CONTINUITY OF ROOTS EMERGENCE AND GROWTH IN Tigridia pavonia Ker. Gawl.

Abstract

Root growth and emergence were studied from October 1996 to April 1997, during the late seasonal plant growth and bulb dormancy period. The objective was to test if the emission of roots was a continuous process and to define types of roots produced by bulbs. Bulbs, with their leaves and roots, were extracted from the soil and placed between sheets of wet newspaper in plastic bags. These were held at room temperature varying from 20-24/18°C (day/night). The sheets of paper were changed monthly. Small bulbs, below 10 g were used. The measurements included the size and the number of roots and leaves. Periodically the dying roots were re-moved. The foliated bulbs or which lost their leaves, ubicated in beds, produced new contractile roots since the second half of the flowering and continued to grow. Both, roots emergence and the longitudinal growth were maintained for a few weeks after the bulbs lost their leaves. The bulbs started to cease the emission of new roots approximately at the end of January. The root forming meris-tems were in dormancy for 4 to 6 weeks. The bulbs reinitiated emitting new roots at the end of February or at the beginning of March. This, was followed by the emission of new shoots. The bulbs produced contractile roots, from the second half of the flowering period; at the start of a new season of growth produced only the feeder roots. Both root types may be present during the flowering period.