Effect of Fruit Thinning Rate on Yield and Fruit Quality of Zaghloul and Haiany Date Palms

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1 Australian Journal of Basic and Applied Sciences, (1): , ISSN Effect of Fruit Thinning Rate on Yield and Fruit Quality of Zaghloul and Haiany Date Palms Mostafa R.A.A. and M.M. El Akkad Horticultural Dept, Fac. Agric, Assiut University, Assiut, Egypt. Abstract: The effect of bes and strands thinning on yield and fruit quality of Zaghloul and Haiany date palms was investigated during three successive seasons, 9, 1 and. Fruit thinning was carried out by adjusting the number of to, or 9 bes. The nine, however, were especially thinned to,, 3, 3, and. The results of the present study indicated a significant negative correlation between b weight and b-number/palm and a positive one between the b weight and strand numbers/b. Reducing the strand-numbers/b to either or strands significantly decreased the b weight and yield/palm compared with the unthinned ones. A remarkable improvement on fruit quality was noticed, after the fruit thinning in comparison to the unthinning. Thinning either bes or strands lead to a significant increase in the fruit weight, size and flesh percentage as compared to unthinning at all. Fruit thinning also positively improved the date palm fruit chemical properties. It is worth notable that, leaving 3 to 3 would result in a considerable yield characterized by high fruit quality of Zaghloul and Haiany date palms. Key words: Fruit quality, thinning,fruit chemical properties. INTRODUCTION Flower or fruit thinning is a critical cultural practice in the date palm production chain that affects fruit development, quality, yield and regulate the tree yearly bearing. Thinning process is generally practiced either manually or chemically. There is much concern regarding the use of chemicals on the environmental pollution and health aspects. Therefore, development of a more save and economic thinning agent for the date palm is critically required especially under harsh conditions (Hassaballa et al., 1983; Khalifa et al., 198; Awad, 6 and Abdel-Galil et al., 8). Such results could be obtained either by reducing the number of bes per palm or fruits per b. Fruit thinning treatments may lead to a decrease of the total yield, soluble tannins %, crude fibers % and total acidity % and are responsible for improving the weight, size and dimensions of fruit, pulp weight %, total soluble solids %, total and sugar contents. Thinning by removing 1-3% of bes number significantly increased the b weight compared to unthinning (Akl et al., ; El-Assar, and Alwasfy & Mostafa, 8). Removing 3% of entire spilelets from "Shamran" and "Nabetet Ali" b center gave a reasonable yield, advancing ripening and best fruit quality (Godara et al., 199; Al-Ghamdi et al., 1993 and El- Shazly, 1999). Zaghloul date fruit weight, dimension, TSS and sugar contents were increased due to strands shortening or reducing its number. Optimum yield with good fruits quality were obtained with 1-3% of fruits thinned as early as to weeks after pollination (Khalifa et al., 198; Abdel-Hamid, ; Hammam et al., ; Bassal and El-Deeb, ; Marzouk et al., and Al-Wasfy and Mostafa, 8). Flower thinning enhanced fruit quality and regulated the yield of Zaghloul, Haiany, Halawy, Sewy and Amry date palm cultivars. In addition removing -3% of b strands by either thinning out or cutting back before pollination were effective treatments (Marzouk et al., and Abdel-Galil et al., 8). Thinning with water significantly decreased both b weight and yield/palm at the tamr stage especially when applied after hours following pollination (Awad, 6). Weight and size of fruits, as well as total soluble solids and reducing sugars of Shahani and Khadrawy date cultivars were improved with the thinning practices over unthinning one (Tavakkoli et al., 6 and Nirmaljit et al., 6). So, this study aimed to find out the effect of different methods of fruit thinning on yield and fruit quality; such practices might be very essential and of great importance for palm growers. MATERIALS AND METHODS This study was carried out during three successive growing seasons (9, 1 and ) on Zaghloul and Haiany date palms grown at the Experiment Orchard of Faculty of Agriculture, Assiut University, Egypt. Zaghloul and Haiany dates were represented by fourteen palms, of years old, with uniform vigour and in good physical condition, free of insect damage and diseases. Corresponding Author: Mostafa, Horticultural Dept, Fac. Agric, Assiut University, Assiut, Egypt. 333

