Differences In Starch Content Research Articles

Difference in responsiveness of expressions of starch synthesis-related genes to CRCT among rice cultivars

ABSTRACT CO2-Responsive CCT Protein (CRCT) is a transcription factor regulating the expression of starch synthesis-related genes in the vegetative organs of rice. Among six rice cultivars (Nipponbare, Koshihikari, Habataki, Takanari, Momiroman, Leafstar), the expression of CRCT was highly correlated with the starch content of leaf sheath in Nipponbare, but not in Koshihikari, Takanari and Momiroman during plant development. Meanwhile, the expressions of starch synthesis-related genes such as ADP-glucose pyrophosphorylase large subunit 1 was correlated with CRCT expression in Nipponbare, Momiroman, and Leafstar, but the correlations were ambiguous in Koshihikari, Habataki, and Takanari. In addition, the slopes of its regression lines in Nipponbare were larger than those cultivars. These results suggest that the influence of CRCT on starch synthesis varies among these cultivars. Additionally, the similar cultivar differences were observed when these gene expressions were analyzed after sucrose treatment in leaf blade. Some mutations in the promoter regions of the starch synthesis-related genes were identified among these cultivars. There were cultivars in which the presence of mutations correlated with decreased expression of starch synthesis genes in response to CRCT. Thus, these mutations can partially explain the responsiveness of the starch synthesis-related genes to CRCT, and difference in starch content of vegetative organs among rice cultivars.

Metabolic profiling of highland barley (Hordeum vulgare var. nudum) genotypes

Highland barley (HB), a valuable crop thriving in challenging conditions on the Qinghai-Tibet Plateau, possesses rich nutrient contents. This study aims to investigate the nutrient profile of HB genotypes and compare the metabolic profiles of three representative genotypes exhibiting high, medium, and low quality. The screening of HB genotypes reveals significant genotype-dependent differences in starch content, protein content, amino acid content, flavonoid content, antioxidant capacity, β-glucan, and γ-aminobutyric acid. The selected genotypes, namely KKDM2021005, ZJDM012, and DCDM2020017, exemplify high, average, and low quality, respectively. Utilizing LC–MS/MS for metabolic profiling, 617 metabolites from 12 major classes, with flavonoids being the most abundant, are identified. Distinct metabolic profiles are observed among the three genotypes, with 262 DAMs for KKDM2021005 versus DCDM2020017, 261 DAMs for KKDM2021005 versus ZJDM012, and 298 DAMs for ZJDM012 versus DCDM2020017. Enrichment analysis of DAMs highlights pathways associated with anthocyanin, phenylpropanoid, flavone and flavonol, and isoflavonoid biosynthesis. Specific DAMs such as l-valine, l-isoleucine, l-leucine, trifolin, spiraeoside, ferulic acid, betanin, cyanidin-3-O-galactoside, and cyanidin-3-O-glucoside, along with others, contribute to the observed quality differences among the genotypes. These findings provide a foundation for further exploration of genotype-specific metabolic profiles to manipulate the quality aspects of HB utilizing the existing gene pool. By enhancing its nutritional value, functional properties, and potential health benefits, HB can receive significant value addition.

Rootstock and Crop Load Effects on ‘Honeycrisp’ Photosynthetic Performance and Carbohydrate Accumulation

Rootstock selection and crop load adjustment are key practices in apple orchard management; nevertheless, the effects of rootstocks and crop load levels on important physiological processes of the scions, such as photosynthetic performance and carbohydrate accumulation, are still unclear. To investigate the impact of different rootstocks and crop load levels on scion photosynthesis and carbohydrate buildup, in 2020, ‘Honeycrisp’ trees grafted on rootstocks ‘G.41’, ‘G.935’, and ‘M.9-T337’ were thinned to low and high crop load levels, and photosynthetic performance and carbohydrate accumulation in leaves and fruit were evaluated. Leaves from ‘G.935’ showed the highest net photosynthesis and electron use efficiency of photosynthesis and the lowest activity for non-net carboxylative processes, all together indicative of enhanced photosynthetic performance. High crop load determined an increase in gas exchange, suggesting a positive feedback of high fruit competition on carbon assimilation. While rootstock ‘M.9-T337’ showed a higher accumulation of starch in leaves, no pattern regarding the composition of leaf-soluble sugars among rootstocks could be identified. Conversely, by the end of the harvest season, leaves from low-cropping trees had higher fructose, glucose, and sorbitol than those from high-cropping trees, but differences in starch content were not significant. Fructose and sorbitol concentrations were affected by rootstock and crop load, respectively. Overall, this study showed that high cropping enhanced photosynthesis in ‘Honeycrisp’ apple and determined lower accumulation of some soluble carbohydrates (fructose, glucose, sorbitol) in leaves. This study also provided insights into how rootstocks affect photosynthetic performance of ‘Honeycrisp’, highlighting ‘G.935’ as the rootstock conferring the highest photosynthetic capacity under the present experimental conditions.

