一株耐盐溶磷真菌的筛选、鉴定及其生物肥料的应用效果

【目的】从内蒙古种植向日葵的盐碱地中筛选高效溶磷真菌,为农业生产中增产节肥,开发耐盐、溶磷微生物肥料提供菌种资源。【方法】利用形态特征和ITS r DNA序列鉴定菌株;LC-MS技术测定菌株M2在液体培养基中分泌有机酸和植物激素含量,明确菌株M2的溶磷和促生机理。采用液体摇床培养试验测定了鉴定菌株的溶磷能力。试验处理包括:在磷酸三钙、磷酸铝和5个磷矿的磷矿粉制备的100 m L难溶磷磷源(含5g/L难溶磷)中,接入1 m L灭菌培养液对照,和分别接种1 m L斜卧青霉菌P83和草酸青霉菌M2共15个处理。置于28℃、160 r/min摇床培养,分别于3、6和9 d,取菌液5 m L,在12000 r/min、4℃离心5 min,取上清液测定有效磷含量。采用含Na Cl的固体培养基测定菌株的耐盐性。Na Cl含量分别为0%、5%、7.5%、10%和12.5%的PDA平板中接入溶磷菌,置于28℃恒温培养箱中5 d,观察并记录菌丝的生长状况。采用盆栽试验方法检验了菌株的溶磷能力。以玉米种子(郑单958)为供试作物,以水稻土、黏性潮土、盐潮土和石灰性潮土为供试土壤,以Ca_3(PO_4)_2、AlPO_4和昆阳磷矿粉(RP)为供试磷源(磷源用量为1.0 g/kg土壤)。设置只加入灭菌草炭和Pikovskaya培养液对照,分别接种溶磷菌P83、M2,共计38个处理,144盆。玉米播种40天后收获,测定植株鲜重、干重和玉米根际土壤有效磷含量。田间试验以花生为供试作物,设置只加灭菌草炭和Pikovskaya培养液对照和分别接种ATCC20851、P83、M2溶磷菌剂三个处理。花生生长155 d后收获,称量花生植株鲜重和干重、花生果实鲜重和干重,同时采集花生根部土壤测定有效磷含量。【结果】溶磷菌株M2鉴定为草酸青霉(Penicillium oxalicum)。液体培养基摇床培养6 d后,接种菌株M2,以Ca_3(PO_4)_2为磷源的上清液中有效磷含量达972 mg/L,Ca_3(PO_4)_2溶解率为59.2%;以AlPO_4为磷源的有效磷含量达988 mg/L,溶解率为48.2%;以江苏锦屏、贵州开阳、云南晋宁、河北钒山和云南昆阳磷矿粉为磷源的有效磷释放量达21.0~556mg/L。菌株M2在7.5%Na Cl培养基中正常生长。盆栽试验结果发现,菌株M2对玉米植株促生效果显著,玉米植株鲜重比不接种菌剂(CK)提高26.4%~99.2%、干重增加20.0%~262.9%,土壤有效磷提高19.2~25.3mg/kg。菌株M2与4种土壤的适配性均高于对照菌株P83。田间小区花生产量结果显示,接种溶磷菌剂M2增产效果最好,花生果实产量达4.50 t/hm^2,比CK增加0.85 t/hm^2,增产23.29%。菌株M2在含有磷酸三钙、磷酸铝和开阳磷矿粉3种难溶磷培养液中经过6 d培养,均产生7种有机酸,其中草酸和柠檬酸含量最高,分别为653.46 mg/L和269.61 mg/L;培养液中均能检测到吲哚乙酸(IAA)和玉米素,IAA含量为32.38~66.17mg/L,玉米素浓度为0.05~0.07 mg/L。【结论】获得了一株耐盐、高效溶解多种难溶磷的草酸青霉菌M2,可显著增加土壤有效磷,促进玉米生长和花生增产,与4种典型土壤适配性好,具有良好的农业应用前景。

