Wheat In South Asia Research Articles

Progress and Prospects of Developing Climate Resilient Wheat in South Asia Using Modern Pre-Breeding Methods.

Developing climate-resilient wheat is a priority for South Asia since the effect of climate change will be pronounced on the major crops that are staple to the region. South Asia must produce >400 million metric tons (MMT) of wheat by 2050 to meet the demand. However, the current average yield <3 t/ha is not sufficient to meet the requirement. In this review, we are addressing how pre-breeding methods in wheat can address the gap in grain yield as well as reduce the bottleneck of genetic diversity. Physiological pre-breeding which incorporates screening of diverse germplasm from gene banks for physiological and agronomic traits, the strategic crossing of complementary traits, high throughput phenotyping, molecular markers-based generation advancement, genomic prediction, and validation of high-value heat and drought tolerant lines to South Asia can help to alleviate the drastic effect of climate change on wheat production. There are several gene banks, if utilized well, can play a major role in breeding for climate-resilient wheat. CIMMYT’s wheat physiological pre-breeding has delivered several hundred lines via the Stress Adapted Trait Yield Nursery (SATYN) to the NARS in many South Asian countries; India, Pakistan, Nepal, Bangladesh, Afghanistan, and Iran. Some of these improved germplasms have resulted in varieties for farmer's field. We conclude the review by pointing out the importance of collaborative interdisciplinary translational research to alleviate the effects of climate change on wheat production in South Asia.

Association of leaf chlorophyll content with the stay-green trait and grain yield in wheat grown under heat stress conditions

Heat stress is a major production constraint of wheat in South Asia, particularly in the Gangetic plains of India and Bangladesh. The leaf chlorophyll status is a key determinant for a high rate of photosynthesis under stress. The present experiments included 238 genotypes in 2016–2017 and 321 genotypes in 2017–2018 under optimum and under heat stress conditions. Subsequently, a set of 100 genotypes selected on basis of the heat susceptibility index was evaluated in 2018–2019 under heat stress conditions to study the relationship between important physiological traits and yield under stress. A significant correlation of soil plant analysis development (SPAD) value of the two upper leaves with stay-green trait and grain yield indicates the importance of chlorophyll content, both in flag and penultimate leaf, in maintaining leaf areas under greenness (LAUG) and grain yield under heat stress. The SPAD in the flag and penultimate leaf was responsible for 8.8% and 10.9%, respectively, of the variation in grain yield. For the stay-green trait, 8.4% and 7.2 % of the variation was governed by the SPAD value in the flag and penultimate leaf, respectively. These results suggest that, in addition to the flag leaf, the chlorophyll status of the penultimate leaf can be an important criterion for the selection of superior wheat genotypes under heat stress. The genotypes SW-139; SW 108; DWR-F8-35-9-1; NHP-F8-130; DWR-F8-3-1 that maintained a high chlorophyll content in the flag and penultimate leaf can be used further in breeding programmes addressing heat resistance in wheat.

Crosses with spelt improve tolerance of South Asian spring wheat to spot blotch, terminal heat stress, and their combination

Spot blotch and terminal heat are two of the most important stresses for wheat in South Asia. A study was initiated to explore the use of spelt (Triticum spelta) to improve tolerance to these stresses in spring wheat (T. aestivum). We assessed 185 recombinant inbred lines (RILs) from the cross T. spelta (H + 26) × T. aestivum (cv. HUW234), under the individual stresses and their combination. H + 26 showed better tolerance to the single stresses and also their combination; grain yield in RILs was reduced by 21.9%, 27.7% and 39.0% under spot blotch, terminal heat and their combined effect, respectively. However, phenological and plant architectural traits were not affected by spot blotch itself. Multivariate analysis demonstrated a strong negative correlation between spikelet sterility and grain yield under spot blotch, terminal heat and their combination. However, four recombinant lines demonstrated high performance under both stresses and also under their combined stress. The four lines were significantly superior in grain yield and showed significantly lower AUDPC than the better parent. This study demonstrates the potential of spelt wheat in enhancing tolerance to spot blotch and terminal heat stresses. It also provides comprehensive evidence about the expression of yield and phenological traits under these stresses.

Quantitative Trait Loci Mapping for Spot Blotch Resistance in Two Biparental Mapping Populations of Bread Wheat.

