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Bean Growing (Part I)Bean growing for grains is considered as an extensive field crop, while green bean is distinctly considered as horticulture.
1. Taxonomy and Origin
The bean is a species of American origin, revealed both by various archaeological findings and by botanical and historical evidences. The earliest evidence of the crop dates back to 7000 BC. The introduction into Spain and the subsequent diffusion to other parts of Europe took place during the expeditions in the early sixteenth century. 2. ECONOMIC IMPORTANCE AND GEOGRAPHICAL DISTRIBUTION Bean growing for grains is considered as an extensive field crop, while green bean or string bean is distinctly considered as horticulture. The cultivated area dedicated to bean growing for grains has declined in recent years (due to dietary changes in the society and its import); yields have remained almost constant but the total production has declined significantly. In the case of green beans, the reduction is also significant, but less important quantitatively. The beans are a legume with great potential for human consumption, for its dual use (grain and pod) and for its protein contribution. Moreover, a part of its production is sold frozen and canned. However, it must progress in genetic improvement and adaptation to farming techniques. Importing countries of Spanish green bean crops are: France, Germany, Switzerland and United Kingdom.
3. MORPHOLOGY - Plant: Annual, quick vegetation. - Buds: They are in the axils of the compound leaves forming triads (3 buds). The triads can be vegetative, flower or mixed. - Flowers: Flowers are white in most important varieties. The flowers can be of different colors, but are unique to each variety. The flowers are arranged in clusters of 4-8 flowers whose peduncles emerge from the leaf axils or in terminal of some stalks. - Fruit: The fruit is a pod in different colours, shapes and sizes, and has 4-6 seeds inside. There are fruits which are green, marbled yellow brown or red on green, etc., but the most demanded by consumers are green and yellow with both cylindrical and flat pod. In advanced fruit stages, the walls of the sheath or shell are reinforced by fibrous tissues. 4. EDAPHOCLIMATIC REQUIREMENTS The proper management of climatic factors together is essential for the proper functioning of the crop, since all are closely interrelated and the action of one affects the other. It is a plant that grows in humid and mild climate areas, giving the best productions in warm climates. - Temperature: The critical temperature for beans is the following:
When the temperature is between 12-15°C, the vegetation is quite vigorous and when it is below 15°C, most of the fruits take the shape of a “hook”. Above 30°C, deformed pods appear and flower abortion occurs. High-growing varieties are 3-4 degrees more demanding in the biological minimum temperature than low-growing ones. - Humidity: The optimum relative humidity of air in the greenhouse during the first phase of cultivation is 60% to 65%, and then oscillates between 65% and 75%. Very high relative humidity favours the development of aerial diseases, hinders fertilization and increases the possibility of non-fertilized flowers. It is important to avoid excessive fluctuations in humidity and temperature because the flowers may fall off. - Light: It is a short-day plant, although in greenhouse conditions, it is not affected by day length, though the brightness affects photosynthesis. It can withstand higher temperatures when luminosity is higher, provided that the relative humidity is suitable. - Soil: Beans can grow in a wide range of soils but the best suited for cultivation is lightweight with sandy loam texture and well drained soil which is rich in organic matter. In soils with high clay and salinity contents, vegetal development is lower, being very sensitive to floods. Moreover, overwatering can be enough to damage the crop, leaving the plant with pale color and stunted. In calcareous soils the plants become chlorotic and stunted, and the fruits become rough. The optimum pH range is from 6 to 7,5; although in sanded field, it grows well up to 8,5. It is one of the most sensitive horticultural crops to soil and water salinity, suffering major losses in harvest time. However, the cultivation techniques of sanding and the application of localized irrigation, can reduce this problem, but with certain limitations. There are bean crop with irrigation water of 2 to 2,4mmhos/cm-1 EC, with sodium and chloride concentrations of 8meq/l and 9meq/l, respectively, that show no decrease in production. The reason for this is the application of magnesium (higher than normal) and calcium, as well as the maintenance of the level of humidity as constant as possible. 