Growth habits, planting methods and fertilization management of Taiwan pomelo variety Madou white pomelo

Madou white pomelo is a grapefruit variety in Taiwan, and it is a very popular grapefruit variety in Taiwan. Do you want to know how this kind of grapefruit is planted?

Madou white pomelo is the same as other citrus plants, the new shoots of adult plants germinate in spring, summer and autumn, and winter shoots grow in warm areas, of which spring shoots germinate the most, followed by summer shoots and autumn shoots. The spring shoot is an important fruiting branch and vegetative branch in that year, and the vegetative branch is also the main fruiting mother branch in the future. The germination site of spring shoot is up to 84.6%, while the formation rate of fruiting branch of spring shoot is 31.7%. The ratio of inflorescence shape of leafy inflorescence branch (including leafy single flower branch) is 41.2%, while that of leafless inflorescence branch (including leafless single flower branch) is 51.7%. The fruiting rate of spring shoot fruiting branches is 3.4-4.8%.

The leaves of Madou white pomelo had fallen leaves in every month of the year, while during the germination and flowering of spring shoots, 57.3% of the leaves on the mother shoots fell and replaced new leaves. When the aging leaf falls, the leaf body falls off first, and the petiole falls again a few days later, and the leaf falls throughout the day. The longest life span of plant leaves is 24 months, and the life span of short ones is only 1 month. The average life span of leaves is 11-12 months. If spring shoots germinate later, the life-span is 11-13 months, followed by 21-24 months. Madou white pomelo plants bloom from March to April every year, and the fruit ripening period is from October to November. Farmers are accustomed to harvest about two weeks after the Frosts Descent season.

Cultivation and management

Pruning and pruning

The pruning of young trees of Madou pomelo mainly lies in the cultivation of tree type and the expansion of crown year by year. When pruning promotes the emergence of new shoots, it should help the weak by pressure and promote the average development of branches. Generally, young trees can draw shoots 3 or 4 times a year, and do not prune temporarily after plant planting. Cultivate root groups and tree potential first. If seedlings grow slowly, they need to grow through 3 or 4 growing shoots, and then prune after the roots are exuberant. If the seedling is bigger and more vigorous, it can be pruned by 2-3 growing shoots, pruning on the principle of a single trunk and pruning at 45-60 cm from the ground, so as to promote the branching of new shoots. The main branch should choose the branch angle and trunk at about 60-70 degrees, leaving 2-3 branches evenly distributed in different directions, in order to cultivate into 2-3 main branches.

After the main branch is selected, the shoot is to grow again, and when the length of the main branch is more than 80 cm 100 cm, it is pruned at 50 cm 60 cm to promote the germination of the sub-main branch, and the branches with appropriate angles are selected to cultivate the sub-main branch so as to stagger the branch points. similarly, when the length of the sub-main branch reaches more than 60 cm, it is pruned at 40-50 cm to promote the sub-main branch to germinate new shoots in the appropriate position. After the main branch and sub-main branch have been cultivated, the future tree shape has been determined, and then the second sub-main branch can be selected for pruning and pruning, with 2 side branches on each sub-main branch, combined with proper irrigation, diligent application of fertilizer and thin application of fertilizer, in order to promote the health and fullness of the branches, and many green branches sprout on the side branches as fruiting mother branches to form a high-yielding crown. During pruning and pruning of young trees, the main branches with strong growth potential will grow upright upward and affect the shape of the tree. Bamboo poles or ropes can be used to induce and adjust their direction and angle, but the induction of the main branches should not be too low, and its base should keep an angle of 60-70 degrees with the ground. Young trees are induced by ropes to adjust the angle and direction of branches.

Young trees are induced by ropes to adjust the angle and direction of branches.