Spot blotch (SB), caused by Bipolaris sorokiniana, is a major fungal disease of wheat in South Asia and South America. Two biparental mapping populations with 232 F2:7 progenies each were generated, with CIMMYT breeding lines CASCABEL and KATH as resistant parents and CIANO T79 as the common susceptible parent. The two populations were evaluated for field SB resistance in CIMMYT's Agua Fria station for three consecutive cropping seasons, with artificial inoculation. Genotyping was done with the DArTseq platform and approximately 1,500 high quality and nonredundant markers were used for quantitative trait loci (QTL) mapping. In both populations, a major QTL was found on chromosome 5A in the Vrn-A1 region, explaining phenotypic variations of 13.5 to 25.9%, which turned up to be less- or nonsignificant when days to heading and plant height were used as covariates in the analysis, implying a disease escape mechanism. Another major QTL was located on chromosome 5B in CASCABEL, accounting for 8.9 to 21.4% of phenotypic variation. Minor QTL were found on 4A and 4B in CASCABEL; 1B, 4B, and 4D in KATH; and 1B, 2B, and 4B in CIANO T79. Through an analysis of QTL projection onto the IWGSC Chinese Spring reference genome, the 5B QTL in CASCABEL was mapped in the Sb2 region, delimited by the single nucleotide polymorphism marker wsnp_Ku_c50354_55979952 and the simple sequence repeat marker gwm213, with a physical distance of about 14 Mb to the Tsn1 locus.

A review on South Asian wheat blast: The present status and future perspective

AbstractThe outbreak of wheat blast (Pyricularia oryzae, syn. Magnaporthe oryzae) in Bangladesh and India in recent times is a cause of grave concern for future wheat production in South Asian countries. In this review, we focus on the origin and pathology of P. oryzae and its current status and impact on trade of wheat in South Asia. We also consider future directions for efficient detection, monitoring, forecasting, and managing this destructive disease. Proper detection and monitoring are essential for imposing disease management strategies. Cutting‐edge tools such as geospatial modelling and remote sensing technologies based on field observation will be pivotal to efficiently contain and manage the disease. Strong quarantine regulations too are critical in preventing the pathogen movement and are also discussed within. Complementary approaches, such as the induction of systemic resistance by applying plant growth‐promoting rhizobacteria or probiotic bacteria, are also considered here. This review provides a comprehensive summary on the status of wheat blast in South‐East Asia and will provide an important resource for wheat blast research in the affected areas.

Management of Spot Blotch and Heat Stress in Spring Wheat Through Azoxystrobin-Mediated Redox Balance

Application of foliar fungicides for the management of spot blotch of wheat in South Asia is needed when the weather is extremely conducive to disease progression. Field experiments were conducted during two consecutive years 2014–2015 and 2015–2016 to evaluate the effect of fungicides in late-sown wheat which suffers from the combined stress of terminal heat and spot blotch. Azoxystrobin (125 g a.i./ha) when applied twice (ZGS 50 and ZGS 60) and thrice (ZGS 40, 50 and 60) was comparable and gave the best control. In two sprays, the area under disease progress curve (AUDPC) was reduced to 161 compared to 763 under unprotected. Application of fungicide maintained the leaf area under greenness, chlorophyll content and normalized difference vegetative index (NDVI) up to physiological maturity. The canopy temperature (CT) was also reduced in fungicide-treated plots. The positive effect of fungicide on increased days to maturity (11.5 days) contributed significantly to thousand kernel weight (TKW) and grain yield. The fungicide appeared to balance the level of reactive oxygen species like hydroxyl radicals (OH−) and superoxide radicals (O2−), reducing membrane damage and increasing antioxidants like superoxide dismutase (SOD), catalase (CAT). The application of azoxystrobin appeared to manage the terminal heat stress through redox balance and reduced the spot blotch resulted in enhanced grain yield.

Resistance to Spot Blotch in Two Mapping Populations of Common Wheat Is Controlled by Multiple QTL of Minor Effects.

