Cyclodimers of p-coumaric and ferulic acids in the cell walls of tropical grasses

Cell walls from leaves and stems of three tropical grasses (Setaria anceps cv Nandi (Schumach) Moss), pangola grass Digitara decumbens Stent and spear grass Heteropogon contortus (L) Beauv ex Roemer & Schultes were extracted with alkali, and ether-soluble fractions were prepared from the acidified solutions. Cyclobutane dimers derived from p-coumaric acid (CA: 3-(4-hydroxypheny) propenoic acid) and ferulic acid (FA: 3-(4-hydroxy-3-methoxyphenyl) propenoic acid) were found in all plant residues. Structural information on the dimers was obtained by gas chromatography-mass spectrometry. Stem cell walls differed from those of leaf in having major dimer components which contained residues tentatively identified as coniferyl alcohol (3-(4-hydroxy-3-methoxyphenyl)-2-propen-l-ol). Species differences in leaf cell wall cyclodimers were evident. Pangola and setaria grasses had dimers mainly derived from FA, whereas spear grass had over 70% of dimers derived from CA. Di-esterification of some dimers in the cell walls was confirmed by the release of dimers containing the reduced forms of CA and FA (coumaryl and coniferyl alcohols respectively) when leaf cell walls were extracted with borohydride. Head to tail dimerisation giving derivatives of truxillic acid (t-2, c-4-diphenyl-r-l, t-3-cyclobutanedicarboxylic acid) predominated, although evidence was obtained for the presence of head-to-head coumaric acid dimers (derivatives of truxinic acid, t-3, t-4-diphenyl-rl, c-2-cyclobutanedicarboxylic acid) in setaria stem and spear grass leaf. The results suggested that cyclodimers in grass cell walls occurred in cross-linking structures of varying complexity between macromolecules, where they would possibly contribute to fibre strength and thus have an adverse efect on the nutritional value of forage.     

Effects of phosphorus on yield of cowpea cultivars intercropped with pearl millet on Psammentic paleustalf in Niger

Phosphorus (P) is the most limiting soil nutrient in the sandy soils of Niger and farmers rarely use chemical fertilizers in producing pearl millet and cowpea. A 3-yr study was conducted in farmer's fields at two locations in South Western Niger to investigate yield response of six cowpea cultivars to applied P-fertilizer (0, 8, 16 kg ha^–1) when intercropped with millet. Significant yield differences were found between cultivars for their seed and dry fodder yield at all rates of applied P. Cultivars responded differently to the application of P. Millet grain was more than doubled with the addition of 8 to 16 kg P ha^–1. Cowpea cultivars did not have significant differential effect on millet yields. Cowpea cultivars differed significantly in the accumulation of P in fodder with the highest yielding cultivars taking up more P than the low yielding ones. The results have important implications for breeding and selection of cowpea cultivars that are adapted to a range of fertility levels.Submitted as Journal Article No. 1211 of ICRISAT.     

流域生态修复科学性思考

流域生态系统规划已经成为流域相关研究中的重点内容,科学的流域生态系统规划理论和方法为流域的健康和可持续发展提供了丰富的研究途径和思路。基于生态学理论,强调了非生物要素作为生物要素的基础,阐述了水文、地形、土壤等对生态修复的作用。倡导基于自然解决方案的流域生态修复,强烈主张以水文修复作为生态修复的基础,以流域水文规划为主导的多专业协同的流域生态保护及修复方法。建议生态修复首先要理解自然生态要素之间的关系,然后统筹规划流域范围内的生物和非生物要素,并协调人类生活和生态系统保护之间的关系,为流域生态系统的健康、稳定和可持续发展提供科学性解决方案。     

Effect of preprocessing techniques on pearl millet flour and changes in technological properties

This study investigated the effect of some preprocessing techniques on the physicochemical and technological properties of pearl millet flour for possible industrial application. Pearl millet was processed into flour using different preprocessing techniques (blanching, debranning, fermentation and malting) and evaluated for physicochemical and functional properties, grain morphology and total viable count. The result showed that fermentation and malting brought about loosening of starch granules. Fermentation significantly reduced the bulk density by 22% and improved the colour lightness and paste viscosity properties of the preprocessed flour. Malting alone resulted in about 50% increase in protein content of the flour with improved solubility up to 64 g/100 g. Total viable count was highest in fermented sample in the order of 10⁸ cfu g^?1. Thus, the combination of fermentation and malting would give the best pearl millet flour with improved technological properties for application in the industries, thereby promoting food security in the region.     

Seed morphology using SEM techniques for identification of useful grasses in Dera Ghazi Khan,Pakistan

In recent study, 15 taxa of family Poaceae from Dera Ghazi Khan were investigated for morphological characterization of seeds. Scanning electron microscopy (SEM) was utilized to study morphological features of grass seeds. Moreover, economic importance of studied taxa has been discussed in present research. Grass seeds or caryopsis were collected in their mature state from different areas of Dera Ghazi Khan. Collected caryopses were subjected to SEM to investigate surface sculpture, epidermal cell shape, and cell wall patterns. Caryopsis shape observed was elliptic to oval. Also, the morphology of plant is being investigated. Cell wall pattern observed was straight and wavy. Surface sculpturing varies from smooth to reticulate. Epidermal cell shape was either wavy or irregular. Hilum position is terminal in all species. Epidermal cell structure and cell wall pattern was not observable in some species. Major variations among studied taxa were observed in terms of seed surface pattern. Five types of caryopsis surface pattern were observed namely, striate, smooth, reticulate, papillate, and granulate. Investigated taxa illustrated variations in terms of studied morphological features. Utilization of SEM has been proved very helpful in exploring seed morphological features. These observed features can aid in delimitation and identification of various grass taxa. Recent research recommends the utilization of SEM for caryopsis morphology to solve the identification issue of problematic grass genera.     

