Potential of the physiological response of pea plants (Pisum sativum L. ) to iron deficiency (direct or lime- induced) / Potencial da resposta fisiológica das plantas de ervilha (Pisum sativum L. ) à deficiência de ferro (direta ou induzida pelo calcário)

Pea (Pisum sativum L.) is an important food crop in Tunisia, where calcareous soils represents the major limiting factor for agriculture production. In the present study a greenhouse experiment was conducted to assess the effects of direct and bicarbonate- induced iron deficiency on plant growth, chlorophyll fluorescence, photosynthesis, spad index and iron nutrition in two Tunisian pea genotypes (Pisum sativum L.). Plants were grown hydroponically and iron deficiency was induced for 3 weeks. Iron deficiency decreased all the above physiological parameters. The direct Fe deficiency is more drastic than bicarbonate- induced Fe deficiency. A close relationship between plant growth, photosynthesis and SPAD index was observed. Fe use efficiency for plant growth and Fe use efficiency for photosynthesis discriminates clearly the studied genotypes and seems to be the main reason of the tolerance of Kelvedon, as compared to Lincoln.

A ervilha (Pisum sativum L.) é uma cultura alimentar importante na Tunísia, onde os solos calcários representam o principal fator limitante para a produção agrícola. No presente estudo, foi conduzido um experimento em estufa para avaliar os efeitos da deficiência de ferro direta e induzida por bicarbonato sobre o crescimento de plantas, a fluorescência da clorofila, a fotossíntese, o índice SPAD e a nutrição de ferro em dois genótipos de ervilha da Tunísia (Pisum sativum L.). As plantas foram cultivadas hidroponicamente e a deficiência de ferro foi induzida durante 3 semanas. A deficiência de ferro diminuiu todos os parâmetros fisiológicos acima. A deficiência de Fe direta é mais drástica do que a deficiência de Fe induzida por bicarbonato. Observou-se uma estreita relação entre o crescimento das plantas, a fotossíntese e o índice SPAD. A eficiência de uso de Fe para o crescimento de plantas e a eficiência de uso de Fe para a fotossíntese discriminam claramente os genótipos estudados e parecem ser a razão principal da tolerância de Kelvedon, em comparação com a de Lincoln.

Diversity, distribution and roles of osmoprotective compounds accumulated in halophytes under abiotic stress.

BACKGROUND AND AIMS: Osmolytes are low-molecular-weight organic solutes, a broad group that encompasses a variety of compounds such as amino acids, tertiary sulphonium and quaternary ammonium compounds, sugars and polyhydric alcohols. Osmolytes are accumulated in the cytoplasm of halophytic species in order to balance the osmotic potential of the Na(+) and Cl(-) accumulated in the vacuole. The advantages of the accumulation of osmolytes are that they keep the main physiological functions of the cell active, the induction of their biosynthesis is controlled by environmental cues, and they can be synthesized at all developmental stages. In addition to their role in osmoregulation, osmolytes have crucial functions in protecting subcellular structures and in scavenging reactive oxygen species. SCOPE: This review discusses the diversity of osmolytes among halophytes and their distribution within taxonomic groups, the intrinsic and extrinsic factors that influence their accumulation, and their role in osmoregulation and osmoprotection. Increasing the osmolyte content in plants is an interesting strategy to improve the growth and yield of crops upon exposure to salinity. Examples of transgenic plants as well as exogenous applications of some osmolytes are also discussed. Finally, the potential use of osmolytes in protein stabilization and solvation in biotechnology, including the pharmaceutical industry and medicine, are considered.