The reasons for the fruiting year of Camellia oleifera and the measures to overcome it

The reasons for the fruiting year of Camellia oleifera and the measures to overcome it

1 the cause of fruiting age of Camellia oleifera

The causes of the fruiting years of Camellia oleifera are not only physiological factors, but also the influence of external environment.

1.1 physiological factors

Physiological factors are the main reasons for the fruiting years of Camellia oleifera.

1.1.1 vegetative growth and flowering and fruiting of branches and leaves

Good vegetative growth of branches and leaves is the basis for tree flowering and fruiting. For the early fruit and high yield of young trees, a certain amount of branches and leaf area are needed to transform the tree from vegetative growth to reproductive growth and to obtain the ability of flower and fruit. for the high quality and stable yield of big trees, a certain ratio of leaf to fruit is needed to ensure the balance between tree growth and fruit. In the forest and fruit planting professional cooperative in Dashi Township, Taihu County, 173.33 h / m 2 Camellia oleifera planted in the early stage, due to the lack of supporting cultivation techniques such as improved varieties and strong seedlings, afforestation with base fertilizer, shaping and pruning, etc., crude camellia oil was not produced until 2008 when Camellia oleifera was 667 m 2 in 2007. The excessive growth of the tree, the excessive consumption of nutrients and the decrease of the accumulation of storage nutrients affected the flower bud differentiation and the development of flower organs in the following year. The fruit quantity in 2008 was less and the fruiting quality was not high. It can be seen from Table 1 that too few roots, branches and leaves cannot be too weak, nor too many and too prosperous. According to the long-term field observation, the best tree state which is beneficial to the fruit of Camellia oleifera is the medium-strong growth potential.

1.1.2 quality of flower bud differentiation and flowering and fruiting

Table 1 relationship among leaves, fruits and buds of different fruiting types of Camellia oleifera

Note: the investigation record of 8-year-old Camellia oleifera forest in Taling, Dashi Forest and Fruit planting Cooperative, Taihu County.

The fruit of the tree has a direct impact on the quality of flower bud formation, the flower bud is large and full, the fruit setting rate is high after flowering, and the fruit develops quickly; on the contrary, the flower bud is thin and flat, which is easy to drop flowers and fruits. The number and quality of flower buds in a tree are mainly affected by the following factors.

(1) the quality of branch development and flower bud differentiation. The potential ability of leaf bud to form flower bud of Camellia oleifera is directly related to the development of branch itself. The flower buds of Camellia oleifera generally occur on the spring shoots of the same year, but few in summer. According to the observation of the 8-year-old Camellia oleifera forest in Dashi Farmers' planting Co-operative in Taihu County, the thin spring shoots have only a few flower buds at the top, and the stout spring shoots not only have dense flower buds at the top, but also have 1 or 2 flower buds in the middle and lower parts. The flower buds developed at the top of Camellia oleifera were large and full, which decreased in turn, and the flower buds of main shoots were fuller than those of lateral branches.

(2) nutrient supply of fruit and flower bud differentiation. The initial period of flower bud differentiation of Camellia oleifera is from mid-May to early June after the spring shoot stops growing, but the flower bud differentiation of Camellia oleifera coincides with the fruit development period. The living habit of Camellia oleifera is that tree nutrients first meet the needs of fruit growth and development. Due to too many results, resulting in a lack of nutrients, the growth and development of flower buds are affected and fall off. Every August, the flower buds fall off seriously, accounting for about 10% of the total buds. It is observed that Camellia oleifera has too much fruit, too much nutrition consumption, small and not full flower buds, and spring shoot development is also affected, as shown in Table 2. Therefore, the leaf-fruit ratio must be adjusted by summer pruning to make the distribution of nutrients in the tree more reasonable, which is the basis and key to ensure the flower bud differentiation and eliminate the "big and small year".

(3) exuberant root activity is beneficial to flower bud differentiation. The flower bud differentiation period of Camellia oleifera is the first growth peak of Camellia oleifera root system, and the two promote each other. The root system can not only provide inorganic nutrients for the production of aboveground branches and leaves, but also use the photosynthates of leaves as nutrients to directly synthesize some structural and regulatory substances needed for flower bud differentiation. Therefore, the fertilization measures implemented during the flower bud differentiation period should be beneficial to enhance the root physiological function and promote the root activity.

Table 2 effect of fruiting amount of Camellia oleifera on spring shoot growth

Note: the experimental record of Camellia oleifera forest in Shiling Village, Dashi Forest and Fruit planting Cooperative, Taihu County.

