الفهرس Only 14 pages are availabe for public view
 |  | from | 232 |  |  |
| | | from | 232 | | |
Abstract
Four field experiments were carried out at the Experimental Research Center, Faculty of Agriculture, Moshtohor, Benha University, Kalubia Governorate during two growing seasons (2004 and 2005) in two different studies.
I. The first study
Irrigation regimes for various summer forage grasses
Experiments were designed and implemented to evaluate fresh and dry forage yield, vegetative growth behaviour, and quality determinations of four summer forage grasses (Pearl millet, Sorghum hybrid, Sudan grass and Teosinte) irrigated with three water regimes in respect of quantities (2000, 3000 and 400 m3/fed) and frequencies (10 and 20 days).
Experiments were layed out and statistically analyzed as split split plot design where were quantities were randomly distributed in the main plots and frequencies or durations in the split plots and summer forage grasses in the sub sub plots. Three individual cuts were obtained in each of the two growing seasons and their average. Results could be summarized as follows:
Fresh forage yield:
- Total fresh forage yield of the three obtained cuts during the first growing season was the highest for G1 (Pearl millet) and the lowest for G4 (Teosinte) which was 52.27 and 30.96 ton/fed, respectively with a significant difference of about 69%. Whereas, G2 (Sorghum hybrid) and G3 (Sudan grass) produced 46.30 and 43.35 ton / fed of total forage yield, respectively with a significant difference.
- In the second season the obtained total fresh forage productivity was 40.87, 60.44, 64.84 and 68.12 ton/fed for G4, G3, G2 and G1, respectively with significant differences among.
- It could be generally concluded that, G1 (Pearl millte) was of the best productive fresh forage followed by G2 (Sorghum hybrid), then G3 (Sudan grass) followed by G4 (Teosinte) during each of the two subsequent seasons with significant variable magnitudes.
- The highest fresh forage yield could be obtained from G1 (Pearl millet) irrigated by the highest water quantity of 4000 m3/fed of water at 10 or 20 days intervals. Whereas, the lowest fresh forage yield was obtained for G4 (Teosinte) irrigated with 2000 m3/fed of water at either 10 or 20 days intervals.
- Significant increase in total fresh forage yield was obtained as the irrigated quantities of water increased from 2000 (Q1) to 3000 (Q2) and up to Q3 (4000 m3/fed.).
- The two frequencies of water application (10 or 20 days) did not show significant differences in fresh forage yield among the individual cuts for each of the two studied seasons.
Dry forage yield:
- The G1 (Pearl millet) was of the highest total dry yield followed by G2 (Sorghum hybrid) and G3 (Sudan grass) which were almost equal for the later two grasses in their total dry yield production. Whereas, G4 (Teosinte) was of the lowest total dry forage yield with significant differences having similar trend for the first and the second season with relatively higher magnitudes for the second rather than the first season.
- Substantial increase in dry forage yield was recorded as the applied water quantities for irrigation increased. Similar observations were recorded for the individual cuts of each growing seasons.
- It is generally noticed that, differences in total dry forage yield due to the applied irrigation intervals were slightly higher for the shorter (10 days) than for the longer (20 days) interval with significant difference in the two seasons.
- Results indicate that the highest total forage yield was recorded for G1 (Peal millet) irrigated with 4000 m3 / fed at 10-days interval in each of the two growing season. Also, it is well noticed that the lowest dry yield was obtained for G4 (Teosinte) irrigated with 2000 m3 / fed water whether the irrigation interval was 10 or 20-days.
Vegetative growth characteristics:
- Plant height:
- It was clear that pearl millet was of the tallest plants and Teosinte was the shortest one, whereas Sudan grass and sorghum hybrid plants were in between, being relatively taller for the previous than the later one.
- As the applied water quantities increase from 2000, 3000 and up to 4000 m3/fed. There was slight tendency of plants to increase in length. Such differences were not significant for the individual cuts or their average in the first season. However, during the second season, those differences were significant for the first and third cuts as well as the average of the obtained three cuts.
- The applied irrigation intervals did not show significant differences in the height of the grown plants neither for the individual cuts nor for their average during the two seasons.
- Stem diameter:
- The average thickness of plants stems decreased to be 0.98, 0.90, 0.80 and 0.64 cm for G1 (Pearl millet), G4 (Teosinte), G2 (Sorghum hybrid) and G3 (Sudan grass), respectively in the subsequent two seasons.
- Increasing water quantities from 2000 to 3000 and up to 4000 m3/fed caused subsequent increase in stem thickness of plants. Whereas, similar results were noticed in the first reason, but the differences did not reach the significant level as in the second season.
- Slight fluctuation of no specific trend for stem diameters of the grown forage plants was noticed as affected by the irrigation frequencies (10 and 20 days). This results was noticed for individual cuts and their average for each of the two seasons.
- Sudan grass was of the thiner stems. Whereas, pearl millet was of the thickest one, where both increased in their stem diameter when using the highest irrigation quantities (4000 m3) of shorter frequency (10 days).
- Leaf area / pant:
- The G1 was of the largest leaf area / plant (494.5 cm2), and G3 (Sudan grass) was of the smallest one (312.7cm2) while G2 (Sorghum hybrid) and G4 (Teosinte) were in between with relatively large leaf area / plant for the earlier than the later grass.
- The irrigated water quantities increased from 2000 to 3000 and up to 4000 cm3/fed, leaf area / plant substantially increased with significant differences on the average basis of 3 cuts of each of the two seasons.
- As the irrigation intervals increased from 10 to 20 days, leaf area / plant were significantly decreased.
