Reasons and Solutions for the Yellowing of Chrysanthemum Leaves
As a traditional famous flower, the yellowing of chrysanthemum leaves seriously affects its ornamental value and growth state. This article analyzes the three major key causes and provides detailed scientific treatment solutions with illustrations to help gardening enthusiasts systematically solve maintenance problems.
Yellowing Caused by Nutritional Imbalance
Consequences of Insufficient Fertilization
Chrysanthemum consumes about 50mg of nitrogen elements per day during the growing period, and insufficient fertilization can hinder the synthesis of chlorophyll in the leaves. Typical symptoms include the yellowing of new leaves and the drying of the edges of old leaves. EC value tests reveal that the soil conductivity of nutrient-deficient plants is often lower than 1.2mS/cm.
Accurate Fertilization Plan
During planting, add 3kg of decomposed sheep manure and 0.5kg of bone meal per cubic meter of substrate. Use a 20-10-20 water-soluble fertilizer at 800 times concentration during the nutrient period, combined with a chelated iron foliar fertilizer applied every two weeks. Switch to a high-phosphorus formula during the bud formation stage, maintaining the soil EC value within the range of 2.0-2.5mS/cm.
Key Technologies for Light Management
Analysis of Light Intensity Requirements
Chrysanthemum is a positive plant and requires at least 6 hours of direct sunlight per day. Experimental data shows that when light intensity is below 15000 lux for 10 consecutive days, the net photosynthetic rate of leaves decreases by 37%, leading to the accumulation of xanthophyll and visible discoloration.
Intelligent Supplemental Lighting System
Use full-spectrum LED plant lights, set 40cm away from the canopy, and provide supplemental lighting for 4 hours per day (light intensity of 25000 lux). Combined with windbreak nets, ensure proper air circulation while reducing sunburn, keeping the leaf surface temperature stable at 25-28°C.
Core Points for Water Regulation
Criteria for Drought Diagnosis
When the soil moisture content is less than 60%, the water absorption rate of chrysanthemum roots decreases, and the stomatal conductance drops to below 0.15mol·m⁻²·s⁻¹. It can be judged by the finger test: if the top 2cm of the soil is dry, additional water is needed.
Scientific Irrigation Regulations
Use a潮汐式 (tidal) irrigation system, ensuring that the substrate moisture content reaches 80%-85% each time watering. Water twice a day in summer, and every other day in spring and autumn. In critical periods, use water-retaining agents (polyacrylamide 0.3g/L) to effectively reduce the frequency of watering by 30%.
By establishing a management system that integrates nutrient monitoring, light control, and precise irrigation, the incidence of yellowing leaves in chrysanthemum can be reduced by over 85%. It is recommended to conduct leaf SPAD value tests monthly and adjust the maintenance plan in a timely manner to ensure the plant maintains a healthy chlorophyll index of 52-58.