Effect of two additives on the fermentation,in vitro digestibility and aerobic security of Sorghum–sudangrass hybrid silages

Two additives (Silo Guard (SG) and propionic acid (PA)) were tested for their effects on the quality and aerobic security of sorghum–sudangrass hybrid silages (JC‐1 and WC‐2). Two sorghum–sudangrass hybrid varieties were harvested for ensiling without additives (CK) or after the following treatments: SG at 0·5% of fresh forage or PA at 0·5% of fresh forage, with three replicates per treatment. The addition of SG and PA both affected the fermentation quality and chemical composition of the silages by lowering pH and NH₃‐N/TN and increasing lactic acid, the LA/TA ratio, WSC and CP concentrations compared with the untreated silages. In vitro DM digestibility (IVDMD), in vitro NDF digestibility (IVNDFD) and in vitro CP digestibility (IVCPD) were increased by SG in the JC‐1 silages and WC‐2 silages. Both additives improved the aerobic stability of sorghum–sudangrass hybrid silages. Furthermore, the additives reduced the mould counts and the aflatoxin and zearalenone levels compared with the untreated silages following aerobic exposure. Therefore, ensiling two sorghum–sudangrass hybrid varieties resulted in high‐quality silages. The addition of SG and PA improved silage quality, in vitro digestibility and aerobic security.     

生活污泥对滩涂土壤性质和苏丹草生长及重金属累积的影响

滩涂盐土农业利用的主要障碍是盐分含量过高和缺乏有机质。施用生活污泥可快速提高滩涂土壤有机质含量,加快土壤熟化,但由于担心污泥含有一定量的重金属,其施用受到一定的限制。采用盆栽苏丹草的试验方法,研究滩涂盐土施用不同量的生活污泥后对土壤性质、植物生长和对重金属累积的影响。结果表明,生活污泥施用于滩涂盐土后降低了土壤pH值,提高了EC值和总盐含量;苏丹草的出苗率、株高和鲜重增加;施用污泥提高了苏丹草植株中全氮、全磷及叶绿素的含量,且随施用量的增加而增大,但对植株中全钾的含量无显著影响;苏丹草中Zn、Cd含量随着污泥施用量增加呈增长的趋势,但Pb、Ni、Cu含量变化不大。在试验条件下,所施用污泥中重金属向苏丹草体内转移的比例介于0.13%~13.44%之间。就该种土壤而言,要更为注意含Pb量较高的污泥施用,而Cu则是最为安全的。总体考虑,一次性施用干污泥应控制在8t·667m-2以下。     

蒙农青饲2号高丹草选育

从高粱雄不育系A4×白壳苏丹草杂种F2代分离群体中开始选择优秀单株,通过4次单株选择、1次混合选择及品比、区域与和生产试验,历经9个世代育成蒙农青饲2号高丹草。该品种根系发达,株高350cm,生育期134d,绿杆成熟,分蘖多,再生性强,每年刈割利用3次,鲜草产量132000kg/hm²,种子产量5600kg/hm²;茎叶柔嫩、多汁,茎叶比3.01,拔节期粗蛋白质含量11.70%,开花期的粗蛋白质含量9.32%、粗脂肪3.48%、粗纤维37.57%、粗灰分5.68%、无氮浸出物42.12%,糖锤度3.89%,富含17种氨基酸,CN-含量低,营养价值高,适口性好,可青饲、青贮或晒制干草;植株抗逆能力强,生态适应性广,适宜在有效积温≥2400℃的地区推广种植。     

苏丹草品种纯度鉴定技术的研究：胚芽鞘颜色及种子形态特征

根据我国审定登记的５个苏丹草品种的种子特征幼功胚芽鞘在温室３种不同营养液及田间条件下的颜色特征,探讨了苏丹草品种决策和纯度鉴定的方法。结果表明,供试苏丹草与蓁个品种在上述性状上均存在显著差异,极易区分;其余４个品种间可以由于千粒重进一步划分为２组。与高梁幼功胚芽鞘的颜色组成相似,苏丹草幼苗的胚芽鞘颜色也可以分为紫红色和绿色,并可作为品种真实性鉴定的特异性状。     

刈割周期对苏丹草叶片生长的影响

刈害周期长短对苏丹草的新叶出露间隔期、叶片发育速度、功能叶比例、叶片伸长速度和叶面积指数均有不同程度的影响。适当的刈害周期可以刺激叶片更新、增加功能叶比例，提高草层中的叶量，改善苏丹草对鱼的适口性。     

苏丹草农艺性状与产量、品质间的灰色关联度分析

使用灰色关联度分析了3个苏丹草(Sorghum)材料6个农艺性状与产量和营养品质之间的关系,结果表明,1)叶长、茎粗对苏丹草干鲜草产量影响最大,且叶长与茎粗呈极显著正相关(P0.01),是影响干鲜草产量的主要限制因素;2)茎粗、叶长、叶宽适当,分蘖数和节数少的苏丹草植株、品系或品种的营养价值较高。在苏丹草育种的过程中,根据具体产量育种或品质育种的目标,选择与苏丹草高产高品质关系密切且表现稳定的农艺性状,明确各性状的主次关系,为苏丹草选育新品种提供理论依据。     

Comparison of Drought Tolerance of Maize,Sweet Sorghum and Sorghum‐Sudangrass Hybrids

