Dinesh Kumar

Evaluation of synergistic effects of bacterial and cyanobacterial strains as biofertilizers for wheat

An investigation was undertaken to screen, select and evaluate a set of bacterial and cyanobacterial isolates from the wheat rhizosphere for their role as biofertilizers in wheat. From an initial set of 23 cyanobacterial strains and 110 bacterial isolates from wheat rhizospheric soil, 3 bacterial and 3 cyanobacterial strains were selected based on their plant growth promoting potential under laboratory and controlled greenhouse conditions. In vitro compatibility studies revealed positive interactions among the six strains. Pot experiments were conducted with wheat variety HD 2687, with a total of 51 treatments, along with recommended fertilizer controls. Various combinations of the selected set of three bacterial (PW1, PW5 and PW7) and three cyanobacterial isolates (CW1, CW2 and CW3) were used along with 1/3xa0N and full dose of P and K fertilizers. Significant enhancement in the soil microbiological (Dehydrogenase activity, FDA hydrolase, Alkaline phosphatase and microbial biomass) and plant growth/yield parameters were recorded. Observations revealed a two-fold increase in panicle weight in selected combinations (PW1+PW7+CW3; PW1+ CW1+CW2/CW1+CW3; CW2+CW3), as compared to control treatment involving full dose of chemical fertilizers. Such combinations, which also provided N savings of 40–80xa0kgxa0N/ha are being further evaluated in field experiments. This study for the first time illustrated the positive and dynamic interactions among bacterial and cyanobacterial strains and their promise in integrated nutrient management of wheat crop.

Relative yield and zinc uptake by rice from zinc sulphate and zinc oxide coatings onto urea

Zinc (Zn) deficiency is prevalent worldwide and is a barrier to achieving yield goals in crops. It is also now recognized as a leading risk factor for disease in humans in developing countries. In general, soil application of 5–17xa0kg of Zn ha−1xa0year−1 as zinc sulphate (ZnSO4) or more is recommended. However, in developing rice growing countries of Asia, ZnSO4 of desired quality is not readily available and is also quite expensive, so the farmers generally fail to apply Zn, resulting in rice crop yield loss. Availability of Zn-coated urea guarantees not only the availability of quality Zn but also ensures its application. Field experiments were therefore conducted during the rice seasons of 2005 and 2006 at the Indian Agricultural Research Institute, New Delhi, to evaluate the relative efficiency of 0.5, 1.0, 1.5 and 2.0% Zn as ZnSO4- or zinc oxide (ZnO)-coated ureas for rice. Soil application of ZnSO4 was also compared in 2006. Rice grain and straw yields, Zn concentrations in grain and straw, and Zn uptake by rice increased with the level of Zn coating onto urea. Crop response was the highest with 2.0% ZnSO4-coated urea, and higher than with the same rate of ZnO-coated urea, possibly related to the higher water solubility of Zn in ZnSO4. Crop response with ZnSO4-coated urea was also higher than with the same rate of ZnSO4 and urea applied separately to the soil. However, apparent recovery data suggest that 1.0% coating with ZnSO4 may be a better choice from the point of view of the utilization of applied Zn. Increased Zn concentrations in rice grain due to application of Zn-coated urea is important from the point of view of Zn nutrition of humans, since rice is the staple food in developing countries of Asia. Also, increased Zn concentrations in rice straw is of importance as regards cattle nutrition since in developing countries of Asia rice straw is the major feed for farm cattle.

Effect of zinc-enriched urea on productivity, zinc uptake and efficiency of an aromatic rice–wheat cropping system

Zinc deficiency is prevalent worldwide and is a barrier in achieving yield targets in crops. It is also now recognized as a leading risk factor for disease in humans in developing countries. Generally, soil application of 5–17xa0kgxa0Znxa0ha−1xa0y−1 (25–85xa0kg zinc sulphate heptahydrate ha−1xa0y−1) or more is recommended for rice. However, in the developing rice-growing countries of Asia, zinc sulphate of desired quality is not readily available and is also quite expensive, and the farmers generally fail to apply Zn, resulting in crop yield loss in rice. Availability of zinc-enriched urea (ZEU) makes possible not only the availability of quality zinc, but also assures its application. Therefore, field experiments were conducted for two consecutive years at the research farm of Indian Agricultural Research Institute, New Delhi, India, during rainy (rice) and winter (wheat) seasons of 2004–2006 on a sandy clay-loam soil to study the effect of various concentrations of zinc enrichment of urea on productivity, zinc concentrations, its uptake and use indices of aromatic rice–wheat cropping system. Eight treatments comprising prilled urea (PU) and 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5% zinc-enriched urea, replicated threexa0times, were compared in a randomized block design. The enrichment of PU was done through zinc oxide containing 80% zinc. The results of this study revealed that the zinc-enriched urea (ZEU) had a significant effect on growth, yield attributes and yields of aromatic rice. Highest values for all these attributes and yields were recorded at the highest enrichment (3.5%) of the PU with zinc. The highest zinc concentration and uptake in rice grain and straw were also significantly higher with the highest level (3.5%) of zinc enrichment. The highest total zinc uptake recorded was 1,168 and 1,353xa0gxa0ha−1, during 2004 and 2005, respectively, with 3.5% ZEU. However, a major increase in grain yield of rice was recorded up to 1.0% zinc enrichment. The residual effect of zinc-enriched urea on succeeding wheat yield and zinc uptake was significant only at a higher level of zinc-enriched urea and only in the second year of study. Overall, 1.0% zinc-enriched urea recorded significantly higher productivity and zinc uptake over PU in the rice–wheat cropping system and is recommended for Delhi and adjoining areas. The recommendation is also made keeping in view the fact that with increased levels of zinc enrichment of urea, the partial factor productivity, agronomic efficiency, apparent recovery and physiological efficiency of applied zinc in a rice–wheat system decreased significantly. Considering all the economic parameters (benefit, benefit:cost ratio, IR gained IR−1 invested in zinc), 1.0% ZEU proved the most economic source for aromatic rice–wheat cropping system and therefore is recommended for rice–wheat cropping system in Delhi and adjoining areas of north India.

