Biological characteristics of sorghum (Sorgum vulgare Pers.)

Importance of sorghum cultivation
Sorghum is grown for grain, green forage or fodder and to extract the sweet juice that is very rich in sugar from the stalk. Sorghum grains are widely used in human, animal and industrial foods. More than 200 million people in Africa, the Middle East, India and China use sorghum as a staple food. For green fodder or fodder, sorghum plants are of particular interest in arid regions.
Some forms of sorghum are grown for their inflorescences, with very long branches, from which various brooms, brushes or braids are made. Other forms of stems are grown, from which a sweet and sugar-rich juice is extracted. By concentrating this juice, a versatile food drink is obtained. The sugar in the sorghum stalk does not crystallize.
The importance of sorghum increases significantly due to its high resistance to drought and the ability to exploit some of the less productive lands (sandy and alkaline soils).

Biological properties
Sorghum seeds form a single embryonic root upon germination. Then coronary roots form from the nodes at the base of the plant, as with other grains.
Sorghum has a highly developed root system. Most of the root mass is found in the soil to a depth of 90 cm, and laterally up to 40 cm. Plants extract about 90% of the water and mineral nutrients from the volume of soil occupied by these roots. The roots of sorghum also have a large number of root hairs, compared to 1 cm2, twice that of corn. As for the leaf surface, the root system of sorghum develops twice as much as the root system of corn. These characteristics explain the high drought resistance of sorghum, which is much higher than that of maize. The stem of the sorghum plant is full of pulp, 0.3-4.5 m long, consisting of 7-20 internodes and a circular cross-section. As in maize, libero woody utensils are arranged irregularly throughout the pulp mass. The stem of sorghum can be more or less juicy. First of all, the sap content is 33-48%, while the stem is only 17-20%. The high juiciness of the stem gives high resistance to shedding and disease and increases the value of the forage. The juice from the stalks of some forms of sorghum (sorghum sugar) contains up to 20% sugar. The drink is extracted from these stems. The largest amount of total sugar is found in pins 6 and 7 of the base.
The germination capacity of sorghum stalks is high which is a desirable characteristic in case of forage crop and undesirable in case of grain crop.
The sorghum inflorescence is a deltoid with longer or shorter (spreading or compact) ramifications, erect or arched, the main length axis accounting for 10-90% of the total length. The paniculate contains 1000-5000 flowers, often between 1500 and 3000. The spikelets are grouped in pairs, one sterile and nodule, or has only stamens, the other sessile and fertilized. An inflorescence can release 15-75 million pollen grains. They are very small and lose their viability within a few hours. The spike usually blooms 2-3 days after the last leaf comes out of the sheath. Flowering lasts from 5 to 10 days and starts from the tip of the spikes.
The grains have a flattened round shape, with MMB between 20-30 grams.
According to Kenny, the different parts of the grain: endosperm 80.0-84.6%; fetus 7.8-12.1%; Peel (shell) 7.9-9.3%.
At the beginning of the vegetation period, the growth rate of sorghum decreases, which is why during this time it is possible to easily remove weeds from plants. After this period, the growth rate of plants becomes very high and the risk of weeding disappears.

Plant factor and vegetation relationships
Sorghum, a plant native to warm climates, has high temperature requirements. Thus, the minimum temperature for germination is at least 10 ° C, and the most favorable temperature for plant growth in general is 26-29 ° C. For the entire vegetation period, sorghum requires 2000-5000 degrees (average cumulative active temperatures). Hybrids grown in Romania reach maturity at 2300-2500 ° C.
At temperatures below 15 ° C, sorghum stops growing, and a temperature of -1 minus 2 ° C, which lasts more than 5-6 hours, destroys the entire plant.
Sorghum has a high drought resistance, a resistance that is determined by a strongly developed root system and the fact that when there is a lack of water, plants sharply reduce their growth rate. When the humidity becomes favorable, the sorghum begins to grow again at a specific density. Drought resistance is also increased by the waxy layer covering the plant and reduced surface transpiration by leaf twisting.
The transpiration coefficient of sorghum is much lower than that of sorghum. In the research conducted in Colorado, it was found that the transpiration coefficient of sorghum was 274, while the transpiration coefficient of sorghum was found to be 361. In Italy, it was found that the transpiration coefficient of sorghum ranged between 153-190.
Due to its high drought resistance, sorghum is grown in the area with less than 500 mm of precipitation. Generally, sorghum is grown where its yield is greater than that of maize. The difference in production in favor of sorghum increases bitterness, the drought intensifies.
In America, sorghum is the main weed crop in the arid and semi-arid region, where endemic drought and high temperatures do not allow the cultivation of corn. Some states (Texas) grow, for example, 40% of the area occupied by sorghum in America.
From the point of view of drought resistance, sorghum can be called a “vegetable camel”.
Earth Sorghum should be included among plants with low soil demands. It can be grown on any type of soil with a pH between 4.5 and 8.5. Undoubtedly, the highest yields are obtained on medium and deep soils. But compared to other plants especially corn, sorghum makes better use of sandy soil and alkaline soil (salts).
The resistance of sorghum to high salinity is also highlighted by the high content of sodium in the stalk ash (13.84%). Large areas of saline soils in North Africa and South Asia are exploited by cultivation of sorghum.
Under the conditions prevailing in Romania, sorghum should be considered a necessary crop only when it gives a low yield, especially in sandy or salt-rich soils, as well as in places where drought and heat are frequent..
Under the same conditions, sorghum is also useful for fodder.
In the irrigated sandy soil of the Pichit Experimental Station (Dolj), the production of sorghum hybrids decreased in the range of 90.90-74.37 f/ha. In Ostroful Maleuk (Tulsia), without irrigation, in the range of 81.0-60.0 F / ha. On saline soils (Luciu-Giurgeni, Ialomița) yields between 58.24 and 50.46 q/ha were obtained; On eroded soils (Aldeni – Buzău), a yield of 52.45 q / ha was obtained, 12.24 q / ha more than that of maize.
Romanian researchers estimate that the expansion of the areas sown with sorghum for cereals to 350-500 thousand hectares is only a starting point in connection with the better exploitation of sandy, saline and alkaline lands, lands with secondary salinization and in all non-irrigated areas. With precipitation less than 500 mm.
However, when conditions permit, sorghum broom should be planted in fertile, medium soil to obtain inflorescences with as long ramifications as possible.

Victor Vatamano

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