Hybrid Tea-rose pollen. I. Germination and storage

Abstract

Germination and storage trials were carried out with pollen of several rose varieties . The pollen grains germinated well in a 15%, sucrose solution with 40 ppm boric acid . Staining the pollen with a 0 .1 tetrazolium solution and standardizing the degree of colour at which the pollen grains are counted as viable, provided a good viability estimate, simpler to carry out than in vitro germination . Germination capacity and staining ability of the pollen were greatly impeded -about halved -by dehydration during storage in desiccators at low humidity . This effect could be corrected by humidifying the pollen beforehand for about one hour, though this pre-treatment increased the percentage of germinated pollen grains more than the percentage stained . There was no difference between the two percentages in fresh or in deep-frozen pollen .Pollen stored at 1 °C and high relative humidity soon lost its germination capacity ; between 0 and 20°" humidity a considerable proportion of the pollen remained viable for 9 months and longer . Storage for the same period in vacuum-sealed glass tubes at -24°C maintained viability as well or better and would probably prolong it further . Some of the cold-stored pollen induced a reasonable seed set after one year, a low seed set was obtained even after two years of storage at I °C and low humidity .

Factors influencing pollen germination in three Explorer™ roses

“…Our results are similar to those of Visser et al (1977) and Voyiatzi (1995). They also correspond closely to those of Calvino (1951), who obtained better results with a saccharose concentration of 20% for six species of roses.…”

“…Several studies report that the saccharose concentration in the media could stimulate or inhibit the germination percentage. Visser et al (1977) and Voyiatzi (1995) obtained the best pollen germination percentage with a saccharose concentration of 15% for hybrid tea roses. Khan (1987) suggested a concentration of 20% for R. rugosa Thunb.…”

“…The literature reports wide variations in the techniques used for drying the anthers and storing the pollen (Calvino 1951;Khan 1987;Marchant et al 1993;Visser et al 1977). Good pollen germination has been reported with drying at ambient temperature for 24 h (Jicinska et al 1976;Koncalova 1975) and 48 h , whereas Voyiatzi (1995) prefers a period of 1 h at 60% relative humidity.…”

Pollen and pollination experiments. VI. Heat resistance of pollen

“…For instance, the lily pollen was only a few days old while the similarly performing pear pollen had been stored for 4 months before testing. It is reasonable to assume that optimal, as well as comparable, results are obtainable with fresh pollen which is dried for a short time prior to treatment and rehydrated prior to germination (VISSER, 1955;VISSER et al, 1977;VISSER • OOST, 1981;VAN TUYL et al, 1982). As it is, the data indicate that pollen of the 'drought resistant' type is also heat resistant.…”

Hybrid Tea-rose pollen. II. Inheritance of pollen viability

“…Pollen from just opened flowers was collected between the end of April and the beginning of July 1976 and checked on the basis of at least six replicates . Viability was evaluated after staining with 0 .1 % anhydrous 3-(4,5 dimethyl thiazolyl -2)-2,5 diphenyl tetrazolium bromide in the manner described earlier (VISSER et al ., 1977) .…”