2 Aust. J. Basic & Appl. Sci., (1): , The number of inflorescences per palm were adjusted to nine by removing excess earliest, latest and smallest clusters. The retained bes were thinned to a constant number of strands. Artificial pollination was uniformly performed in respect of source, date and method. The involved palm trees received the regular horticulture practices. Nine fruit thinning treatments were done on the selected palms as follows: 1- Control: adjusting the number of bes to nine, without fruit thinning. - Thinning by adjusting the number of bes to five (T 1 ) 3- Thinning by adjusting the number of bes to seven (T ). Moreover, six fruit thinning were done on selected bes of other retained five palms as follows: 1- Thinning by adjusting the strands number/b to strands (T 3 ) - Thinning by adjusting the strands number/b to strands (T ) 3- Thinning by adjusting the strands number/b to 3 strands (T ) - Thinning by adjusting the strands number/b to 3 strands (T 6 ) - Thinning by adjusting the strands number/b to strands (T ) 6- Thinning by adjusting the strands number/b to strands (T 8 ). Each treatment was consisted of either three or five replicates, one either palm or b per each, respectively. Thinning of either bes or strands were done before pollination or after four weeks of pollination, respectively. The experiment was arranged in a complete randomized block design including nine treatments with three or five replications (one palm or b each), respectively. All bes were harvested when they reached to the commercially derived color then ultimate fruit retention were estimated. B weight then the yield/palm (kg) was estimated. Samples of fruits were picked at random from each b for the determination of some physical and chemical fruit properties, according to A.O.A.C. methods (198). Data were subjected to statistical analysis according to the procedure reported by Gomez and Gomez (198) and Snedecor and Cochran (199). Treatments means were compared by the least significant difference test (L.S.D.) at the % level of probability in the three experimental seasons. RESULTS AND DISCUSSION This study was carried out to reveal the effect of bes and strands thinning on the yield and fruit quality. Yield: Data presented in Table (1) show the effect of bes and strands thinning on ultimate fruit retention, b weight and yield/palm of Zaghloul and Haiany date palm cultivars during 9, 1 and seasons. It is obvious from the data that the results took a similar trend during the three studied seasons. Results indicated a significant negative correlation between ultimate fruit retention, b weight and bes number/palm. On other side, there were a significant positive correlation between b weight and strands number/b. Whereas, such correlation was significantly negative between ultimate fruit retention and strands number/b. Reducing strands number/b to either or strands significantly decreased the b weight and yield/palm compared with the check treatment (nine b/palm without fruit thinning). However, reducing strands number/b to either 3, 3 or strands unsignificantly decreased both the b weight and yield/palm compared to the control. Moreover, thinning to strands unsignificant increase such traits. Contrarly, thinning the bes to either or significantly increased the fruit retention and b weight compared to 9 whereas, reducing bes number/palm to bes significantly decreased the yield/palm. Reducing either bes number/palm or resulted in a significant increasing in fruit retention. The highest fruit retention percentage were recorded due to reduction of the to b (T 1 ), as well as, reduction the strands to (T 3 ). These values were attained (.19 &.3%), (1. & 3.8%) and (38.8 &.3%) due to T 1 and T 3 against (3., 36.3 & 33.1%) for unthinning (control) on Zaghloul date palm during the three studied seasons, respectively. Also, the recorded highest fruit retention percentage on Haiany date palm were (1.9 &.8%), (3.1 & 6.8%) and (. &.