تأثير كميات البذار و الإجهاد المائي في نمو و حاصل الحنطة

Abstract EN

A field experiment was conducted during the winter season 2014 – 2015 at the plant production farm of Alfayha company which located at singar district (8 Km nrthern of Babylon governorate center) in silty clay loam soil to determine the seeding quantity of bread wheat (CV.

IBA 99) under watern stress at different development stager of plant life cycle .The experiment was arranged as a split – plot in Radomized Complete Block Design with three replicates .The experiment consisted three seeding guantity (120,200 and 280kg/ha) represeuted the main plots , while treatment of water stress (Irrigation after depletion 50% of waliable water as (control), water stress in each tillering ,elongation, earing or grain filling stages) represented the subplots one irrigation was skipped on this stagesBread wheat seeds (CV.Ib-99) was sown in November 29th ,2014 and harvested on May 10th , 2015 .

Results of this experiment were revealed : Cgrain yield did not effected by the increase of quantity which seeding gave grain yield reached 4.46 , 4.72 and 4.59 ton/ha for 120 , 200 and 280 Kg/ha respectively.Water stress at the growth stages caused reduction in grain yield compared with control treatment by 7% (tillering) , 23% (elongation) , 17% (earing) and 20% (grain filling).

Water stress at tillering stage caused reduction in grain yield reached 20% by using 120kg/ha (seeding rate) while the grain yield was not affect in this stage when the seeding rate increased to 200 kg/ha.

The results show that increasing seeding rate from 120 to 280 kg/ha limited the reduction in tillering stage under water stress due to the compensation in number of spikes due to the increase of plant number per unit area as the seeding rate (280kg/ha) gave a higher mean of number of spike reached (330.7 spike/m2) compared with 120 and 200kg/ha which gave (263.7 and 281.0 spike/m2) respectivelg .

Although, the grain yield was determined by number of grain per spike and grain weight in addition to number of spike.The increasing of seeding rate was not affected on the grain yield when the plant exposure to water stress at elongation stage which gave 4.10 ton/ha with 120 kg/ha while gave 4.38 and 4.17 ton/ha with 200 and 280 kg/ha respectively.

Increasing the seeding rate from 120 to 200 or 280 kg/ha increased the number of spike per m2 while the number of grain per spike was decreased which gave was 48.54, 43.64 and 35.30 grain/spike for seeding rate 120, 200 and 280 kg/ha respectively while the grain weight which was not affected the 1000 grain weight was 28.77 , 29.82 and 29.33gm for the seeding rat respectively.Water stress at tillering elongation and earing caused reduction in number of grain per spike when gave 39.98, 39.21and 34.72 grain / spike respectively while the control treatment gave 49.73 grain / spike .

The water stress at grain filling was not affected the number of grain but it decreased grain weight by 34% of control .The reduction in grain yield caused by water stress was caused by significant reduction in plat hight , flag leaf area , and its dry weight.