5. VEGETAL MATERIAL According to plant habit, there two types: - Erect low-growing beans (dwarf bean) from 30 to 40 cm tall. Earlier and are usually less productive than pole beans. Its vegetative cycle is shorter: - High-growing beans (pole bean) with climbing stems reaching 2-3 meters in length. They have twining stems with tendrils and usually have longer and more productive vegetative cycle than low-growing beans. Main selection criteria for green beans, grown in greenhouses: - Characteristics of the commercial variety, which can be high-growing or pole beans (Perona and Helda types with flattened pods) or low-growing (Strike type with round pods). - Target market. - Structure of greenhouses. - Soil. - Climate, considering that the most common planting dates are: August to September (with harvesting in November and December-January), November-December (with harvesting in March-April-May) and February-March (with harvesting in May-June-July). - Quality of irrigation water. 6. GROWING TECHNIQUES 6.1. Soil preparation Before planting, a semi-deep tilling should be done (25-30cm), with which the manure is wrapped. If the soil is in the process of disinfection, it is to be tilled again but shallower than the previous one, once the required time elapses. It follows the application of basal dressing and two skim ploughing (15cm) with harrow or field cultivator. In case of surface irrigation, corresponding ditches and ridges should be done. In sanded crops, after cleaning the previous harvest, the surface of the sanded ground should be leveled. Then, basal dressing is applied. 6.2. Settings for planting The most common settings for planting in greenhouse is 2m x 0,5m, with 2-3 seeds per dibbling hit, or one seed per hit. In outdoors, the distance between lines is 0,5m for dwarf varieties and 0,7-0,8m for pole beans, with 3-5 seeds per dibbling hit. For bush beans (dwarf beans) destined for industry, the planting rows are between 20 and 30cm. 6.3. Direct sowing Planting depth is 2-3cm. The seeds should be properly selected and treated with fungicides and insecticides. If the temperature is not sufficient or if the previous crop is to be left more time in the field, planting in seedbeds could be done which later on should be transplanted to the greenhouse. The emergence of seeds depends on the planting season and the weather, and can range between 7 and 20 days. It is advisable to wait until the weather is favorable in order for the emergence to be faster since it is not desirable to exceed 10 days. If the weather is cold, the soil can be warmed prior to planting by placing plastic tunnels. Several times of watering can also enhance sprouting. 6.4. Weeds Chemical weed control is advisable (especially the use of mulching) since manual weeding increases the cost of manual labor. The use of mulching reduces the labor and cost of weeding. For green beans: The active substances authorized for chemical weeding in green beans are: - Cycloxydim 10% - Clomazone 36% - Quizalofop-P-tefuryl 4% * Against annual grasses: Cycloxydim 10%, presented as emulsifiable concentrate, with doses of 1-2,50l/ha * Against perennial grasses: Cycloxydim 10%, presented as emulsifiable concentrate, with doses of 3-4l/ha Beans for grains The active substances authorized for conducting chemical weeding in green beans are: - Bentazone 48% - Bentazone 87% - Cycloxydim 10% - Ethalfluralin 33% - Prosulfocarb 80% - Quizalofop-P-ethyl-5% - Quizalofop-P-ethyl 10% - Quizalofop-P-tefuryl 4% - Tri-allate 40% * Against annual weeds: Ethalfluralin 33%, presented as emulsifiable concentrate, with a dose of 3l/ha * Against annual dicots: It prosulfocarb 80%, presented as emulsifiable concentrate, with doses of 4-6l/ha * Against dicots: Bentazon 48%, introduced as soluble concentrate with doses of 1,50 to 4l/ha * Against grasses: Ethalfluralin 33%, presented as emulsifiable concentrate, with a dose of 3l/ha * Against annual grasses: Cycloxydim 10%, presented as emulsifiable concentrate, with doses of 1-2,5l/ha Prosulfocarb 80%, presented as emulsifiable concentrate, with doses of 4-6l/ha Quizalofop-P-ethyl 10%, presented as an emulsifiable concentrate, with doses of 1,25-1,75l/ha Triallate 40%, presented as emulsifiable concentrate with doses of 2,50 to 3,50l/ha 6.5. Trellising It is an essential practice in pole beans in order to allow vertical growth and the formation of a homogeneous vegetation wall. It consists of the placement of a wire, usually made of polypropylene (raffia) which is tied to the stem at one end and the other to the upper metal structure of the greenhouse. The placement of stake between each pair of plants increases the uniformity of leaf mass and improves quality and production. 6.6. Leaf thinning It is done in dry season in long-cycled plantations, when the harvest period is extended by removing older leaves, as long as the crop is well developed, with plenty of leaf mass and a significant portion of harvest is already collected (1,5-2,5kg/m2). This practice improves the quality and quantity of production and reduces the risk of disease by improving ventilation and facilitating the application of phytosanitary treatments. 