Basic knowledge of high-quality coffee classification of various parts of coffee trees

1. Root

Coffee is a shallow root crop, and the plants propagated with seeds have conical roots. Root system refers to the general name of root. The root morphological distribution and depth of shade varieties / soil conditions and agricultural technical measures are different. From the point of view of varieties, the roots of small / medium grain species are shallower, while those of large grain species are deeper. Under normal circumstances, there is a thick and short taproot and many developed lateral roots. Yunnan small-grained coffee is a 4-year-old fruiting tree with a depth of about 70 cm. The main roots beyond 70 cm tend to become slender and extend downward in the form of absorptive roots. The main root generally does not bifurcate, but if it is injured when digging seedlings, one or two roots grow down from the wound healing place to replace the severed main root after planting, the lateral root grows horizontally, the horizontal lateral root grows horizontally, and the downward lateral root is called vertical lateral root. the paper roots from the lateral roots are called secondary lateral roots and tertiary lateral roots respectively. The root system of coffee has an obvious layered structure, usually every 5 cm, but most of the absorbing roots are distributed in the soil layer of 30 cm, especially in the soil layer of more than 15 cm. A few of them are distributed in the soil layer of 30 cm and 60 cm, and there are only a few absorbing roots in the soil layer of 60 cm and 90 cm. The absorbing roots in the topsoil layer are thick and white, and the absorbing roots are yellow and delicate beyond 30 cm. The horizontal distribution of coffee root seconds exceeds 15-20 cm of the crown width in infancy, and there are many roots in the topsoil layer of coffee orchards covered or shaded by rows in the adult stage. The roots in the exposed surface layer of the soil are easy to burn, and the roots are deeply rooted during deep ploughing, and the coffee roots have a strong ability of regeneration, which recovers quickly after being damaged or cut off. Within 7 ~ 10 days, they grow good healing tissue and sprout many new lateral roots. The new lateral roots grow root rows for absorption, which is the most active root system.

two。 Stem

The stem of coffee is erect, the tender stem is slightly square, green, corked and round and brown. The length of stem Internode is 4-7 cm, the length of shaded Internode is 20-30 cm, the length of overshaded Internode is 20-30 cm. A pair of leaves grow on each node, with overlapping buds in the axils, upper buds in the upper and lower buds in the lower. The upper bud develops into a branch and the lower bud develops into a straight branch. The upper segment sprouted at the same time as the terminal bud. Each upper bud can be produced only once, while the lower bud can be produced many times. When the terminal bud of the trunk is suppressed or the trunk is bent, the bud will germinate into a straight branch with the shape of trunk growth, and the direct branch can be cultured into the trunk.

The growth of coffee trunk has obvious apical dominance. The branches near the top of the trunk grow very vigorously. But this advantage weakens with the increase of the trunk. Its growth varies with varieties and natural climatic characteristics. When there are 6-9 pairs of true leaves in the main stem of small-seed coffee seedlings (8-12 pairs of medium-grain species), the first pair of branches will be drawn. In the year of planting, it generally grows 4-8 pairs of one minute, and the growth increases gradually in the second year, 7-12 pairs in the second year, and 14-15 pairs in the third year. If the management is good and the climate is suitable, it can be as high as 18-20 pairs. At the same time, two branches grow under the crown, open the stage to form a crown, and bear a small amount of fruit. Generally, the third year after planting is the year with the most vigorous vegetative growth / maximum growth. Management must be strengthened, especially the supply of water and fertilizer, in order to form a robust crown. In the fourth year, the growth of the trunk slowed down, the Internode became shorter, and entered the fruiting stage (there were also those with particularly exuberant vegetative growth, branching in large quantities in the second year, and entering the fruiting stage in the second or third year). If the trunk is allowed to grow naturally, all kinds of coffee can continue to grow according to its growth power. Small seeds up to 4 meters 6 meters, medium seeds 6 meters, large seeds up to more than 10 meters. The harvest is difficult and the yield can be reduced, so the height of the trunk is controlled. The small seed species were shaped in a cylindrical crown 3-4 years after planting by single-stem shaping / unroofing.

The growth of the trunk has seasonal variation, with smaller growth in the dry season, shorter internodes, larger growth in the rainy season and longer internodes, and the smallest growth and shortest internodes in winter. Therefore, according to this growth characteristic, we can know the plant age under natural growth.

The branches of coffee can be divided into the following categories according to their location and growth direction:

One branch: there are two kinds of buds in the axil of the main leaf of coffee. The opposite branch is drawn laterally from the upper bud of the trunk (developing at the same time as the terminal bud of the trunk), which is called a branch.

Second branch: a branch drawn from the axil of a branch at an angle of 45-60 degrees is called a second branch, which is shorter than a branch.

