الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 103 |  |  |
| | | from | 103 | | |
Abstract
This study was conducted during the two seasons of 2000 and 2001 in a private vineyard of Thompson seedless grape (Vitis vinifera,L.) located at AboArsa village near Mansoura City, Dakahlia Governorate, Egypt. The main objective of this investigation was to study the effect of using biofertilizers contained Nfixing bacteria (Azotobacter chroococcum Azospirillum brasilense) and P disolver bacteria (Bacillus polymyxa), mineral nitrogenous and phosphorous fertilizers (Ammonium nitrate 33.5%, Ammonium sulfate 21% and Super phosphate 15.5%) at different levels on vegetative growth, cluster characteristic and yield of Thompson seedless grape. Seasonal changes of NPK during these growing season stages of grapevines as well as dehydrogenase enzyme activity in the soil were also studied. Data obtained in this study could be summarized as follows: 1Leaves area/vine: As for nitrogen fertilization effect, the rate of 60 and 40 units N gave the highest leaves area/vine values in both seasons of study. 40 unit P surpassed 20 unit P especially in the first season. whereas in the second one there were insignificant differences between such two rates. Using biofertilizer either at rate 1 (6.6 g bioculture) or rate 2 (13.2 g bioculture) had the highest values in that respect comparing to without biofertilizer, the differences were significant in this respect. As for interaction between nitrogen, phosphorus and biofertilizer, treatment of (40+40+2) produce the highest effect on leaves area/vine. Also, treatments of (60+40+1) and (60+20+2) gave the highest values in the first and second season respectively. 2 Total chlorophyll: Increasing N level from 20 unit to 40 or 60 unit led to an obvious increase in total chlorophyll at full bloom. Vines treated with 60 unit N gave insignificantly highest values in this respect. As for phosphorus and biofertilization, insignificant differences between all treatments were found, but 20 unit P was superior in that respect. In view of biofertilizer, leaves chlorophyll level was insignificantly increased with increasing the rate of biofertilizer from 0.0 to 13.2 g bioculture. The vines treated with 13.2 g bioculture gave the highest values in this respect. As for interaction between N + P and Biofertilizer, the treatment of (60 +20+2) gave the highest values during the two seasons of study. While treatment of (20+40+0) gave the lowest values. 3Yield/vine: Treatment of 40 and 60 unit N significantly increased yield compared with 20 unit N treatment during the two seasons study. Vines treated with 40 unit N gave the highest values during the two seasons of study. Insignificant differences between 60 and 40 unit N during the two seasons of study. As for phosphorus fertilization, insignificant differences between the two doses of P fertilizer during the two seasons of study. The highest yield value was for 20 units P2O5 in 2000 and for 40 unit P2O5 in 2001 season. Regarding biofertilizer effect, data clearly indicated the superiority of biofertilizer treatment over without biofertilizer, especially in the second season, where the differences were significant. The highest yield values were obtained from 6.6 g culture treatment in the first season and from 13.2 g culture treatment in the second season. Interaction between N, P and biofertilizer gave insignificant differences between all studied treatments. Treatment of (40 + 20 +1) gave the highest effect in that respect. 4Cluster weight and volume: Adding nitrogen at 40 unit was superior than other treatments. While, the treatment of 20 unit N gave the lowest values in this respect. As for phosphorus fertilization effect, vines treated with 20 unit P2O5 gave the highest values. For cluster volume during the two seasons of the study, 40 unit P2O5 gave values lower than 20 unit P2O5 during the two seasons of study. As for using biofertilizer significant differences between all levels were found. All biofertilizer treatment surpassed without biofertilizer, but biofertilizer treatment (6.6g culture) gave the highest values for cluster weight and volume during 2000 and 2001 seasons. Regarding the interaction between N, P and biofertilizers, treatments of (40 + 20 +1) were surpassing other treatments for cluster weight and cluster volume. 5100Berry weight and volume: Increasing N levels from 20 to 60 unit N lead to an increase in 100 berry weight and berry volume. The differences were significant in the first season for 100 berry weight only .The highest values were recorded from 60 unit N treatment. As for P fertilization, the superiority, was for 40 unit P in the second season. The differences between P treatments were significant in the second season only, whereas in the first season, the differences were insignificant. Regarding biofertilizer, the treatment of (13.2 g culture) surpassed other treatments, whereas increasing biofertilizer level led to an increase in 100berry weight and volume. As for all possible interaction, there were insignificant differences between all studied treatments. 