No abstract

Maintenance of high bacterial population in the rhizosphere improves the efficiency of these organisms. This high bacterial population can be maintained by the application of enriched compost which supports their growth and activities. Thus integrated use of Rhizobium, plant growth promoting rhizobacteria (PGPR) containing 1-aminocyclopropane-1-carboxylate deaminase (ACC-deaminase) and P-enriched compost (PEC) could be highly effective for promoting growth, nodulation, and yield of lentil (Lens culinaris Medik.). A field study was conducted to evaluate the potential of Rhizobium, PGPR containing ACC-deaminase and PEC for promoting growth of lentil. For this study, the soil type was sandy clay loam soil having pH 7.6; EC (electrical conductivity) 2.8 dS m -1 ; organic matter (OM) 0.59%; total N 0.032%; available P 7.9 mg kg -1 , and extractable K 129 mg kg -1 . Treatments were replicated thrice, using randomized complete block (RCB) design. Results showed that the integrated use of R. leguminosarum with Pseudomonas spp. containing ACC-deaminase along with PEC was highly effective and caused up to 73.5, 73.9, 74.4, 67.5, 73.3, 65.8, 40.5, and 52.5% increase in fresh biomass, grain yield, straw yield, pods plant -1 , nodule plant -1 , nodule dry weight plant -1 , 1000-grain weight, and N content in grain of lentil, respectively, as compared to respective control. It is concluded that integrated use of R. leguminosarum with Pseudomonas spp. having trait ACC-deaminase plus PEC would be an effective approach for better nodulation which consequently improved yield of lentil under natural conditions.

Increasing atmospheric carbon dioxide (CO2) concentration is both a strong driver of primary productivity and widely believed to be the principal cause of recent increases in global temperature. Soils are the largest store of the world's terrestrial C. Consequently, many investigations have attempted to mechanistically understand how microbial mineralisation of soil organic carbon (SOC) to CO2 will be affected by projected increases in temperature. Most have attempted this in the absence of plants as the flux of CO2 from root and rhizomicrobial respiration in intact plant-soil systems confounds interpretation of measurements. We compared the effect of a small increase in temperature on respiration from soils without recent plant C with the effect on intact grass swards. We found that for 48 weeks, before acclimation occurred, an experimental 3 °C increase in sward temperature gave rise to a 50% increase in below ground respiration (ca. 0.4 kg C m−2; Q10 = 3.5), whereas mineralisation of older SOC without plants increased with a Q10 of only 1.7 when subject to increases in ambient soil temperature. Subsequent 14C dating of respired CO2 indicated that the presence of plants in swards more than doubled the effect of warming on the rate of mineralisation of SOC with an estimated mean C age of ca. 8 years or older relative to incubated soils without recent plant inputs. These results not only illustrate the formidable complexity of mechanisms controlling C fluxes in soils but also suggest that the dual biological and physical effects of CO2 on primary productivity and global temperature have the potential to synergistically increase the mineralisation of existing soil C.

Studies were conducted to determine the efficacy of K salts in alleviating lime-induced chlorosis. Greenhouse studies using a Gibbon silt loam [fine-silty, mixed (calcareous), mesic Typic Haplaquoll] and a 1:1 mixture of Gibbon soil and washed sand were conducted with KCl, KNO 3 , K 2 SO 4 , K 2 HPO 4 , or KHCO 3 applied at rates of 0, 250, and 500 mg K/kg soil. An FeEDDHA treatment was included for comparison. Similar studies were conducted at two field sites known to produce lime-induced chlorosis. Potassium salts were applied at 0, 20, and 40 g K/m of row. In the greenhouse, plants treated with KCl, KNO 3 , and K 2 SO 4 on Gibbon soil were less chlorotic than controls or plants treated with K 2