Kenaf (Hibiscus cannabinus) is a valuable fiber crop.
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Economic importance
Kenaf stems contain up to 24% fiber, which is strong, soft and hygroscopic. Tarpaulin, sacking, container, carpet and furniture fabrics, ropes, ropes and other products are made from fiber.
The kenaf fire is used for the production of building boards and paper. The seeds contain 18-20% oil (fat), which is used in the leather, soap and paint industries. The cake goes to feed livestock.
Crop history
The homeland of kenaf is considered to be South America, where it is distributed in the wild.
Cultivation areas and yield
Kenaf is grown in India, China, Indonesia, Burma, Sudan, Brazil.
On the territory of the former USSR, kenaf is cultivated on irrigated lands in Uzbekistan. The area under crops in the 1980s was about 15 thousand hectares (statistics for the USSR).
On green and seed crops, the yield of kenaf stalks can reach 18 t/ra or more. The largest yields of 20-25 t/ha were obtained annually on the Politotdel collective farm of the Communist region, the Akhunbaev collective farm of the Srednechirchik region, the Lenin collective farm of the Galabinsky region of the Tashkent region, etc.
Botanical description
Kenaf (Hibiscus cannabinus L.) is an annual herbaceous plant of the Malvaceae family .
The root is taproot, well developed, penetrating to a depth of more than 2 m.
The stem is round or slightly ribbed, 2 to 5 m high, branched, with anthocyanin coloration. At the base, the thickness of the stem is 1.5-2.0 cm.
The leaves are alternate: the lower ones are simple, the middle ones are lobed, the upper ones are lanceolate with serrated edges.
The flowers are large, up to 7 cm in diameter, five-petalled, yellow, cream, light lilac, pink in color with a dark cherry or pale reddish spot inside the corolla. Plants begin to bloom from the lower flowers. Each flower blooms for one day. Self-pollination prevails, with underdeveloped anthers, cross-pollination can be observed.
The fruit is a five-celled, ovoid-pointed capsule, about 2.5 cm long, 1-2 cm wide, covered with fine bristles. On one plant, 20-30 boxes are formed.
Seeds triangular, dark gray. One box contains 15-20 seeds. Weight of 1000 seeds 20-28 g.
Biological features
Temperature requirements
Kenaf is a thermophilic plant.
Seeds begin to germinate at a temperature of 10-12 °C. The optimum temperature for the appearance of uniform seedlings is 20-22 °C.
Frosts -1.0 … -1.5 °C lead to the death of seedlings and adult plants.
The optimal temperature for the growth and development of kenaf is 23-25 °C. By the end of the growing season, heat requirements are noticeably reduced.
Moisture requirements
For kenaf, the optimum soil moisture is 80% from the lowest soil moisture capacity. Therefore, kenaf can be cultivated either in irrigated conditions or in regions rich in rainfall.
The greatest need of plants for water falls on the period of rapid growth, that is, when a three-blade leaf appears.
Soil requirements
Typically, kenaf is sown on alluvial soils of river valleys, gray soils, meadow and meadow-marsh soils.
Salt and waterlogged soils are not suitable for cultivation.
Light requirements
Kenaf is a photophilous plant of a short day.
The lack of lighting, which can be observed on heavily thickened crops, leads to short stature and weakening of plants.
Vegetation
The vegetation period of kenaf is 120-160 days.
Crop rotation
In crop rotation, the predecessors of kenaf can be winter cereals, tilled crops, legumes and alfalfa.
Fertilizer system
Kenaf is a rather demanding culture in terms of nutrition. With a stem yield of 10 t/ha, kenaf removes 120-150 kg of nitrogen from the soil, 60-80 kg of phosphorus and 120-160 kg of potassium.
At the beginning of the growing season, the greatest need is noted for phosphorus and potassium. Nitrogen consumption increases significantly during the budding and flowering phases.
Kenaf is responsive to fertilization. A particularly good result is obtained from the joint application of manure (15-20 t/ha) and mineral fertilizers.
