Radical Anatomy, Seedling Morphology and Host Detection of Seedlings of Cassytha filiformis

Abstract

Seed biology is foster for ecologically sound management of parasitic weeds. The seedlingwhich is the first vegetative phase of a plant after the germination has particular importancein the study of seed biology. Distance of parasite from the host plant, and germinationmorphology are two important aspects in life cycle of a parasitic plant. However, the littleattention has been given to the study of germination biology of Cassytha filiformis. Thus, mystudy was conducted to identify the radical anatomy, seedling morphology, and minimaldistance of the host to successful attachment of C. filiformis.

Manually scarified seeds were allowed to germinate on moisten filter papers and germinatedradicals were collected in FAA solution and were used to study the anatomy of radicle usingmicrotome sectioning. Another sample of seedlings was allowed to grow further andphotographs were taken at different developmental stages. Some of selected seedlings wereplanted in soil media which are placed in three different distances from the host plants (5 cm,10 cm, and 15 cm) and number of attached seedlings to their host and maximum days ofsurvival without the aid of host was determined.

Anatomy of radical was similar to the general anatomy of typical dicotyledonous plant rootwhich consist of outer epidermis, cortex and steal with an outer pericycle. After 5-6 days thisis differentiated into 4 adventitious roots. A yellowish, conical hypocotyl is developed ascontinuous event of germination and this curved and formed a n-shaped loop in order toattach the substratum and to raise the cotyledon up. Thus the germination type is epigeal.According to the observations 100% of seedlings were attached to their respective host whichwas placed in 5 cm distance whereas about 60% of seedlings were able to attach where hostwas in 10 cm distance. 94% of seedlings were failed to attach their hosts in 15 cm distance.Attachment rates between 5cm, 10cm and 15cm differ significantly (F= 20.14, p<0.001).Thus the minimal distance for successful attachment, host plant should be ranged from 5cmto 10 cm. And the seedlings can survive for about eight weeks without attaching a host usingstored food reserves.