基于最佳经济效益的冬小麦–夏玉米轮作体系有机肥氮替代率的长期演变

【目的】探索长期不同有机无机肥配施方式下,小麦、玉米周年产量、经济效益及有机肥料氮和化肥氮配比变化规律,为小麦–玉米轮作体系氮肥资源管理提供技术支撑。【方法】长期定位田间试验(2007—2017年)在山东德州进行,种植方式为冬小麦–夏玉米轮作,2007—2009年小麦品种为烟农19、玉米品种为浚单20,2010—2017年小麦品种为济麦22、玉米品种为郑丹958。试验设4个有机肥(牛粪)氮用量(N0、45、120、240 kg/hm^2)和6个化肥氮用量(N 0、45、90、120、180、240 kg/hm^2),完全区组设计,三次重复。化肥氮50%用作基肥,50%在小麦拔节或玉米大喇叭口期做追肥。有机肥或只在冬小麦基施,或分为两份,分别在冬小麦、夏玉米基施。磷、钾肥(P2O5 300 kg/hm^2、K2O 300 kg/hm^2)在小麦或玉米播种前一次性基施。小麦、玉米收获期测产,采集植株样品。根据每年小麦、玉米总产出效益计算最经济的有机肥氮与化肥氮配比,分析有机肥氮与化肥氮配比随时间的演变规律。【结果】1)关于10年小麦和玉米周年平均产量,单施化肥、单施有机肥处理均低于化肥有机肥配施处理。氮用量低于180 kg/hm^2的单施化肥处理小麦和玉米周年产量都随着时间的推移逐年下降,氮用量高于180 kg/hm^2的处理产量基本保持稳定;有机肥料氮配合化肥氮,随着时间推移产量逐年升高。2)最大产值目标下,10年来有机肥氮的比例从60%左右下降到50%,有机肥氮和化肥氮的配比接近于1∶1;最佳经济效益目标下(边际产投比5∶1),当有机肥氮和化肥氮等价格时,最佳有机肥氮的比例从2007、2008的0%上升到2017年的50%左右;按实际肥料价格(有机肥氮是化肥氮的2倍)计算的最佳有机肥料氮比例,2007—2009年的最佳有机肥氮比例为0%,以后逐年上升,2017年提高到30%左右。【结论】长期定位试验结果表明,有机肥氮与化肥氮配施能获得比化肥氮或有机肥氮单施更高的产量和经济效益。按照有机氮的价格是化肥氮的2倍计算,有机无机肥配合施用时间越长,实现最佳经济效益目标的有机肥氮占的比例越高,在本试验条件下,有机无机配施10年后,有机肥氮的最高比例为34%。

Effects of long-term full straw return on yield and potassium response in wheat-maize rotation

The effect of long-term straw return on crop yield, soil potassium（K） content, soil organic matter, and crop response to K from both straw and chemical K fertilizer（K_2SO_4） were investigated in a fixed site field experiment for winter wheat-summer maize rotation in 6 years for 12 seasons. The field experiment was located in northern part of North China Plain with a sandy soil in relatively low yield potential. Two factors, straw return and chemical K fertilizer, were studied with two levels in each factor. Field split design was employed, with two straw treatments, full straw return of previous crop（St） and no straw return, in main plots, and two chemical K fertilizer treatments, 0 and 60 kg K2 O ha^（–1）, as sub-plots. The results showed that straw return significantly increased yields of winter wheat and summer maize by 16.5 and 13.2% in average, respectively, and the positive effect of straw return to crop yield showed more effective in lower yield season. Straw return significantly increased K absorption by the crops, with significant increase in straw part. In treatment with straw return, the K content in crop straw increased by 15.9 and 21.8% in wheat and maize, respectively, compared with no straw return treatment. But, straw return had little effect on K content in grain of the crops. Straw return had significant influences on total K uptake by wheat and maize plants, with an increase of 32.7 and 30.9%, respectively. There was a significant correlation between crop yield and K uptake by the plant. To produce 100 kg grain, the wheat and maize plants absorbed 3.26 and 2.24 kg K2 O, respectively. The contents of soil available K and soil organic matter were significantly affected by the straw return with an increase of 6.07 and 23.0%, respectively, compared to no straw return treatment. K_2SO_4 application in rate of 60 kg K2 O ha^（–1） showed no significant effect on wheat and maize yield, K content in crop straw, total K uptake by the crops, soil available K content, and soil organic matter. The apparent K utilization rate（percentage of applied K absorbed by the crop in the season） showed difference for wheat and maize with different K sources. In wheat season, the K utilization rate from K_2SO_4 was higher than that from straw, while in maize season, the K utilization rate from straw was higher than that from chemical fertilizer. In the whole wheat-maize rotation system, the K absorption efficiency by the two crops from straw was higher than that from K_2SO_4.