J. S. Mishra

Improvement of submergence tolerance in rice through efficient application of potassium under submergence-prone rainfed ecology of Indo-Gangetic Plain

Potassium (K) is one of the limiting factors that negatively influenced rice growth and yield in submergence-prone soils. We conducted an experiment during the wet season of 2014-15 to achieve optimal doses of K and understand the effect of K application on submerged rice in terms of survival, chlorophyll content, non-structural carbohydrates (NSC), anti-oxidant activities and yield. Results revealed that chlorophyll and NSC content were significantly (P≤0.05) lower whereas the activity of anti-oxidants (catalase, superoxide dismutase and total peroxidase) were significantly (P≤0.05) higher after submergence compared with pre-submergence. Further, application of K at a higher basal dose (40kgha-1) was more beneficial to improve survival after de-submergence by maintaining NSC, chlorophyll content and higher activity of anti-oxidants with lower level of lipid peroxidation. Furthermore, results showed superiority of the treatments having application of higher doses with one foliar spray (T9-40kg K2O ha-1 (basal)+one foliar spray at 0.5% K at panicle initiation (PI) stage) for grain yield. We conclude that application of a higher dose of K with one foliar application at PI stage is more beneficial to enhance plant survival, better recovery and yield gain of rice during complete submergence.

Effect of different rice establishment methods on soil physical properties in drought-prone, rainfed lowlands of Bihar, India

To enhance productivity, alleviate environmental and management constraints, and enhance farmers’ incomes in the rice–wheat cropping system of the Indo Gangetic Plains, new approaches that are labour-saving, more productive and sustainable need to be developed. Most systems of rice cultivation use puddling to prepare the seedbed and control weeds in rice fields of rainfed, stress-prone environments. This practice might be helpful to reduce weed pressure and obtain slightly higher productivity, but might have negative impacts on soil physical properties. A better understanding is needed of the comparative advantage of unpuddled rice fields for maintaining good soil physical properties. To study the effect of different rice establishment methods on soil physical properties in a rice–wheat cropping system, we analysed soil samples in 2 years (2012–13 and 2013–14) from an experiment testing puddled and unpuddled rice-establishment methods. The treatments were: (i) puddled, transplanted with best management practices; (ii) puddled, transplanted with the system of rice intensification; (iii) unpuddled, transplanted; and (iv) unpuddled, direct-seeded. Omission of puddling improved soil physical properties such as bulk density, penetration resistance, aggregation stability and cracking behaviour. The absence of soil disturbance also improved soil aggregation, average mean-weight diameter and water-stable aggregates. Thus, unpuddled conditions increased the macro-aggregate fraction by 18–33%. By contrast, the higher frequency of smaller macro-aggregates (0.053–0.25 mm diameter) in puddled conditions clearly indicated the breakdown of larger macro-aggregates (>0.25 mm) into smaller size fractions. Puddled treatments were also characterised by a hard pan and wider, longer and deeper cracks, with a crack volume more than three times higher in puddled conditions. Unpuddled treatments recorded slightly higher nutrient contents in the topsoil. The study reveals that puddling deteriorates soil health. However, a long-term study is required for a better understanding of the soil changes related to different rice establishment technologies.

Evaluation of Rice Varieties against Multiple Diseases Under Middle IGP of Bihar

An investigation was carried out to evaluate the susceptibility of rice cultivation to major field diseases like brown spot, sheath blight and bacterial leaf blight under middle Indo Gangetic Plain. The disease incidence and disease severity were observed at three different growth stages namely flowering, milk and maturity in boro seasons during 2015-16. The incidence of brown spot ranged from 8.93 to 17.83%, 16.67 to 25.67% and 18.33 to 28.33% at flowering, milk and maturity stages, respectively. The severity of brown spot in grade (0-9 scale) ranged from 5.13 to 10.33, 9.33 to 20.00 and 11.57 to 22.67, respectively at flowering, milk and maturity stages. The incidence of sheath blight of paddy ranged from 7. 03 to 16.50%, 13.13 to 22.67% and 19.67 to 35.67% at flowering, milk and maturity stages, respectively. The severity of sheath blight in grade (0-9 scale) ranged from 4.00 to 8.60, 8.33 to 13.93 and 18.33 to 34.33, respectively at flowering, milk and maturity stages. The incidence of bacterial leaf blight ranged from 5.00 to 14.00%, 11.43 to 21.00% and 17.00 to 34.00% at flowering, milk and maturity stages, respectively. The severity of bacterial leaf blight in grade (0-9 scale) ranged from 2.00 to 8.00%, 6.33 to 12.05% and 14.47 to 20.17%, respectively at flowering, milk and maturity stages. Among the varieties, the highest incidence and severity of Brown spot was recorded on Rajendra Bhagawati whereas it was lowest on 27P31 at all growth stages. In the case of Sheath blight, highest incidence and severity was recorded on Sambha Mahsuri whereas it was the lowest on CRL 193. Beside this in the case of Bacterial leaf blight, the highest incidence and severity was recorded on Kranti whereas the lowest was recorded on CRL 193. In general, it was observed that the incidence and severity of diseases increased gradually from flowering to maturity stage and the genotypes with the minimum incidence and severity of diseases gave the maximum yield.

