Shoot Root Dry Weight Research Articles

Differences in Growth and Ontogenetic Development of Plant Raised in Natural and Inverse Orientation Relative to the Earth Gravitational Field

Wheat plants Triticum aestivum L., Apogee cultivar, were grown in natural and inverse orientation relative to the Earth gravitational field. Special vegetation containers with double bottom were used for the cultivation. The upper bottom made of porous titanium served as a hydrophilic porous membrane stabilizing water potential in the root-inhabited zone at a given level. Normal plants yielding viable seeds were obtained in both natural and inverse orientation. In our experiments, the inverse orientation stimulated dry matter accumulation by plants and development of productive tillering shoots, as well as increased the shoot–root dry weight ratio.

Determination of screening techniques to salinity tolerance in tomatoes and investigation of genotype responses

In order to determine the predictive screening parameters that can be applied at early development stages of tomato plants, 55 tomato genotypes were grown in nutrient solution with 200 mM NaCI. The relationships among the salinity scale classes based on the visual appearance and shoot Na + accumulation, K +/Na + and Ca 2+/Na + ratios and shoot-root dry weights were investigated. Tomato genotypes differed greatly for shoot Na + concentration and salinity scale classes were significantly correlated with Na + concentrations. Higher shoot Na + concentrations indicated higher shoot damage. Shoot K +/Na + and Ca 2+/Na + ratios were significantly correlated with the salinity scale classes. The higher shoot K +/Na + and Ca 2+/Na + ratios indicated lower shoot damage. Tomato genotypes grown under 200 mM NaCI stress showed significant variations in shoot and root dry weights. However, no significant correlations were found between the shoot-root dry weight and the scale classes and Na + concentration and the ion ratios investigated. These may indicate that plant shoot and root dry weights were independent of salt tolerance at the growth stage reached in this study.

Influence of nitrogen deficiency on photosynthesis and chloroplast ultrastructure of pepper plants (Research Note)

Pepper plants (Capsicum annuum L. cv. Zlaten Medal) were grown on nutrient solution without nitrogen, and photosynthetic response of plants was examined by determination of leaf CO2 fixation and chlorophyll and carotenoid contents. The absence of nitrogen in the medium resulted in a decrease of the leaf area and of plant biomass accumulation, and in an increase of the root-shoot dry weight ratio. The photosynthetic activity and chlorophyll and carotenoid contents decreased significantly under nitrogen deprivation. Examination of nitrogen deficient leaves by transmission electron microscopy showed dramatic changes in chloroplast ultrastructure. The proportion of starch granules and plastoglobules in the stroma matrix was increased and internal membrane system was greatly reduced. It seems that nitrogen plays an important role in the formation of chloroplast structure and hence to the photosynthetic intensity and productivity of pepper plants.

Effects of mineral nutrient deficiencies on leaf development, visual symptoms and shoot–root ratio of Spathiphyllum

Effects of deficiencies in N, P, K, Ca, Mg, B and Fe on leaf development, visual symptoms and shoot–root dry weight ratio were studied in Spathiphyllum ‘Sensation’ grown hydroponically. Leaf nutrient contents of treated plants were analyzed to confirm suspected deficiencies. Leaf number, leaf area and chlorophyll content were all significantly reduced in the nitrogen-deficient plants similar to plants grown in distilled water. The phosphorus-deficient plants grew slowly but no deficiency symptoms were visible on leaves. Many small yellow specks, usually 2 mm or less in diameter, developed on the adaxial surface of lower leaves in the potassium-deficient plants. Leaf area, but not leaf number, was significantly suppressed by the calcium-deficient treatment and the young leaves developed necrotic margins on the middle and basal leaf blade. Fully expanded leaves in the magnesium-deficient plants were distorted and had lower chlorophyll contents than the controls. The iron-deficient plants showed interveinal chlorosis on younger leaves. The boron-deficient plants showed two types of deficiency symptoms: a marginal necrosis at the leaf apex and distorted and crinkled petioles break at the leaf blade. Shoot–root dry weight ratio was decreased under N, P and Fe deficiencies but was increased under deficiencies of Ca and B. A key was developed for the identification of mineral nutrient deficiencies.

Effects of Some Growth Retardants on Shoot and Root Growth of Two Cool-season Turfgrasses

Effects of mefluidide, paclobutrazol, and their mixture on shoot and root growth of perennial ryegrass (Lolium perenne L. `Wendy') and creeping red fescue (Festuca rubra L. `Dawson') were studied under container culture. Mefluidide applied alone or in combination with paclobutrazol caused significant reduction in shoot and root growth of perennial ryegrass and red fescue. These treatments also enhanced turf green color of both species and increased their root–shoot percentage, with no major effect on turf quality. Paclobutrazol applied alone reduced shoot height of perennial ryegrass and red fescue by 10% and 32%, respectively, and caused little reduction in their shoot weights, with no effect on turf quality and color. Although paclobutrazol applied alone reduced the root length and percentage of root–shoot dry weight of perennial ryegrass, it did not affect red fescue.

Effects of applying etnylene to the root system of Zea mays on growth and nutrient concentration in relation to flooding tolerance

Previous studies have shown increases in the concentration of ethylene in the soil and roots of plants when the soil is water saturated (flooded). In Zea mays L. this occurs in association with an overall reduction in growth but without extensive foliar senescence and in conjunction with the development of an adventitious root system. We have assessed the possibility that ethylene may be involved in these responses to flooding. Mixtures of the gas in air were therefore supplied to the roots and stem‐base of Z. mays growing in nutrient solution.Seven or 14 d exposure to ethylene (1 or 5 νl 1−1) inhibited seminal root elongation and growth in dry weight and accelerated the emergence of adventitious roots, although their final length and dry weight were depressed. Leaf extension was inhibited by 0.1,1.0 or 5.0 μl 1−1 ethylene around the roots; leaves extending rapidiy at the start of treatment were the most sensitive. Final shoot fresh and dry weights were depressed by the gas but tie shootrroot dry weighl ratio and percentage dry matter were not affected greatly. Leaf chlorosis was not observed but the concentration of phosphorus in the shoots was 26 to 31% below normal.When aeration of the nutrient solution was stopped, the concentration of dissolved oxygen declined and the concentration of ethylene in the roots increased. Similar changes occur in response to soil flooding. Root and shoot growth was slowed by non‐aeration although the shootroot dry weight ratio remained unchanged. The phosphorus concentration of the shoots was depressed but there was little chlorosis or leaf death. The similarity in these respects between the effects of ethylene and non‐aeration suggests that in flooded Z. mays, ethylene contributes to their development by accelerating the emergence of adventitioos roots, inhibiting phosphorus accumulation in the shoots and by a non‐toxic inhibition of plant growth.

Root-Shoot Dry Weights in Loblolly Pine

The dry weight of roots in loblolly pine may be accurately estimated from dry weights of stems, leaves, or shoots, and DBH. The weights of stems, leaves, and shoots are highly correlated with DBH. The root/shoot ratios varied inversely with the size of the tree. Greater variability was found in smaller individuals.