Effects of dietary protein on growth performance,nutrient utilization,digestive enzymes and physiological status of grey mullet,Mugil cephalus L. fingerlings reared in inland saline water

A 60 days feeding trial was conducted to illustrate the effect of graded levels of protein on the growth and metabolic enzymes of grey mullet (Mugil cephalus L.) fingerlings reared in inland saline water (ISW). Six isoenergetic (16 MJ/kg) and isolipidic (60 g/kg) diets containing 240, 260, 280, 300, 320 and 340 g crude protein (CP)/kg diet were formulated and fed to triplicate. Weight gain %, specific growth rate, protein utilizing efficiency, feed efficiency and RNA:DNA ratio were significantly higher (p < .05) in 320 and 300 g CP/kg diets. Fish fed with 240 g CP/kg diet showed significantly higher (p < .05) feed intake, whole‐body lipid content, hepatosomatic index value and liver glycogen content. Transaminase enzymes and malate dehydrogenase activities were elevated in fish fed 340 g CP/kg diet. Protease activity increased with increasing dietary CP level, but amylase activities showed an inverse relationship. No significant (p > .05) variations were observed for lactate dehydrogenase, oxidative stress enzymes, blood parameters and serum osmolality among all the treatment groups, but red blood cell count increases with increasing dietary CP levels. Based on the results, feeding dietary protein level of 300 g CP/kg is economically viable for rearing of grey mullet in ISW.     

Tillage and nitrogen management effects with sequential and ready-mix herbicides on weed diversity and wheat productivity

In this experiment, weed management was studied in zero tillage (ZT) and conventional tillage (CT) wheat with and without crop residue and nitrogen (N). The treatment ZT with crop residue retention (R) and 75% of required N plus GreenSeeker? (GS)-aided N management (ZTRNGS) resulted in a reduction of density and dry weight of weeds compared to CT and ZT without residue. Sequential application of pendimethalin and sulfosulfuron (PMT-SSF) reduced the weed density and dry weight compared to the weedy check (WC). Importantly, the richness and diversity indices were high in ZTRNGS and in WC treatments. Greater wheat grain (5.11 t/ha) and biomass yield (13.31 t/ha) were observed in ZTRNGS than CT without residue and blanket split application of N (CTN). The treatment ZTRNGS recorded 14.1% and 16.9% higher gross and net returns, respectively, over CTN. This study demonstrates that surface retention of crop residue in ZT is more useful than residue incorporation under CT for effective weed control, improving crop yield and profitability.     

Molecular breeding technologies and strategies for rust resistance in wheat (Triticum aestivum) for sustained food security

Wheat is an important cereal food crop providing key nutrients to humankind. Rusts are the most destructive pathogens of cereal crops, with the exception of rice, across the world and resistant cultivars have been widely employed to reduce the yield losses caused by them. The modern intensive monoculture of cultivars and changing climatic conditions has created congenial conditions for the emergence of new virulent races such as Ug99, which is a great concern for world food security. Conventional breeding efforts have not been effective in quickly developing new varieties with durable and broad‐spectrum resistance against the rapidly evolving rust pathogen races. However, in the last two decades, biotechnological methods such as marker‐assisted selection (MAS) and transgenic technology have provided novel strategies for enhancing resistance levels and durability in crop plants in a short span of time. Nevertheless, broad application of transgenics in agriculture is hindered by biosafety apprehensions. In recent years, improved versions of biotechnological breeding methods such as genomic selection, genome editing technologies, cisgenesis and intragenesis, RNA‐dependent DNA methylation (RdDM), agroinfiltration and reverse breeding are gaining popularity. These technologies provide a tremendous capability to manipulate crop plants more precisely than before and accelerate crop improvement efforts for sustained food production as well as overcoming safety concerns associated with food crops.     

Screening for blast resistance in rice using AMMI models to understand G x E interaction in Guyana

