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Application of silicon (Si) could greatly boost rice yield and mitigate abiotic stress, especially drought. A field experiment was conducted during 2015 at the research farm of Hong Duc University, Thanh Hoa City, Vietnam, to evaluate the effects of five different combined doses of standard fertilizer practice and Si fertilizer on growth, yield and yield components, as well as nutrient uptake of rice. The treatments consisted of the recommended dose of fertilizer (RDF, 110 kg/hm 2 N + 90 kg/hm 2 P 2 O 5 + 80 kg/hm 2 K 2 O) as the control, RDF + 100 kg/hm 2 SiO 2 , RDF + 200 kg/hm 2 SiO 2 , RDF + 300 kg/hm 2 SiO 2 and RDF + 400 kg/hm 2 SiO 2 . The results showed that the growth, grain and straw yields as well as yield components (number of grains per panicle, seed-setting rate and 1000-grain weight) were significantly affected by Si application. The highest grain yield of 3 705 kg/hm 2 was obtained with the highest level of Si fertilizer in combination with RDF (RDF + 400 kg/hm 2 SiO 2 ), however, it was statistically at par with the yields obtained with RDF + 300 kg/hm 2 SiO 2 (3 664 kg/hm 2 ) and RDF + 200 kg/hm 2 SiO 2 (3 621 kg/hm 2 ). The optimum dose of Si fertilizer with maximized grain yield (3 716 kg/hm 2 ) was 329 kg/hm 2 SiO 2 . The nutrient (Si, N, P and K) uptakes of rice were also significantly enhanced by Si application. Si application at the level of 329 kg/hm 2 along with RDF would help in the sustainable production of rice in the tropical zone of Vietnam. [ABSTRACT FROM AUTHOR]

Field experiments were conducted on cotton to evaluate the different cotton-based intercropping system along with balanced nutrient management practices on enhancing cotton productivity. Cropping systems have been considered as main plots and nutrient management practices have been considered as subplots. The results showed that cotton + onion system recorded the highest cotton equivalent yield (CEY) of 2052 and 1895 kg ha−1which was on par with cotton intercropped with dhaincha, which recorded 2010 and 1894 kg of CEY ha−1in both the seasons. Combined application of 100% recommended NPK with bioinoculants (S5) registered highest CEY in both the seasons. Cotton intercropped with dhaincha (M2) recorded highest uptake of N, P, and K. Among the nutrient management practices, application of 100% recommended NPK with bioinoculants (S5) showed highest uptake of N, P, and K. A similar trend was noticed in the post-harvest soil fertility too and it is significantly higher under cotton + dhaincha and application of 100% recommended NPK with bioinoculants treatment compared to 100% recommend NPK alone. It could be concluded from these results that crop productivity can be improved and soil fertility status can be sustained with integrated plant nutrient management practices. [ABSTRACT FROM PUBLISHER]

Horsetails are unique survivors of a very ancient group of vascular plants, the Sphenophyta, which has a history reaching back to the Upper Devonian. Despite the striking conservatism of Equisetum architecture and anatomy and the small number of species (15) in the modern flora, their ability to thrive under a wide range of conditions is remarkable. This is due to a diverse suite of adaptations that allow tolerance of disturbance, soil anoxia, high metals, and salinity, along with efficient nutrient uptake and nitrogen fixation. The giant horsetails represent the largest living Sphenophyta and provide insights into how their larger ancestors lived and how this ancient lineage has managed to survive in tropical regions. [ABSTRACT FROM AUTHOR]

