Safflower Plant development

Safflower (Carthamus tinctorius) is a highly branched, herbaceous, thistle-like annual plant in the Asteraceae family.It was grown commercially for the extraction of vegetable oil from the seeds and was used as a saffron substitute by early Spanish colonies along the Rio Grande. Plants are 30 to 150 cm (12 to 59 inches) tall and have yellow, orange, or red flowers in globose flower heads.Each branch usually has 1 to 5 flower heads, each containing 15 to 20 seeds.Safflower is native to arid environments with seasonal rainfall. It grows a deep tap root, allowing it to thrive in such an environment.

Biology

Plant form:

Safflower is a fast-growing, erect, winter/spring-growing annual herb similar to thistles.Branched central stems (also called terminal stems) grow from leaf rosettes when day length and temperature increase.Main branches reach a height of 30-150 cm (12-59 in).The plant also develops a strong tap root that reaches a depth of 2 meters (6 ft 7 in).When the main stem is about 20-40 cm (7.9-15.7 inches) tall, the first side shoots begin to develop.These side shoots can then branch again to produce secondary and tertiary branches.The variety and growing conditions chosen affect the degree of branching.The slender, serrated leaves reach a length of 10-15 cm (3.9-5.9 in) and a width of 2.5-5 cm (0.98-1.97 in), and extend down the stem.The upper leaves, which form the bracts, are usually short, stiff, ovate, and terminate in the spine.Buds grow at the ends of shoots, and each compound flower head (flower head) contains 20-180 individual florets.Depending on variety, crop management, and growing conditions, each plant may produce 3-50 or more flower heads 1.25-4 cm (0.49-1.57 inches) in diameter.Flowering begins with the terminal flower head (central stem), followed by primary, secondary and sometimes tertiary branch flower heads.Individual florets usually bloom for 3-4 days.Commercial varieties are mainly self-pollinating.The flowers are usually yellow, orange and red, but white and cream flowers are also available.Exophytic ovaries of double carpels form ovules.The safflower plant then produces achenes.Each flower head usually contains 15-50 seeds; however, the number can exceed 100.The hull content of the seeds varies between 30 and 60%, and the oil content of the seeds varies between 20 and 40%.

Plant development:

Safflowers usually appear 1-3 weeks after planting and grow slowly in cold temperatures.Germination of safflower is epigenetic.The first true leaves form a rosette.This stage occurs in winter with short daylight hours and low temperatures, as safflower can withstand frosts up to −7 °C (19 °F) during the rosette stage.When temperatures and day length begin to increase, the central stem begins to elongate and branch, growing faster.Early sowing allows more time to develop large rosettes and wider branching, resulting in higher yields.Flowering is mainly affected by day length.The time from end of flowering to maturity is usually 4 weeks.Total time from sowing to harvest maturity varies by variety, location, time of sowing, and growing conditions; for June or July sowing, it may take 26-31 weeks.Both wild and cultivated forms have a diploid set of 2n=24 chromosomes.Crosses with Carthamus palaestinus,Carthamus oxyacanthus and Carthamus persicus produced fertile offspring.