Info

5.2.1. The Role of Plant Development 5.2.1.1. Rootstock Diameter

The essential developmental stage for flowering of caraway plants is mostly characterised by the diameter of their rootstock. According to Glusenko (1977), on the base of the leaf mass and the diameter of the rootstock the production of the stand can be estimated. At least six leaves and a rootstock diameter of 5mm are necessary at the end of the first vegetation year for flowering in the next spring. Furthermore, he proved a tight correlation between the mentioned two features (r: 0.92-0.99), so the leaf number itself might give proper information about the plant development. Observations of Havalda (1980) showed, that seed yield of a plantation depends on the presence of plant individuals of at least 6mm rootstock diameter. Between their proportion in the stand and the mass of production a positive linear regression has been described. Individuals of rootstock diameter more than 10mm are of special significance.

Similar results were published from Poland, by investigations of Weglarz (1982). He described the advantage of the more developed individuals in flowering and yielding. As a lower limit of flowering potential, he indicated an individual root mass of 26-50g, and a rootstock diameter of 8-15mm. While among plants under this limit the flowering proportion was only 55-75%, in case of plants of the mentioned size it was 80-95%, and only the largest plants (50-150g and 16-25mm diameter) developed all flowers (in 100%).

In case of the related Daucus carota L. even the effectiveness of artificial flowering induction by GA3 was connected with plant size: while in 12 weeks old plants a maximum value of 84% flowering could be achieved, in 8 weeks old individuals 70% proportion was the best value (Bandara et al. 1995). Apium graveolens L. var. dulce may end juvenility and become competent for effective cold treatment by getting 17-20 leaves, depending on also the cultivar (genotype) (Ramin and Atherton 1991).

Plant size plays an important role both in making the individual capable of flowering as well as developing more and larger flowers. In our experiment, carried out in 1994-95 at the University of Horticulture and Food Industry, Department of Medicinal Plant Production, caraway plants of different rootstock size were planted and examined in phytotron chambers. Four different biennial origins were tested, in all the four population the more developed plants had 9-13mm rootstock diameter and 8-12 leaves, while the less developed ones had 5-8mm rootstock diameter and 5-7 leaves. They were grown under two types of ecological programs. One of them consisted of a two week, the other a seven week vernalization period (8°C at day and 5°C at night), after which the temperature raised from 14° to 21°C. Data of the experiment showed, that the larger plants did not require a long vernalization period, while in case of the less developed roots only a longer induction may result in almost full flowering (Table 1). In general,—independent from genotype—, the thinner rooted plants could never reach the flowering percentage of the thicker rooted ones (Nemeth et al. 1997).

In the average of origins and temperature treatments, the thick rooted plants exhibited also a higher and stronger growth. Especially the number of the stems and that of the umbels were significantly higher in case of the more developed individuals (Table 2). The size of

Table 1 Ratio of flowering individuals (in per cent) according to development and genotype after two weeks vernalization at 8/5°C

Taxon 2 weeks induction 7 weeks induction

Diameter of root stock at the beginning of vernalisation

Taxon 2 weeks induction 7 weeks induction

Diameter of root stock at the beginning of vernalisation

Was this article helpful?

0 0
10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment