为了研究不同食用木薯品种(系)的商品薯可食率,开展调查试验,以桂热10号(GR10)、华南9号(SC9)、561、524、p294等5个食用品种(系)的商品薯为试验材料,通过测定木薯的结薯性状、剥皮难易程度,计算商品薯可食率和剥皮效率等.结果表明:561薯长、薯径、内皮厚度均显著小于其他品种(系);GR10薯径显著大于其他品种(系),商品薯质量、可食部分质量仅次于p294,可食率为80.0%,次于561,但剥皮效率显著大于561与SC9;GR10商品薯大薯剥皮效率显著大于中小薯,可食率显著大于小薯.不同食用木薯品种(系)间的结薯性状差异显著,剥皮效率与可食率,商品薯质量、可食部分质量与薯长、薯径,可食部分质量与商品薯质量均呈极显著正相关.

木薯是全球第六大粮食作物,是我国南方重要的经济作物.中国木薯的研究起步较晚,历经80多年几代人的努力,从起步到发展壮大,取得了较多突破性成果.笔者综述了中国木薯在种质资源收集与应用、育种、栽培管理及综合开发利用等方面的重要研究进展并提出未来的发展方向,为木薯科学研究与生产提供借鉴参考.

试验设置了不同的缓释肥及普通肥料处理,研究了不同缓释肥对木薯生长及土壤速效养分的影响,结果表明:施肥处理显著促进了木薯株高、茎粗、鲜薯产量、淀粉产量等增加,其中T6处理促进效果最佳;不施肥处理(T1)脲酶和蔗糖酶活性最高,6个施肥处理对土壤速效养分及酶活性的影响整体上差异不明显;T4、T5、T6处理较复合肥处理(T2)鲜薯产量分别增加了3.63％、18.52％、21.13％,淀粉产量分别增加了2.11％、20.03％、25.19％;在相同氮、磷、钾施肥量水平下,T4与T7处理两者各项指标均无显著差异,但前者比后者的鲜薯增产了9.49％,淀粉产量提高了5.86％.在一定施肥范围内,木薯鲜薯产量和淀粉产量均随着缓释肥Osmocote 1号施肥量的增加而增加.施肥处理碱解氮含量相比不施肥处理(T1)提高了3.53％～37.94％,速效磷含量提高了17.65％～81.79％,速效钾含量提高了15.49％～88.57％.综合考虑肥料成本、产量和环保等因素,T5(N 75 kg/hm2、P2O575 kg/hm2、K2O 75 kg/hm2)为本研究最佳施肥组合.

为了打破传统木薯行业发展瓶颈,应对木薯行业转型的迫切需求,培育出氢氰酸含量低、可鲜食,支链淀粉含量高、糯性强的木薯糖水专用新品种.以广西防城港市防城区平旺乡横过村采集地方糯米木薯种质"糯米糍"为材料,经过系列比较试验,选育出桂热10号.在区域性和生产性试验中,桂热10号平均鲜薯产量分别为29.45 t/hm2和32.41 t/hm2,比主栽食用品种SC9增产6.81％和8.64％,5年平均支链淀粉含量89.48％,比对照提高了6.75个百分点,氢氰酸含量12.6 mg/kg,粗纤维3.41％,粗蛋白4.79％,β-胡萝卜素0.21 mg/100g.2020年11月3日获得"热带作物品种审定证书"[热品审2020001].桂热10号具有高支链淀粉,低氢氰酸、可鲜食,糯性强,适应性广等优点,适合加工成木薯糖水;可在广西、广东、福建、江西等相似生态区域的木薯种植区推广种植.

土壤微生物是土壤—作物系统养分循环的重要驱动力,其中丛枝菌根真菌(Arbuscu-lar mycorrhizal fungi,AMF)能够促进作物对养分的吸收.木薯是我国南方重要的经济作物,是多种行业的重要原材料.为揭示不同土壤质地木薯根域土壤AMF群落结构特征,解析土壤因子对AMF类群的影响.以木薯品种华南205 (SC205)为材料,通过田间根袋培养,利用高通量测序平台进行真菌扩增子测序,分析不同处理木薯根域AMF类群组成和多样性差异.结果 表明,木薯根域土壤AMF主要为球囊霉属(Glomus)、无梗囊霉属(Acaulospora)、盾巨孢囊霉属(Scutellospo-ra)、类球囊霉属(Paraglomus)和双型囊霉属(Ambispora).优势属为球囊霉属和无梗囊霉属.两种土质各处理AMF属水平上无显著差异,种水平分布受土壤质地及根袋的影响,粘土AMF多样性(Simpson指数)高于砂质壤土.两种土质中都发现独有种,土壤质地对木薯根域AMF群落分布有一定的影响.RDA分析表明Glomus与速效磷、速效氮、铵态氮正相关;Acaulospora与速效磷,速效氮弱负相关;Scutellospora与所有速效养分负相关;Paraglomus与所有速效养分表现出正相关;Ambispora与大部分速效养分表现出负相关.木薯根域AMF资源丰富,不同土壤质地条件下的AMF群落组成和丰度存在差异,土壤速效养分与AMF群落结构差异密切相关.该研究为进一步探索AMF在木薯上的应用提供理论参考.

为研究木薯根域土壤微生物群落结构,开展了根袋试验,处理包括2个木薯品种(华南205:SC205和桂热4号:GR4)和3个施肥处理(包括不施肥T1,普通施肥T3,施2倍氮肥T7),并进行了 Illumina Hiseq高通量测序.结果表明,细菌优势群落为放线菌门(Actinobacteria,8.579％～10.697％),变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)等.根域土壤比非根际土壤相对富集变形菌门和10个细菌属;SC205根域的硝化螺旋菌门(Nitrospirae)、5个纲(δ变形菌纲等)和6个属(Flavisolibacter等)的相对丰度比GR4要高,但鞘脂杆菌纲则相反.真菌优势群落为子囊菌门(43.71％～59.79％)、毛霉门、担子菌门等.根域土壤施肥抑制壶菌门(Chytrid-iomycota)相对丰度.相对于根域土壤,T7提高了非根际土壤中的Agaricomycetes,Geminibasid-iomycetes 和 Microbotryomycetes 纲的相对丰度.T7比 T1 显著降低了根域土壤 Chytridiomycetes纲的相对丰度.LEfSe结果表明:根域土壤施肥降低了哈茨木霉的相对丰度.α多样性结果表明:土壤细菌物种丰度顺序为T7 GR4＜T7 SC205和T7 soil.T3真菌物种丰度比T7高,T7真菌Chao 1指标比T1低.结论:GR4根域土壤细菌物种丰度、硝化螺旋菌门和5个纲、6个属的相对丰度都小于SC205,品种间细菌差异暗示氮转化过程和根系分泌物的差异.施肥降低了真菌物种丰度.壶菌门和4个真菌纲、哈茨木霉受施肥或根系影响,暗示它们与肥料或者根系分泌物的交互作用.本研究为深入认知木薯根际微生物提供了基础.

本文通过大田试验,研究了水肥一体化和覆盖地布等对木薯生长和土壤养分的影响,试验设置地膜/地布,4个施肥量,3种灌溉量等13个处理.结果表明,水肥一体化能显著提高木薯产量(40.18％～51.85％),最高为处理12(地膜+减量施肥2+滴灌2)和处理13(地布+减量施肥2+滴灌2).在无滴灌条件下,覆盖地布或者地膜也能显著提高木薯产量,但水肥一体化各处理间增产不明显;处理3(减量施肥1)和处理5(地布+减量施肥1)的氮肥、钾肥利用率比处理2(常规施肥)提高了 4.18％～10.32％和12.65％～22.66％,而处理11(减量施肥2+滴灌2)和处理13则比处理2提高了 23.32％～36.58％和37.48％～45.72％;处理8～13比处理2的速效磷增加了 11.67 mg/kg～33.79 mg/kg,速效钾含量增加了 24.9 mg/kg～70.2 mg/kg.在覆盖地布/地膜条件下,减量施肥+滴灌能明显提高氮、磷、钾肥料利用率;整体上滴灌处理的土壤速效磷和土壤速效钾含量有明显增加;综合考虑产量、节水、减肥和环保因素,处理13(地布+N 75 kg/hm2、P2O5 37.5 kg/hm2、K2O 75 kg/hm2+333.3 m3/hm2)为本研究最佳处理.

为探讨木薯化肥减量增效技术对木薯土壤肥力、 木薯产量及种植效益的影响,于2019-2020年开展木薯化肥减施种植技术示范.以木薯新品种"桂热10号"为材料,以化肥减量(25％)配施生物有机肥+地膜覆盖处理为示范种植模式,以常规种植(仅施化肥)和不施肥为对照,比较分析各处理土壤速效养分、 土壤酶活性、 木薯养分、 产量及种植效益差异.结果表明:木薯种植会导致土壤有效养分和生物活性下降,示范种植模式可显著缓解木薯种植后土壤养分的降幅,并提高土壤速效磷、 速效钾含量和土壤微生物量碳,显著提高土壤蔗糖酶活性,氮肥和钾肥的利用率分别提高12.8和40.4个百分点;不施肥和常规施化肥情况下木薯种植后土壤微生物量碳显著降低;施肥显著促进木薯植株生长,增加木薯生物量,显著提高木薯鲜薯产量和淀粉产量,常规种植和示范种植鲜薯产量和淀粉产量均显著高于不施肥处理,但施肥对植株氮磷钾含量并无显著影响;示范地块磷肥利用率偏低,应适当减少磷肥施用量;2019年和2020年示范种植较常规种植效益分别增加1532.45元/hm2和1284.45元/hm2.因此,化肥减量配施生物有机肥+地膜覆盖示范种植模式能有效保持土壤肥力,提高木薯产量从而提高木薯种植效益.

本文通过田间试验,研究了水肥一体化滴灌和地布覆盖对木薯生长及产量的影响.结果 表明,地布覆盖可以促进木薯植株生长并有效提高木薯鲜薯产量及淀粉含量,还可以控制木薯地杂草生长.播种期田间土壤水分含量较低时,适当灌溉可以有效提高木薯产量,水肥一体化+地布覆盖可以在减少化肥施用量的前提下促进木薯植株生长并提高木薯鲜薯产量和淀粉产量,且化肥减量25％(N75 kg/hm2、P2O5 37.5 kg/hm2、K2O 75 kg/hm2)效果最好,鲜薯产量最高提高30.0％(T12),淀粉产量最高提高30.3％.由此可见,水肥一体化滴灌+地布覆盖是增加木薯种植效益切实有效的措施之一.

[目的]探讨不同栽培模式下木薯的抗风能力,为木薯抗风栽培技术研究提供参考.[方法]开展种茎环剥、留单(双)茎杆、喷施多效唑、打顶等田间试验,测定木薯株高、茎粗、节间距、分枝数、薯块产量、淀粉等指标.[结果]在环剥双杆条件下,打顶显著降低株高;单杆打顶和2次喷施多效唑均能增加茎粗.环剥双杆+前期(株高0.7 m)打顶显著增加了淀粉含量和产量.[结论]环剥+双杆+前期(株高0.7 m)打顶+单杆打顶+2次喷施多效唑的栽培模式可提高木薯抗风能力.

我国是世界上最大的木薯消费国和进口国,木薯被广泛应用于食品、酒精、造纸等领域,消费需求较大.自2019年12月底爆发的新冠肺炎疫情,对我国木薯产业发展造成了较大影响.主要表现在木薯产品流通受阻使食用产业遭受较大损失,边贸口岸关闭使大量木薯无法正常通关.为应对疫情后期我国木薯供给不足和产品价格上涨的压力,应加大物流疏通力度,加强国际友好协商,保障进口木薯产品有序通关;同时,还应扎实推进春耕春播,适当扩大种植规模.

为了获取木薯根际土壤并研究其细菌群落特征,加深对木薯根际微生态的认知,开展根袋试验,以粘土和砂质壤土根袋内不同土壤质量(100～500 g)为处理.结果 表明,根袋内土质量影响株高,但不影响茎叶重.根袋内100 g土的速效养分受到根系强烈影响,其中铵态氮和速效钾显著高于根袋外.Illumina Hiseq高通量测序结果表明,细菌优势菌门包括变形菌门(31.272％)、放线菌门(25.753％)、酸杆菌门(12.761％)、绿弯菌门(8.799％)等.2种土壤根袋内细菌α多样性增加,粘土细菌丰度也增加.RDA分析表明,土壤速效磷与放线菌门和绿弯菌门正相关,与变形菌门负相关;速效氮、速效钾、铵态氮、硝态氮与芽单胞菌门、酸杆菌门、Parcubacteria等负相关,与厚壁菌门、蓝藻门、梭杆菌门、拟杆菌门正相关;从根袋内外土壤速效养分和土壤细菌多样性综合判定,根袋内100 g土壤时可视为根际土壤,且铵态氮和速效钾可作为判断是否根际土壤的指示指标.根际微生物多样性显著提高.鞘脂杆菌目是木薯品种SC205在不同土质下共同富集的根际细菌.发现了土壤速效养分与部分细菌门的相关性.