The approximate recommended application rate of mineral fertilizers to obtain 18-20 t / ha of stems is: nitrogen – 220-250 kg, phosphorus – 150-170 kg and potassium K – 90-100 kg/ha. When placing kenaf after alfalfa, the fertilizer rates in the first year are somewhat reduced.
Manure and half of the total norm of phosphorus and potash fertilizers are applied for autumn tillage, 25-30 kg/ha of nitrogen and phosphorus – at sowing, the rest of the fertilizer – for top dressing. Top dressing of crops of kenaf is carried out in the phase of 8-10 leaves and in the phase of the beginning of budding.
Tillage system
Tillage for kenaf includes:
- peeling;
- autumn plowing with plows with skimmers to a depth of 28-30 cm in September;
- early spring plowing;
- 1-2 cultivations with simultaneous harrowing.
Before sowing, the field is planned and harrowed.
Sowing
Seed preparation
Before sowing, conditioned seeds are subjected to air-heat treatment in open areas. Seeds are treated with 80% TMTD at the rate of 200 g/100 kg of seeds.
Sowing dates
Sowing of kenaf is started when the soil warms up to 12-15 °C.
For Uzbekistan, the optimal sowing time for greens is April 10-20, when grown for seeds – April 1-10.
Seeding methods
The most progressive method of sowing when growing greens is a two-row belt with a width between the ribbons of 70 cm and a distance between the lines of 20 cm. The seed sowing rate by this method is 25-30 kg/ha.
With the seed crop of kenaf, a wide-row sowing method with row spacing of 60 cm is usually used. The sowing rate in this case is 8-10 kg/ha.
Seeding depth
Sowing depth on light soils is 5-6 cm, on heavy soils – 3-4 cm.
Crop care
Kenaf plants at the beginning of the growing season develop slowly, so the greatest care is required for crops during this period. The destruction of the soil crust at this time is carried out with the help of light harrows.
During the growing season, the number of inter-row treatments reaches 5-6. They are carried out immediately after watering, as soon as it becomes possible due to the state of soil moisture. Usually, inter-row cultivation continues until the rows close.
During the growing season, 5-6 waterings are carried out on green crops: the first watering is carried out at a plant height of 12-15 cm, the next – after 15-20 days. The irrigation rate is 1000-1200 m3/ha.
On seed crops, after the first cultivation, thinning is done, after which the plant density should be 150-180 thousand plants per 1 ha. Three waterings are usually carried out: the first – in the phase of 18-20 leaves, the second – in the budding phase, the third – in the flowering phase. Irrigation rate – 3500-4000 m3/ha.
Harvest
The harvesting of kenaf for greenery is started at the onset of technical ripeness, that is, when at least 50% of the plants bloom. To obtain bast, freshly cut stems are processed using a ЛО-1А bast separator. The resulting green bast is dried, for which it is spread over the stubble in an even layer. After drying, the bast is collected in bales weighing 10-12 kg. Before delivery to the procurement points, the bast is sorted.
Kenaf harvesting can be carried out using kenaf harvesters, for example, КУ-0.2, which cuts the stems, separates the undergrowth and weeds, processes the stems into bast and lays them on the ground to dry.
Harvesters ЖК-2.1 are used for harvesting kenaf for seeds. Harvesting is started when 3-4 lower bolls are browned in 75% of plants. In the conditions of the Tashkent region, which is the only producer of kenaf seeds for all regions of Uzbekistan, harvesting is usually carried out on September 5-16.
Cut stems are dried, for which they are left on the field for 3-4 days. Then the stems are tied into sheaves and set in small musts to dry. Dried sheaves are subjected to threshing, for which mobile threshers МКФ-6 are used. Seeds are sorted, and the remaining stems are tied into sheaves and sent for delivery to bast plants.
Sources
Crop production / P.P. Vavilov, V.V. Gritsenko, V.S. Kuznetsov and others; Ed. P.P. Vavilov. – 5th ed., revised. and additional – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and textbooks for higher educational institutions).