Fertilizer requirement characteristics, high yield fertilization technology and time of kiwifruit

The origin of kiwifruit is in Xiangxi, Hunan Province, China. Shaanxi at the northern foot of the Qinling Mountains is the most abundant area of kiwifruit resources in China, so what are the fertilizer demand characteristics, high-yield fertilization technology and time of kiwifruit? For every 1000 kg of fresh fruit, kiwifruit needs to absorb 1.8kg of nitrogen, 0.2kg of phosphorus, 3.2kg of potassium, 0.45kg of calcium, 1.6kg of magnesium and 0.2kg of sulfur. The absorption of nitrogen, phosphorus and potassium from the rapid leaf growth period to the fruit setting stage mainly came from the nutrients stored by the tree in the previous year, which were absorbed less from the soil; during the fruit development period, the nutrient uptake increased significantly, especially the phosphorus and potassium uptake was larger; certain nutrients were still absorbed before falling leaves, and nutrients were stored in the tree to provide nutrients for germination, leaf expansion and flowering in the coming year.

Fertilization techniques for kiwifruit production

Kiwifruit is fertilized three times a year. The first time is base fertilizer, generally applied after fruit harvest, mainly organic fertilizer, combined with mixed fertilizer, the amount of fertilizer accounts for 50% of the whole year, in order to restore tree potential and store nutrients for growth in the coming year. The second is spring fertilizer, which is applied before spring bud germination to supplement the nutrients needed for flower bud development and promote the growth of axillary buds and new shoots. The third time is summer fertilizer, which is applied during the fruit expansion period to promote the rapid fruit hypertrophy and shoot growth. Spring fertilizer accounts for 20% of the whole year, and summer fertilizer accounts for 30%. The amount of fertilizer used in kiwifruit varies with tree age and soil conditions. For example, the dosage of nitrogen, phosphorus and potassium per 667 square meters is 6.0-8.0 kg, 4.0-6.4 kg and 4.7-7.3 kg, respectively. For adult trees, the amount of fertilizer applied per 667 square meters is 13.3 kg of nitrogen, 10.0 kg of phosphorus and 12.0 kg of potassium (12.0 kg). It should be pointed out here that kiwifruit is very sensitive to chloride ion and does not use chlorine-containing fertilizer as far as possible.

Growing environment

Temperature

Temperature is the main factor that limits the distribution, growth and development of kiwifruit. Each species has a suitable temperature range, beyond which the growth is poor or can not survive. Most species of kiwifruit require warm and humid climate, that is, subtropical or temperate humid and semi-humid climate, mainly distributed in the vast area of 1834 degrees north latitude. The annual average temperature is about 11.3-16.9 ℃, the extreme maximum temperature is 42.6 ℃, the extreme minimum temperature is about-20.3 ℃, the effective accumulated temperature over 10 ℃ is 4500-5200 ℃, and the frost-free period is 160-270 days.

The temperature requirements of kiwifruit populations are not very consistent. For example, Actinidia chinensis grows well at an annual average temperature of 4-20 ℃, while delicious kiwifruit is most widely distributed in the range of 13-18 ℃. The growth and development stage of kiwifruit is also affected by temperature. Some studies have shown that when the temperature rises to about 10 ℃, the buds begin to germinate, blossom only when the temperature is above 15 ℃, and fruit only when the temperature is above 20 ℃. When the temperature drops to about 12 ℃, it enters the dormancy period of deciduous leaves. The whole development process takes about 210-240 days, during which the daily temperature can not be lower than 10-12 ℃.

Moisture content

Kiwifruit is a kind of fruit tree which needs water and is afraid of waterlogging, so it has strict requirements on soil moisture and air humidity. it determines that kiwifruit is most suitable for cultivation in areas with abundant rainfall and uniform distribution, high air humidity, moist but not waterlogged. The annual precipitation in the natural distribution area of Chinese kiwifruit is 800mm ~ 2200 mm, and the air relative humidity is 74.3% ~ 85%. Generally speaking, where the annual precipitation is 1000 mm ~ 2000 mm and the air relative humidity is about 80%, it can meet the water requirements for the growth and development of kiwifruit. If the average annual precipitation is 500 mm, consideration must be given to setting up irrigation facilities in case of drought. There is more fog in the alpine area, the soil on both sides of the stream is moist, and the humidity is high all the year round, which is ideal for the growth of kiwifruit. Rain Water is sufficient in the central and eastern regions from April to June, and the shoot growth is large, which is suitable for the growth requirements of kiwifruit.

The drought resistance of kiwifruit is worse than that of ordinary fruit trees. Kiwifruit has large and dense leaf shape, large transpiration and large demand for water. It is estimated that the transpiration loss of adult kiwifruit trees with a crown area of 25 square meters is more than 75 liters per day. Generally, when the soil water content is reduced to 5%-6%, the water content is insufficient, the growth of kiwifruit branches is blocked, the leaves begin to suffer from drought, the leaves droop and become smaller, and the leaf edges wither. When the leaves begin to dry up during drought, it is necessary to irrigate or spray water in time, especially at the seedling stage, when the root system is not fully developed and sufficient water is needed. In addition to drought resistance, kiwifruit is also afraid of waterlogging, and the plant dies about 40% when it is poorly drained or waterlogged for 2 or 3 days. In the rainy season in the south or north of China, if it rains continuously and drains poorly, the roots will be flooded, affecting the respiration of the roots, and the root tissue will rot and the plants will die. Therefore, deep trench and high border planting should be carried out when planting, and a complete drainage and irrigation system should be built in the orchard.

Light

Most kiwifruit species prefer semi-shade environment, like sunlight but are sensitive to strong light, and belong to moderate light-loving fruit tree species, requiring sunshine time of 1300 Mel 2600 hours, like diffuse light, and avoid direct strong light. As a result, the plant requires a certain amount of light, and the natural light intensity is 42% to 45%.

Soil

It is suitable for sandy soil with deep and fertile soil, good air permeability, underground water level below 1 meter, high content of organic matter, PH 5.5 / 6.5 slightly acidic soil, and strong acid or alkaline soil needs to be improved before cultivation.

Altitude

Kiwifruit can generally be grown at 800 Mel 1800 m, but it is more suitable for 1000 mi 1600 m above sea level.

Other conditions

The wind resistance of kiwifruit is very weak and vulnerable to wind damage, mainly due to its large leaves, lack of elasticity, young shoots broken by strong wind, leaves broken, fruit friction bruising or shaking, thus reducing the yield and commodity performance. Therefore, the construction of the garden in the mountain area should try to avoid the windward mouth, the ridge and the windy area on the top of the mountain, and it is suitable to choose the leeward slope, and the slope direction is early sunny slope and late sunny slope.