An analytical method od determination of luni-solat perturbations of the satellite motion is described here. The motion of perturbing body is described by trigonometrical series with the necessary accuracy. The determination of perturbations is made by numerous analytical transformations of the series by means of computer. As a result of these transformations the original accuracy is lost because of the limitation of the number of terms in series. The loss of accuracy is subjected to analysis by means of numerical tests and intotal accuracy of original series is estimated for fixed required accuracy of the calcualtion of satellite coordinates.
Development of water stress in Trifolium subterraneum L. plants, growing in growth room or in the field during autumn-winter and latě springtime, was studied under ťhe conditions of irrigation replenishing every day the evaporated water (1), withholding watering (WW), and slowly induced drought, replenishing daily with a fraction of water evaporated (SID). The method ušed to induce drought substantially affected the leaf water relations. In WW plants drought developed rapidly and in consequence the leaf water relations dramatically changed afler 10 d of treatment. The treatment maintained a stable moderate water stress (SID) that enabled the development of new acclimated leaves even under high tempertures and low humidity.