Essential Environmental Factors Influencing Mulberry Tree Growth

by Elizabeth / Tuesday, 27 July 2021 / Published in Sericulture

Mulberry tree growth and development are intricately linked to several environmental conditions, including light, temperature, moisture, air, soil, and inorganic nutrients, which influence each other to shape the overall health and productivity of the tree.

1. Illumination: The Driving Force of Photosynthesis

Light is fundamental for mulberry trees as it powers photosynthesis, the process by which they create energy.

Light Intensity (lux)	Photosynthetic Activity	Impact on Growth
500 – 30,000	Increases with intensity	Optimal for growth and development; leads to robust branches, thick leaves, and high leaf yield.
Above 30,000	No further increase	Light saturation is reached, further increase in light intensity does not boost photosynthesis.
Cloudy Conditions	Reduced to 50%	Less dry matter accumulation, and reduced growth.
Rainy Conditions	Reduced to 30%	Significant impact on the ability of the tree to generate energy, and reduced growth.
Short Day Length	Promotes Nutrient Accumulation	Prepares the tree for dormancy and enhances branch strength for winter.
Red and Yellow Light	Beneficial	Enhance growth, especially in artificial environments.
Ultraviolet Light (High Altitude)	Can Dwarf Growth	Can lead to stunted growth, highlighting the effect of specific light qualities.

Light also affects other factors like temperature and humidity, which indirectly impact growth. Adequate sunlight helps in increasing the ambient and ground temperatures, while reducing humidity, all favorable to mulberry trees.

2. Temperature: The Rhythm of Life Activities

Temperature dictates many of the mulberry tree’s life processes.

Temperature Range (°C)	Effect on Growth
Above 5	Root system starts to absorb nutrients.
Above 10	New roots begin to appear.
28-30	Optimal temperature for root extension.
Above 35	Root extension is inhibited.
Above 12	Winter buds begin to germinate and grow.
25-30	Optimum for branch and leaf growth.
Above 40	Photosynthesis is weakened; nutrient consumption exceeds photosynthesis.
Below 12	Tree transitions into dormancy.
Below 0	Freezing damage can occur in certain varieties.
Below -40	Can be tolerated by some varieties, especially those native to Northern China.

Cold resistance depends on the variety and nutritional status of the tree. Proper management and leaf picking can enhance a tree’s cold resilience.

3. Moisture: Crucial for Cellular Functions

Water is essential for a mulberry tree’s physiological functions, accounting for a large percentage of its composition.

Component	Moisture Content (%)
Leaves	70 – 75
Branches	58 – 61
Roots	54 – 60

The ideal soil moisture for mulberry trees is 70-80% of the field’s water holding capacity.

Moisture Level	Impact on Mulberry Tree Growth
Insufficient Water	Delayed germination, reduced germination rates, inhibited shoot growth, wilting, and leaf drop.
Excessive Water	Lowered soil temperature, reduced soil air, impaired root respiration, decreased nutrient absorption, chlorosis, and even death.

Waterlogging can lead to the production of toxic substances in the soil, which can poison the roots of the mulberry trees.

4. Air: The Vital Exchange of Gases

The composition and movement of air greatly affect the health of mulberry trees.

Air Component	Role
Carbon Dioxide	Essential for photosynthesis.
Oxygen	Needed for respiration.
Air Humidity	Affects the rate of leaf transpiration.
Wind	Can improve ecological conditions, but can also cause damage.

Good ventilation and soil conditions can enhance photosynthesis, while strong winds can cause physical damage. Air pollutants, such as those from factories, can also harm mulberry trees and silkworms.

5. Soil: The Foundation for Growth

Soil properties are crucial for mulberry tree development.

Soil Property	Impact on Growth
Soil Texture	Loam and sandy loam are optimal; clay inhibits root stretching, sandy soil lacks water retention.
Soil Thickness	Should be greater than 1 meter for deep root systems.
Groundwater Level	Should be around 1 meter to prevent waterlogging.
Soil pH	Ideal pH is 6.5 to 7.5, but the tree can tolerate a range of 4.5 to 9.0.

Correcting poor soil conditions with organic fertilizer and other soil-enhancing practices is important for healthy growth.

6. Inorganic Nutrients: Building Blocks for Growth

Mulberry trees need various inorganic nutrients absorbed from the soil, including macronutrients and micronutrients.

Nutrient	Role in Mulberry Tree	Deficiency Symptoms
Nitrogen (N)	Essential for cell protoplasm, promotes branch and leaf growth, dark green color, increased nutritional value.	Small leaves, less chlorophyll, yellow-green color, and faster hardening.
Phosphorus (P)	Promotes leaf maturation, enhances cold resistance, is crucial for silkworm feeding.	Smaller leaves, poor luster, loss of green from veins, yellow mesophyll.
Potassium (K)	Improves efficiency of nitrogen and phosphorus, enhances resistance to stress.	Stunted shoots, brown spots on leaf tips and edges, deteriorated leaf quality.
Calcium (Ca)	Relates to nitrogen metabolism, nutrient transfer, and neutralizes oxalic acid.	Water-soaking on young leaf edges.
Boron (B)	Related to carbohydrate conversion and protein synthesis.	Rough bark with proliferated epithelial pores.
Sulfur (S)	Related to chlorophyll formation.	Early yellowing in young leaves, and yellow-green color in older leaves.
Magnesium (Mg)	Component of chlorophyll and enzymes; needed for photosynthesis.	Yellowing of middle and lower leaf margins followed by yellow-brown mesophyll.
Zinc (Zn)	Regulates physiological functions of enzymes and synthesis of auxin.	Growth blockage, yellowing leaf margins, deformed leaves due to partial tissue necrosis.
Iron (Fe)	Component of oxidases.	Chlorosis, with veins turning yellow or white.
Copper (Cu)	Related to chlorophyll formation.	Green and withered leaf tips.
Manganese (Mn)	Promotes oxidoreductase and Vitamin C activity.	Green and yellow deficiency in mid and lower leaves, brown spots, and curled and withered leaves.
Molybdenum (Mo)	Component of nitrate reductase; related to nitrogen metabolism.	Spotted and mosaic-like symptoms, with necrotic and curled leaf edges.
Chlorine (Cl)	Related to photosynthesis, formation of starch, fiber, and lignin.	Wilting leaf tips, chlorosis, and necrotic brown mesophyll areas.

Understanding these complex environmental interactions allows for better cultivation and optimal yields of mulberry trees, which are particularly important for industries that rely on them such as silk production. PandaSilk, for example, benefits from this understanding to ensure the best possible quality of raw material.