Phoma diseases: Epidemiology and control

Phoma is the most widely distributed and omnipresent genus of the order Pleosporales and the largest genus with some 3,000 taxa described so far. Of these, approximately 110 species are pathogenic and occupy varied ecological niches. The genus Phoma is polyphyletic and is not really delimited, with unclear species boundaries that make it a taxonomically controversial genus. Fungi belonging to Phoma commonly occur on crop plants that are economically important, where they cause devastating plant diseases. Pathogenic members of Phoma sensu lato species attack crop plants with symptoms ranging from leaf blight to root rot, and even wilting of the plant. In infected crop residues and field stubbles, the pathogen produces abundant pycnidia and pseudothecia that serve as the source of primary inoculum, whilst repeated crops of conidia produced inside pycnidia are the main source of secondary infection during the same growing season. After successful infection, the pathogen produces various phytotoxins that alter photosynthetic efficiency and actin cytoskeleton-based functions, and cause electrolyte leakage from cells. Controlling the diseases caused by members of Phoma sensu lato is challenging and efforts have been made to identify resistant varieties that can be used in various plant breeding programmes. Studies have also been conducted to devise cultural and biological control measures as well as to evaluate the efficacy of fungicides against members of Phoma sensu lato. In this review we aim to discuss the disease epidemiology and control measures that can be practised to protect crops from Phoma diseases.     

Supplemental effect of <Emphasis Type="Italic">Porphyra</Emphasis> spheroplasts on the growth and feed utilization of black sea bream

ABSTRACT:   A 56-day feeding trial was conducted to evaluate the effects of Porphyra spheroplasts (PS) as a feed additive on growth, carcass composition and feed utilization of black sea bream. Four experimental diets with or without PS (0, 1, 3, 5% inclusion level) were formulated to determine the proper incorporation level for best growth and utilization using white fishmeal as the principal protein source. Three replicate groups of fish averaging 1.28 ± 0.05 g (mean ± SD) were maintained in flow-through thermo-controlled sea water (32–34 psu, 25°C) aquaria (100 L) under the laboratory conditions (L12 : D12) and fed three times a day at 09:00, 13:00 and 17:00 hours by hand at approximately 3% body weight on each diet. The rearing trial revealed that growth performance (in terms of weight gain, specific growth rate) are almost the same level in all the dietary groups, nevertheless the survival, nutrient utilizations and retentions (feed efficiency, protein efficiency ratio, protein retention rate, lipid retention rate) were significantly higher ( P  < 0.05) in a group fed on the diet containing 3% spheroplasts. Further, the fish fed on the diet containing PS had significantly higher ( P  < 0.05) crude lipid level in their dorsal muscles and viscera. The fish fed a PS-based diet showed higher level of eicosapentaenoic acid and docosahexaenoic acid (DHA) in viscera and DHA in dorsal muscles. The results obtained in this feeding trial suggest that the optimum dietary PS supplementation level up to 3% for black sea bream can be considered as improved consequence on growth performance, nutrient utilization or body composition were noticed.     

Critical values of alternative organic amendments on kiwi seedling growth

The present research was conducted to explore the impact of alternative organic amendments on physicochemical properties of soil and their critical value for kiwi seedlings growth. The experiment was laid out in completely randomized design with 3 replications and 20 seedlings per replication. The highest pH (8.0) was recorded in T3 (compost + silt) and the highest electrical conductivity (EC) of 5.91 dS/m, organic matter (24.11%), organic carbon (13.99%), organic nitrogen (1.51%) were recorded in T8 (compost + peat moss (PM) + leaf manure) and the highest soil porosity (SP) (45.95%) and lowest bulk density (0.67) were recorded in T4 (PM + garden soil (GS)). EC higher than 1.99 and SP (45.95%) were found critical and adversely affected seedling survival. The highest plant height (103 and 93 cm), number of leaves (23 and 20), number of first-order lateral roots (NFLRM) (9 and 8.5), whole seedling fresh mass (75 and 72 g), fresh root mass (FRM) (35 and 35 g), shoot fresh mass (46 and 40 g), root collar diameter (RCD) (13 and 12 mm), and shoot diameter (10 and 9 mm) were recorded in T5 (compost + GS) and T7 (compost + PM + GS). Strong and positive correlations were observed among NFLRP, RFM, and RCD (R² = 0.89 and 0.96) and all the above-ground seedling traits (R² = 0.86–0.98). It is concluded that compost is a good soil amendment for producing good quality graftable kiwi seedlings and evaluation of seedling root system architecture could be used to predict the potential and success of seedlings in the field.     

