Dynamics of nitrate and nitrite in saturated sand filters with enhanced substrate conditions for denitrifying bacteria

Substrate conditions for denitrifying bacteria were enhanced by adding carbon sources to a laboratory-scale sand filter system. Temperature, oxidation–reduction potential, and hydrogen ion concentration were measured through the recirculation of nitrogen-dosed wastewater and carbon sources that were mixed to encourage microbial growth, with denitrifying bacteria identified by standard plate counts. Two different external carbon sources (sucrose and ethanol) were added, with and without activated sludge amendments. Nitrate, nitrite, and chemical oxygen demand (COD) concentrations were monitored relative to an untreated control and a treatment with activated sludge under an initial hydraulic loading rate of 0.508 m3 /m2 d and a hydraulic retention time of 2.5 h. Nitrate decay rates were only significantly enhanced for the ethanol treatment without addition of activated sludge. Nitrite initially accumulated when carbon sources were added, but no accumulation was evident by the end of the experiment after 150 min. COD declined when carbon sources were added, but activated sludge had no effect on the rate at which the COD declined. The increased rate of nitrate removal with the addition of ethanol is of technical interest, as the volume of wastewater treated in a unit volume of filter medium for denitrification doubled with ethanol compared with sucrose at the same concentration

STABILITYSOFT: a new online program to calculate parametric and non-parametric stability statistics for crop traits

PREMISE OF THE STUDY: Access to improved crop cultivars is the foundation for successful agriculture. New cultivars must have improved yields that are determined by quantitative and qualitative traits. Genotype-by-environment interactions (GEI) occur for quantitative traits such as reproductive fitness, longevity, height, weight, yield, and disease resistance. The stability of genotypes across a range of environments can be analyzed using GEI analysis. GEI analysis includes univariate and multivariate analyses with both parametric and non-parametric models. METHODS AND RESULTS: The program STABILITYSOFT is online software based on JavaScript and R to calculate several univariate parametric and non-parametric statistics for various crop traits. These statistics include Plaisted and Peterson’s mean variance component (θi), Plaisted’s GE variance component (θ(i)), Wricke’s ecovalence stability index (Wi2), regression coefficient (bi), deviation from regression (Sdi2), Shukla’s stability variance (σi2), environmental coefficient of variance (CVi), Nassar and Huhn’s statistics (S(1), S(2)), Huhn’s equation (S(3) and S(6)), Thennarasu’s non-parametric statistics (NP(i)), and Kang’s rank-sum. These statistics are important in the identification of stable genotypes; hence, this program can compare and select genotypes across multiple environment trials for a given data set. This program supports both the repeated data across environments and matrix data types. The accuracy of the results obtained from this software was tested on several crop plants. CONCLUSIONS: This new software provides a user-friendly interface to estimate stability statistics accurately for plant scientists, agronomists, and breeders who deal with large volumes of quantitative data. This software can also show ranking patterns of genotypes and describe associations among different statistics with yield performance through a heat map plot. The software is available at https://mohsenyousefian.com/stabilitysoft/.Peer reviewe

Crop rotation options for dryland agriculture: An assessment of grain yield response in cool-season grain legumes and canola to variation in rainfall totals

Tausz, M ORCiD: 0000-0001-8205-8561Crop production in dryland systems is mainly dependent on water availability from rainfall which is highly variable between years and locations. We employed the widely used boundary-line analysis, with an existing industry dataset from across the Australian dryland cropping regions, to investigate the relative sensitivity of grain yield in canola (Brassica napus L.), chickpea (Cicer arietinum L.), faba bean (Vicia faba L.), field pea (Pisum sativum L.), lentil (Lens culinaris L.), and narrow-leafed lupin (Lupinus angustifolius L.) to variation in rainfall totals. Chickpea had the lowest non-productive water use, was more responsive to water supply, and reached its maximum yield at a lower water supply than the other species. In contrast canola had the highest non-productive water use, was less responsive to water supply, and reached its maximum yield at a higher water supply than the other species. These results suggest that chickpea offers the most stable outcome, and canola the greatest variation, in response to the variability in rainfall totals between years and locations. © 2019 Elsevier B.V

Transient daily heat stress during the early reproductive phase disrupts pod and seed development in Brassica napus L.