Three branches: branches regularly drawn from the axils of two branches are called three branches.

Other branches at all levels are pushed accordingly. Yunnan small seed coffee can reach up to seven branches.

Secondary branch: a branch that grows irregularly inside or under / under the crown on a first / second branch.

Straight branch: the lower bud of each node of the trunk is mostly in a latent state, when the terminal bud of the trunk is injured or the growth is inhibited, in a short time, the next bud will sprout and pull out the branches that grow vertically, which is called straight branch. some straight branches grow in clusters in the gloomy crown, showing the phenomenon of overgrowth, and the internodes are very long, so they are also called overgrown branches. The growth habit of this branch is similar to that of the trunk, and it can be used to form a new stem during multi-stem shaping.

The growth and fruit of coffee trees varies with different varieties / environmental conditions. In the high altitude area of Yunnan, the small seed coffee cultivated has the advantages of cold climate, large cloud cover, short light and slow plant growth, but the branches develop into sturdy backbone branches after the first branch bears fruit, and the second / third branch has strong ability to produce. The growth is exuberant and the fruit is dense, which is the main fruiting branch, so it is suitable to adopt single trunk shaping. Two / three branches bear fruit and die after 2 or 3 years, and then sprout two / three branches from the backbone branches.

The flowering and fruiting habits of a branch produced in different months of the year are different.

The growth and fruiting habits of the first / second branch of coffee vary with different types and stages: the first branch can be divided into three types:

The first type: the first branch from February to May each year, mainly vegetative growth, the largest growth in the current year, most of the two branches in the next spring, the robust branches in the same year (July to September), individual branches can blossom and bear fruit in the following year. In single-stem plastic surgery, a branch of this type is selected to cultivate backbone branches.

The second type: a branch from June to September every year, after which the reproductive growth and vegetative growth are carried out at the same time. Therefore, every branch can blossom and bear fruit in the next year, and rarely produce two branches. The part of a branch that continues to grow will blossom and bear fruit in the third year, which is the main fruiting branch in the third year.

The third type is a branch which is produced after September, because it enters a period of low temperature and drought shortly after harvest, grows slowly, grows slowly in that year, only 1-6 nodes, blossoms and bears fruit in the next year, continues to grow in the next year, and can produce two branches. The growth and fruiting habit of the second / third branch of the small seed species is different from that of the first branch. The climate is suitable and the management is normal. 2-3 times per year (February-March / May-June / August-September). The branches extracted at the beginning of the year have a large growth in that year and bear more fruit in the next year, while those in autumn have less growth in the same year and less fruit in the next year. But the next year continued a large amount of growth, the third year a large number of results.

3. Leaf

Coffee leaves opposite, usually two rows spreading, individual single leaf whorl, petiole short, leaf leathery, green (dark green on the upper surface, light green on the lower surface). Glossy oval, oval to long oval. The leaf size of small-grain coffee is relatively uniform, the leaf is small and the end is longer, and the leaf edge wave is obvious, about 12-16 cm long and 5-7 cm wide. The leaves of the mid-grain species are long and large, soft and thin, with obvious ripples, about 20 cm long and 8 cm wide. The large-grained leaf blade is leathery, hard and thick, tip-pointed, and the leaf margin is nearly corrugated, about 17-20 cm long and 6-8 cm wide. The leaves of coffee trees are typically ventral and dorsal symmetrical. The leaves contain tannins, starch grains and calcium oxalate.

4. Flowers

Several to dozens of flowers are clustered in leaf axils, and 2-5 flowers per month are planted on a flower axis, pedicels are short, flowers are white, petals of medium / small seeds are generally 5, and 7-8 of large-grained species, petals are connected at the base of the petals to form a high-footed butterfly-shaped Corolla, stamens are generally the same number as petals, inserted in the Corolla throat. Anthers two-loculed at the top of filaments, both forming a "D" shape, pistil style filiform, stigma bifid, ovary inferior, usually two-loculed, also one-loculed or triloculed. There is an anatropous ovule on the central placenta of each locule, the stalk is very short, insect-pollinated flowers, large and small seeds can be self-pollinated, and most of the medium-grain species are cross-pollinated.

1. Characteristics of flower bud development

Flower bud development: the formation of coffee flower bud is closely related to varieties and environmental conditions. Franco was the first to point out and confirmed by Piringer et al that coffee (except perennial flowering mutation) is a short-day plant. Under the condition of artificial light at night when the sunshine is more than 13 hours, the plant only grows vegetatively. Mes found that temperature can affect the budding of coffee. When the day temperature is 23 degrees Celsius and the night temperature is 17 degrees Celsius, the flower buds produced by the plant are more than the day temperature 26 degrees Celsius, the night temperature 20 degrees Celsius, the day and night temperature 30 degrees Celsius, the night temperature 22 degrees Celsius, the flower buds are underdeveloped. Under sufficient sunlight, most of the axillary buds of annual branches of medium-grain coffee are sterile, or only a few flower buds develop, and blossom and bear fruit.