6 Berry firmness and adherence: Insignificant differences between all nitrogen level used during the two seasons of study. Decreasing N level was accompanied with increasing berry firmness and adherence. The highest value was obtained from 20 N unit treatment and the lowest one was recorded for 60 N units. The opposite results were obtained in case of biofertilizers level tested. Using phosphorus fertilizer led to a significant effect in that respect. Fourty units P treatment gave the highest berry firmness and adherence during 2000 and 2001, respectively. As for interaction between N, P and biofertilizer levels, insignificant differences between all combinations used in case of fruit firmness during the two seasons of study. For fruit adherence, data took the same trend as for firmness in the first season only, but the differences were significant in the second season and the highest values were obtained from treatment (20 + 20 + 2) followed by (20 +20 + 1) treatment. 7Juice TSS%, acidity % and TSS/acid ratio: Data indicated insignificant differences among the tested N levels in all juice characters studied in the first season, whereas in the second one, 60 unit N treatment gave the highest TSS, TSS/acid ratio and lowest acidity. Regarding Plevels, there were insignificant differences between all treatments in the first season, whereas in the second season, 40 unit P2O5 treatment surpassed 20 P unit treatment, which recorded highest TSS%, lowest acidity and highest TSS/acid ratio. As for biofertilizer treatments, insignificant differences between all biofertilizer levels were detected. Concerning the interaction between N, P and biofertilizer treatment insignificant differences between all treatments used were recorded. 8Total sugars: Data obtained showed insignificant differences between all nitrogen, phosphorus or biofertilizer used in first season. whereas, in the second season decreasing N fertilizer to 40 or 20 unit led to an increment in total sugars, where decreasing P unit from 40 to 20 led to a decrease in juice total sugars. Biofertilizer level took the same trend as in nitrogen levels. Interaction between N+ P+ biofertilizer on berries total sugars had insignificant in case of all possible combination either in 2000 and 2001, seasons. 9Berries nitrate: It was cleared from data that increasing nitrogen level gradually increased nitrate concentration in berries, 60 unit N gave the highest value in 2000 and 2001 seasons. Insignificant differences between the used phosphorus levels during the two seasons of study were recorded. As for biofertilizer, increasing biofertilizer from 0 to 13.2 g culture decreased berry nitrate concentration during 2000 and 2001 seasons. As for interaction between N, P and biofertilizer, the lowest values of fruit nitrate were obtained from treatment (20+40+2) followed by (20+40+1). Under all nitrogen level increasing biofertilizer from 0 to 13.2 g culture clearly decreased nitrate concentration in the berries. 10 Seasonal changes of NPK in leaves petiole during the growing season: In general, it could be concluded two opposite trend concerning N seasonal changes. The first trend was observed at the first stages of growing season till full bloom and characterized by gradual increase, and the second trend was from full bloom which characterized with gradual decrease as the season advanced. Data also showed an obvious increase in P petioles content at the growing onset till full bloom and then decreased with the season advanced. Data for potassium concentration in petioles showed gradually decrease till harvest stage. 11Dehydrogenase activity: Data obtained clearly indicated that as the season advanced, treatment of (40 + 40+1) had the best effect in that respect. Also, treatment (40 + 20 +1) gave convincing effect in that respect. On the contrary, the interaction treatment (60 + 40 +0) was the inferior treatment in that respect which recorded the lowest dehydrogenase activity values. According to the forcited results in the present investigation, it could be explained that nitrogen and phosphorus fertilizers applied to Thompson seedless grapevines at an adequate amount (40 or 60 N unit and 40 P unit per feddan) have a positive effect on growth (leaves area and chlorophyll contents), yield and most of physical and chemical characteristics measured on both clusters and berries. This effect was true except for berries firmness and adherence along with juice total sugars, which they were increased under low level of nitrogen. It is worth to record herein that the differences between either 40 or 60 N unit and 20 or 40 P unit were insignificant with respect to the results of most characters studied with special emphasis to yield per vine