State six ecological requirements of growing sorghum

i. In general sorghum is tolerant to heat being a C4 plant and thus tolerant to draught and better adapted to arid conditions than any other cereal.
ii. It has xerophytic characteristics that enable it survives in water logging which impairs root functions.
iii. The crop requires warm conditions and grows best where the mean temperatures are 30°C. Sorghum is, therefore, mainly grown in areas below 1 500 m in East Africa.
iv. The crop adapts itself quite well to dry conditions and gives good yield with an annual rainfall of only 250-700 mm.
However, at least 300-400 mm of this rainfall should come during the growing period.
v. In arid and semi-arid, sorghum yields correlate well to amount of soil water at time of sowing.
vi. In silt and clay loams, sorghum can mature using residual moisture only.
vii. Drought tolerant in sorghum is attributed to several factors which facilitate plants acquisition of water and restrict its transpiratory losses.
These factors are:
1.The aerial portion of the seedling grow slowly until the root system become well established
2.There are more lateral and adventitious roots in sorghum than in maize. These roots are able to extract water from the soil. Under ASAL conditions, sorghum roots can penetrate 1.5m laterally and vertically.
3.Sorghum tillers providing after cutting plants called ratoons after 1st harvest and this avoid seeding again and also avoid land preparation (recultivation) that might facilitate soil water loss.
4.Sorghum leaves and stems have white waxy bloom which reduces net radiation and cuticle transpiration.
5.Sorghum has high water use efficiency requiring about 20% less water than other cereals in order to produce an equivalent amount of dry matter.
6.Under mild water condition, photosynthetic rates of sorghum are equal to and sometimes exceed that of those plants which are not stressed.
7.Under dry conditions sorghum roots continue to grow even though aerial parts have stopped growing to reduce transpiration.
8.The leaves of sorghum become more erect and roll inwards along their length reducing energy loss and leaf surface area exposed to transpiration.
9.The stomata on upper leaf surface close due to reduction in instant light while those on the lower surface remain functional. The function of this rise and roll response is more pronounced before flowering than after flowering.
10.Sorghum stomata close at a relatively lower water potential than other cereals.
11.Leaf stomata retain viability during periods of wilting lasting 2 weeks or more and quickly resume their diunal rhythm once water stress is removed. Their functional recovery of stomata follows closely on the restriction of the leaf turgidity.
12.Sorghum shows a lower rate of decline in relative turgidity than other crops when subjected to increasing moisture stress. Increase in osmotic pressure in leaf cells results in turgidity maintenance as the leaf water potential decreases. This assists roots to extract water from the cells to the atmosphere.
13.The whole plant can recover quickly and resume growth when moisture conditions become favourable once again.
14.The plant is able to fill its grain using assimilates formed prior to anthesis.
15.Pre-mature leaf senescence is induced thus reducing transpiring surface and water loss (leaf death).

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Titany answered the question on August 16, 2021 at 08:37