Effects of reduced nutrient and water availability on plant growth and post-production quality of Hibiscus rosa-sinensis.

摘要

A study was conducted to determine if several cycles of drought stress (either as a single factor or combined with reduced P availability, reduced N availability, or reduced application of a chemical growth regulator) can reduce the use of a growth regulator in H. rosa-sinensis. The growth regulator chlormequat-chloride (CCC; 100%) was used. Chemical growth regulation (100% CCC) reduced plant height to 43% compared with the control plants. Same efficient growth regulation was achieved by combining drought with reduced application of CCC (17%), hereby saving 83% CCC and reducing the number of applications from 7 to 3, but the number of flower buds, leaf size and dry weight of the aboveground parts were reduced compared with the chemically growth-regulated (CGR) plants. Drought stress as a single factor reduced plant height to 68% and reduced P to 85% relative to the control plants. Combining reduced P availability with drought stress did not reduce plant height, leaf area, dry matter accumulation and number of flower buds much further than drought stress alone. The CGR plants were the most compact plants with the highest specific fresh weight. The control plants and those grown with a combination of reduced P and reduced application of CCC had a slightly lower specific weight than the CGR plants, and were less compact. The CGR plants formed more flower buds than plants from all other treatments, except for the non-CGR control plants, but from day 14 and onwards very few flowers opened and many flower buds senesced, especially compared with reduced P and N plants and also to some extent compared with the control plants. Despite a much lower number of flower buds at the end of production (day 0, start of post-production evaluation) on plants produced at reduced P they developed the same number of open flowers as the control plants. After 28 days at simulated interior room conditions, the poorest post-production performance was observed in the CGR plants. Also, drought-stressed plants had a higher percentage of senescent flower buds compared with the control plants. However, combining drought with reduced P availability to some extent reduced the number of senescent flower buds. Reduced P and N availability during production improved post-production quality by significantly reducing the number of senescent flower buds and increasing the percentage of open flowers compared with the CGR and non-CGR control plants. The post-production performance of the plants was not improved by several cycles of drought.