Does orientation of raft helps in augmenting yield during lean period?: A case study of Gracilaria edulis cultivation in open sea by vertical raft alignment along the south-eastern coast of India

The food grade agar in India has been almost exclusively obtained from Gracilaria edulis, but the industrial production overwhelmingly relies on exploitation of natural resources. United Nations efforts through Food and Agriculture Organization under Bay of Bengal Program highlighted the necessity of undertaking commercial farming of this species along Indian coast for socio-economic benefits. The pilot-scale experiments established viability of large-scale cultivation by floating raft method. Nevertheless, drastic reduction in yield and quality during summer months due to enhanced sedimentation and severe epiphytism is found to be a major hindrance. Altering the positioning of rafts from horizontal to vertical alignment improved the growth and yield under open sea condition at two different locations along south east coast of India. The average yield in horizontal raft was found to be 3.08 ± 0.61 kg fr wt raft⁻¹ with corresponding DGR of 1.87 ± 0.63% day⁻¹ while same in case of vertical rafts was 13.76 ± 3.86 kg fr wt raft⁻¹ and 5.00 ± 0.5% day⁻¹ in Gulf of Mannar under 45 days growth cycle. The corresponding values along Palk Bay were 2.98 ± 0.52 g fr wt raft⁻¹ and 1.38 ± 0.42% day⁻¹ for horizontal raft and 13.02 ± 6.06 kg fr wt raft⁻¹ and 4.14 ± 1.18% day⁻¹ for vertical raft. ANOVA clearly indicated that raft position significantly influenced the biomass yield and DGR at Palk Bay (F = 75.77; F = 112.81) as well as Gulf of Mannar (F = 27.21; F = 59.16) at p = 0.001. The increment of 1.9–2.6% in fresh weight of individual frond was reported in vertically aligned rafts. The computational fluid dynamics (CFD) based unsteady numerical simulations have confirmed that vertical alignment of raft facilitates relatively free movement of water due to which sedimentation and epiphytism are either minimised or eliminated. Thus these studies can help us to deduce important conclusions pertaining to management of sustained commercial cultivation of this alga in Indian waters.     

Unequal salt distribution in the root zone increases growth and yield of cotton

Soil salinity is often heterogeneous, yet plant response to unequal salt distribution (USD) in the root zone is seldom studied in cotton (Gossypium hirsutum L.). Our objective was to evaluate the effects of USD on growth and yield, as well as its potential application for increasing cotton production. To achieve this objective, greenhouse and field experiments were conducted. In the first experiment, potted cotton plants were grown in a split-root system in the greenhouse. Each root half was irrigated with either the same or two concentrations of NaCl. Plant biomass, leaf chlorophyll (Chl), photosynthesis (Pn) and transpiration (Tr), Na⁺ and K⁺ accumulation, as well as biological and economic yields were determined. In the second experiment, plants were grown in furrow-beds in saline fields with those grown on flat beds as controls. Root-zone salinity, yield and yield components and earliness (the percentage of the first two harvests to total harvests) were monitored. When the entire root system was exposed to the same concentration of NaCl, shoot dry weight, leaf area, plant biomass, leaf Chl, Pn and Tr were markedly reduced relative to the NaCl-free control at 2 weeks after salinity stress (WAS). Significant reductions in biological (23.6–73.8%) and economic yields (38.1–79.7%) were noticed at harvest. However, when only half of the root system was exposed to low-salinity, the inhibition effect of salinity on growth and yield was significantly reduced. Plant biomass and seed cotton yield were increased by 13 and 23.9% with 50/150 mM/mM NaCl, 40 and 44.5% with 100/300 mM/mM NaCl, and 85.7 and 127.8% with 100/500 mM/mM NaCl relative to their respective equal salt distribution (ESD) controls (100/100, 200/200, and 300/300). Unequal salt distribution also decreased concentrations of Na⁺ and increased leaf K⁺ and Chl content, K⁺/Na⁺ ratio, Pn and Tr, compared with ESD. Furrow-bed seeding induced unequal distribution of salts in the surface soil during the field experiment. Under furrow planting, soil salinity was much higher, but soil osmotic potential was much lower on the ridged part than the furrows. Yield and earliness were increased 20.8 and 5.1% by furrow seeding relative to flat seeding. These enhancements were mainly attributed to unequal distribution of salts in the root zone. Thus, specific cultural practices that induce unequal salt distribution such as furrow-bed seeding can be used to improve cotton production in saline fields.     

