Robert Gruszecki
The effect of some factors on ‘Hamburg’ parsley plant growth and yield quantity and quality in the cultivation on early harvest
The aim of the study was to check the possibility of growing ‘Hamburg’ parsley from late summer and pre-winter sowing for early harvest. The objectives the research was to determine overwintering, susceptibility to vernalization and the term of achieving marketable sizes by ‘Hamburg’ parsley plants. An important issue was the assessment of yield quantity and quality, including the content of selected chemical components in roots and leaves. 
Material and methods. Two parsley cultivars were taken into consideration in the experiment: the early ‘Cukrowa’ and the late ‘Berlińska PNE’. Six sowing dates were applied: 5th July, 25th August, 5th September, 15th  September, pre-winter and spring. The harvest was commenced when on the basis of weekly measurements mean root diameter of 30 subsequent plants in a row exceeded 20 mm. The plants from the sowing of July 5th was performed when the first (< 10%) inflorescence sprouts had been noticed. 
Results. Overwintering depended upon the growing phase that the plants had achieved before winter. Almost all  plants that formed 1 leaf died out over the winter. As the plants grew to the phase of  4–5 leaves, their ability to survive unfavorable conditions increased. The plants that formed 5 and more leaves, wintered on a similar level, and the weather conditions affected their wintering much less than in the case of plants that were less advanced in their growth. 
Susceptibility of ‘Hamburg’ parsley plants to vernalization depended upon the growing phase they achieved before winter. Plants that formed 1 leaf did not undergo vernalization. As they acquired more leaves, the participation of plants, which formed inflorescence sprouts in spring, increased. Especially significant differences were found between plants that formed 3 (4,4%) and 4 (31,6%) leaves. The plants that had 4–6 leaves before winter, vernalized in a very broad range, depending on the weather conditions. From among the plants that formed more than 6 (‘Berlińska PNE’) or 7 leaves  (‘Cukrowa’), at least half of them formed inflorescence sprouts, irrespectively of the weather conditions. 
Growing ‘Hamburg’ parsley sprouts from late-summer sowings, made it possible to hasten harvest time, as compared to growing from spring sowing. The plants obtained from late-summer sowing achieved marketable size on average from 52 (25th August) to 44 days (15th September) earlier. However, the term of achieving marketable size depended on the weather conditions in the vegetation period. In the case of plants grown from sowing on the 25th August this term differed in particular years by 35 days, from the sowing on the 5th September – by 30 days, from the sowing on the 15th September – by 16 days, and from the pre-winter sowing – by 15 days. 
From the late-summer terms the best one was the sowing on the 5th September. The plants grown from this sowing term overwintered relatively well, and the participation of those that formed inflorescence sprouts was small (13,4% on average). The root yield of the plants grown from this sowing term was the greatest of the late-summer sowings and it was the least variable, depending on the growing season. 
The ‘Cukrowa’ cultivar was more suitable for late-summer sowing. These plants, as compared to those of ‘Berlińska PNE’ cultivar overwintered better in the phase of  2–3 leaves, were less prone to forming inflorescence sprouts in the phase of 4–6 leaves and achieved marketable size earlier. The plants of ‘Cukrowa’ cultivar from late-summer sowing were characterized by more faithful cropping. Their yield size was less dependent on sowing term and the weather conditions than the plants of ‘Berlińska PNE’ cultivar. 
The contents of the dry matter, L-ascorbic acid and β-carotene in plants from late-summer sowing, at the moment of achieving marketable size, was on a similar level, or even higher than in the plants grown from spring sowing. Only the essential oil contents in roots was lower then plants grown from late-summer sowing. The content of nitrates in the roots and leaves of plants from late-summer and spring sowings was usually on the similar level. More nitrates were often found in plants obtained from pre-winter sowing. Most of the essential oil was contained in the roots of plants from spring and pre-winter sowing, as well as in the leaves of those from pre-winter sowing. In the oil obtained from the roots apiol predominated, with significant  participation of  β-pinene and myristicine, and in the oil from leaves the main components were: myrcene, α-pinene, p-cymenene and β-phellandrene.
Cultivation of ‘Hamburg’ parsley from late summer sowing in climatic condition of Poland is possible. Obtained yield, in comparison for received from spring sowing, was smallest, but about 6–7 weeks earliest and often not worse quality.