Characterization of free-living cyanobacterial strains and their competence to colonize rice roots

A total of 45 cyanobacterial strains isolated from rice fields near Loktak Lake in Manipur, India were tested for their rice root colonization capacity under light and under darkness. Twenty-one of these strains showed significant colonization of rice roots. The average colonization values were 637 and 381?μg chl a g^?1 root dry wt in N₂ medium and 792 and 451?μg chl a g^?1 root dry wt in NO ₃ ^? medium under light and darkness, respectively. Thus, while the colonization was higher under light and in NO ₃ ^? medium, there was significant level of colonization under darkness in N₂ medium (381?μg chl a g^?1 root dry wt). A 16S rRNA gene fragment-based denaturing gradient gel electrophoresis analysis revealed difference in the competence of individual strains to colonize rice roots exposed to individual or mixed population. The colonization pattern of seven strains used in competition experiments was found to be biphasic. A 16S rRNA gene-based phylogenetic analysis revealed high level of molecular similarity among strains of Nostoc and Anabaena.     

Effect of Mixing Pine Needles Litters on Soil Biological Properties and Phosphorus Availability in Soil Amended with Fertilizers and Manures

Effect of different manures and pine needles application on soil biological properties and phosphorus availability was evaluated in sandy loam soils. Fertilizers nitrogen, phosphorus, and potassium (NPK); Sesbania aculeata green manure (GM); farm yard manure (FYM); and vermicompost (VC) were applied alone or in combination with pine needles. Microbial biomass carbon, dehydrogenase, and alkaline phosphatase activity increased significantly due to manures and NPK. Pine needles reduced the microbial biomass carbon (MBC) and dehydrogenase activity in FYM and VC but increased in NPK and GM. Acid phosphatase activities were found to be significantly increased by pine needles application in NPK, FYM, VC, and GM as compared to without pine needles counterparts. No significant differences were found in soil solution phosphorus in manure treated soil due to pine needle application, but phosphorus uptake was reduced significantly in these treatments. Pine needles application clearly influenced the soil biological properties without any perceptible effect on nutrient release from the manures.     

A review on genome mapping of penaeid shrimps of commercial importance

Genome mapping of any organism has become vital and most essential to control the gene related functions and also for the production of new traits of the desired properties. Gene mapping has become a very powerful tool in agriculture sector as well as for terrestrial livestock and going to revolutionize both these sectors from the point of view of enhancing production. However, for aquatic organisms, the information pertaining to gene mapping research is limited and only in recent past few attempts have been made in this direction. The rationale behind genome mapping particularly for aquaculture species is to improve the quality of animals through selective breeding and produce genetically superior traits for commercial production. There is a great potential in this field since most of the aquaculture species have not been subjected to genetic improvement. The advantage of gene mapping tool for any organism is to identify and characterize quantitative trait loci associated with commercial important traits and to use these markers in marker‐assisted selection programmes. Now with advent of gene editing (CRIPSR‐Cas) technology one can modify/repair the gene structure and remove the adverse impact of the gene related characters without replacing the whole genome. Gene mapping of polygenic traits of aquaculture species is also gaining lot of importance because of dominant nature of such additional functional genes with unique predominant character in the species. In the present review, attempts have been made to collect details of information on gene mapping of cultivable penaeid shrimps. Furthermore, how these gene maps can be used to modify the gene structure at the targeted cites using gene editing techniques, has also been discussed.     

Effects of initial nematode population density and water regime on resistance and tolerance to the rice root-knot nematode Meloidogyne graminicola in African and Asian rice genotypes

The rice root-knot nematode (RKN), Meloidogyne graminicola, is an important pathogen affecting rice production in South and Southeast Asia. Efficacy of resistance and tolerance in selected M. graminicola-resistant African rice genotypes TOG5674, TOG5675 and CG14 and -susceptible Asian rice genotypes IR64 and UPLRi-5 were examined under a range of initial population densities (Pi) and water regimes. Resistance to M. graminicola in resistant rice genotypes was not broken with increasing pathogen pressure (Pi = 15,000 to 60,000 J2/plant). Resistant rice genotypes were even tolerant to the damage and yield loss caused by high pathogen pressure. On the other hand, increasing Pi levels caused more damage on susceptible rice genotypes. Final nematode population densities in the root systems of resistant and susceptible rice genotypes were significantly lower under flooded conditions than under upland and drought conditions. TOG5674, TOG5675 and CG14 were more tolerant to M. graminicola infection even when grown under upland and drought conditions while IR64 and UPLRi-5 were highly sensitive.     

Design and implementation of agriculture research digital photo manager

Software tools for photo collection management are proliferating, but they are generally developed for personnel photo management and have limited searching and browsing functions. We implemented the Agriculture Research Digital Photo Manager (ARDPM) prototype to enable researchers, extension personnel and other users to efficiently manage, search and browse their research photo archives. Research Digital Photo Manager provides a set of visual Boolean query interfaces for multiple ways of organizing and viewing the same photo collection. It gives users powerful search capabilities. Using thumbnail display and an easy interface, ARDPM is designed to provide users powerful searching and browsing photo capabilities.     

