Sudhanshu Singh

Physiological basis of tolerance to complete submergence in rice involves genetic factors in addition to the SUB1 gene

Complete submergence reduces survival and yield of modern high-yielding rice cultivars. Tolerant cultivars carrying the SUB1 locus were recently developed. We evaluated survival and growth processes occurring during submergence and recovery that are associated with SUB1 in contrasting genotypes. Sub1 cultivars showed less reduction in shoot biomass and better regulation of non-structural carbohydrates during submergence. They produced new leaves and tillers faster during recovery. FR13A, the source of SUB1 locus showed slower leaf elongation and recovered faster than Sub1 lines, suggesting the possibility of further improvements in submergence tolerance by incorporating additional traits from FR13A or similar landraces.

Productivity of sodic soils can be enhanced through the use of salt tolerant rice varieties and proper agronomic practices

Regaining the agricultural potential of sodic soils in the Indo-Gangetic plains necessitates the development of suitable salt tolerant rice varieties to provide an entry for other affordable agronomic and soil manipulation measures. Thus selection of high yielding rice varieties across a range of sodic soils is central. Evaluation of breeding lines through on-station and on-farm farmers’ participatory varietal selection (FPVS) resulted in the identification of a short duration (110–115 days), high yielding and disease resistant salt-tolerant rice genotype ‘CSR-89IR-8’, which was later released as ‘CSR43’ in 2011. Several agronomic traits coupled with good grain quality and market value contributed to commercialization and quick adoption of this variety in the sodic areas of the Indo-Gangetic plains of eastern India. Management practices required for rice production in salt affected soils are evidently different from those in normal soils and practices for a short duration salt tolerant variety differ from those for medium to long duration varieties. Experiments were conducted at the Indian Council of Agricultural Research-Central Soil Salinity Research Institute (ICAR-CSSRI), Regional Research Station, Lucknow, Uttar Pradesh, India during 2011 and 2013 wet seasons, to test the hypothesis that combining matching management practices (Mmp) with an improved genotype would enhance productivity and profitability of rice in sodic soils. Mmp were developed on-station by optimizing existing best management practices (Bmp) recommended for the region to match the requirements of CSR43. The results revealed that transplanting 4 seedlings hill−1 at a spacing of 15 × 20 cm produced significantly higher yield over other treatments. The highest additional net gain was US

Growing Rice in Eastern India: New Paradigms of Risk Reduction and Improving Productivity

3.3 at 90 kg ha−1 N, and the lowest was US

Participatory evaluation guides the development and selection of farmers’ preferred rice varieties for salt- and flood-affected coastal deltas of South and Southeast Asia

0.4 at 150 kg ha−1 N. Above 150 kg ha−1, the additional net gain became negative, indicating decreasing returns from additional N. Hence, 150 kg N ha−1 was considered the economic optimum N application rate for CSR43 in these sodic soils. Using 150–60–40–25 kg N–P2O5–K2O–ZnSO4·7H2O ha−1 in farmers’ fields grown to CSR43 produced an average of 5.5 t ha−1 grain. The results of on-farm evaluation trials of CSR43 showed that matching management practices (Mmp) increased yield by 8% over existing best management practices (Bmp) recommended by ICAR-CSSRI for sodic soils and by 16% over framers’ management practices; however, combining Mmp with CSR43 resulted in 35% higher yields over farmers’ current varieties and management. This approach of combining cost effective crop and nutrient management options and a salt-tolerant variety can maximize the productivity and profitability of sodic soils in the alluvial Indo-Gangetic plains and in neighboring salt-affected areas of the Ganges mega delta in South Asia.

Trichoderma Species as Abiotic Stress Relievers in Plants

Rice is the staple food for the millions of people in eastern India. However, the productivity of the rice-based system in this region is very low, mainly because of abiotic and biotic stresses, variable monsoons, poor agronomic management, and poor access to knowledge. In addition, farmers are affected by a rising scarcity of labor, climate change, and rising production costs. Introducing and promoting high-yielding, drought-, submergence-, and salinity-tolerant rice varieties to withstand the impact of climate change; promoting the wide-scale adoption of efficient crop and resource management systems to enhance productivity and profitability with lower labor, water, and input use; and introducing ICT-based decision tools for nutrient, water, and weed management can help to bridge the yield gap and decrease the risk from farming. Supporting and strengthening entrepreneurship for rural employment generation and increasing access to capital-intensive technologies for smallholder farmers is also important. Capacity building of different stakeholders can further trigger a sustainable transformation in rice farming.

