Two field experiments were conducted at Fayoum Agric. Res.
Station (Kom Osheem) during 2002/2003 and 2003/2004 seasons to
study the effect of tillage operations (number of ploughing) and
irrigation at different levels of available soil moisture (ASMD), on
yield, its components and some water relations of wheat crop (Giza
168 cv). Three tillage operations, i.e., reduced till. 1, plouphing
once to 20 cm depth (T1), reduced till. 2, plouphing twice to 20 cm
depth (T2) and conventional till., (T3) were combined with three
irrigation regimes, i.e., irrigation at 35% ASMD (I1), at 55% ASMD
(I2) and at 75% ASMD (I3), in a split- plot design with four
replications. The main results obtained were as follows:
- Conventional tillage (T3) and irrigation at 35% ASMD gave the
highest averages of plant height, spike number/ m2, 1000- grain
weight, grain yield/fed. and straw yield/fed. in both seasons. The
lowest averages of yield and its components were obtained from
using reduced till-1 (T1) and irrigation at 75 % ASMD (I3) in both
seasons.
- Increasing tillage operation from T1 to T3 significantly increased
grain and straw yields/fed. and yield components in both seasons.
However, increasing the ASMD significantly decreased the yield
and its components.
- Seasonal consumptive use (ETc) averaged 39.24 and 41.44 cm in
2002 /2003 and 2003/2004 seasons, respectively. Increasing
tillage from T1 to T3 and decreasing the ASMD from 75% to 35%
ASMD increased the seasonal ETc from 33.78 and 36.66 cm to
44.52 and 46.76 in the two successive seasons.
- Monthly ETc rate increased gradually from Nov., to reach its
maximum values during Mar. and April. Then declined till
harvesting. The crop coefficient (Kc) as an average of the two
seasons during the growing season duration from Nov., to May
were 0.53, 0.74, 0.87, 0.91, 0.99, 0.60 and 0.41, respectively.
- The highest water use efficiency values were 1.010 and 0.891Kg
grains / m3 water consumed, resulted from using conventional
tillage and irrigation at 35% ASMD in both seasons.