西瓜砧木种传真菌的初步检测

采用洗涤离心法和PDA培养基法对14个西瓜砧木主栽品种进行了种传真菌检测.结果表明,种子表面携带的优势菌群主要为镰刀菌(Fusarium spp.)、青霉属(Penicillium spp.)、曲霉属(Aspergillus spp.)、根霉属(Rhizopus spp.)、链格孢属(Alternaria spp.)真菌.种子内部寄藏的真菌主要为镰刀菌、青霉属和曲霉属真菌,其中西瓜砧木种子内部寄藏镰刀菌为国内首次报道.不同品种的种子表面携带真菌种类差异较大,种子内部寄藏真菌种类差异不明显,种壳带菌率一般高于种胚带菌率.     

木霉菌T-115D对马铃薯早疫病菌的拮抗作用

为了明确木霉菌T-115D对马铃薯早疫病菌的拮抗作用和拮抗机制,采用平板对峙培养试验和木霉菌T-115D发酵液对马铃薯早疫病菌生长的抑制试验,研究木霉菌T-115D对马铃薯早疫病菌的拮抗作用及其机制。对峙培养结果表明,木霉菌能迅速占领大部分空间,抑制马铃薯早疫病菌的生长,显微镜观察发现,木霉菌菌丝可缠绕和寄生早疫病菌菌丝;木霉菌发酵液对马铃薯早疫病菌菌丝生长有较强抑制作用,在木霉菌T-115D发酵液稀释3倍后对菌丝生长的抑制率为90.4%,发酵原液对马铃薯早疫病菌孢子萌发的抑制率为100%,说明木霉菌T-115D对马铃薯早疫病菌具有明显的拮抗作用,其拮抗机制包括抑制菌丝生长和孢子萌发、营养空间竞争和寄生作用。     

甘肃苜蓿斑点病的初步研究

近年来甘肃省苜蓿(Medicago stativa L.)发生一种叶部病害—-斑点病,严重地降低了苜蓿的产量和饲用价值。为了有效地控制该病害对苜蓿的危害,在室内对其病原菌进行了形态学鉴定及生物学特性研究。结果表明:苜蓿斑点病的病原菌为链格孢菌(Alternaria alternata (Fr.:Fr) Keissler),该病原菌能很好地利用麦芽糖、蔗糖、甘氨酸;其生长最适温度为25℃,最适pH为6.0-7.0,最适宜的RH为98%以上,最适培养基为5%AL和PSA。在上述环境条件下,菌丝生长快,菌丝茂盛,产孢量大,孢子萌发率高。     

新疆瓜类由链格孢霉(Alternaria)侵染所致两类叶斑病的纪录及鉴别

纪录了新疆瓜类作物由真菌Alternaria侵染所致的两类叶斑型的病害.一类鉴定为系由A.cucumerina(Ell.et Hv.)Elliott侵染引起的黑轮斑病,另一类鉴定为系由A.cucurbitae Letendre et Roum侵染引起的褐轮斑病.将两类叶斑病感染的症状及其致病原均分别进行了详细地描述、区分并给予了讨论.     

芦荟黑斑病发生规律及室内药剂筛选

为了解芦荟黑斑病的发生规律,进一步为防治提供理论依据。该文对三种越冬形式的病原菌分别采用直接镜检、组织分离法及致病性测定对芦荟黑斑病菌（Alternaria obpyriformis T. Y. Zhang）进行了越冬场所和越冬方式的研究。通过针刺法、涂抹法及玻片粘着法确定病菌侵入和传播途径。人工接种条件下测定了病菌对5科10种植物的侵染能力。采用孢子萌发法和菌丝生长速率法对病菌进行室内药剂筛选。结果表明,病原菌可在病残体上以菌丝和分生孢子越冬,通过气孔和伤口侵入寄主,分生孢子能借助气流传播;人工接种时能侵染豆科、十字花科的部分植物。供试的7种药剂对病菌菌丝生长和孢子萌发都有显著的抑制作用,其中施保功可湿性粉剂对其病菌的菌丝体抑制效果最好,抑菌率达84.24%;扑海因悬浮剂对分生孢子萌发抑制效果最佳,抑制率为67.44%。     

Supplementation of plant‐based diets for rainbow trout (Oncorhynchus mykiss) with macro‐minerals and inositol

Replacement of fish meal with plant products in aquafeeds results in the elimination of dietary compounds which may be important for optimal growth and physiology. A study was conducted to determine if supplementation with macro‐minerals and/or inositol would improve performance of rainbow trout (Oncorhynchus mykiss) fed a plant‐based diet. Four iso‐caloric and iso‐nitrogenous diets (40 g kg^?1 protein and 15 g kg^?1 lipid) were formulated and consisted of a fish meal‐based control diet (control) and three plant‐based experimental diets. Plant‐based diets were supplemented with either macro‐minerals and inositol (+MM+I), no macro‐minerals with inositol (?MM+I), and no macro‐minerals and no inositol (?MM?I). Sodium chloride, potassium chloride and magnesium oxide were the sources used in the macro‐mineral premix. There was no effect of diet on survival, but there was an effect of diet on weight gain, FCR, feed intake, HSI and nutrient retentions. Significant liver pathology was observed in trout fed plant‐based diets without MM supplementation. Supplementation of MM and inositol significantly improved weight gain of trout fed a plant‐based diet. Supplementation of MM and/or inositol also improved PRE and ERE. This study demonstrates the importance of supplementing these nutrients to trout fed fish meal free diets.     

