Drought and limited availability of water serve as the serious limitation for rice production in rainfed ecosystems. Among the major rainfed rice-cultivating areas, states of eastern India occupy one ...of the largest drought-prone ecologies in the world. Cultivating drought tolerant rice varieties can serve as the most coherent approach to ensure food security in these areas. International Rice Research Institute (IRRI), along with its national collaborators, has developed drought tolerant rice varieties possessing high yield along with desirable grain quality. One such conventionally bred line, IR74371-70-1-1, has been released with different names in the different countries: in India as Sahbhagi Dhan, in Nepal as Sukha Dhan 3, and in Bangladesh as BRRI Dhan 56. This indicates the suitability of this line to show better performance across the wide range of environments. Sahbhagi Dhan is a short duration variety that has genetic drought tolerance and is more efficient at extracting available moisture from the soil. During drought years, farmers cultivating Sahbhagi Dhan obtained the yield advantage of 0.8 to 1.6 t ha−1 over currently grown long duration as well as traditional varieties. In 2012, when the paddy crop was hit by drought, Sahbhagi Dhan revealed the yield advantage of more than a t ha−1, which reduced to 0.78 and 0.56 t ha−1 during non-drought years of 2013 and 2014, respectively. Data taken from head to head trials during 2017 showed that Sahbhagi Dhan exhibited better performance over the existing rice varieties grown by farmers even under non-drought conditions. The important feature of Sahbhagi Dhan is its evident impact under drought and no yield penalty under favorable conditions over the counterfactual varieties of the same duration. Along with better yield under drought, the important advantage of Sahbhagi Dhan is the short maturity duration of this variety. This allows the farmers to advance the succeeding crop and creates an opportunity for accommodating an additional crop under favorable rainfed ecology, thereby enhancing the cropping intensity. Since the majority of the farmers living in drought prone ecologies are socio-economically under privileged, Sahbhagi Dhan, along with other drought tolerant varieties, can serve as one of the most viable and deliverable technologies for eradicating poverty from these ecologies dependent on rainfed rice.
Flooding is one of the major constraints for rice production in rainfed lowlands, especially in years and areas of high rainfall. Incorporating the Sub1 (Submergence1) gene into high yielding popular ...varieties has proven to be the most feasible approach to sustain rice production in submergence-prone areas. Introgression of this QTL into popular varieties has resulted in considerable improvement in yield after flooding. However, its impact under non-flooded conditions or years have not been thoroughly evaluated which is important for the farmers to accept and adopt any new version of their popular varieties. The present study was carried out to evaluate the effect of Sub1 on grain yield of rice in different genetic backgrounds, under non-submergence conditions, over years and locations. The study was carried out using head to head trials in farmer's fields, which enable the farmers to more accurately compare the performance of Sub1 varieties with their recurrent parents under own management. The data generated from different head to head trials revealed that the grain yield of Sub1 varieties was either statistically similar or higher than their non-Sub1 counterparts under non-submergence conditions. Thus, Sub1 rice varieties show no instance of yield penalty of the introgressed gene.
Adoption of any agricultural technology depends upon the way in which farmers are being informed about its benefits. Educational status, caste, gender and other social issues also play a significant ...role in the adoption process. To evaluate the impact of trainings on quality seed production, access to the climate resilient rice seeds, availability of information about seed sources and use of IRRI super bags, a randomized experimental research was carried out over a period of two years across five different states of India. The baseline and a follow-up survey was conducted to capture the farming practices followed by during wet seasons of 2016 and 2017, respectively. The impact of trainings, seed use, information given and agro-based goods was evaluated by comparing the adoption behaviour of treatment and control farmers. There was an increase (28.8%) in the practice of using salt solution to clean seeds primarily due to the impact of quality seed production (QSP) trainings. Female farmers responded more than the male farmers as number of women adopting the practice was higher than men. The impact of the trainings on farmers' knowledge and adoption of climate resilient/stress tolerant rice varieties (STRV) was also more pronounced on females than on male farmers. Farmers’ access to seeds substantially enhanced the adoption and reusability irrespective of the gender. Similarly, the information delivered to the farmers was quite economical in enhancing the awareness and adoption of climate resilient rice, but the effect was predominantly driven by female farmers. Female farmers performed relatively better with respect to the storing the new seeds in IRRI super bags. Thus, incentivising farmers in general and female farmers in particular can serve as a potential means to adopt agricultural technologies that have potential to boost rural economy and enhance the food security. The results are being supported by a rigorous empirical analysis.
•The study provides with evidence that an increase in seed cleaning practice is primarily due to the impact of trainings.•The information intervention is economical that enhances the adoption of new seeds and is mostly driven by female farmers.•Incentivising female farmers can serve as a potential means to boost rural economy and enhance the food security.
Sheath blight caused by Rhizoctonia solani is one of the most important rice diseases worldwide, especially under irrigated agro‐ecosystem. To detect quantitative differences in disease development, ...three inoculum types, viz. mycelial bit, single sclerotium and mycelial ball, were evaluated against five rice genotypes using detached tiller technique. Different disease variables such as number of lesions, disease severity, vertical sheath colonization (VSC), relative vertical sheath colonization (RVSC) and mean lesion length were measured for quantification of sheath blight resistance. All the disease variables were positively correlated with each other. Among the inoculum types, mycelial ball produced significantly higher level of disease variables in all the genotypes and resolved level of resistance better than the other two methods. Significantly lower values of disease severity, VSC and RVSC were observed on rice genotype Tetep, PR 108 and D 256 as compared with susceptible check D 6766 when inoculated with different inoculum types. These results can provide a basis to design methods to evaluate quantitative sheath blight resistance with high precision in rice genotypes.
False smut of rice is an emerging disease and a potential threat to hybrids and inbred rice cultivars grown in Asian countries. The aim of the study was to avoidance of false smut incidence by ...manipulating the planting date in rice. The genotypes including five rice hybrids, namely, KRH 2, US 312, DRRH 3, PHB 71, PA 6644 and three pure‐line cultivars, namely, BPT 5204, PR 116 and HKR 47 were evaluated in different planting dates (PD1: June 25, PD2: July 5, PD3: July 15). All the tested genotypes flowered during 100–110 days, except BPT 5204, which took 115 days to flower. False smut was quantified on rice genotypes using different disease variables such as infected panicle/plant, total false smut ball/plant and disease score. Disease variables were significantly and positively correlated to each other. The significant interaction between the genotype and planting date was observed. The early planting date (June 25) showed higher incidence than late planting (July 15). Overall mean of disease variables was higher in hybrids than pure‐line cultivars. Weather factors such as rainfall, rainy days and high relative humidity during the flowering period were favourable for disease development. The manipulation in the planting date can be utilized as a potential non‐monetary cultural approach for minimizing the incidence of false smut in rice. Cultivar HKR 47 with lower disease variables in different planting date can be used in diseases resistance breeding program.
Quantification of grain yield losses in mega rice varieties of south Asia due to infection by the sheath blight pathogen (Rhizoctonia solani) at different growth stages was carried out in 2 years in ...Northern India. Pathogen inoculation was done at the tillering, booting and grain‐filling stages of the crop under field conditions. The disease variables viz. disease severity, disease incidence, flag leaf infection and relative yield loss were determined on the mega varieties viz Swarna, Swarna Sub‐1 and PR 122. The effect of crop growth stage at inoculation and varieties was more important for disease variables than for relative yield loss. Booting and tillering stages were the most critical for higher sheath blight development with the highest relative yield loss. Among the mega rice varieties Swarna and Swarna‐Sub1, no significant difference was observed in all the disease variables and grain yield loss while the local variety PR 122 outperformed both mega varieties in disease variables and grain yield loss. PR 122 had the lowest yield losses due to low disease severity (14.22%–19.23%) during both years. All disease variables were positively correlated with relative yield losses. Regarding disease management strategies the focus should be on managing the disease initiation, particularly at the tillering and booting stages of the crop.