In rice, totally one hundred and three genotypes were evaluated for resistance against blast disease in three hot spot locations of Guyana. The experiments were conducted in spring and autumn seasons of 2015, 2016 and 2017. The modified upland blast nursery (UBN) method was adopted for screening blast resistance. The Additive Main effects and Multiplicative Interaction (AMMI) analysis was applied to understand the interaction between genotype (G) and environment (E). The results of all seasons at three locations showed the consistent expression of high resistance by genotype FL 127 followed by FG12–08 and FG12–273. The AMMI analysis of variance (ANOVA) revealed that, resistance was dominated by the genotype main effect. The magnitude of genotypes by environment (G x E) sum of square (SS) was 3.64 times smaller than genotype SS, and 6.74 times larger than environment SS. The analysis has indicated that the differences of the genotypes across the environment were not substantial. All of the seven environment vectors appeared to be positively correlated. The screening at Onverwagt Back, autumn 2016 (E7) and Black Bush Polder, spring 2015 (E5) were observed to be the most representative environment. This was clearly revealed by smaller average - environment axis (AEA) angle. Likewise, E4 (Canje, autumn 2015) was observed closer to the “ideal test environment”, thus suggested as an ideal environment for blast resistant screening. Also, genotypes clustered near the origin have showed stable blast disease resistant status and contributed little to both G and G x E. These genotypes proposed as useful ones for breeding disease resistant varieties and hybrids in rice.     

Cage‐pond integration of African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) with carps

Cage‐pond integration system is a new model for enhancing productivity of pond aquaculture system. A field trial was conducted using African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) in cages and carps in earthen ponds. There were four treatments replicated five times: (1) carps in ponds without cage, (2) tilapia at 30 fish m^?3 in cage and carps in open pond, (3) catfish at 100 fish m^?3 in cage and carps in open pond, (4) tilapia and catfish at 30 and 100 fish m^?3, respectively, in separate cages and carps in open pond. The carps were stocked at 1 fish m^?2. The cage occupied about 3% of the pond area. The caged tilapia and catfish were fed and the control ponds were fertilized. Results showed that the combined extrapolated net yield was significantly higher (P < 0.05) in the catfish, tilapia and carps integration system (9.4 ± 1.6 t ha^?1 year^?1) than in the carp polyculture (3.3 ± 0.7 t ha^?1 year^?1). The net return from the tilapia and carps (6860 US$ ha^?1 year^?1) and catfish, tilapia and carps integration systems (6668 US$ ha^?1 year^?1) was significantly higher than in the carp polyculture (1709 US$ ha^?1 year^?1) (P < 0.05). This experiment demonstrated that the cage‐pond integration of African catfish and Nile tilapia with carps is the best technology to increase production; whereas integration of tilapia and carp for profitability.     

Within-plant distribution of an invasive mealybug,Phenacoccus solenopsis,and associated losses in cotton

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), an invasive pest species, has appeared on a large scale on cotton in India since 2006. Its distribution within the plant, and associated yield losses in cotton, were studied over 2 years. Distribution of P. solenopsis was observed within the cotton plant from vegetative to boll formation stage. In the vegetative and square formation stages, the highest mealybug population was recorded on the upper portion of the stem, followed by the middle leaves of the plant. In the boll formation stage, there was no significant difference in distribution of the insect among plant parts. Losses in cotton due to the mealybug varied between 14.9% at Grade 1 and 53.6% at Grade 4, on a 0 to 4 severity index, with a mean reduction of 35% and 32%, during 2008 and 2009, respectively. There was a significant relationship between severity of infestation and decrease in seed cotton yield. The information generated from this study will help in the early detection of mealybug infestation and estimation of yield losses corresponding to the severity grade of the damage.     

Coexpression of 16.8 kDa antigen of Mycobacterium avium paratuberculosis and murine gamma interferon in a bicistronic vector and studies on its potential as DNA vaccine

Paratuberculosis or Johne’s disease is a chronic gastric disease of ruminants. For this disease there is no effective treatment or preventive measure available. 16.8 kDa protein is an immunogenic protein of Mycobacterium avium paratuberculosis and can be an ideal candidate for developing a DNA vaccine construct. In present study a bicistronic DNA vaccine construct pIR16.8/IFN was developed using eukaryotic vector pIRES 6.1. Two genes MPT (expressing 16.8 kDa protein) and murine IFNγ were cloned, expressed and immunoreactivity was studied in murine model. Immunoreactivity was also compared with monocistronic construct pIR16.8 expressing 16.8 kDa protein. Both pIR16.8 and pIR16.8/IFN showed eukaryotic expression of respective proteins in BHK21 cells. The expressed proteins also showed immunoreactivity when reacted with hyperimmune sera raised against recombinant 16.8 kDa protein in western blot assay and immunofluorence assay. Both constructs were used as DNA vaccine in murine model and immunogenecity was studied by DTH, lymphocyte proliferation assay and NO determination. DTH reaction was significantly high in pIR16.8/IFN than pIR16.8 group, similarly lymphocyte proliferation and NO release was higher in pIR16.8/IFN group than pIR16.8 group. This indicated T cell epitopic nature of 16.8 kDa protein. The study also showed that co-expression of IFNγ with mycobacterial gene can enhance immunogenecity of DNA vaccine and can be used as immunoadjuvant.     