Spot blotch (SB) is an important fungal disease of wheat in South Asia and South America. Host resistance is regarded as an economical and environmentally friendly approach of controlling SB, and the inheritance of resistance is mostly quantitative. In order to gain a better understanding on the SB resistance mechanism in CIMMYT germplasm, two bi-parental mapping populations were generated, both comprising 232 F2:7 progenies. Elite CIMMYT breeding lines, BARTAI and WUYA, were used as resistant parents, whereas CIANO T79 was used as susceptible parent in both populations. The two populations were evaluated for field SB resistance at CIMMYT’s Agua Fria station for three consecutive years, from the 2012–2013 to 2014–2015 cropping seasons. Phenological traits like plant height (PH) and days to heading (DH) were also determined. Genotyping was performed using the DArTSeq genotyping-by-sequencing (GBS) platform, and a few D-genome specific SNPs and those for phenological traits were integrated for analysis. The most prominent quantitative trait locus (QTL) in both populations was found on chromosome 5AL at the Vrn-A1 locus, explaining phenotypic variations of 7–27%. Minor QTL were found on chromosomes 1B, 3A, 3B, 4B, 4D, 5B and 6D in BARTAI and on chromosomes 1B, 2A, 2D and 4B in WUYA, whereas minor QTL contributed by CIANO T79 were identified on chromosome 1B, 1D, 3A, 4B and 7A. In summary, resistance to SB in the two mapping populations was controlled by multiple minor QTL, with strong influence from Vrn-A1.

Application of a bias-corrected meta-frontier approach and an endogenous switching regression to analyze the technical efficiency of conservation tillage for wheat in South Asia

Conservation tillage (CT) options are among the most rapidly spreading land preparation and crop establishment techniques globally. In South Asia, CT has spread dramatically over the last decade, a result of strong policy support and increasing availability of appropriate machinery. Although many studies have analyzed the yield and profitability of CT systems, the technical efficiency impacts accrued by farmers utilizing CT have received considerably less attention. Employing a DEA framework, we isolated bias-corrected meta-frontier technical efficiencies and meta-technology ratios of three CT options adopted by wheat farmers in Bangladesh, including bed planting (BP), power tiller operated seeding (PTOS), and strip tillage (ST), compared to a control group of farmers practicing traditional tillage (TT). Endogenous switching regression was subsequently employed to overcome potential self-selection bias in the choice of CT, in order to robustly estimate efficiency factors. Among the tillage options studied, PTOS was the most technically efficient, with an average meta-technology ratio of 0.90, followed by BP (0.88), ST (0.83), and TT (0.67). The average predicted meta-frontier technical efficiency for the CT non-adopters under a counterfactual scenario (0.80) was significantly greater (P = 0.00) than current TE scores (0.65), indicating the potential for sizeable profitability increases with CT adoption. Conversely, the counterfactual TE of non-adopters was 23% greater than their DEA efficiency, also indicating efficiency gains from CT adoption. Our results provide backing for agricultural development programs in South Asia that aim to increase smallholder farmers’ income through the application of CT as a pathway towards poverty reduction.

Potential and challenges of conservation agriculture in sequestration of atmospheric CO 2 for enhancing climate-resilience and improving productivity of soil of small landholder farms.

Abstract The projected climate change, caused by emissions from fossil fuel combustion and land use change, may adversely impact the agronomic yields and aggravate food insecurity of small landholder farms. About 500 million small landholder farms have depleted and degraded soils, while having low soil organic carbon (SOC) pools, low plant nutrient reserves, low plant-available water capacity and low agronomic yield, yet high vulnerability to changing and uncertain climate. Projected climate change may reduce rice yield by 10% for every 1°C increase in temperature, and total maize production may decline by 10% by 2050. Agronomic yield of wheat in South Asia may be adversely affected by increase in temperature during spring. Yield of other cereals (sorghum, millet) and root crops (cassava, yam) may be adversely affected by aggravation of other biotic stresses (smut, fungi, viruses, etc.). Thus, climate-resilience may be a key component of sustainable intensification of small landholder agriculture. It is in this context that conservation agriculture (CA) can be an important option. With fine-tuning for adaptation to site-specific conditions, CA has numerous benefits including erosion control, water conservation, SOC sequestration and increase in profitability and farm income. Further, CA can be implemented in synergism with other practices such as forestry and forest plantations (during early stages of tree establishment), and integrated crop-livestock (ley farming). In several farm operations, CA builds upon the traditional systems and indigenous technology. Widespread adoption of CA could sequester 1 Pg C/year globally, which could create another income stream for small landholders. Further, CA fits in with the '4 per Thousand' programme proposed at the COP-21 in Paris.

