الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
The present study was conducted during the two successive
summer seasons of 1997 and 1998 at the Experimental farm of the
Faculty of Agriculture at Moshtohor, Zagazig University (Benha
Branch) to investigate the effect of irrigation intervals and different
levels of NPK fertilizers and irrigation regime as well as their
interaction on the growth, chemical composition and yield and its
components of taro plants. The obtained results can be summarized
as follows:
1-Increasing water supply ,i. e. irrigation every ~ week by intervals
throughout the growing season increased all the studied
vegetative growth parameters, expressed as plant height, number
of leaves per plant, leaf area, lamina and petiole fresh weight as
well as fresh weight of whole plant. However, dry matter
percentage of different plant parts ( leaf and corm ) were
significantly decreased with increasing the amount of water
applied.
2- The highest used level ofN, P and K fertilizers ( 120 kg N + 64
kg P20S + 120 kg K20/fed. ) resulted in the highest growth rate,
i. e. plant height, number of leaves per plant, leaf area and fresh
weight of lamina and petiole as well as fresh weight of whole
plant and dry matter content of plant.
3- The maximum increments in all the studied growth parameters
were obtained in case of irrigation every ~ week by intervals and
the highest used levels of NPK fertilizers.
4- Increasing the irrigation interval from Yz up to 2 weeks led to a
significant decrease in chlorophyll a, b and total chlorophyll as
well as carotenoids of taro plant leaves .
5- Increasing the fertilization level up to the highest used one ( 120
kg N + 64 kg P20S + 120 kg K20/fed. ) gradually increased
chlorophyll a , b and total chlorophyll as well as carotenoides
content of plant leaves during both seasons of study .
6- The maximum values of all measured photosynthetic pigments,
i. e. chlorophyll a , b and total chlorophyll as well as carotenoides
were obtained as a result of irrigation every ~ week by intervals
and applying the highest used level of NPK fertilization (120 kg
N + 64 kg PzOs + 120 kg K20/fed. ) .
7_Shortening the irrigation intervals from 2 to Vz week by intervals
during the growing seasons led to significant increases in the
uptake of nitrogen, phosphorus and potassium by plant.
8-The maximum increments in all assyed macroelements were
connected with the highest used level of N, P ,K fertilizers
(120 kg N + 64 kg PzOs + 120 kg K20/fed. ).
9- Increasing the irrigation frequencies up to 64 irrigations combired
with the highest used level of fertilization (120 kg N +64 kg
PzOs + 120 kg K20/fed.) resulted in the highest N,P and K
content in different plant parts .
10- Generally, the total carbohydrates percentage of different
plant parts were increased with decreasing the irrigation intervals
from 2 to 1 week. In addition, decreasing the irrigation intervals
less than 1 week tended to decrease the total carbohydrates
content of different plant parts .
11- Application of the highest used level ofNPK fertilization level
(120 kg N + 64 kg P20S + 120 kg K20/fed.) reflected the
maximum increments in carbohydrates content of plant foliage
and corms.
12- Decreasing the irrigation intervals from 2 to 1 week and
increasing the applied level of NPK fertilizers up to the fefth
used level (120 kg N + 64 kg P20S + 120 kg K20/fed.) reflected
the highest carbohydrates content of whole plant except for
lamina which should height values in this respect with the third
used water irrigation intervals (every 1 ’l2 week) .
13- The yield and its components expressed as number and fresh
weight of cormels , fresh weight of main corm, and total yield
per plant as well as height and diameter of main conn were
significantly increased as a result of increasing water applied for
plant either through increasing number of irrigation frequencies
or decreasing the interval between irrigation’s from 2 to ’l2 week.
14- The highest used level offertilizers (120 kg N + 64 kg P20S +
120 kg K20/fed.) reflected the highest values of all studied yield
component ,i. e. number and weight of cormels per plant , fresh
weight and diameter of main conn and yield per plant as well as
total yield per feddan .
15- Total produced yield and its studied components significantly
increased with increasing both the amounts of applied water and
the dosage of fertilizers up to the highest used level ,i. e. 120 kg
N + 64 kg P20S + 120 kg K20/fed.
16- The utilized water was increased with either increasing the
number of irrigations frequency or shortening the irrigation
period up to ~ week by intervals during both seasons of study _
17- The amount of water required to produce one kg of corms was
decreased with increasing the used level of NPK fertilizers during
both seasons of growth.
18- The highest quantity of water supplied to the plants
connected with the highest used level of NPK improved the
efficiency of water utilization.
FinaJlly, it could be concluded that, under such conditions,
irrigation every Y2 week by intervals combined with the highest
used level of fertilizers (120 kg N + 64 kg P205 + 120 kg
K20/fed.) may be recommended for obtaining the highest taro
yield with good nutritional value of taro corms and connels.