INLAND AQUACULTURE IN INDIA: PAST TREND,PRESENT STATUS AND FUTURE PROSPECTS

ABSTRACT

In India, inland aquaculture has emerged as a fast-growing enterprise and a viable alternative to the declining capture fisheries. The present paper is an attempt to assess Indian inland aquaculture with respect to its resource base, output trends, systems and activities, yield gaps, adoption and impact on aquaculturists, economics, returns to inputs, investment needs, and future prospects. The paper is largely based on existing literature and observations made as part of an ICAR-WorldFish demand supply project. Indian aquaculture is primarily limited to inland sector and carp-oriented; for that reason, this activity received special attention. Freshwater aquaculture observed tremendous growth in the past 15 years, but immense scope still exists for horizontal expansion and increases in productivity (vertical expansion). This is evidenced by the fact that the average farm fish yield is only one-third of that achieved in farm trials. The difference was mainly due to much higher input use in on-farm trials. Most of the aquaculturists were practicing extensive aquaculture, but aquaculturists with semi-intensive operations benefited most from adoption of technology. The benefit:cost ratios for different systems of aquaculture varied between 1.22 to 1.86. The return to capital was much higher than the return to labor, due to the low labor input. The semi-intensive aquaculture system would receive the greatest return from projected macrolevel investments, followed by extensive and intensive systems. Dedicated efforts are needed to meet the demand for quality fish seed and feed in order to achieve the desired 45% increase in area and greater than 50% increase in productivity. Based on the observations, activities designed to foster inland aquacultural development in India are recommended.     

Marker‐assisted backcross breeding for improvement of drought tolerance in bread wheat (Triticum aestivum L. em Thell)

Drought stress is presently a major productivity limiting factor in wheat. This study developed five wheat lines with inbuilt tolerance to drought stress using marker‐assisted backcross breeding (MABB) approach employing three linked quantitative trait loci (QTLs) in an initial population of 516 BC₁F₁ plants. The high‐yielding wheat cultivar ‘HD2733’ grown over last few years extensively in the eastern plains of India is largely sensitive to drought and is used as the recurrent parent. ‘HI1500’ released for water‐limiting conditions and carrying drought‐tolerant QTLs was used as donor parent. MABB lines were advanced using foreground and background selection, coupled with stringent phenotyping. We identified 29 lines that were homozygous for targeted QTLs in different combinations with background recovery range of 89.2%–95.4%. Further evaluation of selected lines for physiological traits and distinctness, uniformity and stability (DUS) characters under rainfed condition identified five potential varieties for national varietal evaluation programme in the zone. The report is first of its kind in implementing known QTLs for the development of drought‐tolerant wheat lines through MABB approach.     

Influence of Organic Manure and Lime on Cadmium Mobility in Soil and Uptake by Spinach (Spinacia oleracea L.)

Spinach grown in cadmium (Cd)-contaminated soils accumulates Cd compounds in toxic concentration contaminating the food chain leading to the chronic toxic effects on human and animal health. A study was conducted in a Cd-contaminated soil to examine the ameliorative effect of lime and organic manure on the mobility of Cd and its uptake in spinach. Application of lime or organic manure or both decreased the Cd concentration in soil and shoots and increased chlorophyll content of leaves. As compared to the control treatment, combined application of lime and organic manure decreased the level of Cd in soil by 54.7%, in spinach shoot by 61.3%, and the transfer factor of Cd by 35.0% and increased in leaf chlorophyll content by 29.4%. Combined application of lime and organic manure emerged as a viable option in reducing the mobility of Cd in contaminated soil for growing spinach.     

Effects of biofilm on turbulence characteristics and the transport of fine sediment

Purpose

Biofilm growth changes the sediment properties and the characteristics of the bed, which further influences the interactions between the flow and the sediment bed, such as the turbulence characteristics of the flow and the erosion response of the sediment to hydrodynamic forces. In this study, the effects of biofilm on the turbulence characteristics of the flow and bio-sediment suspension are investigated.