Using hyperspectral remote sensing techniques to monitor nitrogen, phosphorus, sulphur and potassium in wheat (Triticum aestivum L.)

In situ, non-destructive and real time mineral nutrient stress monitoring is an important aspect of precision farming for rational use of fertilizers. Studies have demonstrated the ability of remote sensing to monitor nitrogen (N) in many crops, phosphorus (P) and potassium (K) in very few crops and none so far to monitor sulphur (S). Specially designed (1) fertility gradient experiment and (2) test crop experiments were used to check the possibility of mineral N–P–S–K stress detection using airborne hyperspectral remote sensing. Leaf and canopy hyperspectral reflectance data and nutrient status at booting stage of the wheat crop were recorded. N–P–S–K sensitive wavelengths were identified using linear correlation analysis. Eight traditional vegetation indices (VIs) and three proposed (one for P and two for S) were evaluated for plant N–P–S–K predictability. A proposed VI (P_1080_1460) predicted P content with high and significant accuracy (correlation coefficient (r) 0.42 and root means square error (RMSE) 0.180xa0gxa0m−2). Performance of the proposed S VI (S_660_1080) for S concentration and content retrieval was similar whereas prediction accuracies were higher than traditional VIs. Prediction accuracy of linear regressive models improved when biomass-based nutrient contents were considered rather than concentrations. Reflectance in the SWIR region was found to monitor N–P–S–K status in plants in combination with reflectance at either visible (VIS) or near infrared (NIR) region. Newly developed and validated spectral algorithms specific to N, P, S and K can further be used for monitoring in a wheat crop in order to undertake site-specific management.

Chapter Two - Agronomic Biofortification of Cereal Grains with Iron and Zinc

Abstract Iron and zinc deficiencies in human nutrition are widespread in developing Asian and African countries where cereal grains are the staple food. Effects are therefore underway to develop cereal genotypes with grains denser in Fe and Zn by traditional plant breeding or using genetic engineering techniques. This approach requires a long period and adequate funds. However, the products of genetic engineering are not well accepted in many countries. Also, there is a trade-off between yield and grain biofortification. Agronomic biofortification offers to achieve this without sacrificing on yield and with no problem of product acceptance. From the viewpoint of biofortification, foliar application has been reported to be better than the soil application of Fe and Zn, and for this purpose, chelated Fe and Zn fertilizers are better. When soil applied, water soluble sources of Zn are better. Soil application of Fe is not recommended. Agronomic biofortification depends upon management practices (tillage, water management, nutrient interactions), soil factors (amounts present, pH, mechanisms of Zn fixation other than pH), and plant factors (root characteristics, excretion of phytosiderophores and organic acids by roots, Zn utilization at the cellular level, translocation within plant and mechanisms of Zn accumulation in grain). Genetic and agronomic biofortification are complementary to each other. Once the genotypes having denser grains are developed, they will have to be adequately fertilized with Fe and Zn. However, much more research in agronomy, soil science, and plant physiology is needed to understand the complex soil–plant–management interaction under different agroecological conditions under which cereals are grown. The situation is more complex for rice, which is grown under flooded, upland, and intermediate water conditions.

Rhizospheric Flora and the Influence of Agronomic Practices on Them: A Review

Plants and most of the microorganisms in the rhizosphere have symbiotic relationships. While rhizodeposits (root exudates having lysates, mucilages) provide the food and influence the structure and number of microorganisms in the rhizosphere, the latter benefit the plants through secretion of a number of growth promoting hormones, organic acids and siderophores that help in increased availability and uptake of nutrients by plants. The interactions of roots and microflora may influence the plant growth positively through a variety of mechanisms, including fixation of atmospheric nitrogen by different classes of proteobacteria, increased biotic and abiotic stress tolerance imparted by the presence of endophytic microbes, and direct and indirect advantages imparted by plant growth-promoting rhizobacteria. The soil microorganisms affect plant growth, and are affected by plant growth, but there is incomplete understanding of their cumulative and interactive effects on plant performance, especially under varied crop production regimes. The diversity of cropping systems in both time and space (by rotations, intercropping, and so on) creates a mosaic of soil resources and niches, which in turn, enhances belowground biodiversity and improves the resilience of the system as a whole. Therefore, agronomic practices such as crop rotation, tillage, addition of organic manures, chemical fertilizers and mulches influence the structure and number of microorganisms in the rhizosphere. However, very little data are available on this subject. There is a need to generate such data to develop a strategy for sustainable agriculture.