不同生长期绿洲一号和巨菌草制浆性能探讨

采用超声辅助预处理及蒸煮对1年、2年和3年不同生长期的绿洲一号及巨菌草的制浆性能进行了评价。结果表明,在相同制浆工艺条件下(超声波预处理用碱量4%,硫化度2%,超声时间2 h;蒸煮用碱量6%,硫化度0,固液比1∶4,最高温度170℃,保温时间1 h),3年生巨菌草较适合作为制浆原料,其制浆的粗浆得率49.3%,卡伯值14.5,纸浆黏度850.63 mL/g,白度39.3%。超声波预处理液中木素含量4.3 g/L,还原糖含量2.9 g/L,蒸煮黑液中木素含量2.9 g/L,还原糖含量5.7 g/L。抄造纸张抗张指数56.4 N·m/g,撕裂指数20.5 mN·m~2/g,耐破指数2.35 kPa·m~2/g。     

Lignin in the ‘cell contents’ fraction of tropical forages

In several tropical forage species the neutral detergent extraction used to determine cell wall and cell contents fractions solubilised a substantial UV‐absorbing polymeric fraction which appeared to be a soluble lignin–carbohydrate complex. A crude product was isolated from spear grass (Heteropogon contortus) with a yield of 30 g kg^?1. In other forages an acetyl bromide method was used to estimate lignin extractable by neutral detergent. For eight species of tropical grasses this gave the following values: Aristida calcyna, 38; Mitchell grass (Astrebla squarrosa), 37; Chloris gayana, 31; Eragrostis sp, 37; spear grass, 49; Iseilema membranaceum, 35; Panicum maximum, 36; Sorghum sp, 42; Themeda triandra, 79 g kg^?1. The levels in two legumes were: Alysicarpus bupleurifolius, 29; Macroptilium atropurpureum, 27 g kg^?1 dry matter. Sequential extractions on spear grass and Mitchell grass showed that most of the 50% dioxan‐soluble fraction was also soluble in neutral detergent, raising the possibility that ‘dioxan lignin’, on which studies of forage lignin structure in other species have been conducted, would be found in the cell contents fraction rather than in the fibre fractions on which lignin analyses have been performed. Addition of dioxan extractives reduced the in vitro neutral detergent fibre (NDF) digestibility of spear grass and Mitchell grass. © 2002 Society of Chemical Industry     

Dynamic changes of lignin contents of MT-1 elephant grass and its closely related cultivars

Elephant grass (Pennisetum purpureum Schum.) is a tropical C₄ bunchgrass with high rates of growth and biomass production. It has been considered as a new alternative for energy crop in some countries, and expected to provide abundant and sustainable resources of lignocellulosic biomass for the production of solid biofuels. But in addition to cellulose, plant cell walls contain lignin that hinders the degradation of cell wall polysaccharides to simple sugars destined for fermentation to ethanol and biogas. In this paper, five elephant grass cultivars, such as ‘MT-1’ new line (P. purpureum cv. MT-1), ‘Mott’ (P. purpureum cv. Mott), ‘Huanan’ (P. purpureum cv. Huanan), ‘N51’ (P. purpureum cv. N51) and ‘Guimu-1’ ((Pennisetum americanum × P. purpureum) × P. purpureum cv. Guimu No.1) were tested to determine the lignin content using the acetyl bromide method. The lignin contents increased with the growth development for all five cultivars, but the increasing range was different with the difference of cultivar. In particular, the biggest increasing range was between July and August for ‘Huanan’, ‘N51’, ‘Mott’ and ‘MT-1’. At seedling stage, the contents of five cultivars were not significantly different, but the differences were demonstrated at internode elongation stage. At ripening stage, the upper internode of flowering culm had the lowest lignin content, and the basal internode had the highest content for all the five cultivars. The lignin content was very different at different development stage for different cultivars, indicating the differentiations among the five genotypes. As far as the flowering culm (in December) was concerned, the order of lignin content from the highest to the lowest was ‘Huanan’ (22.04% FW) > ‘N51’ (19.65% FW) > ‘Guimu-1’ (17.45% FW) > ‘Mott’ (15.43% FW) ≥ ‘MT-1’ (14.63% FW). In NJ and UPGMA dendrograms, the five cultivars could be divided into two groups, one for ‘MT-1’, ‘Mott’ and ‘Guimu-1’, one for ‘Huanan’ and ‘N51’. This result is consistent with the pedigree relationships among the five cultivars.     

响应面法优化大麦苗叶绿素提取工艺

为优化大麦苗叶绿素的提取工艺,试验以乙醇-水为溶剂对大麦苗叶绿素进行浸渍提取。采用Plackett-Burman 试验设计筛选影响大麦苗叶绿素提取量的显著因素,通过中心组合试验设计优化其提取工艺参数。结果表明：液料 比、乙醇体积分数及提取时间是影响叶绿素提取量的显著因素。优化所得最佳提取工艺参数为液料比31∶1、乙醇体积 分数92%、提取时间112 min。在此条件下,叶绿素提取量为13.622 mg/g,与预测值13.646 mg/g较一致。故响应面法可 用于优化大麦苗叶绿素的提取工艺,且其优化工艺参数可为大麦苗叶绿素工业化生产提供参考。