Starch depletion in the xylem and phloem ray parenchyma of grapevine stems under drought.

While nonstructural carbohydrate (NSC) storage can support long-lived woody plants during abiotic stress, the timing and extent of their use are less understood, as are the thresholds for cell mortality as NSCs and water supplies are consumed. Here, we combine physiological and imaging tools to study the response of Vitis riparia to a 6-week experimental drought. We focused on the spatial and temporal dynamics of starch consumption and cell viability in the xylem and phloem of the stem. Starch dynamics were further corroborated with enzymatic starch digestion and X-ray microcomputed tomography imaging. Starch depletion in the stems of droughted plants was detected after 2 weeks and continued over time. We observed distinct differences in starch content and cell viability in the xylem and phloem. By the end of the drought, nearly all the starch was consumed in the phloem ray parenchyma (98 % decrease), and there were almost no metabolically active cells in the phloem. In contrast, less starch was consumed in the xylem ray parenchyma (30 % decrease), and metabolically active cells remained in the ray and vessel-associated parenchyma in the xylem. Our data suggest that the higher proportion of living cells in the phloem and cambium, combined with smaller potential NSC storage area, rapidly depleted starch, which led to cell death. In contrast, the larger cross-sectional area of the xylem ray parenchyma with higher NSC storage and lower metabolically active cell populations depleted starch at a slower pace. Why NSC source-sink relationships between xylem and phloem do not allow for a more uniform depletion of starch in ray parenchyma over time is unclear. Our data help to pinpoint the proximate and ultimate causes of plant death during prolonged drought exposure and highlight the need to consider the influence of within-organ starch dynamics and cell mortality on abiotic stress response.

Cloning and gene function of dicarboxylate-tricarboxylate carrier protein in Gastrodia elata

The gene GeDTC encoding the dicarboxylate-tricarboxylate carrier protein in Gastrodia elata was cloned by specific primers which were designed based on the transcriptome data of G. elata. Bioinformatics analysis on GeDTC gene was carried out by using ExPASY, ClustalW, MEGA, etc. Positive transgenic plants and potato minituber were obtained by virtue of the potato genetic transformation system. Agronomic characters, such as size, weight, organic acid content, and starch content, of potato minituber were tested and analyzed and GeDTC gene function was preliminarily investigated. The results showed that the open reading frame of GeDTC gene was 981 bp in length and 326 amino acid residues were encoded, with a relative molecular weight of 35.01 kDa. It was predicted that the theoretical isoelectric point of GeDTC protein was 9.83, the instability coefficient was 27.88, and the average index of hydrophilicity was 0.104, which was indicative of a stable hydrophilic protein. GeDTC protein had a transmembrane structure and no signal peptide and was located in the inner membrane of mitochondria. The phylogenetic tree showed that GeDTC was highly homologous with DTC proteins of other plant species, among which GeDTC had the highest homology with DcDTC(XP＿020675804.1) in Dendrobium candidum, reaching 85.89%. GeDTC overexpression vector pCambia1300-35Spro-GeDTC was constructed by double digests, and transgenic potato plants were obtained by Agrobacterium-mediated gene transformation. Compared with the wild-type plants, transgenic potato minituber harvested by transplanting had smaller size, lighter weight, lower organic acid content, and no significant difference in starch content. It is preliminarily induced that GeDTC is the efflux channel of tricarboxylate and related to the tuber development, which lays a foundation for further elucidating the molecular mechanism of G. elata tuber development.

An Assessment of Starch Content and Gelatinization in Traditional and Non-Traditional Dog Food Formulations.

