الفهرس 
introductionOnly 14 pages are availabe for public view
 |  | from | 141 |  |  |
| | | from | 141 | | |
Abstract
The present study was carried out during two successive seasons of 2006 and 2007 on date palm trees (Phoenix dactylifra L.) grown in a private orchard at El-Badrasheen region, Giza Governorate, about 20 Km. southern Cairo.
The selected palms were about 35 – year- old, planted at 6 × 8 meters apart and subjected to the same cultural practices, irrigation, fertilization, diseases and insects resistance. The leaf /bunch ratio was maintained at the ratio 8:1. This study involved three experiments as followos:
V.I. Experiment, I: Effect of pollen grain sources on palm fruiting and fruit quality of Siwi and Zaghloul date palms.
In this concern, the tested pollen grains for pollination process were selected from three locations namely; Rashid (Behera- Governorate) ;El-Badrasheen (Giza- Governorate) and Naser (Beni-Swef – Governorate). The complete randomized block design with three replications was used for arranging the 3 investigated pollinators ( pollen grain sources), whereas each individual female palm tree from every cultivar was subjected to 3 pollen grain sources (2 /3 bunches were devoted for every pollen grains source). The following measurements were investigated regarding their response to the specific and interaction effects of pollen grain source x date palm cultivar.
V. I. I. palm fruiting indicator (average bunch weight in Kg) :
A- Specific effect:
Regarding the specific effect of date palm cultivars, data obtained during both seasons declared that “Zaghloul” cv. surpassed “Siwi” cv. as average bunch weight (kg) was concerned. Beside, pollen grains source showed an obvious effect on average bunch weight. Herein, Rashid pollinator exerted the highest stimulative effect. While, the reverse was true with Naser pollen grains. However, El-Badrasheen pollen grains were in between the aforesaid two extremes. Differences were significant between the three sources as compared each other.
B- Interaction effect:
Data obtained regarding the interaction effect of (palm cultivars x pollen grain sources) pointed out that the highest values of bunch weight were statistically in concomitant to “Zaghloul” date palm trees pollinated with Rashid pollinator. However, “Siwi” Cv. pollinated with either El-Badrasheen or Naser males produced the lowest value of bunch weight. However, other combinations were in between the aforesaid two extremes.
V. I. 2- Fruit quality:
V. I. 2.1- Fruit physical properties:
In this regard, fruit physical properties in response to specific effect of two studied factors i.e., palm cultivar and pollen grain sources as well as interaction effects of their possible combinations were investigated (fruit length, diameter, L/D shape index, fruit weight, flesh weight and seed weight).
A- Specific effect:
Regarding the specific effect of palm cultivar, data obtained during both seasons revealed that, “Zaghloul” cultivar surpassed “Siwi” cv. in fruit physical properties. On the other hand, Rashid pollen grains positively enhanced all studied fruit physical properties over two other sources. On the contrary, Naser pollen grains showed the least stimulative effect. While, El- Badrasheen pollinator was in between.
B- Interaction effect:
Data obtained revealed that specific effect of each investigated factor was directly reflected on its own combinations. Herein, “Zaghloul” palm trees pollinated with Rashid pollen grains exhibited statistically the greatest values of various fruit physical properties. Moreover, “Siwi” palm trees pollinated with either El-Badrasheen or Naser pollen grains had the least values of the investigated physical properties during 2006 and 2007 seasons. However, other combinations were in between the aforesaid two extremes.
V.1-2. 2- Fruit chemical properties:
In this regard fruits chemical properties i.e., total soluble solids %, acidity %, reducing sugar %, non-reducing sugar % and total sugar % contents of two date palm cultivars in response to pollen grain sources as well as their possible combinations revealed that:
A-Specific effect:
Referring the specific effect of date cultivar, data obtained during both seasons shortly revealed that “Zaghloul” cultivar fruits surpassed “Siwi” fruits in their total soluble solids %, reducing sugar %, non-reducing sugar % and total sugars % while acidity % was not influenced. Beside, Rashid pollen grains had more pronounced effect on fruit chemical properties followed in a decreasing order by El-Badrasheen and Naser pollen grains.
B-Interaction effect:
Regarding the interaction effect of various combinations between two investigated factors (cultivars and pollen grain sources), data obtained during 2006 and 2007 experimental seasons revealed that, specific effect of each investigated factor was directly reflected on its own combinations. Herein, ”Zaghloul” palm trees pollinated with Rashid pollen grains produced fruits with higher total soluble solids %, reducing sugars, non-reducing sugars and total sugar contents. The reverse was true with “Siwi” palm trees pollinated with either El-Badrasheen or Naser pollen grains during two seasons of study. In addition, other combinations were in between.
V.II. Experiment, 2. Pruning level (leaves/ bunch ratio) in relation to palm fruiting and fruit quality of Siwi Cv.