In drought‐prone environments, sweet sorghum and sorghum‐sudangrass hybrids are considered worthy alternatives to maize for biogas production. The biomass productivity of the three crops was compared by growing them side‐by‐side in a rain‐out shelter under different levels of plant available soil water (PASW) during the growing periods of 2008 to 2010 at Braunschweig, Germany. All crops were established under high levels of soil water. Thereafter, the crops either remained at the wet level (60–80 % PASW) or were subjected to moderate (40–50 % PASW) and severe drought stress (15–25 % PASW). While the above‐ground dry weight (ADW) of sweet sorghum and maize was insignificantly different under well‐watered conditions, sweet sorghum under severe drought stress produced 27 % more ADW than maize. The ADW of sorghum‐sudangrass hybrids significantly lagged behind sweet sorghum at all levels of water supply. The three crops differed markedly in their susceptibility to water shortage. Severe drought stress reduced the ADW of maize by 51 %, but only by 37 % for sweet sorghum and 35 % for sorghum‐sudangrass hybrids. The post‐harvest root dry weight (RDW) in the 0–100 cm soil layer for maize, sweet sorghum and sorghum‐sudangrass hybrids averaged 4.4, 6.1 and 2.9 t ha^?1 under wet and 1.9, 5.7 and 2.4 t ha^?1 under severe drought stress. Under these most dry conditions, the sorghum crops had relatively higher RDW and root length density (RLD) in the deeper soil layers than maize. The subsoil RDW proportion (20–100 vs. 0–20 cm) for maize, sweet sorghum and sorghum‐sudangrass hybrids amounted to 6 %, 10 % and 20 %. The higher ADM of sweet sorghum compared with maize under dry conditions is most likely attributable to the deep root penetration and high proportion of roots in the subsoil, which confers the sorghum crop a high water uptake capacity.     

苏丹草与栽培高粱群体生物学性状的相关和主成分分析

察和分析4个苏丹草品种和6个栽培高粱品种的64个生物学性状。利用性状间的相关关系和系统聚类结果,探讨了在田间种植环境条件下生物学性状的分类学意义;利用主成分分析法确定出6个主分量,其中主成分Ⅰ、Ⅱ在苏丹草和栽培高梁2类群演化过程中起着决定性作用,被称作苏丹草分化主因子和高粱分化主因子。以6个主成分的回归因子得分值对10个品种进行聚类分析,结果将苏丹草和栽培高粱划分成两大类。      

Potassium Management for Brown Midrib Sorghum × Sudangrass as Replacement for Corn Silage in the North-eastern USA

In recent years, there has been a growing interest in brown midrib (BMR) sorghum (Sorghum bicolor (L.) Moench.) × sudangrass (Sorghum sudanense Piper) hybrids (SxS) as a replacement for silage corn (Zea mays L.) in the north‐eastern USA. Recent studies suggest it is suitable for both rotational grazing and as a hay crop and could compete with corn harvested for silage in years when wet spring conditions prevent the timely planting of corn. However, little is known about its suitability as forage for non‐lactating cows that require low potassium (K) forages to prevent health problems. Our objective was to evaluate the impact of K fertilizer management (0, 112 or 224 kg K₂O ha^?1 cut^?1) under optimum N management (112–168 kg N ha^?1 cut^?1) on yield, quality and K concentrations of BMR SxS over a 2‐year period. Field trials were established on a fine loamy, mixed, active, mesic Aeric Fragiaquepts with medium K‐supplying capacity and characteristic of a large region in New York. Potassium application did not affect dry matter yields in either of the 2 years. Averaged over 2 years, neutral detergent fibre (NDF) significantly increased with K addition with similar but non‐significant trends observed in each of the years individually. The digestibility of NDF was unaffected by K application. Crude protein (CP) concentrations showed a significant decrease with K application in 2002 and similar trends were observed in 2003, although differences were not significant at P ≤ 0.05. The changes in NDF and CP did not significantly impact forage quality expressed as milk production per megagram of silage. Potassium application increased forage K concentration up to 13 mg K kg^?1 dry matter (in the first cut in 2003). Forage Ca and Mg concentrations decreased with K addition except for the first cut in 2002 where differences between 112 and 224 kg K₂O ha^?1 treatments were not significant. Without K addition in the 2‐year period, K concentrations in the forage decreased from 23 g kg^?1 for the first cutting in 2002 to 15 g kg^?1 for the second cut in 2003. Low K forage was obtained for all second‐cut forage unless 224 kg K₂O ha^?1 cut^?1 had been added. First‐cut forage was suitable only when no additional K had been applied. These results suggest low K BMR SxS forage can be harvested from initially high K soils without loss in dry matter yield as long as no additional K is added.     

Nitrogen, Phosphorus, Potassium, Magnesium and Calcium Removal by Brown Midrib Sorghum Sudangrass in the Northeastern USA

For the long‐term sustainability of the dairy industry in the Northeastern USA, manure nutrient application rates should not exceed crop nutrient removal once above‐optimum soil fertility levels are reached. Dairy producers have shown a growing interest in brown midrib (BMR) forage sorghum (Sorghum bicolor (L.) Moench.) × sudangrass (Sorghum sudanense Piper) hybrids (S × S) as a more environmentally sound alternative to maize (Zea mays L.) but data on S × S nutrient removal rates are scant. Our objectives were to determine N, P, K, Ca and Mg removal with harvest as impacted by N application rate, using six N rate studies in New York. One of the six sites had a recent manure history. Although site‐to‐site differences existed, N application tended to decrease P and K and increase N, Ca and Mg concentrations in BMR S × S forage. Nutrient removal and yield were highly correlated for all sites except one location that showed a K deficiency. The crop removed large amounts of P and K in the manured site, suggesting that BMR S × S is an excellent scavenger of these nutrients. If manure is applied mid‐season, forage K levels are likely too high for feeding to non‐lactating cows.