1.2 impact of the external environment

1.2.1 site discomfort, poor growth and development of Camellia oleifera

The growth of Camellia oleifera requires an external environmental condition suitable for its own growth and development. Due to the changeable geomorphology and topography of the region, the diversity of comprehensive environment varies with different geomorphological conditions, such as elevation, slope, slope aspect, slope position, etc., especially the changes of light, temperature, water and soil properties, thus affecting the growth and fruiting of Camellia oleifera. For example, the growth difference and yield of Camellia oleifera on the shady slope is too high, because the sunshine is short, the wind is strong, and the temperature is low, which is disadvantageous to flower bud differentiation and a large number of falling flowers and fruits. In the mountainous areas with serious soil erosion, shallow soil layer and poor water and fertilizer conditions, Camellia oleifera has poor growth potential and low yield. The middle and lower parts of the hillside have strong photosynthesis, which is beneficial to the growth and development of Camellia oleifera.

1.2.2 varieties (types) are mixed, and there are many low-yield varieties (types)

Excellent varieties (types) are the basis of high quality and high yield of Camellia oleifera. Camellia oleifera is mainly cultivated in Anqing. Due to long-term seed cultivation and cross-pollination, various varieties (types) of flowering, ripening, fruit shape and fruit color are formed. Different varieties (types) have different resistances. some varieties (types) or individual plants with weak disease resistance are easy to be infected with anthracnose and soft rot, causing serious flower and fruit drop. Different flowering periods also have different effects on the fruit setting of Camellia oleifera. The earliest flowering period of Camellia oleifera is the middle of September, and the latest is the beginning of December. The difference in the initial flowering period is more than 2 months. Due to the different climatic conditions in the flowering season, the fruit setting rate, overwintering fruit preservation rate and yield are affected. Camellia oleifera is an insect-pollinated flower, and the fruit setting rate is determined by the flowering and pollination conditions at that time, in addition to the development of flower buds. The varieties (types) with early flowering stage can not get enough conditions for cross-pollination or bloom prematurely because of few flowering plants, the flower bud itself is not sound, and the fruit setting rate is not high; even if the flowering stage is too late, insects can not pollinate because the climate is gradually cold, or pollen is difficult to germinate, resulting in unstable yield.

1.2.3 extensive management and malnourished trees

In the process of long-term growth and breeding, Camellia oleifera has different characteristics from other trees and fruit trees, that is, spring shoots in the first year are fruiting branches in the second year, extensive management and lack of nutrition, which is bound to cause poor growth and development of spring shoots, less fruit in the second year and low yield. From March to April, it is the exuberant season for Camellia oleifera to produce spring shoots, such as excessive fruiting and consuming more nutrients. because the nutrients of the tree give priority to the growth needs of young fruits, the growth of spring shoots is limited, not only the number is small, but also the spring shoots are short and weak, especially the Camellia oleifera forest with old forest age and poor water and fertilizer conditions is more obvious. In the period of flower bud differentiation from June to July, if the fruit bears too much, it will affect the flower bud differentiation, resulting in not many flower buds, sometimes although some flower buds differentiate, but to the long-oil stage of tea fruit, because nutrients give priority to the growth and development of fruit, flower bud growth and development is affected early, seriously, it will also affect plant growth, leaves withered and yellow, resulting in a large number of fallen leaves, and also affect the emergence of spring shoots in the coming year and fruiting in the third year. Therefore, the phenomenon of big year in the first year, small year in the second year, 3 years and 1 cycle in the third year, or 1 cycle in 2 years is gradually formed.

1.2.4 bad weather will also widen the difference between big and small years.

Such as Camellia oleifera flower bud differentiation from June to July, the weather is dry, lack of water, the absorption of inorganic nutrients is difficult, the synthetic nutrients are insufficient, the formation of flower buds is few, and a small year appears in the second year.

2. Management measures

Camellia oleifera fruiting years, if properly managed, scientific measures can be overcome. The professional cooperative of Jinghui Camellia oleifera in Huangpu Town, Qianshan County, adopts comprehensive cultivation techniques such as improved varieties and strong seedlings, fine soil preparation, plastic film mulching, adequate base fertilizer, proper topdressing, shaping and pruning and timely harvesting, etc. it has created better ecological and physiological conditions for the life and development of Camellia oleifera. The demonstration forest of 33.33 h / m 2 planted in 2010 began to bear fruit in 2013. the fresh fruit yield of 7.5 kg ·hm ~ 2 ·m ~ 2 ·m ~ 2 in that year was measured by the experts of the provincial forestry department in 2015. the fresh fruit yield reached 628 kg / m ~ 2 in 2015. the fresh fruit yield was 410 kg / m ~ 2 in 2014. the fresh fruit yield reached 628 kg / m ~ 2 in 2015. Despite the dry weather in 2016, the yield of fresh fruit was measured by the county forestry bureau, the fresh fruit yield reached 714 kg / hm 2, the output value was 19.27 yuan, the yield and output value increased by 14.51%, and the early fruit high yield and high and stable yield were realized. Based on the analysis of the investigation data from various places, it is concluded that in order to overcome the fruiting year of Camellia oleifera or narrow the annual yield gap, diversified management measures should be taken.

