Six species having characteristics of plants with the C4 dicarboxylic photosynthetic pathway, Echinochloa utilis L. Ohwi et Yabuno (Japanese millet), Cynodon dactylon L. (Bermuda grass), Kyllinga brevifolia Rottb., Amaranthus tricolor L. cv. Early splendour, Kochia childsii Hort., and Portulaca grandiflora Hook (rose moss), responded decisively to 0.1 miliequivalent per liter NaCl supplied to their culture solutions initially containing less than 0.08 microequivalent per liter Na.Chlorosis and necrosis occurred in leaves of plants not receiving sodium. Portulaca failed to set flower in the sodium-deficient cultures. Under similar conditions Poa pratensis L. (Kentucky blue grass) having characteristics of the C3 photosynthetic pathway made normal growth and did not respond to the addition of sodium. It is concluded from these results and previously reported work that sodium is generally essential for species having the C4 pathway but not for species with the C3 pathway.

No abstract

No abstract

No abstract

Siunmary. Althoughi the concenitrationi of sodium in leaves of Atriplcxl plants increased rapidly after receiving sodiumi, no growth response was detectable for about 6 days. It was found that respiration rate increased to its maxillum n vithin 3 days. Chlorophyll content also increased from an early stage, whereas the concentrations of sugars and starch did niot inierease, and ratios of soluble to total nitrogen did not (lecrease until later.The respiratory response appears to be specific to sodiumii as different salts of sodiumli caused similar responses, anid no other univalent cationi substituted for sodiuim. In addition, both growth response and respirationi rate tended towards their maxima witlh the same conicenitrationi of applied sodium. The rate of anaerobic CO., production increased when sodiumii as fed to leaves, suggestinig thTat the effect of sodium is in tlle glcolytic sequence.