Decreasing the Vulnerability to Climate Change in Less Favoured Areas of Bihar: Smart Options in Agriculture

Rice is the staple food and provides livelihood for smallholder farmers in the coastal delta regions of South and Southeast Asia. However, its productivity is often low because of several abiotic stresses including high soil salinity and waterlogging during the wet (monsoon) season and high soil and water salinity during the dry season. Development and dissemination of suitable rice varieties tolerant of these multiple stresses encountered in coastal zones are of prime importance for increasing and stabilizing rice productivity, however adoption of new varieties has been slow in this region. Here we implemented participatory varietal selection (PVS) processes to identify and understand smallholder farmers’ criteria for selection and adoption of new rice varieties in coastal zones. New breeding lines together with released rice varieties were evaluated in on-station and on-farm trials (researcher-managed) during the wet and dry seasons of 2008–2014 in the Indian Sundarbans region. Significant correlations between preferences of male and female farmers in most trials indicated that both groups have similar criteria for selection of rice varieties. However, farmers’ preference criteria were different from researchers’ criteria. Grain yield was important, but not the sole reason for variety selection by farmers. Several other factors also governed preferences and were strikingly different when compared across wet and dry seasons. For the wet season, farmers preferred tall (140–170 cm), long duration (160–170 d), lodging resistant and high yielding rice varieties because these traits are required in lowlands where water stagnates in the field for about four months (July to October). For the dry season, farmers’ preferences were for high yielding, salt tolerant, early maturing (115–130 d) varieties with long slender grains and good quality for better market value. Pest and disease resistance was important in both seasons but did not rank high. When farmers ranked the two most preferred varieties, the ranking order was sometimes variable between locations and years, but when the top four varieties that consistently ranked high were considered, the variability was low. This indicates that at least 3–4 of the best-performing entries should be considered in succeeding multi-location and multi-year trials, thereby increasing the chances that the most stable varieties are selected. These findings will help improve breeding programs by providing information on critical traits. Selected varieties through PVS are also more likely to be adopted by farmers and will ensure higher and more stable productivity in the salt- and flood-affected coastal deltas of South and Southeast Asia.

IMPROVED EARLY SEASON MANAGEMENT OF SUB1 RICE VARIETIES ENHANCES POST-SUBMERGENCE RECOVERY AND YIELD

Abstract Drought, flood, soil salinity/sodicity or extreme temperatures are responsible for adverse effects on plant growth and production. More precisely, drought, flood and salinity are the major causes of crop loss worldwide. These stresses are likely to get further aggravated in near future due to climate change. A wide range of adaptations and mitigation strategies are required to cope with such impacts. Trichoderma species, one of the most widely used microbes for the biocontrol of plant diseases, are known to alter the response of plants to abiotic stresses. There is need to exploit its unique properties of genetic diversity, ubiquity, tolerance to extremities, its interaction with crop plants and develop methods for its effective disposition in agriculture production to cope with climate change induced stresses. There is an increasing interest in developing the potential biotechnological applications of fungal endophytes especially Trichoderma species for improving plant stress tolerance and sustainable production of food crops. Subsequently, isolation of genes from this biocontrol agent and their further transfer to a plant genome may result in a significant improvement in plant tolerance to biotic or abiotic stresses. Here, we have described the role of Trichoderma species in alleviating adverse effects of abiotic stresses in plants and providing abiotic stress tolerance. A putative mechanism of stress tolerance by Trichoderma species has also been covered. Since Trichoderma alone may not be enough to provide required degree of protection against abiotic stresses like drought, soil salinity or flooding, there is need to explore the possibility of exploiting the microbes along with the plant gene (i.e. abiotic stress tolerant varieties) for the more effective abiotic stress management.

