Cytological Correlation Between Flower and Vegetative Shoot Development from Immature Embryo-Derived Calli in Wheat

In this paper, the traits of immature embryo culture from 45 genotypes of bread wheat were investigated in detail, and trait correlation analysis in combination with histomorphological examination was used to study the cytological origin of flower as well as the correlation between it and vegetative shoot development from the calli. The rate of floral development in the subculture was highly significantly and positively related to that of the differentiation culture, which reveals that the genetic system of floral development from immature embryo-derived calli in wheat was highly correspondent and stable. The rate of floral development was related neither to the traits in the dedifferentiation culture, nor to the vegetative shoot formation from the total induced calli, but significantly and positively related to that of the calli without leaf-like green spots in the differentiation culture. These findings indicate the partial correlation as well as differentiation between flower and vegetative shoot development. The floral development might only be associated with the genetic system controlling organ regeneration, while vegetative shoots formed from the two ways, including somatic embryogenesis and organ regeneration.

Effects of cutting types and hormonal concentration on vegetative propagation of Zanthoxylum armatum in Garhwal Himalaya,India

Experiments were carried out to define the effects of hormonal concentrations on semi-hard wood（SHW） and hard-wood（HW） branch cuttings of the Z.armatum. SHW and HW cuttings were collected in the month of March. The SHW and HW cuttings were treated with different concentration of indole-3-acetic acid and indole-3-butyric acid（IAA and IBA） and placed in vermiculite rooting medium for 90 days under 1-min misting after 10 min. Sprouting, rooting percentage, sprout number, sprout length, root number, and length were measured.The highest rooting and sprouting rate, 64.0 %, was obtained at the 0.3 % IBA treatment in the SHW cuttings.Similarly sprout length and number of roots per cutting were also higher at the 0.3 % IBA treatment in the SHW cuttings. The number of shoots per cutting was higher at the 0.3 % IAA treatment in the SHW cuttings. Root length per cutting was higher in 0.4 % IBA treatment in the SHW cuttings. The results indicated that 0.3 and 0.4 % IBA treatment produce higher rooting percentages as well as the number of roots and their length in SHW cuttings. The HW cuttings produced maximum rate of 18.0 % rooting in0.5 % IBA treatment. The control set and lower concentrations of IBA and IAA completely failed to root in the mist chamber.

Comparison of phytotoxicity of copper and nickel in soils with different Chinese plant species

Ecological risk assessment of metals in soils is important to develop the critical loads of metals in soils. Phytotoxicity is one of the endpoints for ecological risk assessment of soils contaminated with metals. The sensitivity of eight Chinese plant species（bok choy, mustard, tomato, green chilli, paddy rice, barley, spinach and celery） to copper（Cu） and nickel（Ni） toxicity in two Chinese soils was investigated to assess their potential use for ecological risk assessment in the region. The results showed that bok choy and mustard were the two most sensitive species to Cu and Ni toxicities. Assessment of metal accumulation by the plants demonstrated that bok choy shoot had the highest bioconcentration factor（BCF, the ratio of metal concentration in plant shoots to metal concentration in soil）. Given the importance of bok choy to agricultural production in Asia, it is therefore important that these sensitive plant species are included in species sensitivity distributions for ecological risk assessment of Cu and Ni in soils.

Effects of competitive interactions of different life forms submersed plants on biomass allocation in shallow lakes

Plant competition has been recognized as one of the most important factors influencing the soructure and function of lake ecosystems. Competition from plants of dissimilar growth form may have profound effects on shallow lakes＇. An experiment was conducted to investigate the effects of competitive interactions of submersed plants with dis- similar growth forms on the biomass allocations. Hydrilla verticitlata and Vallisneria natans were selected and were planted in a single-species monoculture and a mixed-species pattern, Results showed that the growth of E natans was＇ significantly affected by the tt, verticillata and caused a sharp reduction of biomass, but the root：shoot ratio of E ha- tans was not affected significantly and there was a minimal increase in mixture： while for H. verticillata, the biomass and the root：shoot ratio were not significantly changed by the competitive interactions ore natans, there was minimal increase of biomass and minimal decrease of the root：shoot ratio. These results may indicate that theplant which can develop a dense mat or canopy at the water surface would be a stronger competitor relative to the plant that depends more on light availability near the sediment.