Outbreaks of different forms of rust, the most destructive wheat disease, have frequently lowered wheat production. Wheat scientists have no doubt successfully overcome this peril every time it emerged, especially after the green revolution, by breeding disease-resistant varieties. But the combat seems endless.
This menace has surfaced again in the form of yellow rust that took a considerable toll on the crop in the key north-western wheat bowl last year and is threatening to do so this year as well. The disease has already been spotted on the standing wheat crop in parts of Punjab and Haryana, jeopardising wheat output. The main worry is that one of the most dominant wheat varieties, PBW 343, grown on about 10 million hectares, has succumbed to this rust.
The silver lining, however, is that New Delhi-based Indian Agricultural Research Institute (IARI, or Pusa institute) seems prepared to tackle the disease. The institute has contributed enormously in fighting wheat rust in the past too. A new wheat variety, HD 2967 – bred and released for cultivation last year by this 107-year old citadel of agricultural research – has been found resistant to yellow rust and is deemed an advantageous replacement to the PBW 343 variety in the main wheat-growing belt. This highly productive strain, yielding about 5.5 tonnes of wheat a hectare against 4.8 tonnes of PB 343, carries several genes that provide wide-spectrum immunity against yellow rust. Moreover, its grains are excellent for making “chapattis”, the main end-use for wheat in India, and are comparatively more nutritious with high iron and zinc content.
Many farmers in Punjab and Haryana, who had access to limited quantities of seeds of the new HD-2967 variety last year, affirm that their crop remained free of yellow rust while other varieties planted by their fellow farmers suffered heavy losses. This strain has also proved immune to Ug99 rust — a new form of stem rust first discovered in Uganda in 1999 (hence the name Ug99) that is rapidly spreading in Africa and Asia to become the potential enemy number-one of wheat worldwide.
IARI is in the process of producing some 20,000 quintals of HD 2967 seeds in the current rabi season. Besides, large-scale multiplication of the seeds is also being undertaken through the agriculture ministry and private seed producers. The aim is to have enough seeds to cover vast areas with this high-yielding and rust-resistant variety in the next wheat season. IARI Director H S Gupta maintains that this variety is capable of ushering in another wheat revolution.
IARI has also bred a few other wheat varieties that apart from being immune to rust, have an innate capacity to cope with climate change. Among these, the HD 3043 variety is meant specifically for farmers in intensive wheat-growing states like Punjab, Haryana, Rajasthan and western Uttar Pradesh who have limited means of irrigation. Another variety, HD 2985 (also named Pusa Basant), is suited for the eastern plains comprising east Uttar Pradesh, Bihar, West Bengal and adjoining areas.
Another new strain, HD 2987 (christened Pusa Bahar), has been bred for cultivation in rainfed areas of the southern peninsula. These varieties are expected to fit well in IARI’s well-judged, long-term strategy for managing wheat rusts through “gene deployment” in different parts of the country. This approach essentially involves introducing improved wheat varieties with area-specific, rust-tolerant genes in different agro-climatic zones that will serve as genetic barriers to rust infection and prevent it from spreading from one part to another. This strategy, notably, had proved its worth during some of the worst rust outbreaks in the 1980s when most wheat varieties responsible for the green revolution had succumbed to this malady.
In fact, since 1980, IARI has released over 70 wheat varieties for cultivation in different parts of the country. As a result, nearly 40 per cent of the country’s present wheat output comes from IARI varieties. These strains, moreover, are reckoned to have helped wheat productivity increase annually by an average of one quintal a hectare. However, since new and unforeseeable challenges cannot be ruled out in future, it can be hoped that IARI will, true to its tradition, come up with technologies to meet them as well.