Higher Stem Length Research Articles

Effects of moisture, nitrogen, grass competition and simulated browsing on the survival and growth of Acacia karroo seedlings

AbstractThe effects of irrigation, nitrogen fertilization, grass competition and clipping were investigated for one growing season at the research farm of the University of Fort Hare in the Eastern Cape Province of South Africa. The aim of the experiment was to assess the short‐term performance of Acacia karroo seedlings under different environmental conditions and the implications of such factors on the long‐term recruitment of plant species in savanna rangelands. There were no significant treatment effects on the survival of A. karroo seedlings. Using stem length and basal diameter as growth parameters, it was observed that irrigation enhanced both variables, while nitrogen fertilization did not have any significant effects. Clipping, grass competition and their interaction greatly suppressed the growth of the seedlings. Clipping increased the mean stem length when they were irrigated and fertilized. Control and fertilized plants had the highest stem length in the absence of grass competition, while grass competition combined with clipping resulted in the lowest stem length in both irrigated and nonirrigated plants. It was concluded that in the presence of grass competition, controlled browsing could be a viable solution to the problem of bush encroachment in savanna rangelands.

Influence of Additional Micronutrient Supply on Growth, Nutritional Status and Flower Quality of Three Rose Cultivars in a Soilless Culture

ABSTRACT The effect of additional supply of iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) on three rose cultivars was investigated. Five fertilizer treatments were utilized: 0 (control), 150 μ mol Fe L− 1, 150 μ mol Fe + 10 μ mol Mn L− 1, 150 μ mol Fe + 10 μ mol Mn + 12 μ mol Zn L− 1, 150 μ mol Fe + 10 μ mol Mn + 12 μ mol Zn + 5 μ mol Cu L− 1. The results demonstrated significant variation among rose cultivars in developing Zn, Fe, and Mn deficiency symptoms and response to micronutrient supplies. For ‘Modern Girl’ and ‘Orange Juice’, all micronutrient treatments resulted in higher stem length and thickness as compared to the control. No significant increase in stem length was observed in ‘Aqua Fresh’. All cultivars had the greatest flower vase life in the added Zn treatments. All fertilizer treatments significantly increased Fe concentration in the leaves of ‘Modern Girl’ and ‘Aqua Fresh’ as compared to the control. The Fe-Mn-Zn-Cu treatment significantly increased leaf concentration of Mn, Zn, and Cu in all cultivars. Leaf sodium (Na) concentration was lower in the micronutrient treatments that included Zn addition as compared to the treatments that did not include added Zn. No visible mildew symptom was observed in the treatments with Zn addition. The results showed that genotypic variation and sufficient micronutrient supply are two key factors in success production of rose in the soilless culture. Furthermore, the results indicated the importance of Zn in enhancing the quality of the rose flower.

Plants interactions between Suaeda salsa individuals are mediated by salinity stress

To test how plants interactions change with environmental stress, neighbors removal experiments in Suaeda salsa communities of beach were conducted in Hangzhou bay Zhejiang Province, China. Results showed that there is a significant shift from positive interaction in high salinity stress to negative interaction in low salinity stress. Removal experiments also clarified the role of phenotype response in linking plants interactions and environmental stress. Under low salinity stress, biomass, stem length, root length, leaf area, and photosynthesis rate, water-use efficiency of neighbors removal plants were higher than those of control plants, while leaf water content of neighbors removal plants were lower than those of control plants. Under high salinity stress, biomass, stem length, root length, leaf area, and photosynthesis rate, leaf water content of neighbors removal plants were lower than those of control plants, while water-use efficiency of neighbors removal plants were higher than those of control plants. It can be concluded that S. salsa interactions were mediated by salinity stress through morphological and physiological plasticity.

Early Growth of Quercus castaneifolia (C.A. Meyer) Seedlings as Affected by Weeding, Shading and Irrigation

The influence of shading, irrigation and weeding on survival, growth and morphology of 1-year Quercus castaneifolia seedlings was studied in north of Iran. The seedlings were grown under eight treatments including full-light versus artificial shading, irrigation versus non-irrigation and weed presence versus weed removing at three replicates. At the end of the first growing season seedling survival in all treatments was 100%. Weed removing had positive effect on height, diameter growth, slenderness coefficient and leaf area of Q. castaneifolia. Irrigation enhanced diameter growth and leaf area and shading increased leaf area. Irrigation had no significant effect on plant growth where the weed was removed. In weed plots seedlings growth and leaf area were greater in shading than in full-light. The results indicated that for 1 year Q. castaneifolia seedlings, weeding, in contrast to irrigation, is an essential factor. Where the weed competition is a difficulty, plantation with higher stem length should be applied.

Genetic studies on cool tolerance in rice.II. Relations between cool tolerance and the other characters.

1. Following tLe previous report (TORIYAMA and FUTSUHARA 1960), this experiment were conducted to clarify the relations between cool tolerance and the other characters in the early generations of the rice crosses Somewake×Aomori N0.5 and Kitakei N0.3204×0u N0.187 (cf. Table 1 and 5). 2. The degree of cool tolerance was evaluated by sterile index [sin√ˆ-1<sterility> of the materials tested in cool water irrigated field. 3. Consequently, close relations between cool tolerance and morphological characters investigated were found in F3 lines of the former cross, as shown in table 2. 4. While, in F2 population of the latter cross, high cool tolerance was positively correlated with high stem length, but the relations between cool tolerance and the other morphological characters except stem length were not statistically significant (cf. Table 6). 5. In both crosses described above, no close relations between cool tolerance and heading date were found. 6. The former cross showed transgressive segregation for cool tolerance and gave high yielding hybrids combining the favourable characters of both parents.