The scarcity of non-renewable resources such as soils and fertilizers and the consequences of climate change can dramatically influence the food security of future generations. Mutualistic root ...microorganisms such as plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) can improve plant fitness. We tested the growth response of wheat (Triticum aestivum L.), rice (Oriza sativa L.) and black gram (Vigna mungo L., Hepper) to an inoculation of AMF and PGPR alone or in combination over two years at seven locations in a region extending from the Himalayan foothills to the Indo-Gangetic plain. The AMF applied consisted of a consortium of different strains, the PGPR of two fluorescent Pseudomonas strains (Pseudomonas jessenii, R62; Pseudomonas synxantha, R81), derived from wheat rhizosphere from one test region. We found that dual inoculation of wheat with PGPR and AMF increased grain yield by 41% as compared to un-inoculated controls. Yield responses to the inoculants were highest at locations with previously low yields. AMF or PGPR alone augmented wheat grain yield by 29% and 31%, respectively. The bio-inoculants were effective both at Zero and at farmers’ practice fertilization level (70 kg N ha−1, 11 kg P ha−1 in mineral form to wheat crop). Also raw protein (nitrogen × 5.7) and mineral nutrient concentration of wheat grains (phosphorus, potassium, copper, iron, zinc, manganese) were higher after inoculation (+6% to +53%). Phosphorus use efficiency of wheat grains kg P grain kg−1 P fertilizer was increased by 95%. AMF and PGPR application also improved soil quality as indicated by increased soil enzyme activities of alkaline and acid phosphatase, urease and dehydrogenase. Effects on rice and black gram yields were far less pronounced over two cropping seasons, suggesting that AMF and PGPR isolated from the target crop were more efficient. We conclude that mutualistic root microorganisms have a high potential for contributing to food security and for improving nutrition status in southern countries, while safeguarding natural resources such as P stocks.
► Crop response to bio-inoculants isolated from wheat was highest in wheat (+41%). ► Consortia of AMF and PGPR were more effective than single inoculants. ► Bio-inoculants were most effective at sites with previously low yield. ► Also soil enzymes and mineral nutrient concentration of wheat grains were increased. ► Inoculants have a high potential to increase food security and resource use efficiency.
Laboratory feeding experiments using transgenic Bacillus thuringiensis variety kurstaki (Berliner) corn plants have been carried out to study the effects of B. thuringiensis-fed herbivores (i.e., ...prey), on the predator Chrysoperla carnea Stephens. Host plants were a transgenic B. thuringiensis-expressing (Cry1Ab) corn hybrid and the corresponding untransformed, B. thuringiensis-free corn hybrid. Two different prey species were used in the experiments, the European corn borer, Ostrinia nubilalis (Hubner) (lepidopterous target pest), and Spodoptera littoralis (Boisduval) (lepidopterous nontarget pest for B. thuringiensis). The objectives were to quantify the effects of B. thuringiensis-fed prey on chrysopid immature development and to determine whether observed effects were caused by sick, suboptimal prey (indirect effects) or associated with B. thuringiensis-related causes (direct effects). Mean total immature mortality for chrysopid larvae raised on B. thuringiensis-fed prey was 62% compared with 37% when raised on B. thuringiensis-free prey. There was no significant difference in mortality between chrysopid larvae reared on B. thuringiensis-fed O. nubilalis or B. thuringiensis-fed S. littoralis. Similarly, no significant difference in mortality was detected when chrysopid larvae were raised on B. thuringiensis-free O. nubilalis or B. thuringiensis-free S. littoralis. Development time of chrysopid larvae was prolonged when B. thuringiensis-fed O. nubilalis was given to the predators but not for B. thuringiensis-fed S. littoralis. Although some unnoticed adverse effects in S. littoralis may have occurred because of the B. thuringiensis corn, our results suggest that the reduced fitness of chrysopid larvae was associated with B. thuringiensis. The prolonged development time of chrysopid larvae raised on B. thuringiensis-fed O. nubilalis was probably because of a combined effect of B. thuringiensis exposure and nutritional deficiency caused by sick prey
Biological diversity is a major criterion in evaluating the effectiveness of measures to enhance the ecological quality of rural areas. Assessments of biodiversity based on selected groups of ...indicator organisms, including both animal and plant groups, are time-consuming and require a high level of expert knowledge: simpler methods are therefore needed. The biodiversity of 18 hay meadows in north-eastern Switzerland (Schaffhauser Randen, Canton Schaffhausen) was investigated using three indicator groups (angiosperms, spiders and true bugs). Simple structural parameters describing the vegetation canopy were investigated in terms of their usefulness as surrogates for biodiversity measures.
