Bud Death Research Articles

DEPENDENCE OF АPRICOT YIELD ON ECOLOGICAL FACTORS

The article provides an overview of domestic and foreign studies on the apricot cultivation, its national economic significance, the spread of culture abroad and on the Russian Federation territory. The role of positive and negative temperatures, precipitation on the condition of fruit trees, the safety of generative buds, yield and quality of fruits is considered. Special attention is paid to the work of plant breeders of fruit growing and vegeculture department of Voronezh State Agricultural University to make large-fruited, winter-hardy apricot varieties, enhanced studying of their biological characteristics and suitability for cultivation in the conditions of the Voronezh region. An agro-ecological justification of apricot cultivation in industrial gardens is also given. The agro-climatic conditions of the Voronezh Region and certain territories: the southern, central and northern parts are studied. The areas with soil and climatic conditions for the apricot cultivation on an industrial scale are identified. The possible reasons causing the death of apricot generative buds in winter are determined: a decrease in air temperature to -30 ° C with a rate of decline of 5 ºС per hour and prolonged thaws and sudden changes in air temperature to -28 ° C The southern regions are less favorable for fruiting apricot, because of spring frosts. According to long-term data, the correlation between yield and environmental factors has been revealed using the example of Apricot cultivar Triumf northern. The dependence of flowering and fruiting on the complex influence of negative weather manifestations in the spring and winter periods has been determined. The favorable areas, whose conditions correspond to the biological characteristics of apricot cultivars of Voronezh State Agricultural University selection, have been identified. Based on statistical calculations, mathematical models were obtained and it is possible to predict the apricot yield, depending on the combination of environmental factors with a high degree of accuracy.

Cyclamen Mite: A Pest of Michaelmas Daisies

SUMMARYStunting, scarring and distortion of stems and leaves and death of flower buds has caused serious failures of Michaelmas daisies (Aster spp.) in recent years. This failure is here attributed to the presence of high populations of cyclamen mite (Steneotarsonemus pallidus (Banks)). Cultivars of A. novi‐belgii are particularly susceptible to damage and although the mite also occurs on other species, these have some degree of tolerance or resistance.Symptoms of mite damage on A. novi‐belgii are described and illustrated and preliminary observations on the biology of the pest are reported.

Cumulative radiation damage in Oak trees

This is a preliminary report of morphological and histological damage in Quercus alba L. and Q. velutina Lam. growing for 10 years (1951–1960) in the vicinity of a Co 60 gamma source. Exposure days per year varied from 111 to 256 and average daily exposure from 0·23 to 13·18 r. During the 10-year period the plants were actually irradiated 20 hrs/day for 2184 days at an average exposure of 7·19 r/day to a total cumulative exposure of about 16,000 r. Gross visible effects include: sparseness of foliage due to death of many lateral or terminal buds or branches; internodes typically reduced in length and increased in thickness; leaves fewer in number, often enlarged, distorted, thickened and somewhat leathery in appearance; leaves occurring in tufts along otherwise bare branches; abnormal inflorescences. Histological studies revealed: many lateral and terminal buds outwardly appearing viable but lacking meristematic tissue; deterioration of the central pith; reduced number of floral primordia; reduction of viable pollen; lateral meristems apparently not inhibited but rather in some cases unusually active, e.g., cork and lentical formation far exceeding the controls suggesting a stimulation effect. It is suggested that differences in actual absorbed dose and/or rate of cell cell division may play important roles in the differential sensitivity of apical and lateral meristems. The oaks are found to be much more radiation resistant than trees of Pinus rigida growing in the same area. This difference may be due in large part to differences in chromosome size or interphase nuclear volume.

GROWTH AND SEXUAL REPRODUCTION OF THE MOSS AMBLYSTEGIUM RIPARIUM UNDER STERILE CONDITIONS

Belkengren, R. O. (Oregon State U., Corvallis.) Growth and sexual reproduction of the moss Amblystegium riparium under sterile conditions. Amer. Jour. Bot. 49(6): 567–571. Illus. 1962.—Growth of Amblystegium riparium as primary or secondary protonemata, or as a leafy gametophyte under aseptic conditions, is reported. Yeast extract appears to be inhibitory for shoot growth but not for protonemal growth; it appears to cause the death of shoot buds on protonemata before they differentiate into leafy shoots, so that the organism grows as protonema only. Sexual reproduction of this organism in continuously illuminated cultures was induced by a CO2‐free period followed by addition of CO2 or sugar. Senescence in a culture may also induce sporophyte formation presumably by interfering with photosynthesis or some other function.

Studies on the sultana vine. II. The course of bud burst.

Sultana vines were examined during bud burst for four seasons, and the date on which each shoot arose was noted. The shoots were later classified as fruitful, barren, or defective. The vines were pruned uniformly in the first season, and two pruning treatments were compared in the other three seasons. In all cases the mean time of bursting a t each bud position was progressively later from the distal to the proximal end of the cane, the number of newly burst buds found at each examination was related to preceding temperatures, and the percentage of fruitful shoots among new shoots found at each examination decreased from the beginning to the end of bud burst. Accessory shoots arising as a result of the death of primary shoots or buds were very rarely fruitful. The results are considered in relation to the discrepancy sometimes found between the percentage of fruitful buds and the percentage of fruitful shoots.