© 2020 The Authors. Food and Energy Security published by John Wiley & Sons Ltd. and the Association of Applied Biologists. Transient daily heat stress during flowering of canola (Brassica napus L.) as a result of global warming is an increasing threat to grain production in this important oilseed crop. We investigated the intensity and duration of transient daily heat stress treatment at different stages of reproductive development in three B. napus genotypes under controlled environment conditions. Heat stress treatments during the week before first open flower on the main stem (S0) or during the first week (S1) or second week (S2) following first open flower greatly reduced pod number and seed yield on the main stem. Heat stress treatment during the third week (S3), fourth week (S4), or fifth week (S5) reduced seed yield more on the branches and less on the main stem as time progressed. Pod number and seed yield were reduced by moderate heat stress (TC2; 32°C/22°C) and high heat stress (TC3; 35°C/25°C), compared with the control (TC1, 25°C/15°C). Each duration of heat stress treatment (3, 5 or 7 days) caused the same reduction in pod number and seed per pod on the main stem. Leaf stomatal conductance, leaf chlorophyll index, plant height, and dry weight of above‐ground biomass increased from TC1 to TC3, which indicates that heat stress in the absence of drought stress does not inhibit vegetative growth. Cool night temperatures (15°C) resulted in recovery of pod number and seed yield after moderate (32°C) but not high (35°C) daily transient heat stress. The range of genotype responses to heat stress was greater under TC2 than under TC3. This research brings forward the critical period for heat stress sensitivity in B. napus to one week before first open flower and defines the conditions for controlled environment screening for heat tolerance in B. napus

Adaptation of broccoli (Brassica oleracea var. italica L.) to high and low altitudes in Bali, Indonesia

© 2020 Astarini IA, Defiani MR, Suriani NL, Griffiths PD, Stefanova K, Siddique KHM. Adaptation of broccoli (Brassica oleracea var. italica L.) to high and low altitudes in Bali, Indonesia. Biodiversitas 21: 5263-5269. Broccoli is an important vegetable worldwide, with expanding markets and opportunities in Asia. In Indonesia, there is demand from high-end hotels, restaurants, and export markets, but the local supply is low quality and low yielding. Crown cuts are typically small and misshapen as the varieties are grown are not adapted to local environments. This study targeted new broccoli varieties to identify those best adapted to environmental stresses in Bali, Indonesia, using two-site replicated field experiments. Experiments were undertaken in two regions in Bali (Bedugul and Tabanan) using 13 commercial varieties that included heat-sensitive varieties and others identified as heat-tolerant in trials on the East Coast of the USA. The trials evaluated the varieties for crown initiation, days to maturity, crown size at harvest, crown diameter, and overall performance. The study demonstrated that all 13 varieties could be used for broccoli production in the Bedugul region (1200 m a.s.l. altitude), with Castle Dome being the best performer due to its earlier maturity and large high-quality crown. The varieties Bay Meadows, Belstar, Imperial, and Sarasota could be used in the Tabanan region

Root trait diversity, molecular marker diversity, and trait-marker associations in a core collection of Lupinus angustifolius

Narrow-leafed lupin (Lupinus angustifolius L.) is the predominant grain legume crop in southern Australia, contributing half of the total grain legume production of Australia. Its yield in Australia is hampered by a range of subsoil constraints. The adaptation of lupin genotypes to subsoil constraints may be improved by selecting for optimal root traits from new and exotic germplasm sources. We assessed root trait diversity and genetic diversity of a core collection of narrow-leafed lupin (111 accessions) using 191 Diversity Arrays Technology (DArT) markers. The genetic relationship among accessions was determined using the admixture model in STRUCTURE. Thirty-eight root-associated traits were characterized, with 21 having coefficient of variation values >0.5. Principal coordinate analysis and cluster analysis of the DArT markers revealed broad diversity among the accessions. An ad hoc statistics calculation resulted in 10 distinct populations with significant differences among and within them (P < 0.001). The mixed linear model test in TASSEL showed a significant association between all root traits and some DArT markers, with the numbers of markers associated with an individual trait ranging from 2 to 13. The percentage of phenotypic variation explained by any one marker ranged from 6.4 to 21.8%, with 15 associations explaining >10% of phenotypic variation. The genetic variation values ranged from 0 to 7994, with 23 associations having values >240. Root traits such as deeper roots and lateral root proliferation at depth would be useful for this species for improved adaptation to drier soil conditions. This study offers opportunities for discovering useful root traits that can be used to increase the yield of Australian cultivars across variable environmental conditions