Starch gelatinization in pet food may be affected by moisture, retention time, and ingredients used. Starch gelatinization has been associated with changes in digestibility but is not well studied using non-traditional ingredients in canine diets. The objective of this research was to examine differences in starch content and gelatinization associated with changes in ingredient profile (traditional vs. non-traditional) and nutrient content requirements associated with differing life stages. Traditional diets (n = 10) utilizing protein sources including chicken, chicken by-product meal, meat and bone meal and plant-based ingredients including rice, barley, oats, and corn were examined in comparison with non-traditional diets (n = 10) utilizing protein sources including alligator, buffalo, venison, kangaroo, squid, quail, rabbit, and salmon along with plant-based ingredients including tapioca, chickpeas, lentils, potato, and pumpkin. Total starch and gelatinized starch (as percent of total diet) were measured with variation due to ingredient type assessed using Student’s t-test in SAS 9.4. Significance was set at p < 0.05. Total starch (as a percent of diet) was higher in traditional diets compared to non-traditional diets formulated for maintenance (p < 0.0032) or all life stages (p < 0.0128). However, starch gelatinization as a proportion of total starch was lower in traditional diets formulated for maintenance (p < 0.0165) and all life stages (p < 0.0220). Total starch and gelatinized starch had a strong negative correlation (r = −0.78; p < 0.01) in diets utilizing traditional ingredients. These novel data reveal important differences between starch content and gelatinization and may impact selection of various ingredient types by pet food manufacturers.

Impact of microclimate on Artocarpus altilis (Parkinson) Fosberg var Ma’afala fruit and nutritional quality

Breadfruit (Artocarpus altilis (Parkinson) Fosberg var. Ma’afala is an important traditional staple food crop of Samoa and Tonga that was recently introduced into commercial cultivation worldwide. To determine the impact of environmental conditions on fruit and nutritional characteristics, we evaluated the performance of Ma’afala trees planted at 23 sites across Hawai’i. Proximate analysis revealed that edaphic properties impacted energy, protein and moisture content and climate factors impacted fat and fiber content. Application of fertilizer was correlated with differences in starch content and composition. Fruit size was found to increase with water balance and soil organic content. Soil micronutrient content was not correlated with fruit micronutrient content, however, soil nitrogen levels were correlated with higher nitrogen content of fruits. We used climate modeling to predict performance of Ma’afala in different ecosystems. Our data demonstrate that ecological niche models for breadfruit cultivation may be useful in determining productivity, but not necessarily for fruit quality or nutrition. These results show that modelled future climate scenarios did not negatively impact the nutritional quality of breadfruit and the importance of breadfruit as a resilient food crop for the future.

Transcriptome Analysis Reveals the Accumulation Mechanism of Starch in Chinese Yam (Dioscorea opposite Thunb.) Tubers Using RNA-Seq and Iso-Seq

The starch composition of tubers affects the quality and yield of yam, and it is of great significance to deeply investigate the mechanism of starch accumulation in yam. In this study, two yam varieties with significant differences in starch content, Bikeqi (Dioscorea opposita Bikeqi) and Dahechangyv (Dioscorea opposita Dahechangyu), were used as materials. The transcriptome of tubers from seven developmental stages were sequenced using RNA-seq and Iso-seq. Differential genes closely contacted with the metabolism of starch and sucrose were screened and the functions were analysed. The results showed that, the starch content of the two yam varieties reached the maximum at 150 and 165 days respectively, and their difference was the largest at 150 days. Total 21623 unigenes were annotated, and 8378 differential genes were identified within varieties by comparing each developmental stage with the beginning of tuber expansion (90 days), respectively. A total of 5177 differential genes were identified in two varieties in the same period. GO and KEGG were used to analyze these differential genes, a variety of key genes closely related to starch and sucrose metabolism were screened. These results help us to better understand the mechanism of starch accumulation in yam.