The tree shape management of Madou white pomelo mainly lies in the use of pruning to maintain the tree shape and increase the crown, while pruning can be divided into summer pruning and winter pruning. Summer pruning should be short, light pruning and thinning, and the tree potential growth of adult trees is relatively moderate during the full fruiting period. if the plant bears more fruit or the tree potential is weak, it is generally dominated by spring shoots, while summer and autumn shoots are rarely produced, only leafless or withered branches without fruit are cut off. If the plant bears little and the soil fertility is high, or if the nitrogen fertilizer is applied too much, the plant grows strongly and produces a large number of summer and autumn shoots, or even a large number of overgrown branches, the overgrown branches should be cut off except for the purpose of renewing the mother branches, and the summer and autumn shoots should also be truncated to promote the branches to form finer fruiting mother branches, and those with too much branches should also be cut off so as not to affect the tree shape and fruit quality. After a large number of summer and autumn shoots are pruned, we should also review and adjust the amount of fertilizer application, so as to avoid a large number of summer and autumn shoots every year, but not too much in summer pruning, so as not to affect the balance between the crown and roots, resulting in a large number of overgrown branches. Winter pruning belongs to a large amount of pruning, but the degree of pruning is determined according to the tree potential, and the pruning amount is no more than 15%. During the period of low temperature and drying around the middle of December, dry and withered branches, pest branches, overlapping branches, slender branches or long branches are trimmed. Sparse pruning of large branch tips with strong tree potential is suitable for pruning in winter, and pruning should be carried out year by year for 2 to 3 years, so as not to affect the distribution of the crown and cause a large number of long branches. When the tree is weak, shorten pruning is used to reduce the crown and stimulate branch germination to cultivate roots to restore tree potential. Excessively weak plants are suitable for light cutting, combined with the application of a large amount of low-nitrogen and high-fiber organic fertilizer to improve the soil, and chemical fertilizer should be applied thinly to restore the tree potential. In addition, the period of winter pruning should not be too early, so as not to produce a large number of winter shoots due to high temperature after pruning, and reduce the number of spring shoots in the following year.

Second, strengthen the management of soil fertility

(1) soil pH improvement

Madou white pomelo is a kind of citrus fruit tree, and its suitable soil pH (pH) is between 5.5 and 6.5. if the soil pH value is less than 5.0, it is a strongly acidic soil, and the reason of soil acidity is that the soil itself belongs to acidic soil, the lime in the soil is leached by Rain Water or the combination of acid chemical fertilizer and so on. In acidic soil, plants are often deficient in calcium or magnesium, which affects fruit quality, and the stronger the acidity is, the more iron, aluminum and manganese are dissolved in the soil, which is easy to form toxicity and is disadvantageous to plant growth, and phosphorus is easy to form insoluble iron phosphate and aluminum phosphate and other compounds. so that the plant can't absorb phosphorus. In strongly acidic soil orchards, limestone powder, shell powder or silicic acid slag can be applied, while magnesium deficient orchards should be treated with dolomite powder (containing 10% magnesium oxide), which can supplement calcium and magnesium at the same time. Every year, during the winter dormancy period, about 2kg per adult plant is applied evenly on the ground and mixed into 1530cm soil. Nitrogen fertilizers such as ammonium sulfate or urea can be applied only one month after application, and simultaneous application with compost can prevent soil hardening. The application of lime materials should be applied appropriately year by year, not too much at one time, and the pH value should be checked once a year. When the pH exceeds 6.0, the application should be stopped, so as to prevent the excessive pH from causing the lack of trace elements, thus affecting the leaf life and early defoliation. After the improvement of acid soil, it can directly increase the content of calcium and magnesium in soil, reduce harmful substances, enhance microbial activity, promote organic matter decomposition, enhance plant nutrient absorption and improve fruit quality.

(2) improvement of soil organic matter content

The content of soil organic matter less than 2% is low, 2% is medium, and more than 3% is high. Soil organic matter will decrease due to the decomposition of microorganisms, while Taiwan has a high-temperature and rainy climate, and the decomposition of organic matter will also accelerate. The application of organic fertilizer can not only be decomposed by microorganisms for crop absorption, but also promote soil aggregate structure, improve soil drainage and ventilation, and increase the capacity of water and fertilizer conservation. Therefore, orchards with organic matter content less than 2% can use grass cultivation or apply organic fertilizer to increase the soil organic matter content to 3%. When a mature organic fertilizer with high carbon (fiber) content is applied, the content of organic matter should reach 60%, and its nitrogen, phosphorus and potassium content is about 1%. Then it can be used in large quantities, and more than 30 kg can be applied per plant.

The application of soybean meal organic matter with high nitrogen content, such as 6.5% nitrogen content of soybean meal and 711% of peanut meal, can only be mixed with a small amount of 3-5kg per plant, so as to avoid damage to the root system due to the large amount of fermentation heat of soybean meal organic matter (the temperature is above 50 ℃) and the high concentration of dissolved soil solution. Organic fertilizer is applied in winter every year and applied to the surrounding soil under the canopy by burrow or ring. At the same time, after the application of organic fertilizer, the amount of chemical fertilizer should be reduced, especially the amount of nitrogen should be reduced, so as not to produce a large number of summer and autumn shoots due to excessive nitrogen fertilizer, thus affecting the fruit quality.

