Studies on the Germination of Pumpkin Pollen

Attempts have been made to germinate the pollen of Cucurbita pepo and Cucurbita moschata on artificial media. Various combinations of sugars and agar dissolved in distilled water were first used. It was found that two grams of agar and 14 grams of sucrose in 100 cc. of solution gave the best results, 10 per cent germination being obtained

Further Species Crosses in the Genus Cucurbita

During the past few years attempts have been made to cross the three cultivated species of the genus Cucurbita. There was used in Cucurbita maxima a pure line of Hubbard squash, known as the Kitchenette ; in Cucurbita Pepo a pure line of the Connecticut Field pumpkin, and in Cucurbita moschata a pure line of the Large Cheese pumpkin

Microsporogensis in Cucurbita maxima

A pure line of Hubbard squash was used for the investigation. In the development of the anther the pollen mother cells are formed from a single longitudinal row of cells of the primary sporogenous layer in each anther lobe. During early diakinesis a perinuclear zone is formed. From the perinuclear zone as well as from the interior of the nucleus fibers are formed which constitute the multipolar spindle. There are twenty bivalent chromosomes at the heterotypic division. Counts in root tip cell showed forty somatic chromosomes. During diakinesis a callose wall is secreted around the mother cell. When the heterotypic division has been completed a special wall composed of callose is formed just inside of the original mother cell wall. Quadripartition of the mother cell is effected by partition walls which originate on the inner surface of the special wall and grow centripetally

Species Crosses in the Genus Cucurbita

Various attempts were made to cross different varieties belonging to three species. Successful crosses have been made as follows: (1) Hubbard Squash (C. maxima) as the pistillate parent x Common Field Pumpkin (C. pepo). Viable seeds which produced vigorous fertile Fl plants were secured from this cross. The reciprocal cross produced normal fruits, but no fertile seeds. (2) Hubbard Squash (C. maxima) as the pistillate parent x Large Cheese Pumpkin (C. moschata) produced fruits which contained no fertile seeds, although otherwise normal. (3) Scalloped Squash (C. pepo) as the pistillate parent x Large Cheese Pumpkin (C. moschata) produced fruits containing no fertile seeds, although otherwise normal. (4) Bush Crookneck Squash (C. pepo) as the pistillate parent x Scalloped Squash (C. pepo) produced many fertile seeds. In the last three cases mentioned no reciprocal crosses were made. In the last three cases mentioned all back crosses produced fertile seed

ESCOBAR\ucdA LEEI B 6DEKER REDISCOVERED IN NEW MEXICO

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