Flash floods leading to complete submergence of rice plants for 10–15 days is one of the major constraints for rice production, mainly in rainfed lowland areas. In India, 30% of the rice growing area ...(12–14 M ha) is prone to flash flooding with average productivity of only 0.5–0.8 t ha
−1
. Coastal Odisha is one of the most flood prone areas of India where the paddy crop in the wet season is often devastated by flash floods, forcing farmers either to discontinue paddy cultivation or to revert to traditional varieties with very low yields. The flood tolerant variety, Swarna-Sub1 (SS1), was introduced through cluster demonstrations in some villages of the Bari block of Odisha in 2013. SS1 seeds were provided to 355 farmers in two villages affected by floods twice in 2013. The majority of the farmers cultivated SS1 in 2013 and about 75% of them persisted with the variety in 2014. There has been a steady and significant increase in paddy cultivation and yields per unit area between 2012 and 2014 and a sharp increase in paddy sales during 2013 and 2014. The present study showed that farmers preferred to cultivate low yielding traditional land races owing to their better flood tolerance and the unavailability of flood tolerant high yielding varieties (HYVs). Traditional varieties gave 30–42% higher yields than non-SS1 HYVs when flooding occurred. SS1 on the other hand offered a significant yield advantage of about twice that of traditional varieties, in both flooding and non-flooding years. There is an additional social advantage of SSI in that famers belonging to scheduled castes in flood prone villages, have greater numbers of plots that are exposed to prolonged floods. Thus they benefit proportionately more from the introduction of SS1.
The use of multiple regression analysis to validate molecular markers associated with sheath blight resistance was carried out in 73 germplasm accessions of rice. Data on disease reaction was ...recorded as lesion size and used for calculation of AUDPC (Area Under Disease Progress Curve) and Percent Disease Index (PDI). A variation in AUDPC ranging from 217.78 to 793.33 with a mean value of 532.51 was recorded for the genotypes infected with sclerotia. PDI ranged from 28.89 to 84.44 with the mean values of 55.40 for infected lines. The AUDPC and PDI values for resistant check Tetep were found to be 432.70 and 45.22, respectively. Higher AUDPC and PDI values serve as an indication for susceptibility towards the disease reaction. The PIC value for the SSR loci varied from 0.225 to 0.743 with an average value of 0.47. Markers RM336, RM209, RM251 and RM224 were most informative on the basis of their high PIC values. UPGMA clustering based on molecular data and AUDPC were found to be in good agreement with each other. Twenty five germplasm accessions were grouped as common in cluster I of dendrogram generated by all alleles, cluster I of dendrogram constructed by Tetep specific alleles, and clusters I and II of the AUDPC dendrogram. Multiple regression analysis revealed that the two markers RM251175 and RM257150 may be considered as markers for association with low disease index (resistance to sheath blight) in rice. Amongst the germplasm accessions, IC383396 and IC426017 behaved as potentially resistant to sheath blight.
Rice is globally a major food crop and its production has progressively been affected by various types of abiotic stresses especially drought, flooding, salinity, heat and cold in most of the ...cultivable rice ecosystems. The incidence, intensity and duration of these stresses are anticipated to aggravate due to climate change consequences, demanding resilient yields in these situations to be essential. Present paper deals with reviewing various types of abiotic stresses and their mitigation strategies for enhancing and stabilizing rice production in stress prone areas. Review of available literature pertaining to the study area has been used as research methodology for this paper. The available literature suggests that stress-tolerant varieties can serve as the most viable strategy to contribute in coping with the problem of abiotic stresses. Although, good progress has been made in the development of stress-tolerant rice varieties (STRVs) and incessant efforts are being made to spread these varieties in target areas, adoption by farmers is yet to meet expectations. Advantage, affordability, awareness and availability are the main factors responsible for adopting of any technology. The adoption of stress-tolerant varieties has not reached its potential, predominantly due to the lack of awareness and non-availability of seeds amongst farmers. Strategic and intentional collaborations should be ensured for scaling the sustainable delivery and diffusion of STRVs. A promotional roadmap that ensures the linkages between private and public seed sectors remains the key factor for its successful adoption. Similarly, strengthening of formal, informal and semi-formal seed systems is crucial to accelerate the dissemination of these varieties. There is an imperative need to create strategic plans for the development of varieties possessing multiple stress tolerance. Significant investments for sustainability of rice production in stress prone areas form the essential component of long-term agricultural development. The sooner these investments and strategies are accomplished, the greater the gains are expected.
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