Antifungal clerodane diterpenes from Macaranga monandra (L) Muell. et Arg. (Euphorbiaceae)

Hexane and ethyl acetate phases of the methanol extract of Macaranga monandra showed fungal growth inhibition of Colletotrichum acutatum, C. fragariae and C. gloeosporioides, Fusarium oxysporum, Botrytis cinerea, Phomopsis obscurans, and P. viticola. Bioassay-guided fractionation led to the isolation of two active clerodane-type diterpenes that were elucidated by spectroscopic methods (1D-, 2D-NMR, and MS) as kolavenic acid and 2-oxo-kolavenic acid. A 96-well microbioassay revealed that kolavenic acid and 2-oxo-kolavenic acid produced moderate growth inhibition in Phomopsis viticola and Botrytis cinerea.     

Enhancing phosphorus availability,soil organic carbon,maize productivity and farm profitability through biochar and organic–inorganic fertilizers in an irrigated maize agroecosystem under semi‐arid climate

Biochar amendments offer promising potential to improve soil fertility, soil organic carbon (SOC) and crop yields; however, a limited research has explored these benefits of biochar in the arid and semi‐arid regions. This two‐year field study investigated the effects of Acacia tree biomass‐derived biochar, applied at 0 and 10 t ha^?1 rates with farmyard manure (FYM) or poultry manure (PM) and mineral phosphorus (P) fertilizer combinations (100 kg P ha^‐1), on maize (Zea mays L.) productivity, P use efficiency (PUE) and farm profitability. The application of biochar with organic–inorganic P fertilizers significantly increased soil P and SOC contents than the sole organic or inorganic P fertilizers. Addition of biochar and PM as 100% P source resulted in the highest soil P (104% increase over control) and SOC contents (203% higher than control). However, maize productivity and PUE were significantly higher under balanced P fertilizer (50% organic + 50% mineral fertilizer) with biochar and the increase was 110%, 94% and 170% than 100%‐FYM, 100%‐PM and 100% mineral fertilizer, respectively. Maize productivity and yield correlated significantly positively with soil P and SOC contents These positive effects were possibly due to the ability of biochar to improve soil properties, P availability from organic–inorganic fertilizers and SOC which resulted in higher PUE and maize productivity. Despite the significant positive relationship of PUE with net economic returns, biochar incorporation with PM and mineral fertilizer combination was economically profitable, whereas FYM along biochar was not profitable due to short duration of the field experiments.     

Essential oil bearing aromatic plants: Their potential for sequestering carbon in marginal soils of India

Continuous rise in the atmospheric CO₂ concentration upshots the genesis of cataclysmic planetary problems such as global warming and climate change. Another critical issue which is environmentally challenging is land degradation. When productive land is poorly managed, it turns to marginal land. And further degradation of marginal land ends up to being unproductive land. On the Contrary, considerable part of depleted soil C pool can be restored through the adoption of conservation agricultural practices, unproductive land could be converted to marginal land and by its further restoration, into productive land. Aromatic plants can sustain various adverse conditions prevailing on the marginal lands. Aromatic plants require low input but the output is quite high due to the production of highvalue essential oil. The pivotal perspective of utilization of marginal lands of India for the production of aromatic plants would explore factors such as land availability, aromatic plants adaptability, C sequestration potential and economic feasibility. India is the largest exporter of essential oils and produces huge amount of aromatic spent residues, which could be converted into several valueadded products. Proficient recycle of distillation waste of aromatic plants in marginal lands will aid to sequester C in soil and enhance the biomass yield. Improvement in the livelihood of farmers especially in developing nations through rise in production and income diversification would encourage farmers to reclaim their marginal lands and accelerate their transition to aromatically cultivable lands.     

Silicon: a beneficial nutrient for maize crop to enhance photochemical efficiency of photosystem II under salt stress

Soil salinity imposes an unprecedented risk to the soil fertility and availability of plant nutrients. The present proposal is designed to address the effect of salt stress on photosynthetic apparatus of maize including chlorophyll a fluorescence and how silicon nutrition helps to overcome this issue. In a sand culture experiment, two maize cultivars were sown in small pots with two levels of silicon (0 and 2 mM H₂SiO₃) and two levels of salinity stress (0 and 60 mM NaCl). Salinity stress reduced dry matter yield and potassium (K) concentration in both maize cultivars and also induced inefficient working of photosynthetic apparatus including photochemical efficiency of photosystem II. Silicon addition alleviated NaCl stress on maize crop by improving the dry matter yield and water use efficiency (WUE). It decreased shoot Na concentration by increasing root and shoot K concentration of maize plants. It enhanced maximum quantum yield of primary photochemistry which leads to smooth electron transport chain. It also significantly enhanced shoot silicon concentration and has a significant positive correlation with WUE. Therefore, silicon-treated maize plants have better chance to survive under salt stress conditions as their photosynthetic apparatus is working far better than non-silicon-treated plants.