Changes in Sugar Quality and Mineral Elements During Fruit Development in Five Date Palm Cultivars in AI-Madinah AI-Munawwarah

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1 JKAU:.S"i.. vol. 6, pp ( A.H./199-1 A.D. Changes in Sugar Quality and Mineral Elements During Fruit Development in Five Date Palm Cultivars in AI-Madinah AI-Munawwarah ABDUL AZIZ A. GASIM Dept. of Natura.! Sciences, Faculty of Education, King Abdulaziz University, AI-Madinah AI-Munawarrah, Saudi Arabia ABSTRACT. The reducing and non-reducing sugars and nine nutrient were determined in fruits of Ajwa.. Burni, and Date Palm cultivars. grown at AI-Madinah AI-Munawwarah, during four stages of fruit development. Results showed that most of the studied characters (physical and chemica! composition) at four stages of fruit maturity differed from one cultivar to another. Higher values of fruit and seed weight as well as length and diameter were found during the early stages of development and minimum in the stage. Sugars contents accumulated gradually during fruit development in all cultivars were also found to vary among the five cultivars. Nitrogen and potassium contents were higher as compared to the minerals in the different cultivars. Also in the micro-elements. iron was present in higher concentration than zinc and copper. The change from to the stage was accompanied with a reduction in the amounts of all minerals for all the cultivars. Introduction Date Palm (Phoenix dactylifera L.) is considered as one of the most important fruit trees in the Arab countries, particularly Saudi Arabia. However, earlier study of physical and chemical composition of the fruits of different date palm cultivars has been reported at different countries by several workers (Haas[I], Furr & Cook[2], Hussein etal.[3], Hussein & EI-Zeid'-I', Minessy etal.15], Sawaya et al. [609], and Saad et al.iio]). AI-Madinah AI-Munawwarah is number one producer of dates in Saudi Arabia (Asifetal.IIII). 29

2 30 Gasim The main aim of this study is to evaluate the fruit growth and changes in sugars and nutrient element content of five date palm cultivars Ajwa,, Burni, and growth at AI-Madinah AI-Munawwarah region at four different development stages (,, and ). Material and Methods Five date palm (Phoenix dactylifera L.) cultivars grown at an orchard in Quba area in Al-Madinah Al-Munawwarah, were used in this investigation. Five date palm varieties were included; Ajwa,, Burni,, and. The trees were about 17 -year-old. Three palm trees of similar vigour were selected from each cultivar. Orchard was fertilized and irrigated according to the requirement of the field. All trees were pollinated by hand on April 15, Fruit samples were collected on July 2, 12 weeks after pollination, and continued at 15 days interval upto September 1. Fruit samples were collected at four different stages of fruit development. These stages were as follows: (1), (2), (3), and (4). Three samples were taken from each cultivar at the fourth stage of fruit development. Each sample, consisting of 120 dates, was collected from each of the three trees of the five cultivars. Physical characteristics of the fruits (fruit length and diameter, fruit and seed weight, pulp weight) were determined. Vernier caliper was used for measuring length and diameter of fruits. Total sugars, reducing and non-reducing sugars, were estimated according to the A.O.A.C. methods[12]. Mineral content of the flesh were carried out. Oven-dried and ground for chemical analysis, nitrogen was determined by microkjeldahl method (A.O.A.C.)112] and P, K, Na, Ca, Mg, Fe, Zn and Cu, were determined by AA-775 series, atomic absorption spectrophotometry (A.O.A.C.)l121. Morphological Changes Results and Discussion The data on the morphological changes occurring during the development of fruits of Ajwa,, Burni, and are presented in Table 1. The average length and diameter of the fruit, in the five cultivars increased as the dates reached the KhalaJ stage and then decreased in the stage. The fruits of cultivar were largest in size followed by Burni and cultivars while and Ajwa were about the same measurements in both stages ( and ). The weight of fruit and seed in the five cultivars increased at the stage and then decreased in the stage. Also data showed that the Pulp percentage was higher during developmental stages. Similar results were obtained by Sawaya et al. [6J in Khudari, Selej and Sifri date palm cultivars grown in Riyadh. Sugar Analysis Total sugar content of the fruits in the five cultiyars reached its maximum in the stage (Table 2). At the stage, the content ranged from and then increased rapidly in the stage. Thereafter, the total sugar content in-