Herbicides for weed management in lentil under rainfed drought prone ecology of Bihar

Anthropogenic climate change results from developmental activities across various sectors including agriculture. Threats resulting from these have variously been proposed to be manageable with mitigation and adaptation mechanisms by the stakeholders. The population inhabiting the less favoured environments is much more vulnerable to climate change. Despite the potential to produce under designated management, these environments have not received the due attention for development initiatives. This could partially be because of the lack of infrastructure facilities and partly also due to the tendency to concentrate in the comfort zone. Hence management adaptations that can directly influence the responsive indicators of climate change such as the concentration of green house gases in the atmosphere could be promising. System intensification is an unambiguous choice keeping in view the increasing population. Subtle climate smart technologies are also available as simple production techniques that can potentially reduce the vulnerability to climate change such as competent cultivars and cropping systems apart from time tested modifications in production practices. System diversification is a key component of disaster risk reduction and seen as a tool for reducing vulnerability to climate change. Precision nutrient management for smallholders aided by IT enabled tools helps in filling the deficit between the crop needs and indigenous nutrient supply of the soil for rational yield targets and results in saving fertilizers, increase fertilizer use efficiency and reduce greenhouse gas emissions vis-a-vis conventional management. Sustainable biochar technology can trap atmospheric carbon dioxide in the soil for a time scale of the order of thousands of year and at the same time improve crop productivity and soil physical conditions.

Responses of SUB1 rice introgression lines to submergence in the field: Yield and grain quality

More than 10 Sub1 rice varieties carrying the submergence-tolerance gene have been released for flood-prone environments in tropical Asia. Improved management practices have been shown to enhance yields of these varieties. The objective of this study was to dissect the growth response of IR64-Sub1 to integrated crop management in a flash flood at the late vegetative stage. Field experiments were conducted at the International Rice Research Institute, Philippines in the dry and wet seasons of 2013. Complete submergence was imposed for 14 days starting at 37 days after transplanting. Integrated management practice (IMP) consisting of: (i) application of fertilizer (compared with no fertilizer use in conventional practice), (ii) use of lower seeding rate (400 vs. 800 kg ha −1 ) in the nursery bed, (iii) use of slightly older seedling for transplanting (30 vs. 18 day-old), and (iv) higher planting density (33.3 vs. 25.0 hills m −2 ) gave yields higher by 8–87% compared with the conventional practice (1.3–2.4 t ha −1 ) in both seasons. This was attributable to higher shoot biomass after water recession, more tillers m −2 , greater leaf area expansion and shoot biomass accumulation during the recovery period, and higher filled-grain percentage at maturity. The improved management had no positive effect on panicle formation, spikelets panicle −1 , and harvest index since stress was imposed at the transition period between vegetative and reproductive phases. Our results suggest the appropriate nursery management, for submergence-resilient seedlings to further alleviate damage caused by flash floods and increase the yield of Sub1 varieties in flood-prone rainfed lowlands.

The contribution of submergence-tolerant (Sub1) rice varieties to food security in flood-prone rainfed lowland areas in Asia

In context of the emerging challenge of weed management in lentil under rainfed drought prone ecologies in India, a field experiment was conducted in the winter seasons of 2012–13 and 2013–14 to evaluate the performance of different herbicides in lentil under rainfed conditions. Among the herbicidal treatments, the maximum plant height (40.5 cm), plant population (143.7 plants/m2), branches per plant (5.67), pods per plant (59.03), nodules per plant (21.27), dry weight of nodules per plant (29.44 mg) and dry matter accumulation (486.30 g/m2) of lentil at maturity were recorded in plots treated with pendimethalin (preemergence) followed by quizalofop-ethyl (post-emergence) at 750 g and 50 g/ha. Pendimethalin followed by quizalofop-ethyl recorded significantly lower weed index (12.97%) with higher grain yield (1741.0 kg/ha) as compared with control and it was closely followed by pendimethalin alone (14.64%). Imazamox plus imazethapyr caused severe crop phytotoxicity and the crop had a slow growth and reduced crop biomass. The maximum benefit cost ratio of 3.83 was recorded in the plot treated with pendimethalin at 750 g/ha (pre-emergence) as compared to other herbicides. Thus, pendimethalin alone and with quizalofop-ethyl were equally effective in controlling the broad-spectrum of weeds in lentil with high yield advantage.