons of study through thinning fruits of on-years (2006&2008) and increasing flowering and fruiting in off-years(2007&2009) and improved fruit quality. In addition, the treatment produced fruits with good quality sincerity increased fruit weight, flesh/stone ratio, fruit dimensions and oil content, The most effective treatments were, Ethrel at 300 p.p.m and NAA at 150 p.p.m. Various concentrations (2, 4, and 6%) of Urea as chemical thinner were applied to „Nocellara del Belice‟ olive cv. at full bloom (FB), FB+10, FB+20. Crop load and fruit characteristics were affected by treatments. When Urea was applied 20 days after full bloom, crop load and the number of small drupes decreased and fruit weight increased with increasing concentrations of Urea. (Barattà et al., 1990).

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7- Effect of thinning compounds on oil content Nafea and Abdulfatah , (2014) found that foliar application on olive trees, GA3 (75, 100 and 125) mg/l, NAA (50 and 100) mg/l in addition of control was done after 15 days after fruit set for two seasons 2009-2010, 2010-2011, fruit harvested at mid- October. The effect of growth regulators (GA3 and NAA) was not uniform in different treatments. However, GA3 (100 and 125) mg/l in combination with NAA (50 and 100) mg/l gave maximum value of oil of olive trees cv.

Taghipour et al.,(2011) used three levels of boric acid (0, 50, and 100 mg/l) and of Urea (0, 500, and 1000 mg/l) were sprayed. The results of the study revealed that the treatment (boric acid at 100 mg/l and Urea at 500 mg/l) resulted in the highest oil content of olive. SUMMARY AND CONCLUSION This work was carried out in two seasons (2009 – 2010) on 13 years old of two olive cultivars (Eggizi Shami and Manzanillo cvs.) in sandy soil of a private orchard at Alex. desert road (50 kilo meters from Cairo).

The trees selected for this study were planted at 4x5 meters spaces and subjected to the same horticultural practices such as fertilization, irrigation, pruning and pest control. Trees were sprayed with Gibbrellic acid (GA3) concentrations 100,150 and 200 p.p.m, Naphthalene acetic acid (NAA) at 100,150 and 200 p.p.m, Urea at 4,6,8, 10% and control trees were sprayed with water only.

Treatments were applied at : Full bloom (FB), full bloom+5 days after full bloom, full bloom+10 days after full bloom and full bloom+15 days after full bloom.

Number of fruits/m at (21 days after full bloom), number of fruits/m at (45 days after full bloom), number of fruits/m at (60 days after full bloom) and number of fruits/m at harvest time. Fruit characteristics and oil percentage were determined.

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The experiment was laid out as a randomize block design with three factors (cultivars * dates * treatments). The treatment means were compared by least significant difference (L.S.D.) test as significance level of 0.05 as given by Snedecor and Cochran (1976) using Mstat-c program. (1989).

The obtained results can be summarized as follows: 1- At 21 days after full bloom the number of fruits per meter at (FB+ 21 days) was significantly higher in control treatment while, it was the lowest with Urea treatment 10%, also fruits per meter was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., the number of fruits per meter was significantly higher in treatment sprayed at (FB +15 days) while, it was the lowest in treatment sprayed at (FB), the number of fruits per meter was the highest in treatment NAA 200 p.p.m with Manzanillo cv. at (FB +15 days), while it was the lowest with treatment GA3 200 p.p.m in Manzanillo cv. at (FB). 2- At 45 days after full bloom the number of fruits per meter at (FB+ 45 days) was significantly higher with control treatment. While, it was the lowest with Urea 10% and Urea 6% treatments, also fruits per meter was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., fruits per meter was significantly higher in treatment sprayed at (FB+15days) while, it was the lowest in treatment sprayed at (FB), fruits per meter was the highest in control treatment in Eggizi Shami cv. at (FB), while it was the lowest in GA3 200 p.p.m treatment in Manzanillo cv. at (FB). 3- At 60 days after full bloom the number of fruits per meter at (FB+ 60 days) was significantly higher in control treatment. While, it was the lowest in Urea 6 %, NAA 150 p.p.m and Urea 10% treatments, also fruits per meter was significantly higher (12.63 fruits/m) in Eggizi Shami cv. compared with Manzanillo cv. which recorded (8.78 fruits/m), fruits per meter was significantly higher in treatment sprayed at (FB+15 days) while, it was the lowest in treatment sprayed at (FB), fruits per meter was the highest in control treatment in Eggizi Shami cv. at (FB), while it was the lowest in GA3 100 p.p.m treatment in Eggizi Shami cv. at (FB). 4- At harvest time the number of fruits per meter was significantly higher in control treatment. While, it was the lowest in Urea 6 % and NAA 150 p.p.m

12 treatments, also fruits per meter was significantly higher (12.63 fruits/m) in Eggizi Shami cv. compared with Manzanillo cv. which recorded (8.78 fruits/m), fruits per meter was significantly higher in treatment sprayed at (FB +15 days) while, it was the lowest in treatment sprayed at (FB), fruits per meter was the highest in control treatment in Manzanillo cv. at (FB+5 days), while it was the lowest in GA3 100 p.p.m and NAA 200 p.p.m treatments in Manzanillo cv. at (FB). 5- Fruit length was significantly higher in Urea 6% treatment. While, it was the lowest in NAA 100 p.p.m treatment, also fruit length was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., fruit length was significantly higher in treatment sprayed at (FB +10 days) while, it was the lowest in treatment sprayed at (FB+15 days), fruit length was the highest in control treatment in Eggizi Shami cv. at (FB+10 days), while it was the lowest in NAA 150 p.p.m treatment in Manzanillo cv. at (FB+5 days).