3 Changes in Sugar Quality and Mineral Elements. ILE Morphological characteristics of Ajwa,, Burni, and date cultivars. Stage of development Cultivar Kimr F.length cm diameter cm Wt/frult g WI/seed Pulp I F,length g cm F. diameter cm Wt/fruit g WI/seed Pulp g Ajwa Burni 1.22:!:O.06 O.79:!:O :!:O :!:O :!:O.O2 1.18:!:O :!:O :!:O :!:O.15 O.56:!:O.O2 4.96:!:O :!:O.O :!:O.17 O.51:!:O :!:O :!:O.1O xO.18 O.85:!:O.O5 5.21:!:O.19 1.~:!:O :!:O :!:O :!: :!:O :!:O :!:O :!: :!:O :!:O :!:O :!: :!:O :!:O :!:O :!:O :!:O :!:O :!:O :!:O :!:O F,length F,diameter crn cm Wt/fruit g WI/seed Pulp I F.length g cm F. diameter cm WI/fruit ~ WI/seed Pulp 1\ Ajwa Bumi S.D. 3.19:!:O :!:O :!: :!:O :!:O :!:O :!: :!:O :!:O :!:O :!: :!:O :!:O :!:O :!:O :!:O :!:O :!:O :!:O :!:O :!:O :!:O.OI 8.24:!:O.32 O.97:!:O.O :!:O :!:O.O3 7.14:!:O.28 O.80:!:O.O :!:O.O5 2.II:!:O :!:O.32 O.75:!:O.O :!:O.IO 2.13:!:O.O5 7.88:!:O.33 O.95:!:O :!:O.O7 2.45:!:O :!:O.43 I.OO:!:O.O5 89 creased slightly upto stage and were 84.2, 75.5, 81.5 and 75.2 for Ajwa,, Burni, and cultivars, respectively. These results are in harmony with those reported by Ragab et al.[13], Mawlood(14J, Hussein et al.[3], and Sawaya et al.[6.7] on different date-palm cultivars. Table 2 also represented the development changes in reducing sugars content in fruits of the cultivars under study. The preparation of glucose to fructose changed with development of fruits, from : 1 at the early stages of the development to 1: 1 in stages. In general, the reducing sugars in the five date cultivars showed a trend similar to that of total sugars. At stage, fruits were highest in reducing sugars (54.3), while Ajwa fruits recorded the lowest values Afterwards, the fruits continued to gain more reducing sugars during all developmental stages to reach a maximum at stage. Table 3 presents the accumulation of total sugars in fruits of the cultivars under study at stage. Statistical analysis indicated that no significant differences among, and with regard to their contents of total sugars, and they had the lowest values, while Burni was in between. On the other hand, Ajwa had the highest total sugar values that significantly excelled the other cultivars. Similar results were obtained by Sawaya et al.[7]. With respect to non-reducing sugars, (which consisted of sucrose only), data showed that it increased from low level in the stage ( ) to relatively higher level in the stage ( ). However, at stage, fruits

4 32 'Means. A.A. A. Gas;. TABLE 2. Sugar contents of Ajwa,. Burni, and date cultivars at different stage of development ( of dry weight). Stageof development Total sugar Reducing sugar (R.S.) Sucrose non-r.s Glucose of R.S. Fructose ofr.s. Ratio G/F AJwa Burni A TABLE 3. Comparison of sugar contents of fruits between the date cultivars l1t stage. Cultivars Tot Red Suc Glucose Fructose Ajwa Burni 84.2a' 75.5b 81.5 ab 77.7b 75.2b 81.1 a 72.2b 78.5a 7~.9b 70.4b 3.1 b 3.3b 3.0b 4.8a 4.8a 5t.2b 52.7b t.3b 5t.7b 48.7b 47.3b 45.8a 48.2b 48.3b within a column followed by the same Ictter do not differ significantly of the 5"/0 Icvel of probability Duncan's Multiple Rangc Test. according to were highest in sucrose (5.0), while Ajwa fruits recorded the lowest values (1.3). These results are in agreement with those reported by Sawaya et al.ln] in three Riyadh date palm cultivars. The data indicated that reducing sugars were the dominant for sugars during all developmental stages as compared with in a decrease in non-reduc-

5 Changes in Sugar Quality and Mineral Elements 33 ing sugars. Haas and Bliss[15], working on different date palm cultivars, pointed out that at the early stage of development, the sugars' content was largely in the form of reducing sugars. Cook and Furr[!6] found that soft date cultivars contained little amounts of sucrose. Hussein[!?] suggested that fruits of soft date cultivars contained little or no sucrose, while those of dry cultivars contained a relatively high proportion of sucrose to reducing sugars. The present data on sugar status of the fruits indicate that all the five cultivars, Ajwa,, Burni, and belong to the softdate group. Mineral Content Mineral composition of date palm fruits is presented in Table 2. Data showed that the level of concentration in the five cultivars ranged for N , P , K , Ca -0.50, Mg -0.37, Na -32, Fe , Cu and Zn The data clearly showed that K is the predominant macro-element in the flesh of the five date palm cultivars, whereas phosphorus was found in smaller quantities than the other macro-elements. With respect to micro-elements, data also showed that Fe is the predominant microelement, while Cu was found in small quantities (Table 4). TAB~E 4. Mineral composition of Ajwa,, Burni, and date cultivars of various stages of maturity. Cultivars Stage of develop ment N P "/0 K "/0 Ca Mg Na Fe Cu Zn pprn Ajwa Burni : : ;

