Responses of young cucumber plants to a diurnal temperature drop at different times of day and night

In greenhouse production of a number of vegetable and ornamental plant species, a short diurnal temperature drop in the end of the night or in the morning is commonly used to reduce stem elongation as an alternative to chemical growth retardants. Experiments were carried out to quantify the effects of a temperature drop at different times of the day and night on growth and photosynthetic activity of young cucumber plants. During 6 days plants were exposed daily to a temperature of 10 °C for 2 h at the beginning, in the middle and at the end of the night and day periods. The results have shown that plant response to drop may be qualitatively different in the light and darkness. While strongest effects of drop are observed when it is given in the daytime, for practical application in greenhouses it is more appropriate to reduce temperature at night. However, it may not be strictly necessary for cucumber seedlings to apply drop at the end of the night as it was stated in the literature. Thus, our results may cast doubt on the following statements: (a) temperature drops are not effective when delivered at other times of the day or night (except before sunrise), (b) optimal time for drop effects depends on the daily dynamics of stem and petiole elongation rate. It is rather drop itself is capable of modifying the dynamics of plant growth in the daily cycle.</p

ЗАВИСИМОСТЬ ШИРИНЫ ГОДИЧНЫХ КОЛЕЦ СОСНЫ ОБЫКНОВЕННОЙ ОТ ТЕМПЕРАТУР ВОЗДУХА И ПОЧВЫВ ЛЕСОСТЕПНОЙ ЗОНЕ ЮГА СИБИРИ

Paper contains analysis of Scots pine (Pinussylvestris L.) radial growth response on annual fluctuations of temperature of air and soil at different depths in the forest-steppe zone of South Siberia. Effect of temperature on the radial growth was identified and explained. It is positive in the cold (November-February) and negative in the warm season (May-October). It was shown that in different months influence of temperatures at different depths is significant. This climate response in the forest steppe zone varies depending on the local conditions of the site.Проведен анализ климатического отклика радиального прироста сосны обыкновенной (PinussylvestrisL.) на погодичные колебания температуры воздуха и почвы на разных глубинах в лесостепной зонеЮга Сибири. Выявлено и объяснено влияние температур на радиальный прирост - положительное в холодный (ноябрь-февраль) и отрицательное в теплый период (май-октябрь). Показано, что в различные месяцы более значимо влияние температур на различных глубинах.Эта климатическая реакция в лесостепной зоне различается в зависимости от локальных условий места произрастания

Parathyroid function and cardiovascular remodeling in arterial hypertension patients

Aim. To investigate structure and function of left ventriculum (LV) and brachial artery (BA) in arterial hypertension (AH) patients, according to blood levels of parathyroid hormone (PTH).Material and methods. In total, 95 untreated patients with Stage I-III AH were examined. Blood PTH, total calcium levels, and 24-hour urine calcium excretion were measured. All participants underwent Doppler echocardiography, 24-hour blood pressure monitoring (BPM), and BA ultrasound. According to PTH levels, the patients were divided into three groups: Group I – 0-25 pg/ml, Group II – 26-50 pg/ml, and Group III – 51 pg/ml.Results. LV hypertrophy prevalence in Group III was 80,6%, in Group I – 43,7%. In “dippers” (24-hour BPM data), PTH level and 24-hour urine calcium excretion were 1,5 times lower than in “non-dippers”. Comparing to Group I, Group III demonstrated significantly greater intima-media thickness (+17,8%) and linear blood flowvelocity (+19,7%), but lower BA diameter (417,3%) and endothelium-dependent vasodilatation (415,5%).Conclusion. PTH levels correlated with prevalence and severity of LV and BA remodeling