Effect of Global Warming on pulses in Northern India

India is the largest producer of pulses in the world with the 25 % share in the global production. Chickpea, Pigeonpea, Mungbean, Urdbean, Lentil, Fieldpea are important pulse crops contributing 39 %, 21%, 11%, 10%, 7%, & 5% to the total production of pulses in the country.

Suring 2007-08, the total production was 14056 million tones from an area of 23.63 million hectares with average productivity of 625 kg per hectare. Climate change will surely have an adverse effect on productivity on account of reduction in total crop cycle duration. Most of the pulses like mungbean and urdbean are short duration crops (65-75 days).

Further reduction in crop duration will amount to a lower field per unit area. Reduction in yield as result of climate change are predicted to be more pronounced for  those pulse crops which are generally grown under rainfed conditions and there is hardly any option for providing life saving irrigation.

 

Pulses in Northern rainfed area at high risk

Rainfed pulses under in Northern plains are becoming a high risk crops mainly due to wide fluctuations in temperature and rainfall characteristics (uncertain, erratic and inadequate rainfall). The cultivation of pulses in these regions has now turned to be a big gamble for traditional farmers growing pulses.

The climate modeling systems envisage that as the 21^st century progresses, there will be higher levels of warming in Northern parts of India with rapid increase in night temperatures which will in turn adversely affect the crop productivity.

The winter legumes under rainfed conditions in northern plains are experiencing a kind of hidden stress that is atmospheric drought, associated with insufficient or lack of due precipitation, as a result of high night temperature. The moisture available in the air termed as in "visible water reservoir of nature" which can be easily accessed by the crops provided nights are cool to form dew.

 

Low precipitation

With changing climate, the phenomenon of dew precipitation is gradually diminishing in the northern rainfed regions, consequently the crops are subjected to more dry weather and high evapotranspiration.

Therefore, the area under pulses is progressively shifting towards central and south India where temperature fluctuation is not sop pronounced and rainfall is not so unpredictable. Further, the black soils of central and peninsular regions once recharged do support a good crop.

Impact of temperature rise on pulse productivity

India is most vulnerable to climate change. Under the vagary of extreme temperature and a heat wave, The surface air temperature is rising alarmingly at a rate of 0.4 degrees Celsius per century. The most worrying part of prediction is the estimated increase in the winter and summer temperatures by 3.2 degrees and 2.2 degrees Celsius, respectively by 2050.

Among pulses, pigeonpea is very sensitive to abrupt fluctuations of temperatures either lower or higher extremes leding top massive flower drop.

 

Poor yield in the existing varieties

During the past few years, an abrupt rise in temperature has been observed in the months of January and February in north India, Which led to poor yield in the ruling variety HUDP 15.In an experiment at Kanpur, it was observed that high temperature coincided with the onset of reproductive phase of HUDP 15 adversely affected not only total biomass, but also pod setting by 30 per cent, seeds per pod 41 per cent and seed weight by 36 per cent and yield by 48 per cent.

 

Impact of CO2 rise on the pulse productivity

 In fact, increase in atmospheric CO2 concentration can have a positive impact on pulse yields by stimulating plant photosynthesis, enhancing fertilization and reducing the water loss via plant respiration.

This carbon fertilization effect is strong for all pulses falling in the category of C3 crops. It is projected that yields in pulses having C3 mechanism of photosynthesis may increase by 10-25 per cent when atmospheric CO2 reach upto the level of 550 ppm (IPCC2007), but the higher atmospheric temperature due to green house effect the physiological processes and productivity.

 

Emergence of new insect-pest

There is clear evidence that climate change is altering the distribution, incidence and intensity of pests and diseases. Increase in temperature, variability in rainfall intensity and distribution, change in seasonality, drought, and CO2 concentration in the atmosphere and extreme events all affects the pest dynamics in a cropping system. Generally, insects are poikilotherms and hence, processes like growth and development are all dependent more on temperature.

Any shift in environmental temperature is likely to influence the insect behaviour more than plants and larger animals. In the past, gram pod borer (Helicoverpa armigera) has been a major pest of pegeonpea in most parts of country.      

Impact may be less severe

The impact of climate change in pulses productivity may be less severe than that of cereals. Pulses are generally C3 crops and increased CO2 concentration will have a positive effect on productivity, however , the beneficial effects of CO2enrichment is largely nullified by abrupt increase in temperature which is often detrimental to crop growth and grain yield. The effect of global warming shall have profound change in rainfall pattern (delayed monsoon, inadequate precipitation, uneven distribution, early cessation etc.) which adversely affect rainfed crops like pulses.

Therefore, breeding strategies should be directed towards developing heat and drought tolerant high yielding cultivars, so as to have suitable varieties in hand when climate change effects are experienced widely. The genetic recourses, especially land races sustaining environmental extremities could serve as the starting genotypes for building the genes for tolerance, and other yield attributes.

 

Reference- The Hindu Survey of Indian Agriculture 2009.