Increasing global agricultural production by reducing ozone damages via methane emission controls and ozone‐resistant cultivar selection

Meeting the projected 50% increase in global grain demand by 2030 without further environmental degradation poses a major challenge for agricultural production. Because surface ozone (O3) has a significant negative impact on crop yields, one way to increase future production is to reduce O3-induced agricultural losses. We present two strategies whereby O3 damage to crops may be reduced. We first examine the potential benefits of an O3 mitigation strategy motivated by climate change goals: gradual emission reductions of methane (CH4), an important greenhouse gas and tropospheric O3 precursor that has not yet been targeted for O3 pollution abatement. Our second strategy focuses on adapting crops to O3 exposure by selecting cultivars with demonstrated O3 resistance. We find that the CH4 reductions considered would increase global production of soybean, maize, and wheat by 23–102 Mt in 2030 – the equivalent of a ∼2–8% increase in year 2000 production worth $3.5–15 billion worldwide (USD2000), increasing the cost effectiveness of this CH4 mitigation policy. Choosing crop varieties with O3 resistance (relative to median-sensitivity cultivars) could improve global agricultural production in 2030 by over 140 Mt, the equivalent of a 12% increase in 2000 production worth ∼$22 billion. Benefits are dominated by improvements for wheat in South Asia, where O3-induced crop losses would otherwise be severe. Combining the two strategies generates benefits that are less than fully additive, given the nature of O3 effects on crops. Our results demonstrate the significant potential to sustainably improve global agricultural production by decreasing O3-induced reductions in crop yields.

RELAY PLANTING OF WHEAT IN COTTON: AN INNOVATIVE TECHNOLOGY FOR ENHANCING PRODUCTIVITY AND PROFITABILITY OF WHEAT IN COTTON–WHEAT PRODUCTION SYSTEM OF SOUTH ASIA

SUMMARYCotton–wheat (CW) is the second most important cropping system after rice–wheat in South Asia. Sowing of wheat after cotton is usually delayed due to late pickings coupled with time needed for seedbed preparation, resulting in low wheat yield. Lack of suitable machinery is a major constraint to direct drilling of wheat into the heavy cotton stubbles. An innovative approach with much promise is the ‘2-wheel tractor-based self-propelled relay seeder’ with seed-cum-fertilizer attachment. On-farm trials were conducted at four locations during 2009–2010 and at 10 locations during 2010–2011 to evaluate the following four wheat establishment methods in CW-dominated areas of south-western Punjab, India: (1) zero till seeding in standing cotton using a self-propelled relay seeder, (2) relay seeding in standing cotton with a manual drill without prior tillage (2010 only), (3) relay broadcast seeding in standing cotton following light manual tillage and (4) conventional sowing of wheat after cotton harvest (conventional tillage and sowing with a seed–fertilizer drill). Planting of wheat under conventional practice was delayed by 20–44 days compared with relay seeding. Seed cotton yield was also significantly higher with relay seeding due to opportunity for one additional picking. Yield of wheat sown with the self-propelled relay seeder was 41.2% and 11.8% higher than with conventional practice in 2009–2010 and 2010–2011 respectively. The increase in wheat yield under relay seeding of wheat was primarily due to higher spike density and more grains per spike. The net income from the CW system was 28.2% higher for the self-propelled relay seeder than with conventional sowing.

Exploring the possibility of obtaining terminal heat tolerance in a doubled haploid population of spring wheat (Triticum aestivum L.) in the eastern Gangetic plains of India

High temperature during grain filling stage causes significant yield losses to wheat in south Asia and many other parts of the world. One hundred and forty doubled haploid (DH) wheat lines (including parents), derived from the cross Berkut (heat susceptible)×Krichauff (heat tolerant), were grown in six environments comprising two dates of sowing in three consecutive years (2007–2008, 2008–2009, and 2009–2010) at Banaras Hindu University, Varanasi, India. The objective was to assess DH lines for heat tolerance and to identify superior lines under hot humid environments of the eastern Gangetic plains (EGP) of India. Considerable variation was observed for grain yield (GY), thousand grain weight (TGW), grain fill duration (GFD), and canopy temperature (CT). Likewise, considerable variation was also observed for heat susceptibility index (HSI) of GY, TGW, and GFD. The DH lines were grouped into four categories based on the HSI and around 5–10% lines were categorized as heat tolerant. A few lines yielded significantly more than the better parent and possessed good expression of other traits. The most promising 20 lines have been listed as sources of heat tolerance, with 3 lines better yielding than the superior parent Krichauff. The results demonstrated that it is possible to obtain lines that perform better for yield and yield related traits in heat stressed environments of the EGP of India.

