The state of gravity sensors and peculiarities of plant growth during different gravitational loads.

In the primary roots of lettuce shoots grown under altered gravitational conditions--180 degrees inversion on the centrifuged clinostat, horizontal clinostat and in dynamic weightlessness--localization of the cellular organelles, cell morphology and peculiarities of growth have been studied. Significant changes took place in the localization of amyloplasts on the horizontal clinostat. The changes of amyloplast position in the cap cells on the horizontal clinostat and under weightlessness are similar.

Gravity as an obligatory factor in normal higher plant growth and development.

Gravity may influence different aspects of plant activity. The present report deals with two questions: gravity as an ecological factor determining spatial orientation of plant growth; and second, a possible requirement for gravity in the process of normal growth, morphogenesis and generative development of plants.

Biological experiments on the orbital station Salyut 4.

Two series of experiments were carried out on the orbital station Salyut 4: one series consisted of two experiments (30 and 62 days respectively) designed to study the effect of space-flight factors on the growth and development of Drosophila melanogaster, strain D-32, and the second series consisted of two experiments (24-33 days) designed to study the effect of space-flight factors on the growth and development of the dwarf pea, variety "Pioneer". Analysis of the progeny from flies exposed to space flight showed an increase in the rate of visible mutations for y, ct, w and vg loci over those observed in the earth control. Space flight factors produced no noticeable effect on the first growth stages of pea plants.

The development of seedling shoots under space flight conditions.

The assumption that gravity is the major factor in the process of formation of plant polar axis was used as a working basis for the experiment. It was hypothesized by Merkys in 1973 that the effect of gravity related to axial polarity is similar to the process which determines the lateral polarity of shoots under the influence of gravity. There are two possibilities: (i) the development and morphogenesis of shoots takes place directly under the influence of gravity, or (ii) this process, at least during the first growth phases, is determined in the course of the germ development in the seed.