为探讨增施中微量元素肥料在木薯种植中的作用,在大田条件下,以南植199、桂热9号为材料,设不施肥、常规施肥及增施中微肥(穴施、叶面喷施及浸种)等不同处理,研究增施中微量元素肥料对木薯生长及产量的影响.结果 表明,施肥可促进木薯生长并增加鲜薯产量及淀粉产量.品种间中微量元素肥效存在差异,增施熟石灰、硫酸镁、叶面喷施硼砂、综合处理及钙镁磷肥处理能显著提高南植199鲜薯产量;其中,钙镁磷肥处理鲜薯增产39.7％,淀粉增产达到51.3％;其次为增施熟石灰处理鲜薯增产35.6％,淀粉增产44.8％.而桂热9号增产效果为综合处理鲜薯增产10.6％,淀粉增产32.5％;穴施硫酸镁淀粉增产21.2％;钙镁磷肥处理鲜薯增产10.0％.综上所述,本试验条件下主要增产因素为镁和钙;因此木薯种植中施用中微量元素肥料应考虑品种差异和不同施用方式差异;尿素+钙镁磷肥+氯化钾替代常规施肥中尿素+普通复合肥+氯化钾可有效提高木薯鲜薯产量及淀粉产量.

从国外引进的5个食用木薯品系在南宁进行品比试验,结果表明:各参试品系适应性好,农艺性状除了Bading都表现较好,综合评价表现最好的是老挝6,每亩产量达3031.3kg,比对照增产24.54％,淀粉含量比对照增加1.43％.

木薯是我国热带亚热带地区重要的经济作物,培育和推广高产优质的木薯新品种,可以有效提高木薯单产,改良木薯品质,对木薯产业的发展起着重要的作用.木薯"桂热7号"是广西亚热带作物研究所和广西木薯研究所于2001年从国际热带农业中心引进的杂交种子[CM9948-1(SM805-15×SM1438-2)]选育而成,2015年通过广西省品种审定(桂审薯2015003号),2016年获广西科技重大专项资助(桂科AA16380012).该品种集高产、优质于一体,适宜热带、亚热带地区种植.项目创建了木薯"桂热7号"的综合配套高产栽培技术体系,创造了显著的经济效益和社会效益.

A field trial with double factors (seed-stem girdling and transplanting) was carried out to study the dynamic changes in various growth indexes of aboveground part and belowground part of cassava variety South China 205(SC205).The results showed that: at the seedling stage of cassava, the weight of both above-ground part and root in the transplanting treatment was higher than that in the no transplanting treatment;the root number in the girdling treatment was higher than that in the no girdling treatment due to the growth of roots at the girdling ring.At the earlier stage of tuberous root enlargement, the weight of above-ground part in the transplanting treatment was still higher than that in the no transplanting treatment;the total root number was increased by both transplanting and girdling treatments.At harvest, the plant height, stem diameter, tuberous root number on the top and base of seed-stem were increased by the transplanting treatment, and the total tuberous root number was increased by 1.2 root/plant, but the weights of tuberous roots and single tuber on the base of seed-stem were significantly decreased by the transplanting treatment;the number and weight of tuberous roots on the base of seed-stem were significantly decreased by the girdling treatment, while those on the top of seed-stem were significantly increased by the girdling treatment.There were no significant differences in fresh tuber yield and starch yield among various treatments, and transplanting treatment and girdling treatment had a significant interaction effects on some growth indexes of cassava.