TRIANGULATING TECHNOLOGY DIFFUSION INDICATORS: ZERO TILLAGE WHEAT IN SOUTH ASIA'S IRRIGATED PLAINS

SUMMARYImpact assessment hinges on reliable indicators of technology uptake, but this poses particular challenges for new agronomic practices in emerging economies. This paper presents a triangulation approach to assess technology diffusion and illustrates it by assessing the extent and dynamics of zero tillage wheat in South Asia's rice-wheat systems. Various diffusion indicators from three different data methods (secondary data, supply-side surveys, demand-side surveys) are contrasted for two different locations (India's Haryana State and Pakistan's Punjab province) for the period 2000–2004. Such multi-indicator, multi-site and multi-year triangulation enhances the robustness of the inferences and provides the necessary perspective. The three sources coincide in terms of diffusion of zero tillage wheat having increased since 2000, but in particular the empirical surveys show a much slower uptake and subsequent stagnation in the Pakistan Punjab study area. The paper thereby reiterates the need for empirical ground truthing of technology uptake and the need for robust and complementary diffusion indicators.

Need based nitrogen management using the chlorophyll meter and leaf colour chart in rice and wheat in South Asia: a review

Fertilizer nitrogen (N) is one of the major inputs in rice–wheat production systems in South Asia. As fertilizer N has generally been managed following blanket recommendations consisting of two or three split applications of preset rates of the total amount of N, improvement in N use efficiency could not be achieved beyond a limit. Feeding crop N needs is the most appropriate fertilizer N management strategy to further improve N use efficiency. Since plant growth reflects the total N supply from all sources, plant N status at any given time should be a better indicator of the N availability. The chlorophyll meter and leaf colour chart have emerged as diagnostic tools which can indirectly estimate crop N status of the growing crops and help define time and quantity of in-season fertilizer N top dressings in rice and wheat. Supplemental fertilizer N applications are thus synchronized with the N needs of crop. The chlorophyll meter may not be owned by South Asian farmers individually, but it can be made available to farmers through village cooperatives, extension specialists, and crop consultants. Leaf colour chart, a simple and cost-effective device has already penetrated into South Asian farming and increasing numbers of farmers are finding it helpful in efficiently managing N fertilizers. This paper reviews the results of investigations carried out using these diagnostic tools in managing need based N applications in rice and wheat in South Asia.

The Role of the Himalayan Mountain Systems in Food Security and Agricultural Sustainability in South Asia