Effect of Climate Change on Growth and Physiology of Rice-Wheat Genotypes

Under the changing climatic condition, both CO2 and temperature are the key variables that may cause significant changes in crop productivity. To understand the effect of these key variables of climate change on rice and wheat genotypes, a study was conducted under different sets of varying environments inside open top chambers (OTCs). The sets of conditions were ambient condition, ~25 % higher CO2 than ambient, 25 % higher CO2 + 2 °C ˃ ambient temperature, and 2 °C higher than the ambient temperature. Finding of the study showed that C3 crops (rice and wheat) respond positively toward increasing atmospheric CO2 in the absence of other stressful conditions, but the beneficial direct impact of elevated CO2 can be offset by other effects of climate change, such as elevated temperature. Climate changes affect the development, growth, and productivity of plants through alterations in their biochemical, physiological, and morphogenetic processes. The rising level of atmospheric CO2 led to the fertilization effect on C3 crops which in turn improved their growth and productivity. Increasing CO2 concentration in the atmosphere could lead to higher crop yields. Increased temperatures during the growing period may also reduce CO2 effects indirectly, by increasing water demand. Among different rice genotypes, IR83376-B-B-24-2 was highly responsive, while IR84896-B-127-CRA-5-1-1 was least responsive toward elevated CO2. Moreover, the response of wheat genotypes HD 2967 (4.18 t ha−1) and HD 2733 (4.17 t ha−1) was more positive toward elevated CO2 as compared to other genotypes. In terms of tolerance to heat, the wheat genotype Halna followed by DBW 17 was least affected due to elevated temperature as compared to other genotypes. Finding also suggests that various physiological traits, viz., content of sugar, stability of membrane (MSI %), plant leaf water status (RWC %), and photosynthetic rate, were improved under elevated level of CO2. However, rising temperature led to the negative response in terms of physiological traits. Advance knowledge of the future climate change scenarios in the zone on agroclimatic zone level would help in determining future climate risks and in identifying vulnerable areas to serve as the basis for crop planning and identification of suitable genotypes.

Rice Breeding for Drought Tolerance Under the Changing Climate Scenario

Rice (Oryza sativa L.) is one of the most important staple food crops for about two third of the world’s population. Rice is cultivated in diverse ecosystems extending from rainfed upland to deep water. The rainfed rice covers ~45 % of the world’s rice area. In a rainfed ecosystem, the recurrent event of drought has been attributed as the major reason to the low productivity. Present speculations regarding higher frequency of drought event along with a 1.1–6.4 °C rise in average global soil surface temperature by the end of this century pose an alarming threat to the production and productivity of rice posing a question mark to the food security of Asia. Drought is the greatest single yield-reducing factor among all other stresses influencing more than 23 M ha area of South and Southeast Asia. Out of the total 20.70 M ha located in India, ~16 M ha of area falls in eastern India including 6.3 M ha of upland and 7.3 M ha of lowland areas, which are highly susceptible to drought condition. Rice crop is very susceptible to soil moisture deficit and high-/low-temperature stresses, particularly at the reproductive stage. The majority of the existing high-yielding and traditional varieties of rice in the eastern part of India are very susceptible to moisture stress (drought). The majority of the high-yielding as well as traditional varieties of rice cultivated in the eastern part of India are very susceptible to moisture stress (drought). Farmers of drought-prone areas require such type of rice varieties that give them with high yield in years of normal rainfall and sustainable good yield in drought years. In this scenario, 42 advanced rice breeding lines were evaluated under drought stress at the reproductive stage with the objective of identifying drought stress-tolerant genotypes. The effect of drought stress on morphophysiological and biochemical traits was also studied. In the study, significant yield reduction was noticed almost in all rice genotypes under drought stress condition in comparison to control (non-stress). The varying responses of genotypes to the applied drought stress condition indicate its drought tolerance capacity. Grain yield was varied from 1.26 to 4.76 t/ha and 2.47–7.48 t/ha under stress and control condition, respectively. Based on preliminary screening, rice genotypes, viz., IR88867-4-1-1-4 (4.76 t/ha), IR88964-24-2-1-4 (4.73 t/ha), and IR88867-9-1-1-4 (4.55 t/ha), showed tolerance to drought at the reproductive stage as compared to check varieties Lalat (2.42 t/ha), IR64 (2.04 t/ha), and Sahbhagi Dhan (2.87 t/ha). Reproductive-stage drought also caused a decline in relative water content (RWC), membrane stability index (MSI), and plant biomass and an increase in grain sterility. These drought stress-tolerant rice genotypes may be cultivated in large areas of rainfed ecology where the occurrence of reproductive-stage drought is very frequent, especially in eastern India.