Increased biogas production using microbial stimulants

Laboratory studies were undertaken to evaluate the effect of microbial stimulants Aquasan and Teresan, on biogas yields from cattle dung and combined residues of cattle dung and kitchen waste, respectively. The addition of single dose of Aquasan at the rate of 10, 15 and 20 ppm to cattle dung on the first day of incubation resulted in increased gas yields ranging between 45.1 and 62.1 l/kg dry matter. Subsequent addition of Aquasan at 15 and 20 ppm dosage after a period of 15 days increased the gas yields by 15-16%. The gas production was found to be optimum at a dosage level of 15 ppm and was 39% and 55% higher with single and dual additions, respectively, than untreated cattle dung. In another bench scale study (1:1 dry matter) the addition of Teresan at 10 ppm concentration to the mixed residues of cattle dung and kitchen wastes at different solids concentration, produced 34.8% more gas (272.4 l/kg d.m.) than the uninoculated mixture at 15% TS concentration (202.4 l/kg d.m.).

Potato processing scenario in India: Industrial constraints, future projections, challenges ahead and remedies — A review

Indian potato (Solanum tuberosum L.) processing industry has emerged fast due to economic liberalization coupled with growing urbanization, expanding market options and development of indegenous processing varieties. India’s first potato processing varieties ‘Kufri Chipsona-1’ and ‘Kufri Chipsona-2’ were developed in 1998, followed by an improved processing variety ‘Kufri Chipsona-3’ in 2005 for the Indian plains and first chipping variety ‘Kufri Himsona’ for the hills. These varieties have >21% tuber dry matter content, contain low reducing sugars (<0.1% on fresh wt) and are most suitable for producing chips, French fries and dehydrated products. The availability of these varieties and standardization of storage techniques for processing potatoes at 10–12°C with sprout suppressant isopropyl N-(3-chlorophenyl) carbamate have revolutionized the processing scenario within a short span of 10 years. Currently about 4% of total potato produce is being processed in organized and unorganized sector. Potato processing industry mainly comprises 4 segments: potato chips, French fries, potato flakes/powder and other processed products. However, potato chips still continue to be the most popular processed product. The major challenge facing the industries lies in arranging round the year supply of processing varieties at reasonable price for their uninterrupted operation, besides several others which have been discussed at length and addressed with concrete solutions.

Relative efficiency of diammonium phosphate and mussoorie rock phosphate on productivity and phosphorus balance in a rice–rapeseed–mungbean cropping system

The field experiments were conducted at the Indian Agricultural Research Institute, New Delhi, India for 3xa0years from 2001–2002 to 2003–2004 to study the relative efficiency of diammonium phosphate (DAP) and Mussoorie rock phosphate along with phosphorus solubilizing bacteria inoculation (MRPxa0+xa0PSB) at different rates of application on productivity and phosphorus balance in a rice-rapeseed-mungbean cropping system. Phosphorus application significantly increased the productivity of rice-rapeseed-mungbean cropping system and resulted in an increase in 0.5xa0M NaHCO3 extractable P content in soil. The relative agronomic effectiveness (RAE) of MRPxa0+xa0PSB in relation to DAP as judged by the total productivity was 53–65% in the first cycle but reached 69–106% in the third cycle of the cropping system. The P balance (application—crop removal) was generally more positive for MRPxa0+xa0PSB than DAP and the highest P balance was recorded with an application of 52.5xa0kgxa0Pxa0ha−1 as MRPxa0+xa0PSB, resulted in highest 0.5xa0M NaHCO3 extractable P content in soil. The present study, thus, shows that MRPxa0+xa0PSB could be usefully employed as an alternative to DAP in long term in the rice–rapeseed–mungbean cropping system.

Relative Efficiency of Zinc Sulfate and Zinc Oxide–Coated Urea in Rice–Wheat Cropping System

Abstract Rice–wheat cropping system covers about 24 million hectares in China, India, Pakistan, Nepal, and Bangladesh, and zinc deficiency is widespread in rice–wheat belts of all these five countries. The current practice of applying zinc sulfate heptahydrate (ZnSO4 · 7H2O) to soil is problematic because of the poor quality of the nutrients available in the market to the farmers. Zinc (Zn)–coated urea is therefore being manufactured to guarantee a good‐quality Zn source. This article reports the results from a field study conducted to study the relative efficiency of zinc sulfate and zinc oxide (ZnO)–coated ureas in rice–wheat cropping system. The highest grain yield of rice–wheat cropping system was obtained with 2.0% coating of urea. Zinc sulfate was also a better coating material than ZnO. Partial factor productivity, agronomic efficiency, apparent recovery, and physiological efficiency of applied Zn decreased as the level of Zn coating was increased.