This experiment was conducted on 16 Siwi date palm trees to investigated four pruning levels i.e., 4, 6, 8 and 10 leaves per bunch during 2006 and 2007 experimental seasons. The complete randomized block design with four replications was employed. The influence of the investigated four leaves/ bunch ratios was evaluated through the response of the differential fruiting and fruit quality measurements piviously examined in the experiment, 1 as follows:
V.II.1. Average bunch weight (yield indicator):
Data obtained during booth seasons displayed that average bunch weight of ”Siwi” date palm cultivar was positively correlated with the number of leaves left per bunch after pruinning process. However, tree higher leaves/ bunch ratios exceeded statistically the least one (4 leaves/ bunch) from pne hand but two highest ones i.e., 8 and 10 leaves/ bunch didn’t significantly differ as compared each other from the other hand.
V.II.2. Fruit quality:
V.II.2.1. Fruit physical properties:
The average fruit weight, flesh weight, seed weight, fruit dimensions 9 length & diameter) and shape index (fruit length: fruit diameter) were the fruit physical charatistics investigated regarding their response to pruning level (leaves/ bunch ratio). Data obtained during booth 2006 and 2007 experimental seasons displayed that all fruit physical characteristics except seed weight followed the same trend. Hence, two fruit dimensions (length & diameter) and fresh weight of whole fruit and its flesh, as well as fruit shape index were increased by raising the number of leaves left per bunch. However, the differences were more pronounced and significant with the former four measurements (length, diameter, fruit and flesh weights) as four investigated leaves / bunch ratios were compared each other. Meanwhile, difference in fruit shape index was relatively less pronounced, whereas differences was significant only with comparing both least and highest leaves/ bunch ratio i.e., 4 and to 10 leaves/ bunch ratios each other.
On the other hand average seed weight didn’t respond to leaves/ bunch ratio.
V.II.2.2. Fruit chemical properties:
In this regard fruit juice TSS%, acidity %, total sugars, reducing and non-reducing sugars contents were the fruit juice chemical properties investigated pertwining the influence of leaves/ bunch ratio. Data, obtained during booth experimental seasons displayed that all the abovementioned fruit chemical characteristics were increased with raising the leaves/ bunch ratio except fruit juice acidity which didn’t show a noticeable response.
On the other hand, the rate of response was relatively more pronounced with TSS%, total sugars and reducing sugars content than that the analoyars one of non-reducing sugars % from statistical point of view, especially as two lower ratios ( 4 & 6 leaves/ bunch) were compared to two higher ones (8& 10 leaves/ bunch).
Conclusively, it could be recommended that the 8 leaves/ bunch was the most preferable pruning level from the statistical standpoint especially as booth yield indicator ( average bunch weight and fruit properties) were together taking into consideration.
IV.III. Experiment, 3. Effect of thinning level, method and time on yield and fruit quality of Siwi and Zaghloul date palm cultivars:
This experiment was conducted during 2006 & 2007 experimental seasons on 35 year old trees of Siwi and Zaghloul date palm Cvs. to investigate specific and interaction effects of four factors i.e., a- two thinning times ( 4 & 6 weeks after pollination ), b- two thinning methods ( strands removal and strands shortening), c- four thinning levels (10, 20, 30 and no thinning as control ) and d- two date palm cultivars ( Siwi & Zaghloul). The complete randomized block design with three replications was used, whereas, each replicate was represented by an individual palm. So, 96 date palm trees were needed, where one half of them was carefully selected from each cultivar.
The response of yield, bunch weight and fruit quality (physical & chemical properties) were investigated pertaining the specific effect of four factors under study and interaction effect of their possible combinations.
IV. III.1. Yield and average bunch weight:
A-Specific effect:
Concerning the specific effect of four investigated factors, data obtained during both 2006 & 2007 experimental seasons displayed the following:
1- Earlier fruit thinning time (4 weeks after pollination) increased significantly both yield (harvested fruits / tree in Kg) and average bunch weight per the later time (6 weeks after pollination).
2- Thinning fruits by strand removal significantly surpassed statistically strand shortening as yield / tree and average bunch weight were concerned.
3- All fruit thinning levels (10, 20 and 30 %) decreased significantly yield and average bunch weight below control (unthinning). The reduction was in a linear relationship with the thinning level.
4- Zaghloul date Cv. had significantly higher yield and heavier bunches than Siwi Cv.
B- Interaction effect:
Data obtained during both seasons displayed that specific effect of each investigated factor was directly reflected on their combinations.
Herein, the unthinned Zaghloul date palm trees followed by those belonging to the same cultivar which had been thinned earlier (4 weeks after pollination) at the lightest thinning level (10 %) exhibited statistically the greatest yield and bunch weight, regardless of method of thinning. The reverse was true with Siwi thinned trees at the highest thinning level (30 %), regardless of method and time of thinning. In addition, other combinations were in between the aforesaid two extremes with a noticeable tendency pointed out that combinations of thinned Zaghloul trees at 20 % level after 4 weeks from pollination exceeded other combinations of such intermediate category.