Labile soil organic carbon,soil fertility,and crop productivity as influenced by manure and mineral fertilizers in the tropics

In recent years, organic agriculture has been receiving greater attention because of the various problems like deterioration in soil health and environmental quality under conventional chemical‐intensive agriculture. However, little information is available on the comparative study related to the impact of use of mineral fertilizers and organic manures on the soil quality and productivity. A long‐term field experiment was initiated in 2001 to monitor some of the important soil‐quality parameters and productivity under soybean–wheat crop rotation. The treatments consisted of 0, 30, and 45 kg N ha^–1 for soybean and of 0, 120, and 180 kg N ha^–1 for wheat. The entire amount of N was supplied to both the crops through urea and farmyard manure (FYM) alone or in combination at 1:1 ratio. Results indicated that Walkley‐and‐Black C (WBC; chromic acid–oxidizable) exhibited a marginal increase under only organic treatments as compared to control treatment (without fertilizers and manure) after completion of five cropping cycles. In case of labile‐C (KMnO₄‐oxidizable) content in soil, relatively larger positive changes were recorded under organic, mixed inputs (integrated) and mineral fertilizers as compared to WBC. Maximum improvement in the values of C‐management index (CMI), a measure of soil quality was recorded under organic (348–362), followed by mixed inputs (268–322) and mineral fertilizers (198–199) as compared to the control treatment after completion of five cropping cycles. Similarly there was a substantial increase in KCl‐extractable N; in Olsen‐P; as well as in DTPA‐extractable Zn, Fe, and Mn under organic treatments. Although labile soil C positively contributed to the available N, P, K, Zn, Fe, and Mn contents in soil, it did not show any relationship with the grain yield of wheat. After completion of the sixth cropping cycle, organic treatments produced 23% and 39% lower grain yield of wheat as compared to that under urea‐treated plots. Relatively higher amount of mineral N in soil at critical growth stages and elevated N content in plant under mineral‐fertilizer treatments compared to FYM treatments were responsible for higher yield of wheat under mineral fertilizers.     

Effect of Gluconacetobacter diazotrophicus and Trichoderma viride on soil health, yield and N-economy of sugarcane cultivation under subtropical climatic conditions of India

Intensive cropping and exhaustive nature of sugarcane–wheat–rice cropping system in the Indo-Gangetic Plains of South Asia have led to the depletion of soil organic carbon content and inherent soil fertility resulting in a serious threat to the sustainability of these production systems. Bioagents like Gluconacetobacter diazotrophicus and Trichoderma viride have great potential to restore soil fertility and promote sugarcane growth. Field experiments, therefore, have been conducted to study the integrated effect of bioagents (G. diazotrophicus and T. viride), Farm Yard Manure (FYM) and fertilizer N on sugarcane rhizosphere, crop yield and N economy for two crop cycles during 2004–2006 and 2005–2007 crop seasons at Lucknow, in the middle Indo-Gangetic plain region. Both bioagents could survive and colonize sugarcane rhizosphere and FYM improved their colonization. Enhanced soil microbial population and microbial carbon (SMC) and nitrogen (SMN) with increasing N level were probably due to more available N in the soil. FYM/bioagents amendment further enhanced the microbial carbon. The uniform increase in the fraction of SMC and SMN of total organic carbon indicated that immobilization/mineralization was being maintained in the soil where enhanced microbial biomass might act later as a source of nutrients.Bioagents ammended FYM enhanced the uptake of N, P and K in sugarcane at all the levels of fertilizer N. It was mainly due to the enhanced nutrient availability in the rhizospheric soil as the soil organic C and available N, P and K content increased with the application of bioagents/FYM. A saving of 76.3 kg N ha⁻¹ was envisaged by the use of G. diazotrophicus inoculated FYM with marginal (2.4 t ha⁻¹) decline in the cane yield. Application of T. viride enriched FYM, however, brought economy in the use of fertilizer N by 45.2 kg ha⁻¹ and also increased the yield by 6.1 t ha⁻¹compared to the control treatment. Overall, strategic planning in terms of an integrated application of these bioagents/manures with fertilizer N will not only sustain soil fertility but will also benefit farmers in terms of reducing their dependence and expenditure on chemical fertilizers.