Effect of cadmium on barley seeds treated with kinetin and gibberellic acid was investigated. As usual, cadmium has inhibited seed germination, and showed important inhibitory effects on roots and coleoptile growth after germination. In general, increase in cadmium concentration caused a greater inhibition of germination, root and coleoptile growth. The adverse effect of cadmium on root and col...

Etiolated whole rice seedlings enclosed in sealed vials produced ethylene at a rate of 0.9 picomole per hour per seedling. When 2-centimeter-long shoots were subdivided into 5-millimeter-long sections, the sections containing the tip of the shoot evolved 37% of the total ethylene with the remaining 63% being produced along a gradient decreasing to the base of the shoot. The tip of the coleoptil...

Successful stand establishment is prerequisite for optimum crop yields. In some low-precipitation zones, wheat (Triticum aestivum L.) is planted as deep as 200 mm below the soil surface to reach adequate soil moisture for germination. To better understand the relationship of coleoptile length and other seed characteristics with emergence from deep planting (EDP), we evaluated 662 wheat cultivar...

Rice cold tolerance at the germination stage is important in Rio Grande do Sul (RS) where temperatures below 15°C prevent or reduce germination and plant establishment in early sowings. The present study aimed at identifying an adequate method for cold tolerance evaluation of the rice germination stage and at verifying the variability among 24 rice genotypes of different origins. Cold tolerance...

Growth response of coleoptile segments excised from 3-day-old seedlings of wheat (Triticum vulgare cv. Baart) to gibberellic acid, indoleacetic acid, and 2,4-dichlorophenoxyacetic acid, to red light, and to several microtubule disorganizers depends on the initial position of the excised segment in the intact coleoptile. Red light, 660 nm, stimulates the growth of the apical cells, but inhibits ...

Sources of free indole-3-acetic acid (IAA) for the mesocotyl of intact etiolized maize ((Zea mays L.) seedlings are evaluated. The coleoptile unit, which includes the primary leaves and the coleoptilar node, is the main source of free IAA for the mesocotyl. The seed and the roots are not immediate sources of IAA supply. Dependence of the apical growing region of the mesocotyl on the coleoptile ...

Wheat (Triticum aestivum L.) cultivars with long coleoptiles can be sown deeply for better seedling establishment in drought environments. A population of 139 recombinant inbred lines (RILs) from a cross between a long-coleoptile Chinese landrace, Wangshuibai, and shortcoleoptile U.S. wheat cultivar, Wheaton, were characterized for coleoptile length and plant height. Heritabilities for coleopti...

Initial results on particle yields obtained by the HARP experiment are presented. The measurements correspond to proton–nucleus collisions at beam energies of 12.9 GeV /c and for a thin Al target of 5% interacion legth. The angular range considered is between 10 and 250 mrad. This results are the first step in the upcoming measurement of the forward production cross-section for the same target ...

The effects of cadmium (Cd; 0.1-1000 μM) and fusicoccin (FC) on growth, Cd(2+) content, and membrane potential (E(m)) in maize coleoptile segments were studied. In addition, the E(m) changes and accumulation of Cd and calcium (Ca) in coleoptile segments treated with Cd(2+) combined with 1 μM FC or 30 mM tetraethylammonium (TEA) chloride (K(+)-channel blocker) were also determined. In this study...

The mechanism by which endogenous cessation of coleoptile elongation after emergence of the primary leaf is brought about was investigated in rye seedlings {Secale cereale L.) that were either grown in darkness or irradiated with continuous white light. In 3-d-old etiolated (growing) coleoptiles a turgor pressure of 0.59 MPa was measured. In 6-d-old coleoptiles, which had ceased to elongate, ce...