%), (36., 3.3 & 38.%) in the three studied seasons, respectively. The heaviest bes were obtained as a response to the reduction of the b number/palm to bes, whereas, the least one was recorded on the palm that is thinned by leaving. These results were true in both the cultivars and during the three studied seasons. The obtained b weights of Zaghloul date palm were (18.1, 1.8, 8.3, 9.9, 1.,.6, 1., 1.6 and 1. kg), (1.3, 1., 9.1, 1., 1.6, 13.1, 13., 1. and 1. kg) and (., 16.9, 9.3, 1.,.9, 1., 13., 13.9 and 13. kg) due to the thinning to, (T 1, T ), leaving,, 3, 3, and es (T 3, T, T, T 6, T, T 8 ), compared to the control during the three studied seasons, respectively. The increment percentage of the b weight due to the process of b thinning over unthinned ones (control) were (8.36 & 1.31%), (.1 &.%) and (3.1 & 8.3%) for T 1 and T during the three studied seasons, respectively. Whereas, the decrement percentage of b weight due to reduction the 33

3 Aust. J. Basic & Appl. Sci., (1): , compared to unthinned ones (control) were (31.6 & 18.8%), (3.6 &.%) and (9. &.%) due to leaving and (T 3 & T ) during the three studied seasons, respectively. Also, the recorded b weights of Haiany date palm were (19.3, 1., 9., 1.,., 1., 1.6, 13.1, and 1. kg), (1.8, 16.3, 9.,.6, 1., 13., 13., 13.9 and 13.6 kg) and (., 1., 1., 1., 13.6, 1.1, 1., 1. and 1. kg) due to T 1 to T 8 compared to the control, during the three studied seasons, respectively. Moreover, the increment percentages due to T 1 and T were (3.8 &.1%), (6.9 & 19.8%) and (.1 & 18.96%) during the three studied seasons, respectively. These results may be attributed to the increase of fruit retention on b and the increase in fruit weight as a result of increased supply of food materials to each individual fruit and consequently, the heavy b weight at harvest. Table 1: Effect of fruit thinning methods on fruit retention (%) and b weight (kg) of Zaghloul and Haiany date palm cultivars during 9, 1 and seasons. Fruit retention B weight (kg) Season Control T T T T T T T T L.S.D Table : Effect of fruit thinning methods on yield/tree (kg) and fruit weight (g) of Zaghloul and Haiany date palm cultivars during 9, 1 and seasons. Yield/tree Fruit weight (g) Season Control T T T T T T T T L.S.D On the other hand, thinning by reducing either the b/palm to or the to or lead to a significant decrease in the yield/palm as compared with control. The obtained yield/zaghloul palm were (9., 13.6,.,, 99., 1., 18., 3. and 19.8 kg/palm), (16., 1., 8., 93.8, 3.9, 8.3, 1.6, 13.3 and 16. kg/palm) and (., 8.3, 83., 9., 1.1,.1,., 1.1 and 8.8 kg) due to T 1 to T 8 compared to the control, during the three studied seasons, respectively. The decrement percentages of yield/zaghloul palm were (1., 31.1 & 18.8%), (1., 3.6 &.6%) and (1.81, 9. &.3%) due to T 1, T 3 and T during the three studied seasons, respectively. In addition, the obtained yield/haiany palm were (96., 19.9, 83.3, 96., 13.1, 33

4 Aust. J. Basic & Appl. Sci., (1): , 19.8, 3.,.9 and.9 kg/palm), (19.,.1, 8., 1.,., 8.8, 8.8, 1.1 and 1. kg/palm) and (., 1., 91.8,.3, 1., 16.9, 18., 13.3 and 13. kg/palm) due to T 1, T, T 3, T, T, T 6, T, T 8 and control, during the three studied seasons, respectively. The corresponding decrement percentages were (1.6, 6. & 1.