Although South Asian countries made impressive progress in food production during 1960s, 1970s and 1980s, the dynamism in the agricultural sector has, however, lost recently. Productivity of major food grains has slowed down and even declined, for some crops and food production is failing to keep pace with population growth. Therefore, food security has remained a major concern in South Asian countries. The linkage between food production and the Himalayan mountains is poorly understood though the Himalayan mountains are the major source of dry season water in Pakistan, Nepal, Bangladesh and Bhutan for irrigated rice and wheat, which are the staple food in South Asia. In view of that this article briefly examines the role of the Himalayan mountain systems in food production and agricultural sustainability in South Asian countries looking at the emerging challenges posed by the increasing water stress and climate change. The analysis suggests that a common challenge is being faced by all South Asian countries—for increased food production to meet the demand of burgeoning population, the growing stress of water as rice and wheat , the staple food in South Asia, require huge amounts of water. Moreover, the increased food production in South Asia has to come from the same amount of land, by increasing productivity through bringing additional land under irrigation, as the frontier for expansion of agricultural land has almost been exhausted. The availability of irrigation water is, therefore, critical for increased food production and agricultural sustainability in entire South Asia. Climate change introduces a new challenge to agriculture and food security in South Asia. Recent studies suggest that the impact of climate change on cereal production in South Asia could be negative and that may be as high as 18.2–22.1 per cent. Our analysis reveals that the Hindu Kush-Himalayan mountain systems play a significant role in agriculture and food security in South Asia through water supply, climate and wind regulation, groundwater recharge and in sustaining wetland ecosystems. It is the major source of dry season water for several large river systems, such as the Indus, the Ganges and the Brahmaputra from the snow and glacier melt of the Himalayas, which provide the main basis for surface and groundwater irrigation. These three rivers form the largest river basins (Indo–Ganga–Brahmaputra) which are the major source of rice and wheat in South Asia. Besides surface water, the contribution of mountain discharge to groundwater is also significant, which makes it an important resource for agriculture and food security in South Asia. In addition to providing surface and groundwater, the Himalayan mountain system provides huge inputs to agriculture through regulating micro-climates as well as wind and monsoon circulation, and by supporting river and wetland ecosystems in South Asia. It is estimated that the Ganges river ecosystem alone supports 25,000 or more species, ranging from micro-organisms to mammals, which support agricultural sustainability and provide livelihoods for millions of people. This article concludes that the long-term agricultural sustainability and food security of South Asia is heavily dependent on the water and other ecosystem services it receives from the Himalayan ecosystems. Attention therefore must be paid to conserve the Himalayan ecosystems in order to ensure sustained flow of ecosystem services required for agriculture, food production and overall well-being of Himalayan and downstream population. Options and opportunities for enhancing the agricultural sustainability and food security by sustainable utilization of Himalayan resources and ecosystem services are briefly analyzed and suggestions have been made.

Specification effects in zero tillage survey data in South Asia's rice–wheat systems

Specification effects in terms of how technology options are contrasted can introduce bias in impact assessment. In a companion paper we evaluated the on-farm impacts of zero tillage (ZT) wheat as a resource-conserving technology in the rice–wheat systems of India's Haryana State and Pakistan's Punjab province [Erenstein, O., Farooq, U., Malik, R.K., Sharif, M., 2008. On-farm impacts of zero tillage wheat in South Asia's rice–wheat systems. Field Crop Res. 105, 240–252]. The underlying field work surveyed plots of full adopters (only ZT plots), partial adopters (ZT and conventional tillage [CT] plots on same farm) and non-adopters (only CT plots). The companion paper assumes that the comparison between the ZT plots of full plus partial adopters and CT plots of partial adopters is the least-biased assessment of ZT's on-farm impact. Here we revisit this underlying assumption and draw on complementary farm survey findings to illustrate the extent of specification effects in the assessment of on-farm impacts of ZT wheat in the same study areas. The study thereby distinguishes between three contrasts between ZT and CT within the same dataset: (1) plain contrast (all plots of adopters and non-adopters); (2) adopter-only contrast (full and partial adopters only, as used in Erenstein et al. [Erenstein, O., Farooq, U., Malik, R.K., Sharif, M., 2008. On-farm impacts of zero tillage wheat in South Asia's rice–wheat systems. Field Crop Res. 105, 240–252]); (3) pair-wise contrast (partial adopters only). Proceeding from type 1 to type 3 comparisons the number of observations decrease but this is compensated by an increasing ability to control for variation. The ability of type 3 comparisons to pick up relatively small but significant differences is an important consideration in farm survey impact assessment. However, there is also an increase in partial adoption bias and further follow-up studies are needed to understand the implications of this. The comparisons show that the ZT effects on savings for diesel, tractor time and cost for wheat cultivation are particularly robust. In Haryana ZT's positive implications for yield and the other financial indicators were also statistically robust, but in Punjab these were sensitive to specification effects. Particularly sensitive to specification effects were the ZT effects on the productivity of applied water in both sites.