Understanding rice phenology and nutrient uptake pattern is important for adequate crop management and improving yields. A greenhouse experiment was conducted with the objective to monitoring upland rice (cv. Talento) phenology and nutrient uptake pattern during its growth cycle. Growth observations and plant analysis were performed at initiation of tillering (IT), active tillering (AT), panicle initiation (PI), booting (B), flowering (F) and physiological maturity (PM). Shoot dry weight plus grain yield and root dry weight increased significantly (P < 0.01) with age and followed exponential cubic responses. Similarly, plant height, number of tillers per plant, number of leaves on main culm and maximum root length increased significantly (P < 0.01) in quadratic fashion with increasing plant age. Concentrations of nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe) and manganese (Mn) increased significantly (P < 0.01) and quadratically with plant age, whereas, phosphorus (P), copper (Cu) and zinc (Zn) decreased quadratically with increasing plant age. Uptake of macro- and micronutrients increased significantly in quadratic fashion with increasing plant age. Plant growth parameters had highly significant (P < 0.01) association with shoot dry weight plus grain yield in the order of shoot dry weight > root dry weight > plant height > root length. Similarly, uptake of macronutrients also had highly significant (P < 0.01) association with dry matter plus grain yield in the order of Ca > Mg > K > P > N, indicating deficiency of these nutrients in Brazilian Oxisols for rice production. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the study was to determine optimum nutrient norms for laterite soils (Ultisols) and to assess quantitative relationship of soil fertility, leaf nutrients and nutrient uptake with yield of arecanut. At 0–30cm soil depth, optimum nutrient concentration for P, K, Ca, Mg, Fe, Mn, Cu, Zn and B was established as 15, 192, 925, 179, 37, 88, 26, 5.5 and 1.4mgkg−1, respectively. Optimum ranges for different nutrients were found out from second degree polynomial equations. Optimum nutrient values were higher for laterite soils in arecanut tract than generalized guidelines for interpretation of soil analysis data. Multivariate analysis of nutrient data indicated that nutrient uptake/removal would explain the variability in yield more than actual nutrient concentrations in soil and leaf with high degree of relation (R2 =0.92–0.98). Stepwise regression analysis identified the soil and leaf nutrient variables with a significant influence on the kernel yield of arecanut. The loadings of principal component analysis were in confirmation with the correlations among the nutrient variables and yield. The study clearly establishes the direct and significant relationship between soil nutrient status/nutrient uptake and yield. The findings of the study give scope for precision agriculture and judicious use of inputs. [Copyright &y& Elsevier]

Effluent lagoons on dairy farms can overflow and potentially pollute adjacent land and associated water bodies. An alternative solution to effluent disposal is needed by dairy operators in island environments. An attractive win-win alternative is to recycle nutrients from this resource through effluent irrigation for forage grass production that minimizes environmental pollution. This study assessed biomass production and nutrient removal by, and high application rates to, tropical grasses that were subsurface drip-irrigated with dairy effluent. Four grass species - Banagrass ( Pennisetum purpureum K. Schumach.), California grass ( Brachiaria mutica (Forssk.) Stapf.), Stargrass ( Cynodon nlemfuensis Vanderyst) and Suerte grass ( Paspalum atratum Swallen) - were subsurface (20-25 cm) drip-irrigated with effluent at two rates based on potential evapotranspiration (ETp) at the site (Waianae, Hawaii) −2·0 ETp (16 mm d−1 in winter; 23 mm d−1 in summer) and 0·5 ETp (5 mm d−1 in winter; 6 mm d−1 in summer). Treatments were arranged in an augmented completely randomized design. Brachiaria mutica and P. purpureum had the highest dry-matter yield (43-57 t ha−1 year−1) and nutrient uptake especially with the 2·0 ETp irrigation rate (1083-1405 kg ha−1 year−1 N, 154-164 kg ha−1 year−1 P, 1992-2141 kg ha−1 year−1 K). Average removal of nutrients by the grasses was 25-94% of the applied nitrogen, 11-82% of phosphorus and 2-13% of the potassium. Average values of crude protein (90-160 g kg−1), neutral detergent fibre (570-620 g kg−1) and acid detergent fibre (320-360 g kg−1) were at levels acceptable for feeding to lactating cattle. Results suggest that P. purpureum and B. mutica irrigated with effluent effectively recycled nutrients in the milk production system. [ABSTRACT FROM AUTHOR]

