تأثير موعد الزراعة في مدد مراحل نمو ثلاثة تراكيب وراثية من زهرة الشمس (Helianthus annuus L.)‎

Abstract EN

A field trial was conducted at Abu-Ghraib research station, Baghdad, Iraq, during the spring season of 2001, The objectives were to study the effect of sowing dates on the performance of three sunflower genotypes.

A split-plot lay in a randomized complete block design with three replications were used.

Five sowing dates (16th Jan, 4th, 14th and 26th of Feb.

and the 15th of March) were assigned to main plots, where as genotypes in sub-plots.

Any delay in sowing dates after the 16th Jan.

Hastened the physiological processes of the developmental stages of the crop.

And reflect, the effects of environmental factors such as (higher temperature, longer photoperiod and lower relative humidity), consequently the optimum periods of the life cycle of the crop was shortened.

First planting date16 / 1 showes longer period to emergence compared with later dates.

Plating dates affect only on the days number from emergence toB3-B4 the second pair of opposite leaves appears and is 4cm long plants that planted at first planting date more days reach this stage days from B3-B4 to E1 the floral bud appears in the middle of the young leaves.

First and second planting date needs more days from E1 to F1 The bud bends down, There is a significant effect only for planting dates, The first planting date need more day from F1–F3.2 The flower unfolds, F3.2-M3 maturity is the back of the sunflower head turns brown the stem dries up the stem leaves become brown, planting to 50 % flowering and planting to maturity.

The genotype Manon was earlier in emergence, flowering and maturity and later at period of F3.2-M3 compared with other tow genotypes.

Interaction between genotypes and sowing dates were also detected.

The plants of Euroflor and Pan7392 lated at first sowing date at the period of flowering (from F1-F3.2) and from sowing to maturity and they need more days from the F3.2-M3 at second sowing date.