Sweetness and acidity in apple and pear inherit independently and can be organoleptically evaluated separately, but less accurately in pear than in apple . For breeding purposes an analysis of fruits for acidity and sweetness with pH indicator paper and a hand refractometer is to be prefered to the organoleptic method .In apple, the acidity -decreasing with time -of the unripe fruit was already strongly indicative of that of the eating-ripe fruit ; sugar -increasing with time -not before the fruit was picking ripe . Sugar content in apple and pear, and the pH in pear, appeared to be normally distributed ; the pH in apple showed a segregation into an acid and a low-acid group, which occurred in both the unripe and ripe stage . The segregation ratio between these groups was found to be highly variable . On the whole, the mean acidity and sugar content of apple and pear progenies is significantly determined by that of the parents . Most of the observations made did not support the theory that low acidity in apple is determined by one recessive gene . The relationship between the pH of leaf juice and fruit juice in apple may offer a possibility for pre-selection .
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 .
In vitro propagation of the rose rootstock 'Moneyway' was investigated on the following media: Murashige and Skoog (MS), Quoirin and Lepoivre (QL) and Woody Plant (WP). Growth, which was measured as length of shoots after a 6-week period, was faster on MS and QL than on WP. In spite of the better growth, chlorosis of newly formed leaves occurred from the third week on and was correlated with a lower chlorophyll content of shoots.
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