Interventi agronomici e genetici per la definizione della tecnica colturale e la costituzione di ibridi F1 in carciofo
Author(s)
Cardarelli, Luigi
Date Issued
June 7, 2013
Type
Doctoral Thesis
Abstract
In recent years, the artichoke has undergone intense genetic improvement both on the part of multinational seed companies and scientific institutions. This has led to the first uniform and stable F1 hybrids, with high agronomic and commercial value.
However, it should be noted that despite the several studies concerning physiology, farming techniques and phytosanitary protection about conventional culture, there are only few indications regarding the management of the artichoke field implanted from plants obtained by gamic pathway, both as regards the use of seedlings with protected root and, even less, the direct seeding.
Therefore, in a modern cultivation of artichoke which is likely to increase the use of plants obtained via seed, it is crucial to deepen the knowledge of appropriate technics regarding the time of sowing, density of transplanting, the weeds control and the irrigation system. Those technics should consider not only the type of production (fresh market, industrial processing, production of achenes) but also the implantation technique adopted such as direct seeding (e.g. U.S.A.) or transplant (e.g. Italy).
The achenes net yields, although lower, are comparable to those of plants such as sunflower and cultivated cardoon, species already involved in specific genetic improvement programs.
Hence, considering that the recent genetic improvement of the artichoke has been concentrated mainly on the production of immature heads (i.e. fresh market and processing industry), it is assumed that there good possibilities to increase both the net yield in achenes and oil through the formation of F1 hybrids.
Thereafter, the present Ph.D. project had, as its main objective, the setup of agricultural techniques in the cultivation of the artichoke propagated by seed to be used both in direct seeding and for obtaining seedlings with protected root.
A second issue of the research was to study the effect of sowing on the yield response for some F1 artichoke’s hybrids, making direct seeding on a monthly basis for a total of 15 months.
In the course of the project it has been also possible to cooperate in the work of genetic improvement in place for several years at the DAFNE in order to contribute to the establishment of F1 hybrids. From the experiments it emerged that the time and density of transplantation significantly influence both the growth of the plant and the heads production both in terms of quantity and quality.
Anticipating the transplant to the first days of July, it is possible to advance to the month of November the collection of the heads of very early varieties such as Istar Hy. Conversely no significant advances for late hybrids have been recorded.
Also, it was noted that if the transplant is delayed beyond the third decade of July, for the early varieties, and over the end of August, for the late cultivars, both types show a reduction of the biomass produced.
Such behavior suggests that, despite being considered a microthermal species the artichoke prefers high levels of temperature and light in the first phase of growth.
Besides the time of planting, the density was also important to achieve satisfying levels of production. As a matter of fact, for the Istar variety, the optimum density was much larger than for the Romolo cultivar which requires densities equal to, or even lower than that usually achieved in the Lazio region for the old cultivars used.
Relatively to the test of direct sowing, it was observed a similar behavior to the one detected in the test that involved the use of protected root seedling for the constitution of the artichoke.
In fact, the cv Romolo was more productive with lower densities while the production of Istar, being less vigorous, reached the highest levels with the highest density. Regarding the times, none of the two varieties showed significant differences in the two compared periods.
Among the cultivars used in the study of the thermo-photoperiodic response, the insertion of an early cultivar as Istar was found very important as it has responded differently to all other cultivars used. In particular, the first three sowing have underlined the precocity of Istar. As a matter of fact, the plants sown in March and April in both years have started the production cycle in the fall.
For the Romolo cultivar, the heads yield was not affected by the time of sowing.
The experience gained on some cross-combinations has showed that the use of the two selections of cultivated and wild cardoon is very useful in order to obtain information on the possible use of new male sterile in breeding programs, reducing the number of hybrids to be tested.
In fact, being the two cardoon lines stable and uniform, because of the cross within very small populations followed by a few cycles of selfing, any variability observed in hybrid plants can be likely attributed to the male sterile used in the cross.
The best male sterile identified, will be subsequently used in specific cross, not only to test the uniformity of the hybrid but also some morpho-physiological and agronomic features, essential for their future cultivation.
Based on the experience gained, a positive opinion on the use of new genotypes multiplied by "seed" can be expressed.
The use of seed varieties characterized by different degree of precocity and low cost of the seedlings can be an advantage for both covering those market niches where the supply of artichokes can not meet the demand and reducing the production costs and, thus, make the Italian artichoke more competitive.
During the course of the PhD interesting material (clones) to be multiplied by vegetative propagation and suitable for the fresh market has been selected.
Additional information
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