With the flowering regulation technology of cassava recently developed by our research team,we successfully induced bisexual cassava flowers.These bisexual cassava flowers had the ability for self-pollination bearing fruits.Here,we report the morphological characteristics of bisexual cassava flowers and their capsules and seeds from self-pollination development.Bisexual flowers contain both pistils and stamens,but unisexual flowers contain only one of these.The bisexual flower capsule is ovate and has a large length/width,but the unisexual flower capsule is broadly ovate and has a small length/width.The raphe of bisexual flower seed is not uplifted,but that of unisexual flower seed is uplifted.Bisexual flowers and their seeds are valuable for studying heredity and breeding in cassava,which has important significance for revealing heritable characteristics and cultivating new germplasm in cassava.

以国外引进的木薯品种(系)为材料,分析不同贮存天数其块根子物质、淀粉和β-胡萝卜素含量的稳定性,为耐贮藏本薯品种的选育提供依据.结果表明,木薯块根在贮存过程中,干物质含量最稳定,其次为淀粉含量,β-胡萝卜素含量最不稳定.干物质含量、淀粉含量和β-胡萝卜素含量均较稳定的木薯品种(系)为HL2012、NMC08、SM937-26,均不稳定的木薯品种(系)为南植199.木薯品种(系)HL2012、NMC08、SM937-26常温下耐贮存时间较长,在耐贮木薯品种的选育上具有较高的利用价值.

采用随机区组试验,研究了坡耕地木薯不同种植方式对土壤保持及木薯产量的影响.结果表明:各处理的土壤流失量均极显著少于对照;除“犁耙—施肥—起畦”和“犁耙—施肥—不起畦—高度分枝品种”外,其它处理的木薯块根产量均显著或极显著高于对照;处理的木薯茎叶产量均极显著高于对照.“犁耙—施肥—不起畦—间种花生”的土壤流失量极显著少于其它处理,木薯产量也较高.坡耕木薯地土壤流失量与降雨量呈显著或极显著正相关.降雨是木薯坡耕地土壤流失的主要原动力, “犁耙—施肥—不起畦—间种花生”是木薯坡耕地土壤保持的首选种植模式.

A long-term fertilizer trial on cassava from 1989-1996, including 2 cassava varieties (SC201 and SC205) and 15 fertilization treatments (chemical fertilizers and farmyard manure), to provide scientific basis for cassava fertilizing. Results showed that cassava yields and weight of shoot were both significantly different among years and cassava cultivars, respectively. The cassava yield of SC201 and SC205 increased significantly in 3/8 and 5/8 years, respectively, with the application of farmyard manure (FYM). Cassava yields were significantly improved, in most of the observed years (SC201 6/8, SC205 7/8), after NPK fertilizers were applied with the proportionate quantity according to the "suggested NPK fertilization", which is 100∶50∶100 kg/hm2 N∶P2O5∶K2O. The correlation of cassava yields and the NPK fertilizing amount could be fit with parabolic equation in 3/8 years and 6/8 years for SC201 and SC205, respectively. The shoot weight increased following a parabolic curve with the increase of NPK fertilization, while the starch content decreased. N fertilizer increased cassava yields in most of the years (5/8 and 8/8 years for SC201 and SC205, respectively). And quantity of N fertilizers and cassava yields could be fit with parabolic equation in 5/8 and 3/8 years for SC201 and SC205, respectively. The shoot weight was increased with N fertilizer applied. P fertilizers increased the yield of SC201 and SC205 in 3/8 and 5/8 years, respectively. The K fertilization increased the cassava yield of both varieties in 2/8 years, respectively, but significantly increased shoot weight in 3/4 years for each variety, respectively. Cassava yield and shoot weight was increased by N fertilization, N is the first limiting factor to cassava yield in the typical red soil;K fertilization can also increase shoot weight. Application of P fertilizer could increase the yield of SC205 in more years than K fertilizer. The shoot weight, yield, starch yield of SC201 was higher than those of SC205. Fewer yields were produced by SC205 than SC201, with more fertilization needed. Thus, variety should be considered in cassava fertilization. The optimum fertilization in this long-term trial was 50% (50∶25∶50 kg/hm2 N∶P2O5∶K2O ) of the "suggested NPK fertilization" + 5 t/hm2 of FYM (pig manure). The NPK application for SC201 and SC205 was 124∶62∶124 and 161.6∶50∶100 kg/hm2 N∶P2O5∶K2O respectively, if there were only chemical fertilizers to be applied.