Materials and methods

Cohesive sediments were collected from the bottom of the Three Gorges Reservoir, which have a median size of less than 0.1 mm. Flume experiments were conducted for the erosion of the sediment bed with and without biofilm under the same flow rate. Acoustic Doppler Velocimetry (ADV) was used to measure the velocities along the depth, based on which the distribution of Reynolds shear stress, time-average velocity, turbulence intensities, turbulence kinetic energy flux and budgets, and bursting events of the flow were determined. Meanwhile, the biofilm effects on the physical characteristics of sediments, such as the diameter, density, and falling velocity, were summarized from previous studies. Then, the changes of the vertical distribution of suspended sediment concentration and the near-bed concentration were evaluated.

Results and discussion

After biofilm growth, the time-averaged velocity increases by approximately 6.7% under the low flow rate condition with a flat bed, and by more than 20% under the high flow rate condition with a deformed bed. The vertical distribution of the turbulence intensity becomes more uniform under the high flow rate condition. However, the changes of the turbulence kinetic energy flux and budgets due to biofilm are hardly observed by the scattered measurement data, and more experiments need to be conducted in the future.

Conclusions

Biofilm exerts an influence on the turbulence characteristics, mostly by affecting the deformation extent of the sediment bed. Meanwhile, the changes of the physical properties of sediments due to biofilm significantly influence the transport of suspended sediment.

     

Restoration of hard mast species for wildlife in Missouri using precocious flowering oak in the Missouri River floodplain, USA

Increased planting of hard mast oak species in the Lower Missouri River floodplain is critical as natural regeneration of oak along the Upper Mississippi and Lower Missouri Rivers has been limited following major flood events in 1993 and 1995. Traditional planting methods have limited success due to frequent flood events, competition from faster growing vegetation and white-tailed deer herbivory. Results of early growth response of swamp white oak (Quercus bicolor Willd.) seedlings in relation to initial acorn mass and size, and early rapid shoot growth for seedlings produced by containerized root production method (RPM™), are presented. Containerized RPM™ seedlings grown in the greenhouse under optimal conditions demonstrate that seed size had no discernable impact on first-year root or shoot size. Seedling survival for the first two years and acorn production for the first three years after outplanting are presented, comparing use of containerized RPM™ swamp white oak seedlings to nursery stock. Flood tolerant precocious RPM™ oak seedlings in the floodplain provide a source of food for acorn-consuming wildlife ten to fifteen years sooner than oaks originating from natural regeneration, direct seeding or traditional bare root planting. Compared to bare root nursery stock that produced no acorns, some RPM™ swamp white oak seedlings averaged 4.3, 5.2, and 6.3 acorns/seedling in the first three years after fall outplanting. This revised version was published online in August 2006 with corrections to the Cover Date.     

Morphological indicators of stock quality and field performance of red oak (Quercus rubra L.) seedlings underplanted in a central Ontario shelterwood

The value of initial stem diameter near the root collar, shoot length and number of first-order lateral roots (FOLR) as morphological indicators of stock quality and field performance was examined for bareroot (1+0, undercut) red oak (Quercus rubra L.) underplanted in a shelterwood in central Ontario. These three attributes were measured on more than 400 seedlings prior to planting, and their relationship with height and basal diameter growth two years after planting was determined using correlation and regression analysis. Initial diameter, shoot length and number of FOLR were positively and significantly correlated with second-year height and diameter. These relationships were strongest for diameter, but this variable explained less than 25% of the total variation in growth. Of the three indicators, diameter was also the best predictor of several physical characteristics of root systems two years after planting. Initial diameter was significantly correlated with root volume, root area and lateral root, taproot and total root dry mass. Weaker relationships existed between initial shoot length and number of FOLR and second-year root system features. Stem diameter two years after planting was more strongly related to root volume, area and dry mass than was initial diameter, the probable result of adjustment in root-shoot balance of planting stock to the shelterwood environment.     

Recombinant antigen-based dipstick ELISA for the diagnosis of leptospirosis in dogs

A recombinant LipL 32 antigen-based dipstick ELISA was developed as a screening test for the detection of leptospiral antibodies in serum samples from dogs. The antibodies were detected by a change in the colour of the substrate solution when the recombinant antigen-coated dipsticks were dipped into it. The relative sensitivity, specificity and accuracy of the test, compared with the standard microscopic agglutination test, were 95.9 per cent, 93.8 per cent and 94.8 per cent, respectively.