STUDIES ON YARROW" Achillea mille folium L." PLANTS: I. EFFECT OF SPRING AND AUTUMN CULTIVATION AND TIME OF HARVEST ON GROWTH, FLOWERING, AND YiELD OF THE DRiED FLOWERS AND ESSENTIAL OiL.

Yarrow (Achillea mllletctium, L.), locally known as "Thousand leaves"
is a member of the Family "Asteraceae", and is an important medicinal and
aromatic plant. The aerial parts of the plant contain high quality essential oil
and is also used as an aromatic bitter and stringent herb. The flowers are the
richest part of the plant in the essential oil. This study was carried out during
the two successive seasons 2000/2001 and 2001/2002, at the Experimental
Station of Olericulture and Floriculture, Faculty of Agriculture, Mansoura
University. It aimed to compare between two planting seasons (spring and
autumn) and two consequent cuts of each of them on growth, flowering, and
yield of the dried flowers and essential oil of Achillea under the conditions of
Dakahlia Governorate.
           .     Data were recorded on time taken to flower, plant height, herb and
flowers weight, and oil percentage in the flowers, and the yield of both the
dried flowers and the essential oil. Temperature and day-length change
during the course of the study were also recorded.
The results showed that plants at the 1^st cut took longer time to flower,
were taller, produced more herb and flower weight per plant, and yielded
more dried flowers and essential oil than those at the 2^nd cut in both plantings
(spring and autumn).
Results also showed that, in the first season, spring planting produced
shorter plants, less herb weight per plant, but produced more flower weight
per plant, and more dried flowers and essential oil yield per feddan than
autumn planting. In the second season, spring plants suffered from
inconsistent temperature and produced less flower and oil yield than autumn.
In both seasons, spring plants flowered earlier and took shorter time to be
ready for the first and second cuts than autumn plants regardless of
temperature changes. On basis of the meteorological data, it was concluded
that flowering of Achillea was mainly dependent on day-length, but its growth
and yield were greatly influenced by temperature changes. Results also
showed that the planting season and time of harvest did not affect the oil
percentage in the flowers, and that the increase in oil yield was a tributed to
the increase in the yield of the dried flowers not in their oil content.