Eighteen sites varied widely in terms of species richness, diversity and abundance for all indicator groups. Numbers of angiosperm species varied from 21 to 57, spiders 25 to 45, and true bugs 12 to 37. Species numbers of the three indicator groups were significantly correlated with each other (angiosperms versus spiders:
r=0.53,
P=0.02; angiosperms versus true bugs:
r=0.59,
P=0.01; true bugs versus spiders:
r=0.61,
P=0.01). Management had a strong influence on species richness, the sites under extensive management showing the highest species number and diversity. The strongest correlations were those between true bugs and the two other indicator groups. However, the number of angiosperm species per 120
m
2, which was easy to assess, was also an acceptable predictor of the other two indicator groups.
Several parameters of the vegetation canopy were significantly related to species numbers and multiple regression models based on these parameters explained 25–60% of the variance in species richness and composition. Canopy density, plant biomass distribution and plant height were the most important parameters for all indicator groups.
The results indicate that parameters describing the structure of the vegetation provide useful information about the relative species richness of sites. In combination with parameters describing the surrounding land-use and an inventory of the angiosperms present, they offer a promising method for assessing biodiversity on a large scale.
Leaf rust (Puccinia recondita Rob. ex Desm. f. sp. tritici) resistant near isogenic lines (NIL) of wheat (Triticum aestivum L.) have generally lower yields than the susceptible recurrent parent under ...disease free conditions. Analysis of growth and yield should increase our understanding of the reduced yielding ability of NIL. In a 3-yr field study, the yield components of the leaf rust susceptible cultivar Arina were compared with six resistant NIL carrying the resistance gene Lr9 introduced from Aegilops umbellulata. The NIL were derived from two independently developed backcross populations with Arina as the recurrent parent. The NIL were phenotypically very similar to Arina. At anthesis and at medium milk stage, the total aboveground dry matter was similar for the NIL and Arina. Differences in the dry matter accumulation appeared only after the medium milk stage. At maturity, the NIL had a 12% lower grain yield than Arina (5.88 t ha-1) with a range from 5 to 14%. The lower grain yield resulted from a 3 to 11% reduction in grain number per square meter and a 2 to 7% reduction in mean grain weight. The smaller grain number per square meter was the result of a 6% smaller tiller number per plant and a 2% smaller grain number per ear. Artificially reducing grain number per ear suggested that both a reduced supply of assimilates and a diminished capacity to incorporate assimilates in the grain caused the reduced grain yield of the NIL. Deleterious effects of alien genes linked with the Lr9 gene from Aegilops umbellulata cannot be ruled out. However, the small differences within and between the NIL of the two Lr9 populations for the parameters tested suggest a direct relation between the yield depression and the leaf rust resistance conferred by the Lr9 gene
The Ins and Outs of Organic Farming Goklany, Indur M.; Mäder, Paul; Flieβbach, Asdreas ...
Science (American Association for the Advancement of Science),
12/2002, Volume:
298, Issue:
5600
Journal Article
As of yet, effective direct control of potato late blight in organic potato production requires the application of copper fungicides. However, with common dosage, copper is ecologically harmful. ...Hence, a considerable reduction or replacement of copper compounds in disease control is desirable. In the framework of the EU-project Blight-MOP comprising a systems approach to manage late blight in organic potato production without copper, 53 commercialised and experimental copper-free preparations were evaluated for their potential to control the disease by means of laboratory, greenhouse and field trials. Additionally, the potential to reduce copper fungicide input through optimised timing using the decision support system Bio-PhytoPRE developed at ART was assessed. In the laboratory, one-third of the copper-free preparations completely inhibited germination of sporangia and one-forth that of mycelial growth of Phytophthora infestans. In the greenhouse experiment one fifth of the copper-free preparations reduced foliar blight of tomato plants by at least 80 %. In microplot field trials, several copper-free preparations significantly reduced foliar blight of potatoes compared with the untreated control. However, the efficacy of the copper fungicides was never obtained. In small-plot field trials using practice-like application strategies, none of the copper-free preparations adequately controlled late blight sufficiently. The poor performance of the copper-free preparations under field conditions could be attributed to their low persistence and their lack of rain fastness compared to copper fungicides. In contrast to copper replacement, the strategy of using reduced application rates of copper fungicides according to the decision support system Bio-PhytoPRE proved to be successful.
