In this article we will discuss about the climate and soils suitable for growing pigeonpea.
Photothermal Effect on Flowering:
Pigeonpea is described, in general terms, as having a quantitative short day flowering response. In other words, the onset of flowering is hastened as day length shortens. However, both variations in sensitivity to photoperiod and major effects of temperature on time of flowering are evident.
Results on date of sowing experiments revealed that three of the genotypes when sown from March to June flowered in the same year during December, while those sown from October to December flowered in December next year.
Pigeonpea varieties, in general, are divided into early, medium and late types depending on the duration. Early types take 100 to 150 days, medium types 150 to 180 days and late types more than 200 days for maturity. When sown in June-July, early and medium types flower in September- October, whereas late types flower in January-February.
Thus, all the three types flower when the day length is decreasing below 12 hrs or increasing above 11 hrs. Both these conditions would qualify them for being called as short day responsive. At IARI, New Delhi, BS I variety took a minimum of 75 days to 50 per cent flowering when seeded in September. January seeding, however, took 205 days to 50 per cent flowering, clearly indicating that the variety was sensitive to day length, temperature or both.
When the same variety was tested at Coimbatore (TN), where the day length and temperature fluctuations are relatively much less than at Delhi, it flowered all the year round and took only 50-80 days to 50 per cent flowering.
Pigeonpea variety ST 1 was sown every month at Coimbatore, Hyderabad and Pantnagar. At Coimbatore, November to January sowing took a minimum of 80-86 days to 50 per cent flowering, whereas a maximum of 175 days were required for March sowing. The same variety took a maximum of 240 days at Hyderabad in January sowing and a minimum of 84 days with December sowing.
At Pantnagar, a maximum of 321 days and a minimum of 92 days to 50 per cent flowering were taken in January and September sowings, respectively. Thus, it appears that the minimum number of days to 50 per cent flowering did not very much at the three places but there was marked difference in maximum number of days to flower.
From the available evidence it seems justified that pigeonpea like greengram, could be considered short day plant while chickpea and lentil be designated as long day plants.
Temperature:
The thresholds mean temperature for pigeonpea emergence under field conditions is 12.8°C. Emergence (50%) required 58 day degrees above the threshold temperature, which would accumulate in 26 days at 15°C, 8 days at 20°C and 5 days at 25°C. About 85 per cent germination occurred at temperature range between 19° and 43°C but germination did not occur either at 7° or 6.5°C.
Growth increase with increase in temperature up to around 35°C. In northern India, where the daily maximum temperature is between 35° and 45°C for two months on either side of summer Solstice suggest that such temperatures do not present a serious limitation to the vegetative growth of pigeopea if soil moisture is adequate.
Radiation:
In general, pigeonpea crop is more likely to be limited by water than irradiance, although two important exceptions are extended cloud cover during monsoon and intercrop shaded by the component crop. Pigeonpea is most sensitive to low irradiance during pod formation. Pod set will be poor if the cloud cover persist for long but will recover once it dissipates.
Low initial CGR of pigeonpea is primarily the result of lower assimilatory surface of the seedlings. The critical LAI (that is required for 95 per cent interception of radiation) is also high (5-7). The low early CGR has several implications for sole crop. The period of growth prior to full canopy cover is relatively long. In environments characterised by terminal drought, faster growing pulses may be able to out yield pigeonpea due to their shorter duration.
Weed competition can cause substantial reduction in yield if weeds are not controlled in early stages. By contract, the low early CGR of pigeonpea and its apparent tolerance of low irradiance enhances its suitability as an intercrop because it has little effect on development of the component crop but can respond immediately the component crop is harvested.
Soil:
Major soils on which pigeonpea is grown in India are alluvial, red and black with soil reaction from pH 6.5 to 8.5. Pigeonpea, in general, is unresponsive to fertilisers and hence soil fertility may not be a limiting factor for dryland crop. Major problem on alkaline soils is likely to be specific nutrient deficiencies. Pigeonpea is relatively sensitive to salinity.
Among the pulse crops, pigeon is rated as more sensitive than cowpea and blackgram and less sensitive than greengram. Waterlogging of heavy soils can cause extensive plant mortality in seedling stage.