%), (1.9, 3. & 1.1%) and (13.9, 9.66 & 1.1%) due to T 1, T 3 and T during the three studied seasons, respectively. Such reduction in the yield may be attributed to the great reduction in number of fruits per palm or b as a result of some bes or strands removal. These results are in agreement with those of Khalifa et al. (198), Moustafa (1998), El-Shazly (1999), Abdel-Hamid (), Hammam et al. (), Marzouk et al. (), Al-Wasfy and Mostafa (8) and Abdel- Galil et al. (8) who concluded that the fruit thinning by removing one third (central or strand-tip) decreased the yield compared with control. Fruit Properties: Physical Characteristics: Data presented in Tables ( & 3) show the efficiency of different treatments of fruit thinning on some physical fruit properties of Zaghloul and Haiany dates. It is obvious that fruit dimensions and flesh percentages reacted similarly taking the same trend of fruit weight in response to the fruit thinning treatments for both the studied cultivars. Data showed that fruit weights were significantly increased as a result of fruit thinning treatment comparable to unthinned ones (control). The Zaghloul fruit weights were (18., 16., 3.,., 1.6, 19.36, 18. & 1. g), (1., 18.3,.,., 3.,.3, 1.6 &. g) and (3.,.8, 9.1, 6.8, 6.,., 3.8 &.1 g) due to T 1 to T 8 compared to the control 1.1, 16.8 & 18.1 g, during the three studied seasons, respectively. The increment percentage of fruit weight due to thinning treatments over unthinned ones were (., 1., 61.6, 3.8, 9.3, 33.3, 6.81 & 18.88%), (9., 1.9, 3.3,.1, 1., 3., 3.8 & 3.9%) and (31.1, 1.9, 6., 8.,.1, 36., 31. &.38%) due to T 1 to T 8 during the three studied seasons, respectively. The corresponding, Haiany fruit weights were (., 18.8,., 3.6,.9, 1.8,.9 & 19. g), (.6,.3,.,.6,.3, 3.6, 3.3 & 1.18 g) and (3., 1.,.8, 6.,.8,.3,.1 &.8 g) due to T 1 to T 8 compared to control 1.6, 1. & 1.9 g. Also, the increment percentage were attained (9.93,.1, 6.6, 1.8,., 39., 33.9 & 6.6%), (31.39, 18., 6.1, 8.83,.9, 3.1, 3.6 & 3.1%) and (31.8, 18.3,.31, 6.3,.13, 3., 3.63 &.3%) due to T 1 to T 8 during the three studied seasons, respectively. Therefore, fruit thinning by removing some strands significantly improved the physical fruit traits as compared to either the b removal or control. Moreover, leaving,, 3 or 3 strands was more effective compared to other thinning treatments. Such finding may be due to the reduction of either the number of bes per palm or fruits per b that consequently lead to the improvement of the ratio of leaves to fruits number, induce a better supply of food materials (carbohydrates) that are manufactured in the leaves. Such fruit thinning treatments are very important in dates production since the increase in fruit weight and size is the most important target than total yield due to the increase in fruit weight induce an increase in packable yield. Fruit Chemical Constituents: It is noticed, from data in Tables ( & ) that all fruit thinning significantly increased the total soluble solids and sugar contents as compared to unthinned ones. It is, also obvious from the obtained data that the total sugar contents taking the same trend of change as total soluble solids in response to the effect of fruit thinning treatments during the three studied seasons for both the studied cultivars. The improvement in fruit chemical quality was associated with increasing the number of either the bes or the strands removal. The highest values of total soluble solids and sugar contents in dates juice were obtained as a result of leaving,, 3 or even 3. Hence, it is concluded that fruit thinning by strands removal is more effective than bes removal in improving the fruit weight and size, as well as fruit chemical constituents. The values of Zaghloul dates juice total soluble solids were (33.8, 3.9, 3.6 & 3.3%), (36.3, 3.8, 3. & 3.%) and (3.9, 3., 3.3 & 3.1%) due to leaving (T 3 ), (T ), 3 (T ) or 3 (T 6 ) strands, compared to the control, 3., 3.6 & 31.%, during the three studied seasons, respectively. The increment percentages of total soluble solids due to these thinning treatments compared to unthinned ones were (.3, 8.93,.93 & 6.8%), (.3, 9.81, 9. &.98%) and (.13, 1.6, 9. & 8.3%) due to T, T, T 6 and T during the three studied seasons, respectively. The corresponding values of Haiany dates juice were (3.8, 3.3,

