Groundnut

Soils And Climate

Soils Climate

Soil

  • An ideal soil for groundnut is described as a "well drained, light coloured, loose, friable, sandy loam soil, well supplied with calcium and a moderate amount of organic matter".
  • A well-drained soil facilitates adequate exchange of air to meet nitrogen, carbon dioxide and oxygen requirements of the crop. The respiration of roots is affected when oxygen supply is low due to lack of proper drainage. This results in inhibition of root growth and retards metabolic functions. In the absence of adequate oxygen in the root zone, the nitrogen fixing bacteria are ineffective and the roots are unable to take up soil nitrogen.
  • In loose, friable, sandy loam soils germination of seeds and emergence of seedlings are higher. The pegs can penetrate soil more easily and the pods can be removed from the soil with minimum loss.
  • Adequate calcium is essential in soils for the production of pods with sound matured kernels. A moderate amount of organic mater (less than 2%) increases the water and nutrient holding capacities of the soil.
  • More than fertility, the texture of the soil is also important. Fine textured soils, heavy and stiff clays are avoided for rainfed crop as they cause difficulties in harvesting. High yields are obtained on slightly acid soils with pH 6.0 to 6.4. Alkali soils are undesirable.

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Climate

  • Weather affects groundnut crop directly through temperature, light and rainfall and indirectly through the incidence of pests and diseases.

Temperature

  • The effect of soil temperature is more critical on seed germination, seedling emergence and early plant growth. The embryo is killed when the soil temperature is above 54°C.
  • Temperature plays an important role in determining the rate of flowering, peg initiation and pod setting. Reproductive growth is maximum between 24 to 27°C. Constant temperature above 33°C affects pollen viability. Temperature below 20°C affects flowering and the ratio of fertilized flowers.
  • Positive correlation exists between aerial temperature and oil content in pod. Oil content from the pods of summer groundnut is higher than from the rainy season crop.

Light

  • Groundnut is a C3 plant and light influences both photosynthesis and respiration. Groundnut canopy responds to increased light intensity up to full sunlight. It was observed that 60% solar radiation for 60 days after emergence is critical for groundnut. * Flowering is independent of photoperiod, however, opening of flower buds and total number of flowers formed are highly dependent on light. Low light intensity in the early flowering phase caused the abortion of flowers. Low light intensity at pegging significantly reduced peg and pod numbers and also pod weight. Low light intensity during pod filling and maturity phases slightly decreased the number and weight of mature pods and significantly increased the percentage of shrivelled kernels.
  • If water stress is avoided, clear, cloudless days have the greatest potential for photosynthesis leading to high yields.

Rainfall

  • Groundnut has been found to grow and yield well in areas receiving 50 to 125 cm of well distributed rainfall. Variability in the amount and distribution of rainfall is the most important factor limiting yields of rainfed groundnut which constitutes more than 90% of the area under crop.
  • Adequate rains at sowing are necessary for proper germination and good plant stand and well-distributed rainfall during the crop period ensures normal vegetative growth, increased flowering and proper development of pods.
  • Bright sunny weather facilitates harvesting and drying of pods and haulms and ensures good quality of the produce. Rainfall at harvest time causes germination of kernels in non-dormant varieties (Spanish and Valencia cultivars) and also interferes with proper drying of pods and haulms. Groundnut cannot withstand frost or water logging.

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Tamilnadu

Groundnut

Groundnut Management