Optimization of the greenhouse environment for Rosa hybrida L. production using computer growth modeling
Abstract
A central composite rotatable design was used to estimate quadratic equations describing the relationship of radiation as measured by photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT) to the growth and development of Rosa hybrida L. in controlled environments. Plants were subjected to 15 treatment combinations of constant PPF, DT, and NT for the plant growth cycle from pinch to flowering according to the coding of the design matrix. Eleven plant characteristics were recorded to describe plant growth, and four characteristics were measured to describe flower bud development. Response surface equations were displayed as 3-dimensional plots. Canonical analysis indicated that all stationary points of the significant models were located outside the original design space, and all but one surface was a saddle shape. Both the plots and analysis showed greater stem diameter as well as greater fresh and dry weights of stem, leaves, and flower bud to occur at flowering under combinations of low DT ($<$ 17$\sp\circ$C) and low NT ($<$ 14$\sp\circ$C). However, low DT and NT delayed both visible bud formation and development to flowering. Increasing PPF over the range studied enhanced overall flower stem quality by increasing stem diameter and the fresh and dry weight of all plant parts at flowering, as well as decreasing the time until visible bud and flowering. Difference equations and quadratic models were included in a SLAM II simulation model, ROSESIM, to predict growth and development over time. Accuracy of model predictions was verified by plotting predicted growth curves along with original data from selected treatments that represented the full range of the model. One-way ANOVA procedures compared the difference of ROSESIM predictions from the 15 treatment means, finding significant differences at 20 days from pinch, but no significant differences (except for flower bud fresh and dry weights) at 30 and 40 days from pinch and at flowering. Tolerance intervals (95%) were calculated when daily integrated PPF was randomly estimated over three holiday growing seasons. This indicated how response may vary with changing weather conditions over years.
Degree
Ph.D.
Advisors
Hammer, Purdue University.
Subject Area
Plant propagation
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