6- Fruit diameter was significantly higher in NAA 150 p.p.m treatment. while, it was the lowest in GA3 100 p.p.m treatment, also fruit diameter was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., fruit diameter was significantly higher in treatment sprayed at (FB+5days) while, it was the lowest in treatments sprayed at (FB and FB+10 days), fruit diameter was the highest in NAA 150 p.p.m treatment in Eggizi Shami cv. at (FB+5 days), while it was the lowest in GA3 100 p.p.m treatment in Manzanillo cv. at (FB). 7- Fruit weight was significantly higher in Urea 6% treatment. While, it was the lowest in NAA 100 p.p.m treatment, also fruit weight was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., fruit weight was significantly higher in treatment sprayed at (FB +10 days) while, it was the lowest in treatment sprayed at (FB+15 days), fruit weight was the highest in control treatment in Eggizi Shami cv. at (FB+10 days), while it was the lowest in NAA 150 p.p.m treatment in Manzanillo cv. at (FB+5 days).

8- Fruit L/D ratio was significantly higher in GA3 100 p.p.m treatment. while, it was the lowest in NAA 100 p.p.m treatment, also fruit L/D ratio was significantly higher in Eggizi Shami cv. compared with Manzanillo cv.,

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fruit L/D ratio was significantly higher in treatment sprayed at (FB) while, it was the lowest in treatment sprayed at (FB+15 days), fruit L/D ratio was the highest in GA3 100 p.p.m treatment in Eggizi Shami cv. at (FB), while it was the lowest in NAA 100 p.p.m treatment in Manzanillo cv. at (FB+15 days).

9- Seed diameter was significantly higher in Urea 6% treatment. while, it was the lowest in GA3 150 p.p.m, GA3 200 p.p.m, NAA 200 p.p.m, Urea 4%, Urea 8% and control treatments, also seed diameter was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., seed diameter was significantly higher in treatment sprayed at (FB+5 days) while, it was the lowest in treatment sprayed at (FB+10 days), seed diameter was the highest in NAA 100 p.p.m and Urea 6% treatments in Eggizi Shami cv. at (FB and FB +10 days), while it was the lowest in NAA 200 p.p.m. treatment in Manzanillo cv. at (FB+5 days).

10- Seed length was significantly higher in Urea 4% and Urea 6% treatments. While, it was the lowest in NAA 150 p.p.m treatment, also seed length was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., seed length was significantly higher in treatment sprayed at (FB+10 days) while, it was the lowest in treatment sprayed at (FB+5 days), seed length was the highest in GA3 200 p.p.m treatment in Eggizi Shami cv. at (FB and FB +10 days), while it was the lowest in NAA 150 p.p.m treatment in Manzanillo cv. at (FB+5 days).

11- Seed weight was significantly higher in Urea 6% treatment. While, it was the lowest in control treatment, also seed weight was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., seed weight was significantly higher in treatment sprayed at (FB +5 days) while, it was the lowest in treatment sprayed at (FB+15 days), seed weight was the highest in GA3 100 p.p.m treatment in Eggizi Shami cv. at (FB +5 days), while it was the lowest in GA3 100 p.p.m and Urea 4% treatments in Manzanillo cv. at (FB and FB +15 days).

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12- Seed L/D ratio was significantly higher in Urea 4% treatment. While, it was the lowest in NAA 150 p.p.m treatment, also seed L/D ratio was significantly higher in Eggizi Shami cv. compared with Manzanillo cv., seed L/D ratio was significantly higher in treatments sprayed at (FB+15 and FB +10 days) while, it was the lowest in treatments sprayed at (FB and FB+5 days), seed L/D ratio was the highest in GA3 200 p.p.m treatment in Eggizi Shami cv. at (FB +10 days), while it was the lowest in GA3 200 p.p.m and Urea 4% treatments in Manzanillo cv. at FB.

13- Oil content recorded higher percentage with thinning treatments compared with control such as 20.99 % in Urea 4% at FB+10 at Manzanillo cv. but it recorded 15.35 % at same time and cultivar.

14- Similar results were noticed with Eggizi Shami cv. in thinning treatments which oil % was higher compared with control.

It could be concluded that: 1- Using chemical thinning compounds GA3, NAA and Urea are effective in reducing fruit set in both studied cultivars (Manzanillo and Eggizi Shami). 2- Using chemical thinning compounds GA3, NAA and Urea are effective in improving fruit quality and oil content in both studied cultivars (Manzanillo and Eggizi Shami). 3- The highest concentration of each chemical thinning compound was more effective compared to lower concentration. 4- Urea spray was more effective in reducing fruiting compared to GA3 and NAA in both studied cultivars. 5- In general, Manzanillo fruit set was lower than Egizzi Shami at the same conc. and time of application. 6- Spraying chemical thinning compounds at full bloom reduced fruit set significantly compared with spraying at other dates. 7- It is applicable to spray Urea as chemical thinning compound at (4%) at ten days after full bloom .

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