2.1 selection of improved varieties and strong seedlings for afforestation

Afforestation with improved varieties and strong seedlings is a fundamental measure to overcome the fruiting years of Camellia oleifera. According to the survey, where the yield is relatively high, the economic character is more stable Camellia oleifera forest, the variety (type) is better. In recent years, Anqing City has comprehensively popularized and applied the Changlin series introduced from Jiangxi, the province's Dabie Mountain No. 4 and the local Wanqian No. 1 No. 2, and the planting effect is good. Since 2010, farmers' planting cooperatives in Dashi Township, Taihu County have cultivated Camellia oleifera 350 h / m 2, all of which are mixed forests of long forest series varieties (types). Among them, 173.33 h / m 2 planted in the early stage have flowered and hung fruit, and the 8-year-old Camellia oleifera forest has produced tea oil 3.5 kg / hm 2, which has achieved high and stable yield in a large area.

2.2 Deep reclamation

Deep digging and reclamation is a basic technical measure for high yield cultivation of Camellia oleifera. Through reclamation, we can not only remove weeds, shrubs and clean woodland, reduce the occurrence of diseases and insect pests, but also turn litter weeds into the soil, improve soil economic structure and physical properties, promote soil ripening, and increase soil organic matter and trace elements. Improve soil water and fertilizer conditions, which is beneficial to root growth. Exuberant roots, increase the absorption of nutrients, is conducive to the supply of nutrients and nutrients needed for flower bud differentiation.

Deep digging is mostly carried out in winter. According to the soil structure, geomorphology and slope of Camellia oleifera woodland, different reclamation methods are adopted, generally along the horizontal direction around the mountain on the horizontal belt, the method of semi-excavation and abundant filling is adopted to repair the slope into a horizontal ladder belt, which is high on the outside and low on the inside. to facilitate water storage and soil conservation.

2.3 rational fertilization

Camellia oleifera has the physiological characteristics of "holding son and pregnant child". It does not leave branches all the year round and consumes a large amount of water and fertilizer, so it is necessary to adjust measures due to forest and tree, apply fertilizer scientifically and rationally, and supplement the deficiency of soil nutrients, so as not to affect flower bud differentiation, spring shoot growth, flower bud and fruit drop. The types of fertilization should be based on the seasons, land and trees, generally with phosphorus and potassium fertilizer in the big year, nitrogen fertilizer or compound fertilizer in the small year, organic fertilizer in autumn and winter, and quick-acting fertilizer in spring and summer. Fertilization is combined with ploughing and reclamation.

2.4 shaping and pruning

Through proper pruning, Camellia oleifera trees have good structure, ventilation and light, concentrated nutrients and reduced diseases and insect pests. In particular, the flower bud differentiation period and fruit growth and development period of Camellia oleifera overlap, there is obvious competition in nutrient demand, if not pruned in time, both will be damaged. At the same time, the adjustment of leaf-fruit ratio through summer pruning is beneficial to the flower bud differentiation of the tree and lays the foundation for the yield and harvest next year. The practice shows that pruning not only improves the relationship between tree body and environment, but also improves the rational utilization of nutrients in tree body. Technical means such as truncation, retraction, thinning flowers and fruits, twisting branches and ring cutting are commonly used in production to control the flow of nutrients between vegetative organs and reproductive organs so as to regulate the balance of nutrient supply among flower bud differentiation, fruit development and vegetative branch growth.

2.5 cultivation and utilization of pollinated insects

Camellia oleifera is a cross-pollinated tree species. The fruit setting rate of cross-pollination is 20%-35%, and the fruit setting rate is closely related to pollination insects. There are more than 40 species of pollinating insects in Camellia oleifera forest, such as flies, ants, gadflies, butterflies and bees, among which native wild bees have the best pollination effect, especially Camellia oleifera, Camellia oleifera and striped wasps. This kind of bee colony has wide distribution, large number and strong resistance, and can adapt to the ecological environment of Camellia oleifera forest and the habit of flowering and pollination in the aspects of physiology, ecology, life and reproduction. Therefore, in order to improve the fruit rate of Camellia oleifera and shorten the gap between large and small years, it is an important measure to cultivate, introduce and protect pollination bees.

Ground bees can pollinate Camellia oleifera because they collect a large amount of pollen during activities to make bee food for their offspring. When collecting pollen, the pollen of different plants is transferred frequently, which plays the role of multi-flower mixed pollination, improves the seed setting rate and promotes the high and stable yield of Camellia oleifera.

2.6 strengthen pest control

The disease and insect damage of Camellia oleifera is common and serious. According to the investigation, in 2016, the incidence of Camellia oleifera swelling disease reached more than 30% in Taihu Lake, buried hill, Susong and other key producing areas, resulting in the shedding of a large number of leaves, fruits and buds. The flower and fruit drop rate of Camellia oleifera is as high as 70% to 80%, of which the disease accounts for 1%. Anthracnose is the main cause of Camellia oleifera fruit drop. Camellia oleifera diseases and pests are mainly treated and prevented, combined with tree management, fungicides and insecticides are sprayed in time at the initial stage of the occurrence of diseases and insect pests, so as to achieve "early prevention, small prevention and prevention" and reduce tree damage and yield loss.