Accumulation of various osmolytes was examined in plants of sugar beet cv. Janus grown under two soil water treatments: control (60% of the field water capacity; FWC) and drought (30-35% FWC). The water shortage started on the 61st day after emergence (DAE), at the stage of the beginning of tap-roots development and was imposed for 35 days. Osmotic potential of sugar beet plant organs, particularly tap-roots, was decreased significantly as a consequence of a long-term drought. Water shortage reduced univalent (K + , Na + ) cations concentrations in the petioles and divalent (Ca 2+ , Mg 2+ ) ions level in the mature and old leaves. Cation concentrations in the taproots were not affected by water shortage. The ratio of univalent to divalent cations was significantly increased in young leaves and petioles as a consequence of drought. Long-term water deficit caused a significant reduction of inorganic phosphorus (P i ) concentration in young and old leaves. Under the water stress condition, the concentration of proline was increased in all individual plant organs, except proline concentration in the youngest leaves. Drought treatment caused a significant increase of glycine betaine content in shoot without any change in tap-roots. Glucose concentrations were significantly increased only in tap-roots as the effect of drought. In response to water shortage the accumulation of sucrose was observed in all the examined leaves and tap-roots. Overall, a long-term drought activated an effective mechanism for osmotic adjustment both in the shoot and in the root tissues which may be critical to survival rather than to maintain plant growth but sugar beet organs accumulate different solutes as a response to water cessation.

Growth response of sugar beet plants to drought stress applied at different growth stages has been investigated. Cessation of watering imposed moderate water stress and resulted in the reduction of the relative water content of young and old leaves maximally by 6%. However, water content in taproot was more drastically decreased than in the shoot. Water withholding reduced dry ma�er accumulation and leaf assimilatory expansion when imposed at successive growth stages, especially in the case of earlier stress application. Substantial change in distribution pa�ern was observed when stress affected foliar development, more than 80% of dry ma�er was accumulated in the taproots. Water shortage negatively influenced both taproot and sugar yield by 16-52%, depending on the stress timing in the season. Drought stress did not change the sucrose concentration but when occurred in foliar and early stage of root development, decreased the contents of important non-sugar compounds like potassium and α-amino-N solutes in the final yield. Overall, data concerning the different water status in particular organs implies that a hydrodynamic equilibrium does not exist within the sugar beet plant as a response to water stress. Drought imposed on the earlier stage, most drastically influenced plant growth and final yield. When water stress occurs at the end of crop cycle, sugar beet plants had a higher ability to recovery their growth.Keywords: Beta vulgaris L.; drought; dry ma�er partitioning; growth; leaf area; water content; yield quantity and quality Supported in the frames of KBN Grant 5 PO6A 028 18.

The experiments were carried out to study the effect of salt-stresses and ABA on the growth, photosynthesis and translocation of assimilates in bean plants. It was planed to reduce the content of GA₃ and cytokinins and increase ABA content in salinized plants. The results show that salt-stress (NaCl and concentrated nutrient solution), reduce all the investigated processes in a different degree. NaCl-stress retarded most seriously growth of apical part and blades in contrast to 7-times concentrated nutrient solution decreasing mainly the rate of root and blade growth. Photosynthesis and ¹⁴C-translocation of ¹⁴C-assimilates were retarded more seriously by NaCl than by 7-times concentrated nutrient. solution. In the case of seriously stressed plants GA₃ and cytokinins (more effectively) reversed the ,negative effect of stress conditions both on the photosynthesis and on the ¹⁴C-tramslocation. On the basis of the obtained results, it seemes that changes in the rate of investigated processes in salinized plants are due to hormonal disturbances which cause directly or indirectly retardation of photosynthesis and trans-location of assimilates.

Studies were performed on young bean plants, grown in water culture. The effect of salt stress, X-flays and flooding on growth, photosynthesis and translocation of assimilates was investigated. Salt stress (NaCl and Na₂SO₄), especially at - 4.5 atm. of water potential, depressed all the mentioned processes, but most dramatically - photosynthesis. Export of photosynthetes from the blades decreased. Salt stress not only reduced the rate of translocation, but also influenced the pattern of ¹⁴C-distoibution, especially inhibited transport to apical part, with growth seriously retarded. Gibberellin (GA₃, 100 ppm sprayed on leaves) counteracted the negative effects caused by salinization, but did not affected either photosynthesis, or translocation in plants from normal nutrient solution. The conclusion may be advanced, that salt stress disturbed the balance of plant hormones especially gibberellins, which probably participate in. regulation of assimilate translocation.

SummaryTwo tomato morphotypes (cvs. Favorita, Organza and Azarro) of different fruit size were grown during 2005-2006 on a rockwool substrate under greenhouse conditions. Leaf area index (LAI), solar radiation absorption coefficient (TAO) and leaf area duration (LAD) were determined. Tested tomato cultivars proved different yielding strategies expressed by dissimilar values of the measured and calculated physiological indices (LAI, LAD, TAO and the canopy yielding efficiency). Cv. Organza showed the highest canopy yielding efficiency, cv. Azarro showed a negative dependence between LAD and yield, while cv. Favorita canopy architecture allowed to achieve better penetration of light energy to lower canopy layers and showed better tolerance of this cultivar to thermal stress.