EVALUATION OF SOME RICE MUTANTS UNDER WATER STRESS CONDITIONS.

Two field experiments were carried out during two successive growing
seasons (2004 and 2005) in a farm located at Sahafa village. Sharkia Governorate, to
evaluate some new rice mutants comparing with the local variety Giza 177 ( sensitive
)and exotic rice variety lET 1444 ( tolerant) for drought tolerance and efficient use of
irrigation water under three irrigation intervals, i.e., irrigation after 4 ( control ), 6 and 8
days for water stress treatments.
The results showed that:
        1-    Maximum grain yield and its components were obtained when rice plants were
irrigated every 4 days intervals, while increasing irrigation intervals up to 8 days
significantly decreased grain yield and its components.
        2-         Mutants MG 16 and MS 6 were superior in plant height, panicle length, number of
grains per panicle, panicle weight and 1000 grain weight, while the maximum
values of number of panicle I m² and straw yield were obtained by lET 1444
variety.
        3-    The ranking for grain yield (tlfed.) was as follows: MG 16 > 1FT 444 > MS 6 >
Giza177.
        4-    The interaction between irrigation intervals and rice genotypes had no significant
effect on yield or any of its attributes.
        5-    According to stress susceptibility index for different rice genotypes Mut. MG16
was tolerant to drought comparing with the other genotypes.
        6-    The highest water use efficiency (WUE) was obtained by Mut. MG 16 under sever
water stress comparing to the other genotypes.
        7-    Irrigation of rice plant every 6 days interval saved 2140.74 m³ I fed. (24.9 %)
comparing with the control treatment.
        8-    Mut. MG 16 with its highest yield, water use efficiency and lowest values of stress
susceptibility index under drought conditions, So, it was consider the most tolerant
comparing with the rest of genotypes.