Marchesi, Giuseppe.
During the year 1958 rates of natural cross-pollination in Lycopersicon esculentum were obtained at Piacenza. The measurement of natural cross-pollination was made through the use of the potato-leaved cultivar Red Jacket. This cultivar was grown in five plots randomly distributed among cut-leaved cultivars. Potato leaved plants (c/c) comprised about 3% of the population. The area of every plot was 50 m^2. In the plots the plants of Red Jacket were spaced 0.4 m in the rows and 1 m between the rows.
The seeds obtained from plants of the potato-leaved cultivar should produce only potato-leaf seedlings when self-pollinated or crossed with other potato leaf cultivars. We have considered the cut-leaf seedlings that appeared in the progeny of the Red Jacket as the result of cross-pollination.
The average rates of natural cross-pollination were 3.9%, 3.6%, 4.2%, 7.2% and 10.6% respectively in seedlings obtained in greenhouse controls from fruits harvested during the period August 8 to September 30 (five successive harvests).
An analysis of the data shows that cross-pollination is higher at the end of the growing season. This seems correlated with the greater insect population and activity during the months of July and August. The wind and the extrusion of stigmas from the anthers may be also involved.
Table. Percentages of natural cross-pollination in progeny from
seeds of Red Jacket measured with +/c
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Date of Number Seedlings Per cent
harvest of fruits _____________________ of +/c
c/c +/c
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12/8 350 25.111 1.014 3.88
25/8 290 11.056 427 3.60
8/9 439 11.860 524 4.23
19/9 872 24.907 1.939 7.22
30/9 1.286 57.085 6.774 10.61
Total 3.237 130.019 10.678 7.59
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