- Leaf area / plant varied according to the grown forage grasses and increased with increasing water quantities with no specific effect for the application intervals in most cases.
- Leaf / stem ratio:
- Pearl millet (G1) was of the highest leaf /stem ratio and Sudan grass (G3) was of the lowest one. Whereas Teosinte (G4) and Sorghum hybrid (G2) were in between with relatively higher ratio for the earlier than the later grass.
- Increasing quantities of water for irrigation caused substantial significant increase in leaf/stem ratio of plants over the grown grasses.
- Leaf/stem ratio was slightly higher at the shortest irrigation interval (10 days) than the longest one (20 days).
- Leaf / stem ratio of the grown grasses proved superiority of Pearl millet (G1) in its leaf / stem ratio when supplied with 4000 m3 water at the shortest irrigation interval (10 days) in the two seasons.
- Number of tillers/m2 :
- Average over the 3 cuts, G3 (Sudan grass) produced the highest number of tillers / m2 followed by G2 (Sorghum hybrid) then, G1 (Pearl millet) followed by G4 (Teosinte) where the lowest number of tiller/m2 was obtained.
- Results evedentiated that as the water quantity for irrigation increased from 2000 to 3000 and up to 4000 m3/ feddan, number of tillers / m2 substantially increased. This increase was significant for each of the individual cuts and their average during the first season and in the second cut and the average of the 3 individual cuts of the second season .
- The applied irrigation frequencies (10 or 20 days) did not exert significant effect on the numbers of tillers / m2 which fluctuated with no significant or specific trend. This result was noticed through the individual cuts and their average either in the first nor the second season.
- The highest number of tiller/m2 was noticed for Sudan grass (G3) that was irrigated by the highest quantity of water (4000 m3/fed) at 20 days interval.
Chemical analyses:
Crude protein (CP) content:
- Results indicate that G2 (Sorghum hybrid) and G3 (Sudan grass) were of the highest CP content, but the earlier grass was slightly higher in CP content than the later one with significant difference in the first but not in the second season. Also, G4 (Teosinte) was significantly higher in CP content than G1 (Pearl millet) with relatively higher magnitude in the first rather than the second season. This means that G1 was of the lowest CP content in the two growing season.
- Over the grown grasses, increasing irrigation water quantities from 2000 to 3000 and up to 4000 m3/fed caused substantial significant increase in CP content of grasses.
- Irrigation intervals (10 or 20 days) did not show definite trend regarding its effect on CP content of forage grasses under study.
- Results indicate that each of the grown forage sorghum has its owen behaviour in its CP content (on dry matter basis) which increased as the water quantities increased from 2000 to 3000 and up to 4000 m3/fed at any of the applied duration (10 or 20 days).
Crude fiber (CF) content:
- Pearl millet (G1) have the highest CF content, followed by Sudan grass (G3), then Sorghum hybrid (G2), followed by Teosinte (G4) which have the lowest CF content among the other grasses.
- Slight substantial decrease in CF content of grasses was recorded as the applied irrigated water quantities increased from 2000 to 3000 and 4000 m3/fed. However, such differences were found to be significant in the second season but not in the first one.
- The applied irrigation frequencies (10 or 20 days intervals) did not exert specific effect on the CF content of grasses.
- Results indicate that pearl millet (G1) was of the highest CF content which decreased as the applied water quantities increased when at any irrigated intervals (10 or 20 days). Whereas, Teosinte (G4) was of the lowest CF content among the other grasses where and decrease by increasing quantities of water supply at any of the two frequencies (10 and 20 days).
Ash content:
- Pearl millet (G1) was of the highest ash content (12.00%), whereas, Teosinte (G4) have the lowest content (10.58%) on dry matter basis over the applied irrigation regimes.
- As the applied water quantities increased from 2000 to 3000 and up to 4000 m3/fed, ash contents slightly but significantly increased especially when comparing between the effect of the lowest (2000 m3/fed) and the highest (4000 m3/fed) quantity of water.
- Slight ignorable decrease in ash content was noticed in the obtained forage grasses as irrigation intervals increase from 10 to 20 days with insignificant differences in the two seasons.
- Most of the grown grasses have more ash content especially when comparing between the effect of the lowest (2000 m3/fed) and highest (4000 m3/fed) water quantities at the short irrigation interval of 10 days.
- Ether Extract (EE) content:
- The obtained ether extract (EE) contents for grasses were in the following descending ranking order: G1 (Pearl millet), G2 (Sorghum hybrid), G3 (Sudan grass) and G4 (Teosinte) with a respective EE content of 3.00, 2.68, 2.28 and 2.21% having significant differences except for the last two grasses where differences in EE contents were not significant.
- Increasing water quantities of irrigation from 2000 to 3000 m3/fed caused slight significant increase in EE content of the obtained forage (over the applied factors). However the extra increase of water quantity (4000 m3/fed) did not show appreciable increase in EE content of the forage grasses.
- Extended the application frequency from 10 to 20 days caused very slight significant increase in EE content of the obtained forage in the second season.
- The highest increase in EE content was noticed up to 3000 m3/fed for G2 (Sorghum hybrid) and G4 (Teosinte) at the longer duration of 20 days with significant differences in the second season.
- Total Digestible Nutrients (TDN) content:
- The G2 (Sorghum hybrid) and G3 (Sudan grass) were of the highest TDN content in both seasons of the study with slightly higher content for G2 than G3 in the first season and without appreciable difference in the second season. However, G1 (Pearl millet) was of the lowest TDN% compared with the other tested grasses with significant differences in the two seasons.