On-farm impacts of zero tillage wheat in South Asia's rice–wheat systems

The recent slow down in productivity growth in the irrigated areas of the Indo-Gangetic Plains of South Asia has led to a quest for resource-conserving technologies that can reduce production costs, save water and improve production. Findings from farm surveys are used to evaluate the on-farm impacts of zero tillage (ZT) wheat in the rice–wheat systems of India's Haryana state and Pakistan's Punjab province. ZT-induced effects primarily apply to the establishment and production costs of the wheat crop. Both study sites confirmed significant ZT-induced resource-saving effects in farmers’ fields in terms of diesel, tractor time and cost savings for wheat cultivation. Water savings are, however, less pronounced than expected from on-farm trial data. It was only in Haryana, India that there were significant ZT-induced water savings in addition to significant yield enhancement. The higher yield and water savings in Haryana, India result in significantly higher water productivity indicators for ZT wheat. In both sites, there are limited implications for the overall wheat crop management, the subsequent rice crop and the rice–wheat system as a whole. The combination of a significant “yield effect” and “cost-saving effect” makes adoption worthwhile and provide a much needed boost to the returns to wheat cultivation in Haryana, India. In Punjab, Pakistan, ZT is primarily a cost-saving technology for wheat cultivation. The prime driver for ZT adoption is not water savings or natural resource conservation but monetary gain in both sites. Water savings are only a potential added benefit.

Development of somaclonal variants of wheat ( Triticum aestivum L.) for yield traits and disease resistance suitable for heat stressed and zero-till conditions

In a substantial rice–wheat cropping system area of South Asia, wheat sowing often gets too delayed and exposed to terminal heat stress. Therefore, farmers prefer varieties that are able to perform well under a short growing period. Tissue culturally regenerated plants of wheat variety cv. HUW 234, the most widely cultivated variety of North Eastern Plain Zone (NEPZ) of India were screened using immature embryo as explant. Days to heading and maturity, yield and other yield components and resistance to leaf rust and spot blotch were evaluated. A few somaclones in R 3 and R 4 generations displayed significant earliness for days to heading and maturity, improved yield traits and resistance to leaf rust and spot blotch diseases. The superior performance of two of the variants was confirmed in the R 5 generation in 3 years of testing under two dates of conventional and zero-till sowing. Stability analysis also suggested superiority of the two somaclones across 12 environments. This appeared to confirm the possibility of obtaining useful somaclonal variants of wheat for very late sown as well as zero-till managed agriculture. The superior performing somaclones can be used as parents in the ongoing breeding programmes targeting late sown wheat in South Asia exposed to terminal heat stress.

Agricultural Productivity and Sources of Growth in South Asia

Estimates of partial factor productivity growth for rice and wheat in India, Bangladesh, and Pakistan show relatively rapid growth in yields per hectare since adoption of modern rice and wheat varieties began in the mid to late 1960s (Byerlee, Rosegrant). While partial factor productivity growth for rice and wheat in South Asia has been extensively analyzed, there is relatively little understanding of total factor productivity growth and the sources of productivity growth in the crops sector, or of the relative contribution to output growth from productivity growth compared to increased factor use. This paper assesses total factor productivity (TFP) growth in India, examines the sources of productivity growth, and estimates the rates of return to public investments in research and extension. A comparison is made with results for Bangladesh (Dey and Evenson) and Pakistan (Azam, Bloom, and Evenson). The paper describes the methodology for estimation of TFP, decomposition of TFP, and estimation of rates of return to public investments; describes the data; and presents results and policy implications.

Food for the Future: A Perspective

The early and middle years of decade of 1960s were a period of significant concern about prospective adequacy of world food supplies. Production shortfalls in grain-the major source of calories for world-occurred in China, Soviet Union, and South Asia. By 1965 therewas serious concern about possibility of mass starvation in South Asia, and there may have been severe food stringencies, including famine, in China in early years of decade. In United States, President's Science Advisory Committee undertook a major study and issued a major two-volume report, The World Food Problems, in 1967.1 Numerous Congressional hearings were held. By time The World Food Problems was published, however, world food situation had eased substantially, grain exports were declining, and world grain stocks were increasing. The rapid spread of new highyielding varieties of rice and wheat in South Asia led at least one prominent government official to announce in late 1968 that the world has recently entered a new agricultural era attributed to the sweeping advances in food production in several major developing countries.2 The rapid change in availability of world grain supplies and sharp increase in grain reserves in years following 1967 led industrial countries and most developing countries to turn their attention to other and seemingly more pressing problems. As a result, in period from 1967 through 1972 little was done, at least as a matter of conscious policy, that would contribute to a sustainable increase in per capita food supplies in developing countries. Will world's policy makers behave