Water potential and ionic effects on germination and seedling growth of two cold desert shrubs

Abstract

We tested expectations that two desert shrubs would differ in germination and seedling relative growth rate (RGR) responses to Na and Ψ(s) stress. The study species, Chrysothamnus nauseosus ssp. consimilis and Sarcobatus vermiculatus (hereafter referred to by genus), differ in their distribution along salinity gradients, with Chrysothamnus inhabiting only less saline areas. In growth chamber studies, declining Ψ(s) (-0.82 to -2.71 MPa) inhibited germination of both species, and Chrysothamnus was less tolerant of Ψ(s) stress than Sarcobatus. Germination fell below 10% for Chrysothamnus at -1.64 MPa (NaCl and PEG), and for Sarcobatus at -2.4 MPa PEG. Neither species exhibited ion toxicity. There was substantial ion enhancement for Sarcobatus in lower Ψ(s), allowing for 40% germination in -2.71 MPa NaCl. For seedling RGR, species were not different at -0.29 or -0.82 MPa (0 and 100 mmol/L NaCl, respectively), but Chrysothamnus RGR declined substantially at -1.3 MPa (200 mmol/L NaCl). The greater stress tolerance of Sarcobatus was not associated with a lower RGR under nonsaline conditions. Species differences in seed and seedling Ψ(s) stress tolerance probably contribute to the restricted distribution of Chrysothamnus to less saline areas. The Na uptake of Sarcobatus seedlings enhances its ability to deal with declining Ψ(s) and establish in more saline areas.

Effect of PEG Induced Drought Stress on Seed Germination and Seedling Characters of Maize (Zea mays L.) Genotypes

“…Water stress not only affects seed germination but also increases mean germination time in maize plants (Willanborb et al, 2004). The adverse effect of water shortage on germination and seedling growth has been well reported in different crops (Mostafavi et al, 2011;Khodarahmpour, 2011).The polyethylene glycol (PEG)-induced inhibition of germination has been attributed to osmotic stress (Dodd and Donovan, 1999;Sidari et al, 2008).…”

Comparative Effects of Drought and Salt Stress on Germination and Seedling Growth of <i>Pennisetum divisum</i> (Gmel.) Henr.

“…The PEG-induced inhibition of germination has been attributed to osmotic stress (Dodd and Donovan, 1999;Sidari et al, 2008). Temperature plays a crucial role in many biological and physiological processes of plants (Al-Ahmadi and Kafi, 2007;Berti and Johnson, 2008).…”

Parcelamento e fontes de nitrogênio na qualidade fisiológica de sementes de trigo

“…O processo de germinação depende basicamente da capacidade da semente absorver água (DODD & DONOVAN 1999) e das reservas armazenadas no endosperma serem convertidas e mobilizadas para suporte energético do embrião (LIN & KAO 1995). No entanto, a constituição genética da cultivar e sua interação com o ambiente em que foi originada, podem afetar o percentual de germinação das sementes (DODD & DONOVAN 1999), principalmente devido as mudanças na organização estrutural e síntese proteica no momento da germinação do embrião (RAMAGOPAL 1990).…”

“…No entanto, a constituição genética da cultivar e sua interação com o ambiente em que foi originada, podem afetar o percentual de germinação das sementes (DODD & DONOVAN 1999), principalmente devido as mudanças na organização estrutural e síntese proteica no momento da germinação do embrião (RAMAGOPAL 1990). Em nível fisiológico, a formação de proteínas, importantes no processo de germinação das sementes, envolve mecanismos de absorção de nitrogênio pelas raízes, acúmulo nos órgãos vegetativos e posterior remobilização para os grãos para a formação e configuração proteica (TRIBOÏ et al 2003).…”