Biocontrol of rice blast by the phenaminomethylacetic acid producer of Bacillus methylotrophicus strain BC79

Strain BC79, isolated from primeval forest soil in Qinling, Mountains, China, was identified as Bacillus methylotrophicus based on morphological, biochemical, physiological and chemotaxonomic analyses as well as phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi in dual cultures on solid media. For exploring potential biocontrol activity, we assessed fermentation conditions for studying B. meth1ylotrophicus BC79. The active substance of BC79, phenaminomethylacetic acid, was extracted by TLC and HPLC, and identified as the strongest inhibitory substance described in B. methylotrophicus. Experiments in a greenhouse showed that application of BC79 culture filtrates 24 h before inoculation of Magnaporthe oryzae, the causal agent of rice blast, had 89.87% biocontrol efficiency. B. methylotrophicus BC79 colonized rice plant tissues and at 10 days after filtrate application, its population in leaves (1.65 × 10⁸ CFU/g) was much larger than in stems (6.78 × 10⁷ CFU/g) or roots (3.56 × 10⁷ CFU/g). Field trials indicated that BC79 culture filtrate (4000 g/667 m²) showed the highest efficiency for M. oryzae, with 84.8% biocontrol effect, followed by of 15% phenaminomethylacetic acid extract (75.5%) and 20% tricyclazole (76.1%). Seedling and post-transplant stages were the best periods to apply BC79 for control of rice blast. The B. methylotrophicus BC79 strain hence has enormous potential as an agricultural agent for biocontrol of rice blast.     

Short-term water management at early filling stage improves early-season rice performance under high temperature stress in South China

Asymmetric warming and frequent temperature extremes are the consequences of climate change that are affecting crop growth and productivity over the globe while heat stress at early filling stage is of serious concern for the early-season rice in double cropping rice system of South China. In present study we assessed different short-term water management strategies to cope with the high temperature at early filling stage in rice. Water was applied as flood irrigation at two various depths i.e., 4–5 cm (I1) and 5–10 cm (I2) during 9:00–18:00 and then drained off at 18:00 as well as applied over-head during different time spans i.e., over-head sprinkle irrigation during 11:00–12:00, 13:00–14:00 and 14:00–15:00 at 60–80% relative humidity (RH) at early filling stage and regarded as S1, S2 and S3, respectively. A control was maintained with the maintenance of 1 cm water layer as normal farmer practice of this region. A fragrant rice cultivar, ‘Yuxiangyouzhan’ in early March (regarded as early season rice) in both 2014–15 and the effectiveness of different water management strategies were measured by estimating physio-biochemical responses, photosynthesis, yield and quality of rice exposed to high temperature stress at early filling stage. Our results showed that water treatments lowered lipid peroxidation (in terms of reduced malondialdehyde (MDA) contents) whilst proline and protein contents were affected differently. The water treatments also regulated the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), nevertheless, improved plant photosynthesis and gas exchange, rice yield and quality attributes considerably by lowering severity of canopy temperatures than control (CK). On average, both flood and sprinkler water application were proved effective against high temperature stress, nonetheless, flood irrigated treatments were remained more effective than sprinkler which provided 26.58 and 43.63% higher grain yields in 2014–15, respectively than CK. On average, 5.58 and 11.92% higher grain yields were recorded in flood irrigation than sprinkler irrigation whereas among individual water application treatments, I1 was noted as the most effective regarding grain yield of rice (26.76 and 49.35% higher yield than CK) in both years which suggests that maintenance of 4–5 cm water layer might be helpful for the rice to withstand against high temperature stress at post heading and/or early filling stage in early-season rice production in South China.     

Bioactive carbazole alkaloids from Murraya koenigii (L.) Spreng

Four new carbazole alkaloids (1–4) and fourteen known carbazole alkaloids (5–18) were isolated from Murraya koenigii. Their structures were elucidated on the basis of extensive spectroscopic analysis. Compounds 4, 6, 16, and 17 (10 μM) had moderate hepatoprotective activities against d-galactosamine-induced HL-7702 cell damage. Compounds 11, 12 and 18 showed significant PTP1B inhibitory activity with IC₅₀ values of 1.773, 1.875 and 2.286 μM, respectively.     

