Saprophytic and pathogenic behaviour of R. solani AG2-1 (ZG-5) in a soil amended with Diplotaxis tenuifolia or Brassica nigra manures and incubated at different temperatures and soil water content Abstract The Brassicaceae species Diplotaxis tenuifolia and Brassica nigra contain high concentrations of glucosinolates, the precursors of isothiocyanates (ITCs) that can have biofumigation effects in amended soils. In a laboratory experiment, incorporation of these plants as green manures into soil was expected to suppress Rhizoctonia solani AG2-1 (ZG5), the causal agent of damping-off in canola (Brassica napus). The manures were incorporated at 1 (1% w/w) or 5 (5% w/
The sensitivity of different forms of propagules of Rhizoctonia solani anastomosis group (AG)2-1/zymogram group (ZG)5 to volatile compounds produced in soil amended with green manure will influence the efficacy of green manures used to manage the disease. In laboratory experiments, we determined the impact of volatiles arising from residues of five species of Brassicaceae, and Avena sativa (oat), a non-Brassicaceae species, and volatiles of pure allyl isothiocyanate (AITC) or 2-phenylethyl isothiocyanate (2-PEITC) in either their soluble or vapour phase on the hyphal growth of R. solani arising from different propagules. The brassicaceous species were Brassica napus var. Karoo, B. napus B1, B. napus B2, B. nigra and Diplotaxis tenuifolia (a brassicaceous weed). Colony growth and hyphal density on water agar were measured up to 7 days. The amendment of a sandy soil with green manures at a high (100 g kg 21 , 10%) concentration generally suppressed the growth of the pathogen, but at a low (10 g kg 21 , 1%) concentration, the amendment had little effect on the radial fungal growth of the pathogen but increased the density of hyphae through more branching. The inhibition by volatiles from the residues of Brassicaceae species at 10% concentration was stronger (82-86%) than that by volatiles from oat (64%) amendment at the same rate. Hyphae arising from sclerotia and precolonised ryegrass seed were less sensitive than hyphae growing out of potato dextrose agar plugs. This indicates that thickpigmented cell walls may have protected the fungus from these unfavourable conditions. Pure AITC and 2-PEITC in the range of 0.5-2.0 mM inhibited the growth of R. solani from all forms of propagules, but hyphae originating from agar plugs were the most vulnerable compared with the two others. Thus, hyphae arising from the medulla of the sclerotia may be relatively tolerant to volatile compounds emanating from decomposing Brassica green manure amendments in the field and in vitro inhibition of the vegetative growth of the pathogen may not reflect its response to the amendments in the field.
<p>Endofit merupakan mikroorganisme (bakteri, jamur, atau aktinomisetes) yang hidup dan berkoloni di dalam jaringan inang tanpa menimbulkan efek negatif, bahkan banyak memberi keuntungan terhadap inangnya. Salah satu keuntungannya adalah sebagai agensia pengendali hayati baik untuk serangga hama maupun pa-togen penyebab penyakit tanaman. Sebagai agensia hayati, endofit dapat mengurangi kerusakan tanaman oleh serangga, nematoda, atau patogen penyebab penyakit melalui induksi ketahanan tanaman. Selain itu endofit juga dapat berfungsi sebagai agensia hayati melalui interaksi antagonis dan kompetisi. Dalam artikel ini akan dibahas kemampuan endofit sebagai agensia hayati serangga hama dan patogen; mekanisme yang berlang-sung; serta aplikasi endofit dalam dunia pertanian, khususnya tanaman perkebunan.</p><p> </p><p>Endophytes are recognized as microorganisms (bacteria, fungi, or actinomycetes), living and colonizing within host tissues without causing any harm, but giving many benefits to their host. One of the advantages is their role as biocontrol agents for insect pest or plant pathogen. As biocontol agents, endophytes could re-duce plant damage by insects, nematodes, and pathogens through induction for plant resistant mechanisms. Endophytes can also act as biocontrol agents through antagonistic and competition interactions. This article reviews the ability of endophytes as biocontrol agents for insect pest and plant pathogen, the mechanism, and application of endophytes in agriculture, particularly in estate crops.</p>
Shrimp culture is carried out by ponds in open areas, especially near coastal areas. The ponds water condition or water quality has a significant impact on the shrimp culture. There are also frequent problems among these shrimp ponds, such as crop failure caused by bad water quality. The water quality monitoring in shrimp ponds is often done manually by the farmer in periodical times. The water quality monitoring that is done manually tends to be impractical, requires high worker wages, and has a high human error rate. With the advances in the field of Information Technology, data may be retrieved through sensors and collected into a server. Then the data may be processed and visualized in order to support precision aquaculture using the Internet of Things (IoT). Precision Fish Farming (PFF) or precision aquaculture is a concept that applies control-engineering principles to aquaculture industries. The PPF concepts allow farmers to have the ability to monitor, control, and document biological processes in aquaculture farms. This research aims were to design and build a multi node sensor and master board to monitor water quality in real time using the prototyping method. The system consists of several sensors for monitoring temperature, pH, and salinity in shrimp ponds that are installed at each node. Nodes are actively sending data to the master board. This model is done to reduce the need for direct data access to the internet. The monitoring system is tested in PB Tunas Baru shrimps pond in order to check if the system may work properly. The sensor is set to retrieve pond water quality data every 5 minutes in a total 100 minute period. The result shows that the model works properly, and the means value of the total error rate for the salinity sensors, pH, and temperature sensors consecutively is 1.65%, 1.25%, and 0%. This information allows the farmers to maintain the water quality precisely in aim to produce high quality shrimp crops toward the precision aquaculture concepts.
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