(3) rational fertilization

The amount of fertilizer applied in orchard varies with tree age, fruit amount, soil fertility and tree nutritional status. The amount of fertilizer application can be based on the recommended amount of fertilization in citrus orchards. If the yield per plant is 60 kg, each plant needs 600 grams of nitrogen per year. Phosphorus anhydride is 300 grams and potassium oxide is 600 grams, and then use the results of soil and leaf analysis to adjust the type and amount of fertilization. Madou white pomelo requires a high amount of fertilizer, if the soil fertility is low and the amount of fertilizer application is insufficient, the plant will blossom and bear less and the fruit quality is poor, which should be increased by 20% and 30% according to the recommended amount of citrus fertilization. The basic fertilizer of chemical fertilizer is based on the principle of deep application of organic fertilizer in winter, while sprinkling is the principle of spring fertilizer and summer fertilizer. According to the distribution ratio of chemical fertilizer, according to base fertilizer, spring fertilizer and summer fertilizer, nitrogen fertilizer is 40%, 40% and 20% respectively, phosphate fertilizer is 50%, 50% and 0%, or base fertilizer can be applied at one time, and potash fertilizer is 30%, 30% and 40%. The application period of base fertilizer is from December to January, spring fertilizer is from April, and summer fertilizer is from June to July. When excessive nitrogen fertilizer is applied in the soil, and the leaf nitrogen content is higher than the standard value (2.9-3.1%), the leaf color of the plant is thick green, and a large number of summer and autumn shoots are produced, which increases the fruit and thickens the pericarp, reduces the sugar content and juice content, and affects the fruit quality. nitrogen fertilizer should be reduced. The content of available potassium in soil is insufficient, and if the content of potassium in leaves is lower than the standard value (1.4-1.7%), the fruit is smaller and the sugar acidity is lower, so the amount of potassium fertilizer should be increased appropriately. If the content of available phosphorus in the soil is 600~1000ppm and the content of available potassium is 600~800ppm, then the content of phosphorus and potassium fertilizer in the soil is quite sufficient. When the pH value is 6.0, the content of available calcium in soil can reach more than 1000ppm. If the content of available magnesium in soil is also above 100ppm, and the ratio of calcium to magnesium is less than 6, the plant will not be deficient in calcium and magnesium. However, if the potassium fertilizer is applied excessively, the available potassium content is more than 1000ppm, and there is a large amount of available magnesium in the soil, which will also cause magnesium deficiency in plant leaves due to antagonism, and the magnesium content in leaves is lower than the standard value (0.26 ~ 0.5%), while the yellowing leaves with magnesium deficiency will fall ahead of time, and potassium fertilizer should be reduced during fertilization.

III. Proper soil moisture management

The amount of soil water supply during the growth period of Madou white pomelo has a great influence on plant growth, yield and quality. Due to the uneven distribution of annual rainfall in Taiwan, there are obvious dry and rainy seasons. In order to stabilize the yield and quality of Madou white pomelo, orchard drainage should be carried out in flat orchards in the rainy season to prevent root flooding leading to leaf and fruit drop. Sloping orchards should prevent soil loss and replenish water timely and appropriately in the dry season. Madou white pomelo is a subtropical citrus fruit tree, the soil also needs moderate drying during winter, but the soil water content is too low, it is easy to cause serious defoliation due to lack of water, but too much irrigation is easy to produce a large number of winter shoots, and reduce the number of flowers in the following year. Therefore, during winter drought, a small amount of soil surface water should be replenished by micro-sprinkler irrigation to maintain a low soil water content of 10% at a depth of 60 cm, so as to maintain normal plant growth and facilitate plant flower bud differentiation. If the soil is too dry in spring, when the soil water content is less than 10%, the plant is easy to cause serious leaf drop, flower drop and fruit drop. If the soil is dry in winter and often irrigated too much in spring, and the soil water content is often as high as 20% (- 8 cm / m / 12 min) of the field capacity, the dry and wet change of the root system is too large, which will also cause the plant to drop flowers and fruits seriously. Therefore, before the spring shoot is born, before and after the the Beginning of Spring solar term on February 4, the soil should be fully irrigated, and then, 1-2 weeks before the plant flowering, the soil should be irrigated with a moderate amount of water to maintain a sufficient moisture content of about 15% (- 30 minutes per minute), so as to facilitate plant root growth, spring shoot emergence, flowering and fruit bearing. During the period of fruit hypertrophy, the soil water content can be maintained at about 15% to facilitate the growth and development of the fruit, while irrigation should be stopped one month before harvest, and the soil water content should be maintained at 10% (- 50 ℃ / 70 min / m) in a dry environment to accumulate fruit sugar to improve fruit quality. If it rains and the soil moisture is too much before harvest, it is easy to crack fruit, so drainage facilities should be strengthened.