Diversity Among Rice Landraces Under Static (Ex Situ) and Dynamic (On-Farm) Management: A Case from North-Western Indian Himalayas

Crop genetic diversity is the building block of sustainable agricultural development. Crop landraces contain enormous genetic diversity. The genetic structure of rice landraces is an evolutionary approach to existence and performance, especially under rainfed and to some extent under irrigated conditions in valleys and organic inputs in Himalayan agroecosystems. The combined effects of farmer and natural selection led to the building of genotypes representing diverse combinations of traits. The better understanding into the dynamics of genetic resources of rice is needed in order to identify detrimental evolutionary patterns and draw up conservation priorities. During the last two to three decades, the introduction of high-yielding varieties as well as important changes in rice farming systems has led to the loss of genetic diversity particularly from valleys in lower elevation ranges. In order to develop a rational conservation plan, in global climate change scenario, a conservation concept is required that goes far beyond ex situ conservation. In situ conservation on farm has been reflected as a backup and complementary strategy to ex situ conservation. In this scenario, the current study demonstrated farmer management and temporal evolution of rice genetic diversity in traditional production systems. The study also compared gene bank-conserved (ex situ) populations and on-farm-managed (in situ) landrace populations of same landraces Jaulia and Thapachini and revealed a greater number of alleles per locus under on-farm-managed populations as compared to static management. The marker diversity by using STMS indicates the genetic diversity among populations resulting from combined effects of many evolutionary forces operating within the biological and historical context of the landrace. The results indicated the low diversity of the populations under static management. On the other hand, the variations in adaptations indicate the degree to which populations are adapted to their environments and their potential for continued performance or as donors of characters in plant breeding. It also provides particular information on loss of diversity over time and space at allelic and genotype level. This piece of writing is a step towards understanding the impact of traditional farmer management on rice landrace populations in Himalayan agroecosystems of India.

Impact, Adaptation Strategies and Vulnerability of Indian Agriculture Towards the Climate Change

Change in climate is one of the most important worldwide environmental challenges, with implication for production of food, supply of water, health, energy resources, etc. Proper scientific understanding with coordinated action at global level is required for addressing the climate change. Climatic system of the earth has apparently changed on both regional as well as global scales since the pre-industrial era. The Intergovernmental Panel on Climate Change (IPCC) declared that the daily mean temperature (globally) may be increased between 1.4 and 5.8 °C by the twenty-first century. Historically, the responsibility for greenhouse gases (GHGs) emissions’ increase lies largely with the developed world, though the developing nations are likely to be the major cause of a growing proportion of future emissions of GHGs. Agriculture sector is not only sensitive to climate change but also one of the key drivers for climate change. The sensitivity of climate towards agriculture is uncertain, as there is regional variation of climatic factors like rainfall, temperature (maximum and minimum), crop stands and different cropping system, soils properties and management practices. Overall, in the winter season (rabi), rise in the average temperature is likely to be much higher than in the monsoon season (kharif). Agriculture is one of the sectors where impact of climate change will be significant, and it will affect every part of agriculture including crops, fisheries, livestock, etc. Hence, it is necessary to identify the possible impacts of climate change on agricultural productivity and its allied sectors in order to recommend adaptation and mitigation strategies. Developing countries is reducing the vulnerability of their natural and socio-economic systems to the projected climate change that is the issue of the highest importance for developing countries. Developing countries will face the challenge of promoting mitigation and adaptation strategies for climate change, bearing the cost of such an effort, and its implications for social and economic development. We conclude by making interim recommendations on the practical strategies needed to develop a more resilient and dynamic world agriculture in the twenty-first century.