The large-effect drought-resistance QTL qtl12.1 increases water uptake in upland rice

Drought stress is the most important abiotic factor limiting upland rice yields. Identification of quantitative trait loci (QTL) conferring improved drought resistance may facilitate breeding progress. We previously mapped a QTL with a large effect on grain yield under severe drought stress (qtl12.1) in the Vandana/Way Rarem population. In the current paper, we present results from a series of experiments investigating the physiological mechanism(s) by which qtl12.1 affects grain yield under drought conditions. We performed detailed plant water status measurements on a subset of lines having similar crop growth duration but contrasting genotypes at qtl12.1 under field (24 genotypes) and greenhouse (14 genotypes) conditions. The Way Rarem-derived allele of qtl12.1 was confirmed to improve grain yield under drought mainly through a slight improvement (7%) in plant water uptake under water-limited conditions. Such an apparently small increase in water uptake associated with this allele could explain the large effect on yield observed under field conditions. Our results suggest that this improvement of plant water uptake is likely associated with improved root architecture.     

Productivity status of traditional agrisilviculture system on northern and southern aspects in mid-hill situation of Garhwal Himalaya, India

The productivity of traditional agrisilviculture system (agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004-2006. A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system. The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system. The results show that the annual productivity of all tree species was 3775 kg·ha-1·a-1 in northern aspect (site-N) and 3101 kg·ha-1·a-1 in southern aspect (site-S). G. Optiva had the highest productivity in both site-N and site-S among the tree species, followed by M. Azedarach, Quercus leucotrichophora and C. Australis. The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area. The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system. The sole agricultural crop productivity (without trees) in northern aspect was also higher than that in southern aspect. An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect. The overall productivity in traditional agrisilviculture system (crop + tree) was 24% (in northern aspect) and 21% (in southern aspect) higher than that in sole cropping system.     

Evaluation of raw and hydrothermically processed Prosopis juliflora seed meal as supplementary feed for the growth of Labeo rohita fingerlings

Hydrothermically processed Prosopis juliflora (PJ) seed meal as a supplementary diet for Labeo rohita is found to be rich in protein (330 g kg^?1) having antinutritional factors in permissible limits and containing essential amino acids adequately except lysine, methionine and cysteine. Ten iso‐nitrogenous and iso‐energetic diets with crude, soaked and autoclaved seed meal at 20%, 35% and 50% replacement of fish meal were tested (D1–D9, respectively). The growth of fish (weight gain, specific growth rate, feed conversion ratio and protein efficiency ratio) fed diet D4 (soaked seed meal at 20% replacement) was higher among the test diets, but lower than reference diet (RD). Diets with 50% seed meal resulted in lowering of growth, carcass composition, digestive enzyme activity and digestibility compared to test diets at 20% and 35% inclusion levels in the respective groups. Hydrothermically processed seed meal improved the growth compared to unprocessed one, though not up to RD level. This could be because of amino acid imbalance and presence of non‐starch polysaccharides in seed meal. Looking to the easy availability and its nutritional quality, processed PJ seed meal can be incorporated in carp diet at lower inclusion level.     

放线菌制剂对连作草莓根区微生物区系的影响及其防病促生作用

【目的】探索放线菌制剂对草莓根域微生态的影响及其防病促生效果。【方法】采用露地小区试验和平皿培养法,测定接种放线菌制剂对草莓生长及其根域微生态的影响。【结果】①草莓移栽时,接种放线菌制剂Act11和Act12可以显著增加草莓根表细菌数量及根区、根表、根内放线菌数量,接种处理的草莓根表细菌、放线菌数量分别较对照提高71.4%~100.0%,112.9%~234.9%,根内真菌、放线菌数量分别较对照提高236.4%~254.5%,366.7%~916.7%;接种Act11和Act12可极显著提高草莓根表、根内A/B及根表B/F、A/F,Act12接种处理根区、根表及根内A/B分别为对照的1.63,1.67及8.8倍,根表、根内A/F分别为对照的3.2,3.3倍,与对照的差异达到了极显著水平(P<0.01),Act11处理与之类似。②Act11和Act12能在草莓根区、根表土壤和根内定殖,其中根表的定殖密度最大,分别为1.30×107和5.76×107cfu/g,其定殖率分别为32.3%和92.4%。③Act11和Act12能显著促进草莓根系、匍匐茎及地上部分生长,新根生物量分别较对照增加了31.3%和112.5%,匍匐茎增加了109.4%和168.8%。④Act11和Act12对草莓连作病害有较为明显的防效,在露地试验中的相对防效分别为28.6%和84.7%。【结论】草莓移栽时接种Act11和Act12能显著改善草莓根域微生物生态,促进草莓生长,提高抗病性。     

Germination strategies of annual and short-lived perennial species in the Arabian Desert

Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation. In deserts, the spatiotemporal distribution of plant-available water is highly episodic and unpredictable, making winter months more favorable for seed germination when other abiotic conditions co-occur. We hypothesized that changes in photoperiod and thermoperiod would impact germination more in seeds that had undergone in situ storage. We assessed 21 annual and short-lived perennial species in the Arabian Desert to find (1) if seeds were dormant at maturity, (2) if in situ seed storage increased germination percentage compared with no storage, (3) if photoperiod and thermoperiod germination requirements were influenced by in situ storage, and (4) if a phylogenetic association in seed germination could be observed. Seeds of each species collected in early 2017 were divided into two batches. One was tested for germination within one week (fresh seeds). The other was stored in situ at the maternal location (stored seeds) until October 2017 and tested for seed germination in the first week of November. Seed germination was conducted in incubators at two thermoperiods (15°C/20°C and 20°C/30°C; 12 h/12 h), and two photoperiods (12 and 0 h light per day). Results indicated that seed germination percentages of 13 species were significantly enhanced by in situ storage. A thermoperiod response was exhibited by stored, but not fresh seeds. Light exposure increased germination of fresh seeds but had only a minimal effect on stored seeds. Germination traits exhibited no phylogenetic correlation. This result indicated that selection pressure for germination strategy was stronger than that for taxonomic traits of these desert species.