Effect of Temperature on Triticum aestivum L. Seedlings Growth and Phytohormone Balance

The study aimed to determine the effect of short-term heat and cold stresses on growth, accumulation and distribution of abscisic acid (ABA) and indole-3-acetic acid (IAA) in 7 and 14-day-old Triticum aestivum L. seedlings of the frost resistant cultivar Volodarka. A high performance liquid chromatography method has been used to provide a qualitative and quantitative analysis of hormones in leaves and roots. Biometric analysis showed that at the early stage of vegetation (7 days) seedlings were more resistant to temperature stresses, especially to cold, than at the later ones (14 and 21 days), that correlates with the frost resistance of cultivar. The results indicated that at the early stages of growth, after a short-term cold stress (2 h., +20C), the amount of free ABA substantially increased in roots, while at the later ones, it occurred after a short-term heat stress (2 h., +400C) in leaves. After a heat stress the leaves of 7-day-old seedlings accumulated a conjugated form of IAA. Heat stress caused the accumulation of free IAA in roots of 14-day-old seedlings. Cross stress (cold+heat) caused some increase in the pool of endogenous ABA both in roots and leaves while the amount of free IAA increased only in leaves. Сhanges in the accumulation of the free and conjugated forms of ABA and IAA depended both on the organs and the age of seedlings, and the type of stress and correlated with frost resistance of the cultivar Volodarka

Pecularities of Cytokinin Accumulation and Distribution in Triticum aestivum L. Seedlings Under Temperature Stresses

The objective of this research was to investigate the effect of short-term heat (2 h., +400C) and cold (2 h., +20C) stresses on accumulation and distribution of cytokinin (CK) in 7 and 14-day-old seedlings of the frost resistant Triticum aestivum L. cultivar Volodarka. A high performance liquid chromatography method has been used to provide a qualitative and quantitative analysis of hormones in leaves and roots. It was shown that in the early stages of growth (7 days) after exposure to high temperature the total content of cytokinin in roots increased 1,6 and in leaves in 2,55 times. The most pronounced changes were registered for trans-zeatin (t-Z) and izopenteniladenozin (iPa) in roots and for zeatinriboside (ZR), izopenteniladenin (iP) and iPa in leaves. After cold stress the total content of hormone in roots increased but decreased in leaves. ZR and iPa were not identified in the leaves. The total level of CK in 14-day-old seedlings as compared to 7-day-old ones under control conditions decreased from 685,3 to 158,3 in roots and from 396,8 to 368,4 ng / g fresh weight in leaves. After cold stress the total content of CK in the roots decreased to 99,9 and in the leaves – to 195,8 ng/g of wet weight. Trans-zeatin was actively accumulated in leaves, ZR - in the roots. After heat stress the total content of CK in roots increased to 316,3, whereas in leaves decreased to 184,6 ng / g fresh weight. Roots actively accumulated cis-zeatin (c-Z) and iPA, leaves – iP and iPa. Changes in the accumulation and distribution of CK depended both on the organs and the age of seedlings, and the type of stress and correlated with frost resistance of the cultivar Volodarka

Reducing future nutrient inputs to the Black Sea

Rivers export increasing amounts of dissolved inorganic (DIN, DIP) and organic (DON, DOP) nitrogen and phosphorus to the Black Sea causing coastal eutrophication. The aim of this study is to explore future trends in river export of these nutrients to the sea through a sensitivity analysis. We used the Global NEWS (Nutrient Export from WaterSheds) model to this end. We calculated that between 2000 and 2050 nutrient inputs to the Black Sea may increase or decrease, depending on the assumed environmental management. We analyzed the effects of agricultural and sewage management on nutrient inputs to the sea in 2050 relative to two Millennium Ecosystem Assessment (MEA) scenarios, Global Orchestration (GO) and Adaptive Mosaic (AM). In these baselines, total N and P inputs to the Black Sea decrease between 2000 and 2050, but not for all rivers and nutrient forms. Our results indicate that it is possible to reduce nutrient inputs to the sea further between 2000 and 2050 in particular for dissolved inorganic N and P and for many river basins, but not for all. For scenarios assuming combined agricultural and sewage management dissolved inorganic N and P inputs to the Black Sea are reduced by up to two-thirds between 2000 and 2050 and dissolved organic N and P inputs by one-third. River export of DIN is mainly affected by agricultural management and that of DIP by sewage management. On the other hand, in scenarios assuming increased fertilizer use for, for instance bioenergy crops, nutrient inputs to the sea increase. An increase in DIP inputs by southern rivers seems difficult to avoid because of the increasing number of people connected to sewage systems

Drought Stress Effects on Triticum spelta L. Structural and Functional Characteristics

Effects of a soil drought on the growth, microstructure of leaf surface and photosynthetic pigments composition of Triticum spelta L. 14-days-old plants have been studied. It was shown that the root system whose length diminished by 19% and weight - by 48% turned out to be more sensitive to the impact of a 4-day soil drought. On the 23d day after rehabilitation the difference between biometric parameters of control and experiment samples reduced, but a complete recovery of plants did not occur. A microstructural analysis of the amphistomatic leaf lamina revealed the same number of stomata with similar sizes of stomatal pores on the adaxial and abaxial surface. Following the soil drought, some increase in wax density was observed, stomata on the both leaf surfaces remained closed. The pigment complex of 14-days-old plants responded by decreasing the quantity of chlorophyll and carotenoids. On the 23th day after rehabilitation a further decrease in the photosynthetic pigments level was observed. The changes in the ratio of pigments content after stress and peculiarities of microstructure of leaf surface corresponded with drought tolerance of T. spelta. The retention of rather high parameters of the green pigment content immediately after dehydration on the 18th day corresponded to biometric study data demonstrating a stable growth in the plant over ground part