It has long been thought that jumping by the ciliate Mesodinium rubrum can enhance its nutrient uptake. However, jumping can be energetically costly and also dangerous by inducing hydrodynamic disturbances detectable by rheotactic predators. Here, a computational fluid dynamics (CFD) model, driven by published empirical data, is developed to simulate the jump-induced unsteady flow as well as chemical field around a self-propelled jumping ciliate. The associated phosphorus uptake, hydrodynamic signal strength, mechanical energy cost and Froude propulsion efficiency are also calculated. An equatorial ciliary belt (ECB), i.e. the morphology used by M. rubrum for propulsion, is considered. For the purpose of comparison, three other strategies (pulled or pushed by cilia, or towed) are also considered. Comparison of the CFD results among the four strategies considered suggests: (i) jumping enhances phosphorus uptake with simulated values consistent with available field data; (ii) the M. rubrum-like propulsion generates the weakest and spatially most limited hydrodynamic disturbance and therefore may effectively minimize the jump-induced predation risk; and (iii) the M. rubrum-like propulsion achieves a high Froude propulsion efficiency (∼0.78) and is least costly in mechanical energy expenditure among the three self-propelled strategies considered. Thus, using the ECB for propulsion can be essential in ensuring that M. rubrum is a successful ‘fast-jumping’ primary producer. [ABSTRACT FROM AUTHOR]

1. Lowland tropical streams have a chemically diverse detrital resource base, where leaf quality could potentially alter the effect of high nutrient concentrations on leaf breakdown. This has important implications given the extent and magnitude of anthropogenic nutrient loading to the environment. 2. Here, we examine if leaf quality (as determined by concentrations of cellulose, lignin and tannins) mediates the effects of high ambient phosphorus (P) concentration on leaf breakdown in streams of lowland Costa Rica. We hypothesised that P would have a stronger effect on microbial and insect processing of high- than of low-quality leaves. 3. We selected three species that represented extremes of quality as measured in leaves of eight common riparian species. Species selected were, from high- to low-quality: Trema integerrima > Castilla elastica > Zygia longifolia. We incubated single-species leaf packs in five streams that had natural differences in ambient P concentration (10–140 μg soluble reactive phosphorus (SRP) L−1), because of variable inputs of solute-rich groundwater and also in a stream that was experimentally enriched with P (approximately 200 μg SRP L−1). 4. The breakdown rate of all three species varied among the six streams: T. integerrima ( k-values range: 0.0451–0.129 day−1); C. elastica ( k-values range: 0.0064–0.021 day−1); and Z. longifolia ( k-values range: 0.002–0.008 day−1). Both ambient P concentration and flow velocity had significant effects on the breakdown rate of the three species. 5. Results supported our initial hypothesis that litter quality mediates the effect of high ambient P concentration on leaf processing by microbes and insects. The response of microbial respiration, fungal biomass and invertebrate density to high ambient P concentration was greater in Trema (high quality) than in Castilla or Zygia (low quality). Variation in flow velocity, however, confounded our ability to determine the magnitude of stimulation of breakdown rate by P. 6. Cellulose and lignin appeared to be the most important factors in determining the magnitude of P-stimulation. Surprisingly, leaf secondary compounds did not have an effect. This contradicts predictions made by other researchers, regarding the key role of plant secondary compounds in affecting leaf breakdown in tropical streams. [ABSTRACT FROM AUTHOR]

In this paper, distribution of different nutrients in different life forms, their allocation in different tree components and nutrient cycling in some teak forests of Satpura Plateau are described. The nutrients in tree biomass were higher for disturbed and mature sites (I and II) as compared with younger and undisturbed sites (III and IV). The allocation of nutrients was higher for bole and lowest for leaves, irrespective of sites. The accumulation of nutrients in bole was higher for disturbed and mature sites whereas the trend was reverse for leaves. The contribution of belowground nutrients in tree biomass was higher for disturbed site I and lower for undisturbed site III. Tree, shrub and herb, contributed 87-94, 0.73-6 and 3.47-6.69% nutrients in aboveground biomass at different sites respectively. Nutrient uptake by trees was 41-51% of the total uptake at different sites, while herbs contributed 42-52% to the total uptake. Nutrient use efficiency as per unit biomass was higher for herbs followed by shrub and trees, irrespective of sites. The contribution of teak in total tree biomass nutrients were 62.66, 70.08, 84.60 and 99.92% for site I, II, III and IV respectively. The young and undisturbed sites showed higher contribution of nutrients in teak. [ABSTRACT FROM AUTHOR]