Evaluation of mosquito fish Gambusia holbrooki (Girard) as a partial and complete pellet replacement for juvenile barramundi Lates calcarifer (Bloch)

Barramundi (Lates calcarifer, Bloch) fed live mosquito fish (Gambusia holbrooki, Girard) exhibited faster growth and a better food conversion ratio (on a dry‐weight basis) than those fed an iso‐calorific ration of commercial barramundi pellets and a 50:50 ration of mosquito fish and pellets. The improved performance of barramundi fed mosquito fish was attributed to their higher protein content, higher protein to energy ratio and lower carbohydrate content. The essential amino acid indices and fatty acid profiles of the two diets were similar, suggesting that imbalances or deficiencies in these nutrients were not the limiting factor to the slower growth of barramundi fed on pellets. The use of mosquito fish as barramundi food offers a potential use of this noxious species and may allow barramundi to be cultured without the use of conventional fish meal.     

青风藤叶枯病病原菌的分离鉴定及防治药剂的筛选

2021年春季，从湖南省怀化市中方县正清制药青风藤基地和湖南农业大学试验基地分别采集青风藤叶枯病病叶，利用组织分离法获得病原菌，并进行柯赫氏法则验证。借助形态学鉴定和分子系统学分析，明确青风藤叶枯病病原为交链隔孢(Alternaria alternata)。利用菌丝生长速率法对5种药剂(95%苯醚甲环唑、98%咪鲜胺、96%己唑醇、96.5%丙硫菌唑、98%嘧菌酯)进行筛选，结果显示95%苯醚甲环唑抑菌效果最好，EC₅₀为0.043 6 mg/L;98%嘧菌酯抑菌效果最差，EC₅₀值为8.447 3 mg/L。     

Effect of fertigation frequency on soil nitrogen distribution and tomato yield under alternate partial root-zone drip irrigation

Alternate partial root-zone drip fertigation (ADF) is a combination of alternating irrigation and drip fertigation, with the potential to save water and increase nitrogen (N) fertilizer efficiency.  A 2-year greenhouse experiment was conducted to evaluate the effect of different fertigation frequencies on the distribution of soil moisture and nutrients and tomato yield under ADF.  The treatments included three ADF frequencies with intervals of 3 days (F3), 6 days (F6) and 12 days (F12), and conventional drip fertigation as a control (CK), which was fertilized once every 6 days.  For the ADF treatments, two drip tapes were placed 10 cm away on each side of the tomato row, and alternate drip irrigation was realized using a manual valve on the distribution tapes.  For the CK treatment, a drip tape was located close to the roots of the tomato plants.  The total N application rate of all treatments was 180 kg ha–1.  The total irrigation amounts applied to the CK treatment were 450.6 and 446.1 mm in 2019 and 2020, respectively; and the irrigation amounts applied to the ADF treatments were 60% of those of the CK treatment.   The F3 treatment resulted in water and N being distributed mainly in the 0–40-cm soil layer with less water and N being distributed in the 40–60-cm soil layer.  The F6 treatment led to 21.0 and 29.0% higher 2-year average concentration of mineral N in the 0–20 and 20–40-cm soil layer, respectively and a 23.0% lower N concentration in the 40–60-cm soil layer than in the CK treatment.  The 2-year average tomato yields of the F3, F6, F12, and CK treatments were 107.5, 102.6, 87.2, and 98.7 t ha–1, respectively.  The tomato yield of F3 was significantly higher (23.3%) than that in the F12 treatment, whereas there was no significant difference between the F3 and F6 treatment.  The F6 treatment resulted in yield similar to the CK treatment, indicating that ADF could maintain tomato yield with a 40% saving in water use.  Based on the distribution of water and N, and tomato yield, a fertigation frequency of 6 days under ADF should be considered as a water-saving strategy for greenhouse tomato production.     

Improved management of mango fruit though orchard and packinghouse treatments to reduce lenticel discoloration and prevent decay

Mango fruit are exposed to complex postharvest handling management, intended to improve postharvest quality retention during export shipment. Susceptibility to lenticel discoloration and to Alternaria side rots and Phomopsis stem-end rot under current handling conditions led us to re-evaluate and modify the chain of postharvest treatments, from the orchard to the packinghouse. The previously developed hot-water brushing (HWB) treatment was found effective in reducing incidence of Alternaria and stem-end rots, but it significantly induced development of red lenticels. Two factors were key to improving fruit quality, by simultaneously reducing lenticel discoloration and decay development: (a) postharvest water and/or NaOH washes in the orchard, and (b) hot-water spray (HWS) applied over rollers without brushes in the packinghouse. The present results indicate that optimal management involves combinations of water washes in the orchard with packinghouse HWS treatment; this significantly reduced the severity of lenticel discoloration by 50–60%, and the incidence and extent of postharvest side rots caused by Alternaria by 60% or more. These results indicate that appropriate handling of fruit can appreciably improve their quality during prolonged storage and shipment.