6 34 A.A. A. Gasim There were significant differences in the dates' mineral contents of the whole season of the five date cultivars, when the averages of all trees were compared (Table 5). Date mineral contents ranged for N , P , K , Ca , Mg , Na , Fe , Cu and Zn The results were in parallel with those reported by Haas!!], Minessy et al.!5], Sawaya et al.[8], and Saad et al.[io] for many date palms cultivars grown in Saudi Arabia. TABLE 5. Average of the whole season mineral composition of Ajwa,, Burni, and date cultivars. / Cultivars N P K Ca Mg Na Fe Cu Zn Ajawa Bumi ' 0.520b 0.715b O.668b 0.157a b O.l04ab O.084b 0.079b 0.963b 1.208a 0.905b b 1.215a b 0.280b O.l65b 0.213a O.l75b O.l93b 0.214a O.ISOb 8 b 7b 8b 0.280a 0.215b 175.3c 187.2ab 183.4b 192.9a 2O1.0a 4567 a b a 3.852ab 3.152b c 36.9ab 42.67b c a "Means, within a column followed by the same letter do not differ significantly of the 5 level of probability according to Duncan's Multiple Range Test. References [I] Haas, A.R.C., Inorganic composition of date fruits, Date Grower's Inst. Rep. 12: 6-8 (1935). [2] Furr, J.R. and Cook, J.A., Nitrogen content of pinnae, fruit and seed of Deglet Noor and Khadrawy date palms as related to nitrogen fertilization, Date Grower's Inst. Rep. 29: (1952). [3] Hussein, F., Mustafa, S., AI-Kahtani, M.S., EI-Shamiraea, F. and AI-Zeid, A., Studies on physical and chemical characteristics of eighteen date cultivars grown in Saudi Arabia, Coil. Agric. Res. Bull., King Saud Univ., Riyadh 2: (1974). [4] Hussein, F. and EI-Zeid, A.A., Chemical composition of Khalas dates grown in Saudi Arabia. Egypt J. Hort. 2: (1975). [5] Minessy, F.A., Bacha, M.A. and EI-Azab, E.M., Changes in sugars, and nutrient elements content in fruits of four soft date varieties in Egypt, Alex. J. Agric. Res. 23: (1975). [6] Sawaya, W.N., Khalil, J.K. and Saft, W.M., Fruit growth and composition of Khudari, Sellej and Sifri date cultivars grown in Saudi Arabia, Proc. 1st Symp. Date Palm. March King Ftiisal Univ., AI-Hassa, Saudi Arabia, pp (1982). [7] Sawaya, W.N., Khalil, J.K., Khatchadourian, H.A., Saft, W.M. and Mashadi, A.S., Sugars, tannins and some vitamins contents of twenty date cultivars grown in Saudi Arabia at the (Mature color) and (Ripe) stages, Proc. 1st Symp. Date Palm, King Faisal Univ., AI-Hassa, Saudi Arabia, pp (1982). [8] Sawaya, W.N., Saft, W.M., Khalil, J.K. and Mashadi, A.S., Physical measurements, prominate analysis and nutrient elements content at twenty-five date cultivars grown in Saudi Arabia at the (Mature color) and (Ripe) stages. Proc. 1st Symp. Date Palm, King Faisal Univ., AI- Hassa, Saudi Arabia, pp (1982). [9] Sawaya, W.N., Khalil, J.K. and Saft, W.M., Chemical composition and nutritional quality of date seeds,j. FoodSci. 49:617-:619(1984). [10] Saad, F.A., Shaheen, M.A. and Bacha, M.A., Chemical analysis of fruits of some Saudi grown date palm cultivars with emphasis on their mineral content, Proc. Saudi Bioi. Soc. 9: (1986). [II] Asif, I., AI-Tahir, O.A. and AI-Kahtani, M.S., Inter-Regional and Inter-Cultivar variations in dates grown in the Kingdom of Saudi Arabia, Proc. 1st Symp. Date Palm, King Faisal Univ., AI-Hassa, Saudi Arabia, pp (1982).

7 Changes in Sugar Quality and Mineral Elements. 35 [12] A.O.A.C., Official Methods of Analysis, 12th ed., Association of Official Analytical Chemists. Washington, D.C. (1975). [13] Ragab, M.H.H., EI-TobeyShehata, A.M. and Sedky,A., Studies on the Egyptian dates. 2. Chemical changes during development and ripening of six varieties, Food Tech. 10: (1956). [14] Mawlood, E.A., Physiological studies on fruits development of Sam many and Zaghloul date palm cultivars. Ph.D. Thesis, Hort. Dept., Fac. Agric., Cairo Univ. (1980). [15] Haas, A.R.C. and Bliss, D.E., Growth and composition of Deglet Noor dates in relation to water injury. Hilgardia 9: (1935). [16] Cook, J.A. and Furr,J.R., Kinds and relative amounts of sugars and their relation to texture in some American grown date varieties, Proc. Amer. Soc. Hort. Sci. 61: (1953). [17] Hussein, F., Kinds and relative amounts of sugars in some Egyptian date cultivars. Beitr. Trop. & Subtrop. Landwist and Tropenveterina armedizin 10(2): (1972); (Hort. Abst. 44(6): 4295).

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