Moisture loss is the major cause of firmness change during postharvest storage of blueberry

Blueberry softening is known to be influenced by cell wall modifications accompanying ripening but these changes appear to be largely complete by the time of harvest. In this study postharvest storage conditions were controlled so only the extent of water loss varied between treatments. A linear relationship between weight loss and loss of firmness (as assessed by a non-destructive compression test) was demonstrated. This relationship did not hold at very low weight loss, where instead, firming of blueberries during storage was found. Magnetic resonance imaging of berries confirmed significant shrinkage and loss of water in berries which had high weight loss, compared with more subtle effects on sub-epidermal water content in berries with very low weight loss. Treatments which restrict blueberry water loss to below 8% are likely to be beneficial in retaining acceptable berry firmness for up to three weeks’ storage.     

Bacterial community structure of nirK-bearing denitrifiers and the development of properties of soils in created mitigation wetlands

We investigated the abundance and genetic heterogeneity of bacterial nitrite reductase genes (nir) and soil structural properties in created and natural freshwater wetlands in the Virginia piedmont. Soil attributes included soil organic matter (SOM), total organic carbon (TOC), total nitrogen (TN), pH, gravimetric soil moisture (GSM), and bulk density (D_b). A subset of soil attributes were analyzed across the sites, using euclidean cluster analysis, resulting in three soil condition (SC) groups of increasing wetland soil development (i.e., SC1 < SC2 < SC3; less to more developed or matured) as measured by accumulation of TOC, TN, the increase of GSM, and the decrease of D_b. There were no difference found in the bacterial community diversity between the groups (p = 0.4). NirK gene copies detected ranged between 3.6 × 10⁴ and 3.4 × 10⁷ copies g⁻¹ soil and were significantly higher in the most developed soil group, SC3, than in the least developed soil group, SC1. However, the gene copies were lowest in SC2 that had a significantly higher soil pH (~6.6) than the other two SC groups (~5.3). The same pattern was found in denitrifying enzyme activity (DEA) on a companion study where DEA was found negatively correlated with soil pH. Gene fragments were amplified and products were screened by terminal restriction fragment length polymorphism (T-RFLP) analysis. Among 146 different T-RFs identified, fourteen were dominant and together made up more than 65% of all detected fragments. While SC groups did not relate to whole nirK communities, most soil properties that identified SC groups did significantly correlate to dominant members of the community.     

百色杧果栽培种质果实品质多样性分析

广西的杧果(Mangifea indica L.)以百色右江干热河谷为重要栽培地区,百色地区的杧果栽培品种仍然以传统品种为主,伴随着新兴杧果产区的崛起,急需选育适宜百色的杧果新品种,以提升百色杧果的竞争力.目前,在广西以外的其他地区已经开展了不同杧果品种性状评价的研究,而针对广西百色地区杧果栽培种质的多样性分析评价鲜有...     

氧化沉降条件下草甘膦对福寿螺的急性毒性效应

【目的】探究草甘膦与H₂O₂复合污染条件下草甘膦对福寿螺Pomacea canaliculata的急性毒性效应。【方法】采用静水式生物测试法,采集田间生长均匀一致的成年福寿螺,使其暴露于不同浓度草甘膦和近似广州地区降水H₂O₂浓度(50μmol·L^-1)的水体中。研究氧化沉降条件下草甘膦对福寿螺生境的水质部分指标和急性毒性效应的影响。【结果】水体水质指标中,氧化还原电位（Oxidation-reduction potential,ORP）随暴露时间增加而上升,由330 mV上升至540 mV左右;pH随暴露时间增加,不同处理有上升也有下降的趋势,最终都维持在7.0～8.5;溶解氧（Dissolved oxygen,DO）在8.5～16.0 mg·L^-1之间,无固定变化规律;这3个指标都维持在福寿螺生长能适应的范围内。急性毒性试验表明,草甘膦对福寿螺为低毒,在有或无H₂O₂添加时其48 h的半致死浓度(LC