The axillary buds germinated in different periods of the same kind of coffee take different time to develop into flowers, such as medium-grain coffee, the axillary buds sprouted before May need the longest time (about 6-8 months), the axillary buds sprouted from May to October need medium time (about 4-5 months), and the axillary buds formed from October to November need the shortest time from beginning to flowering (3-4 months).

two。 Flowering characteristics

2.1 Coffee has the characteristics of multiple flowering, flowering and florescence concentration. the flower buds of coffee are compound buds, and there are 2-6 flower buds in each leaf axilla. at the same time, the germination of one leaf axillary bud (or different plant flower buds) is inconsistent, first and later, forming the phenomenon of multiple flowering, but there is a relative middle stage of flowering every year, that is, the full flowering period. the flowering period of coffee varies with different species and environmental conditions. The florescence of small seed coffee in Hainan Island is from November to April, and the flowering period is from February to April. In Yunnan (Dehong Dai Jingpo Autonomous Prefecture), the florescence is from February to July, the full bloom is from March to May, and in Guangxi, the florescence is from February to June and from April to June.

2.2 the flowering of coffee is greatly affected by climate, especially rainfall and air temperature. it takes a certain amount of water to develop flower buds to separate buds / flowering. High temperature and drought, small seed coffee bud development is normal, forming "star flower" / "melon flower". Excessive drought, coffee buds are small, do not bloom or do not bear fruit after flowering. The flower buds do not open when the temperature is below 10 degrees Celsius, but the temperature above 13 degrees Celsius is conducive to flowering.

The life span of coffee flowers is short, only 2-3 days. Small coffee flowers usually bloom at 3: 5 a.m. and bloom at 5-7 a.m., and the stamen anthers release a small amount of pollen before they bloom. At about 9-10:00, the pollen sac cleaves and releases a large amount of pollen. Medium-grained species have more pollen than small-grained ones. The style and stamens of different kinds of coffee matured sooner or later, and the stigma of small species matured earlier than stamens. The ability of stigma pollination was the strongest on the day of flowering and the next day, and then gradually lost its pollination ability, and the petals withered quickly. In the case of drought / wind or cold current at the flowering stage, the style is vulnerable to drying up, and if it rains continuously, the Corolla is easy to rot, which affects pollination / fertility and yield.

5. Fruit

The fruit is a berry, also known as comb fruit. Oval, 9-14 mm long, young fruit green, red at maturity, purplish red. Each fruit generally has two seeds, but also one or three, showing a semi-oval, there is a longitudinal groove, called grooves. In the structure of the fruit, the exocarp is composed of a thin layer of hardwood human cells, with stomata scattered on the outside; the mesocarp (that is, pulp) is composed of several layers of polygonal large and Lignified parcels, and the innermost layers of cells are slightly compressed. Vascular bundles containing a large amount of fiber can be seen between the cells, and the endocarp, also known as the sheepskin (seed shell), is a thin horny shell composed of stone cells. The seed coat, also known as the silver coat, is the thin coat of the outer layer of the seed. The color and thickness of the seed coat is one of the distinguishing characteristics of the variety. The seed kernel is the coffee bean without silver coat, which is called "commercial coffee bean" on the market. The seed contains two parts of embryo. The embryo is at the base of the endosperm. Cutting the endosperm shows a pair of fleshy sunflower fan-shaped cotyledons and white embryos.

1. Fruit development

The development time of coffee fruit is long, and the time from flowering to ripening varies with species, small seed coffee takes 8 ~ 10 months (maturing from October to December of that year), medium grain coffee takes 10 ~ 12 months (from November to May next year), and large seed takes 12 ~ 13 months.

The rate of fruit development also varies with different species. Small-seed coffee fruit increases fastest 2-3 months after anthesis, and after 4 months, its volume is basically stable and dry matter accumulation increases. The growth of dry matter was the fastest at 5-6 months after anthesis, the development of medium-grain coffee fruit accelerated at 3-4 months after anthesis, the fastest at 4-6 months, and slowed down at 7-9 months. At this time, the dry matter of the fruit accumulated rapidly and its volume increased slightly before fruit ripening.

two。 Rainfall has a great influence on fruit development, and climatic conditions directly affect fruit development.

One month after flowering, in case of drought, the young fruit often dries up due to lack of water, resulting in low fruit rate. During the period of fruit development, the fruit will be small / early maturing, while the wind (or strong wind) will easily lead to fruit drop, resulting in yield reduction or failure.