IV. III.2. Fruit quality:
IV. III. 2. 1. Fruit physical properties:
In this respect fruit dimensions ( length & diameter), shape index (L/D), fresh weight of the whole fruit, flesh and seed were the investigated fruit physical characteristics regarding their response to specific and interaction effects of four studied factors (date palm Cv., time, method and level of fruit thinning).
A-Specific effect:
The investigated fruit physical characteristics varied greatly in their response to specific effect of fruit thinning time was significantly absent with both fruit dimensions (length & diameter), fruit shape index and average seed weight. However, with fresh weight of either the whole fruit and its flesh both exhibited significantly an increase by earlier thinning time (4 weeks from pollination).
With regard to the specific effect of thinning method data obtained during both seasons revealed that no considerable response was detected with fruit dimensions, shape index and seed weight, while fruit and flesh weights were significantly increased in thinned bunches with strand removal than those of strand shortening.
Referring the specific effect of thinning level, three investigated levels (10, 20 and 30 %) increased significantly weight of whole fruit and its flesh comparing positive relationship with thinning level in spite of differences between two higher thinning levels i.e., 20 and 30 % was too few to be significant as compared each other.
On the other side, both fruit shape index and seed weight did not respond to thinning level.
As for specific effect of date palm cultivar Zaghloul Cv. significantly surpassed Siwi Cv. with all investigated fruit physical properties except fruit shape index where the reverse was true.
B-Interaction effect:
Specific effect of each of four investigated factors reflected directly on interaction effect of their possible combinations. Anyhow, Zaghloul fruits of earlier (4 weeks of pollination) thinned bunches at 20 and 30 % levels mainly and to same extent those thinned later (6 weeks of pollination) particularly when strand removal method was applied showed significantly the highest values of fruit dimensions ( length & diameter) and average fruit weight of whole fruit and flesh. The reverse was true with Siwi date fruits of either unthinned trees or thinned ones at 10 % irrespective of time and method of thinning, where the least values of fruit dimensions and fresh weight of fruit and flesh were exhibited.
In addition, other combinations were in between the aforesaid two extremes with a noticeable tendency showed that combinations of Zaghloul Cv. surpassed significantly the analogous ones of Siwi Cv. of such intermediate category in this concern.
IV. III. 2. 2- Fruit chemical properties:
In this respect, fruit juice TSS(%), acidity and total sugars content ( percentage of reducing, non- reducing and total sugars) were investigated regarding their response to specific and interaction effects of four investigated factors (date palm Cv., time, method and level of fruit thinning).
A-Specific effect:
Data obtained during both 2006 & 2007 experimental seasons revealed obviously the great variance in response of all fruit chemical properties to specific effect of each investigated factor as follows:
1- Specific effect of fruit thinning time was too slight to be taken consideration and differences between two investigated thinning times (4 and 6 weeks of pollination) could be safely neglected.
2- The response to specific effect of thinning method was approximately absent with acidity and sugars content (reducing, non-reducing and total sugars), while with total soluble solids percentage (TSS %) it was significantly increased in fruits of thinned bunches by strands removal as compared to those of strands shortening.
3- Specific effect of fruit thinning levels, all investigated three levels (10, 20 and 30 %) increased significantly T.S.S. % and sugars % ( reducing, non-reducing and total) as compared to control (unthinning), however, two higher the thinning rates (20 &30 %) were significantly the superior. On the other hand, the trend took the other way around for acidity while the highest value was significantly coupled with control (unthinning).
4- As for the specific effect of date palm cultivar, it was quite evident that, Zaghloul Cv. surpassed Siwi Cv. as their TSS (%) and sugars (reducing, non-reducing and total sugars) contents were concerned. However, with fruit juice acidity difference was not so fern in spite of Siwi was relatively richer than Zaghloul.
B-Interaction effect:
Data obtained during both seasons revealed that, the more pronounced effect for each of date palm cultivar and thinning level from one hand associated with the relative slight / less pronounced effect of both time and method of fruit thinning from the other was reflected on the interaction effect of different combinations between these investigated factors. Herein, the thinned Zaghloul trees at the severest level (20 %) and / or to same extent combinations of the same cultivar thinned at 20 % had significantly the richest fruits in their TSS (%) and sugars (reducing, non-reducing and total sugars) contents. The reverse was true and those thinned at the lowest level (10 %) whereas, their fruits were the poorest in their TSS (%) and sugars (reducing, non-reducing and total sugars) contents. In addition, other combinations were tendency of superiority of Zaghloul combinations, over the analogous ones of Siwi Cv. of such intermediate category.
On the other hand, the trend of response for fruit juice acidity to interaction effect of date palm x thinning level x thinning time x thinning method, took the other way around with comparison with the aforesaid discussed trend exhibited for TSS (%) and sugars contents.