5 Aust. J. Basic & Appl. Sci., (1): , Table 3: Effect of fruit thinning methods on fruit length (cm), fruit diameter (cm) and flash (%) of Zaghloul and Haiany date palm cultivars during 9, 1 and seasons. Fruit length (cm) Fruit diameter (cm) Flash (%) Zaghloul Haiany Zaghloul Haiany Zaghloul Haiany Cultivar Season Control bes/ palm bes/ palm 3 3 L.S.D. T T T T T T T T N.S. N.S. N.S. N.S. N.S. N.S. Table : Effect of fruit thinning methods on TSS and total sugars % of Zaghloul and Haiany date fruits during 9, 1 and seasons. Total soluble solids % Total sugars % Season Control T T T T T T T T L.S.D & 31.%), (3.8, 3.3, 3.8 & 3.3%) and (3., 33.8, 33. & 33.%) compared to (9., 3. & 3.%). Hence the increment percentages were (1.6, 1.9, 9. & 8.%), (1.3, 1.31, 8.91 &.19%) and (1.3, 1.98, 1. & 8.36%) due to T, T, T 6 and T 8 during the three studied seasons, respectively. These results might be due to the adequate carbohydrates and other essential foods for the remained fruits, consequently enhanced the fruit maturity and increased its contents of total soluble solids and sugars. In addition, fruit thinning effectively lowered the competition occurred between fruits and consequently raised total soluble solids and sugar contents for each fruit

6 Aust. J. Basic & Appl. Sci., (1): , Table : Effect of fruit thinning methods on reducing and non-reducing sugars of Zaghloul and Haiany date fruits during 9, 1 and seasons. Reducing sugars Non-reducing sugars Season Control T T T T T T T T L.S.D N.S. N.S. N.S. N.S. N.S. N.S. In general, it could be concluded that there is a positive relationship between fruit thinning treatments and improvement of the chemical constituents of it as well as fruit weight and size. The enhancing effect of fruit thinning on date fruit quality are in harmony with the results obtained by Khalifa et al., (198), Godora (199), El-Shazly (1999), Abdel-Hamid (), Bassal and El-Deeb (), Hammam et al., (), El-Assar (), Nirmaljit et al., (6), Tavakkoli et al., (6), Marzouk et al., (), Al-Wasfy and Mostafa (8) and Abdel-Galil et al., (8). In regard of the previously mentioned results, it can be stated that leaving 9 with 3 to 3 would result in producing a considerable yield characterized by high fruit quality of Zaghloul and Haiany date palms. REFERENCES A.O.A.C., 198. Association of Official Agricultural Chemists. Official Methods of Analysis. A.O.A.C. 1 th Ed. Published by A.O.A.C. Washington, D.C. (U.S.A.). Abdel-Galil, H.A., A.M. El-Salhy, M.M. El-Akkad and Y.M. Diab, 8. Effect of different methods and dates of fruit thinning on "Sewy" date yield and quality under New Valley conditions. The 3 rd Int. Conf. on Date Palm, - April, El-Arish, Egypt. Abdel-Hamid, N.,. Effect of time, rate and patterns of thinning, leaf b ratio and male type on Zaghloul date yield and quality. Arab, J. Agric. Sci. Ain Shams Univ., Cairo, 8(1): Akl, A.M., M.A. Ragab and A.Y. Mohamed,. Yield and fruit quality of Sewy date palms in response to some fruit thinning treatments. The Second Inter. Conf. on Date Palm Faculty of Envir. Agric. Sci., El-Arish, Suez Canal Univ. Egypt. 6-8 Oct. Al-Ghamdi, A.S., O.A. Al-Tahir and A.A. Al-Khateeb, Thinning stage effects on fruit size, yield and fruit quality of date palm (Phoenix dactylifera L.) cv. Khalas. Third Symposium on date palm, Saudi Arabia, Book of Abstracts, p: 88. Al-Wasfy, M.M. and R.A.A. Mostafa, 8. Effect of different methods of fruit thinning on Zaghloul date palm production and fruit quality. Assiut J. of Agric. Sci., 39(1): Awad, A.M., 6. Water spray as a potential thinning agent for date palm flowers (Phoenix dactylifera L.) c.v. "Lulu" Abstract J. Int. Conf. on Date Palm Production and Processing Technology, May 9-, Muscat Oman, p: 1. Bassal, M.A. and M.D. El-Deeb,. Effect of thinning and some growth regulators on yield and fruit quality of Zaghloul date palm. Zagazig J. Agric. Res., 9(6): El-Assar, A.M.,. Response of "Zaghloul" date yield and fruit characteristics to various organic and inorganic fertilization types as well as fruit thinning models in a rich carbonate soil. J. Agric. Sci. Mansoura Univ., 3(): El-Shazly, S.M., Effect of fruit thinning on yield and fruit quality of Nabtet Ali Saudi date palm. The International Conference on date palm Nov. 9-, Assiut Univ., Egypt, pp: Godara, R.K., N.R. Godara and N.S. Nehra, 199. Effect of level of thinning on ripening of date palm fruit (Phoenix dactylifera) cv. Shamran. Res. Dev. Rep., (1-):

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