Growth Responses of Tomato Plants in Non-aerated Water Culture to Foliar Sprays of Gibberellic Acid and Benzyladenine

Tomato plants were grown to the five-six leaf stage in aeratedwater culture and aeration then discontinued. Foliar spraysof gibberellic acid (G), N⁶ benzyladenine (B), and ammoniumnitrate (N) were applied for periods up to 7 days and the plantsharvested on the eighth day. A mixture of 2·5 ppm G,5·0 ppm B, and 280 ppm N increased growth of the wholeplant and this was attributable almost entirely to G and B.In the leaf, both increased water content (B>G) and dry weight.G, but not B, increased leaf area; B, but not G, increased freshweight leaf/unit area. In the stem, G increased dry weight andheight; B reduced height but increased diameter and water content.Inclusion of O·I ppm indol-3yl-acetic acid in the mixturewas ineffective. The percentage increase in growth of non-aerated plants withG+B+N was greater with non-acrated than with aerated plantsfor weight of whole plant and leaf area, but not for stem height.Growth of non-aerated plants could not be increased by increasingthe volume of the nutrient solution, by ‘aerating’with nitrogen, or by applying minerals in foliar sprays.     

Leaf Water Diffusion Resistance in Clonal Tea (Camellia sinensis L.): Effects of Water Stress, Leaf Age and Clones

Leaf diffusion resistance was influenced by leaf age in well-wateredand water-stressed clonal tea plants. In well-watered plantsand in two of the three clones studied, young leaves showeda significantly lower diffusion resistance than old leaves.In water-stressed plants young leaves always exhibited a higherdiffusion resistance than old leaves. The highest diffusionresistance, irrespective of leaf age and water stress, occurredin clone DN which is known to be the most drought tolerant ofthe three clones studied, suggesting that drought tolerancein clone DN is caused, at least in part, by a stomatal regulationmechanism. Water release characteristic curves for the threeclones indicated differences in the water content-water potentialrelationship between young and old leaves as well as betweenclones. The drought tolerant clones had a higher relative watercontent for a given water potential compared with the drought-susceptibleclone. Camellia sinensis L., tea, diffussion resistance, water stress