6.7. Watering Bean is very demanding in water intake especially in relation to the frequency, volume and timing of irrigation which depend on the phenological state of the plant and the environment in which it develops (soil type, climatic conditions, water quality, irrigation, etc.): - Influence of soil: Must be a soil with low salt content (EC<2mmho/cm). . In silt-clay soils, irrigation should be of greater volume but less frequent since they retain more water. . In sandy soils, irrigation should be of lower volume and more frequent since they retain less water. - Water quality: Must be a water with low salt content (EC<1mmho/cm). . If the soil is sandy and there is a good drainage system, water with higher salinity level can be used but it should be in large volumes. In this way, salinity content of the soil can be washed away during irrigation. . Mulching technique hinders salt accumulation. - Period: Most water demand coincides with fruit formation period. . At the beginning and during the flowering period, the plant is sensitive to excess moisture. . After flowering, irrigation should be more frequent to favor the elongation of pods. . After several harvest collections, watering should be done in order to favor the recovery of the plant. - Frequency: 2-3 irrigations/week in low volumes. In this way, the occurrence of crown and root diseases can be avoided. - Watering Schedule: 1-2 days before planting to facilitate planting and germination. . When the plant reaches 10 to 15cm. . After 15-20 days of sowing. . At 7-10 days after sprouting. In early stages of development, a soil with little moisture should be maintained, however water intake are very high just before and after flowering. Excessive moisture can cause chlorosis and yield loss, especially in heavy soils. Unbalanced water intake decreases the quality of the fruit. Finally, in ground and in sanded field, setting the timing and the amount of irrigation is guided basically by the following parameters: - Voltage of soil water (matric tension), which can be determined by installing a set of tensiometers at different depths. - Soil type (field capacity, saturation rate). - Evapotranspiration. - Efficiency of Irrigation (flow uniformity of the droppers). - Quality of irrigation water (the poorer the quality of water, the higher the salinity level is, and the volume of water needed to move the salts is higher). Media consumption (l/m2·day) of pole beans in greenhouse Source: Agricultural Technical Documents. Experimental Station "Las Palmerillas". Caja Rural of Almeria. SPRING
B: Sowing 1st half of January C: Sowing 2nd half of January D: Sowing 1st half of February E: Sowing 2nd half of February AUTUMN
G: Sowing 2nd half of September H: Sowing 1st half of October Media consumption (l/m2·day) of dwarf beans or bush beans in greenhouse Source: Agricultural Technical Documents. Experimental Station "Las Palmerillas". Caja Rural of Almeria. SPRING
B: Sowing 2nd half of December C: Sowing 1st half of January D: Sowing 2nd half of January AUTUMN
F: Sowing 1st half of October G: Sowing 2nd half of October 6.8. Fertilization Beginning from germination and sprouting, and up to flowering, fertilization should be low in nitrogen, to avoid excessive vegetative growth in detriment of flowering. An appropriate balanced N-P-K could be 10-15-23. From the beginning of flowering to the beginning of harvest (15-25 days) the plant is very demanding and any nutrients and water deficiencies will adversely affect the flowering and eventually the production. In this period, fruit and flower developments coincide; therefore, even when the balanced N-P-K is maintained, the electrical conductivity must be increased by 1,2-1,4 points above water electrical conductivity unless the latter exceeds to 2,2mmhos/cm, in that case it will only be increased by 0.8 points. From the beginning of harvest until the end of the cycle, it is important to increase nitrogen fertilization and water irrigation, with balanced N-P-K: 13-12-14. The most widely used are simple fertilizers: in soluble solid form (calcium nitrate, potassium nitrate, ammonium nitrate, monopotassium phosphate, monoammonium phosphate, potassium sulfate and magnesium sulfate) and in liquid (phosphoric acid and nitric acid) due to its low cost and they allow easy adjustment of the nutrient solution. However, complex crystalline solid and liquid fertilizers also exist in the market that can be used alone or in combination with simple fertilizers, to keep the balance required at different stages of crop development. The symbiosis with Rhizobium should allow the crop without nitrogen input, but the reduced presence of strains of bacteria and/or their infectivity and nodulation, usually low in general, makes it necessary a basic nitrogen fertilization. The contribution of microelements, which had been largely neglected in the past, is vital for proper plant nutrition. There is a wide range in solid, liquid and mineral chelates form in the market, when it is necessary to promote the absorption of nutrients and the stability of the plant. There are also numerous deficiency correctors both macro and micronutrient which can be applied through foliar or drip irrigation. Examples are aminoacids - for preventive and curative use, which help the plant at critical stages in its development or under unfavorable environmental conditions and other products (humic and fulvic acids, saline correctors, etc.) that improve environmental conditions and facilitate the assimilation of nutrients by the plant.
Author: Infoagro
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Bean Growing (Part I)