DIELECTRIC PROPERTIES OF FRESH CASSAVA TUBER AT 2-2.90 GHZ MICROWAVE FREQUENCY

Rapid quantification of starch present in fresh cassava tuber by electronic means requires a conductivity work at various points of the tuber. The dielectric parameters of different samples of cassava tuber (Manihot esculenta L.) at the S-band of the microwave frequencies were determined. Tubers of cassava varieties of CTCRI, H-226, H-97, Sree Harsha, Sree Prabha, Sree Rekha, Sree Jaya, Sree Sahya, Sree Vijaya, Sree Prakash, Sree Visakham and H-165 were subjected to the cavity perturbation technique. The range of S-band microwave frequency tested were 2247, 2440, 2684 and 2970 MHz. Tubers of the variety H-226 had significantly lower conductivity value was 0.02s/m and the variety H-165, 1.49s/m and are significantly different. The dielectric constant (real part) of tubers of the varieties, H-165 and H-226 were 34.82 and 14.97 respectively and were significantly different. The proximal part of the tuber had the lowest level of conductivity followed by the middle portion and then the distal portion being 0.60s/m, 0.65s/m and 0.69s/ m respectively. The dielectric constant decreases steadily with increase in frequency between 2.00-2.90GHz range for fresh cassava tubers and the dielectric loss factor follows the same pattern. The moisture content of different varieties of fresh cassava tuber, H-226, H-97, Sree Harsha, Sree Prabha, Sree Rekha, Sree Jaya, Sree Sahya, Sree Vijaya, Sree Prakash, Sree Visakham and H-165 ranged between 44.52% and 58.66% as analysed using the moisture analyser at 80 °C. The starch content values estimated by the chemical method for all the varieties of fresh tuber ranged between 20.78% and 35.94%. The difference in starch content of tuber between the proximal and the middle region was found to be 3% and that of the middle and distal region was found to be 2%. The conductivity values of fresh cassava tuber can be used for the development of a starch indicator based on moisture content.

Effect of sowing time, seed rate and harvesting duration on quality of Ashwagandha Withania somnifera

The experiment was carried out at Herbal garden, Rajendranagar, Hyderabad during the 2009-10. The experiment was laid out in Completely Randomized Block Design with factorial concept comprising a total of 18 treatments replicated thrice with two sowing dates (August 15th and August 30th), three seed rates (10 kg/ha, 12 kg/ha and 14 kg/ha) and three harvesting durations (150 DAS, 180 DAS and 210 DAS). The data indicated that fresh root yield (13.91 q/ha) and dry root yield (3.38 q/ha) were maximum in August 15th sown crop when compared to August 30th crop. Among the harvesting durations, H3 (210 DAS) recorded maximum fresh root yield (13.48 q/ha) and dry root yield (3.12 q/ha). Among the three way interactions, maximum fresh root yield (15.63 q/ha) and dry root yield (4.40 q/ha) were recorded with August15th sown crop with a seed rate of 12 kg/ha and harvesting duration of 210 DAS (D1S2H3). There was significant difference in starch content due to dates of sowing. Significantly maximum starch content (11.81%) was recorded in D2 (August 30th) followed by D1 (August 15th) recording 11.64%. Reducing sugars were reported to be maximum (2.89%) in August 30th sown crop when compared to August 15th crop. Among the seed rates, S1 (10 kg/ha) recorded maximum reducing sugars (3.26%). Among the harvesting durations, H3 (210 DAS) recorded maximum reducing sugars (3.25%). Maximum non- reducing sugars (7.70%) was recorded in August 30th sown crop when compared to August 15th crop. Among the harvesting durations, H3 (210 DAS) recorded maximum non reducing sugars (7.70%). Among the three way interactions, maximum non reducing sugars (7.78%) was recorded with August 30th sown crop with a seed rate of 12 kg/ha and harvesting duration of 210 DAS (D2S2H3).

Targeted mutagenesis in ryegrass (Lolium spp.) using the CRISPR/Cas9 system.

Targeted mutagenesis in ryegrass (Lolium spp.) using the CRISPR/Cas9 system.

Separate hydrolysis and fermentation and simultaneous saccharification and fermentation methods in bioethanol production and formation of volatile by-products from selected corn cultivars

Corn (Zea mays L.) is a widely used raw material in the production of bioethanol. Creating new cultivars and applying appropriate fermentation techniques to increase production efficiency is still important for bioethanol producers. The purpose of the study presented here was to evaluate the correlation between differentiators of corn cultivars and fermentation methods in view of the efficiency of bioethanol production. The five selected cultivars differed by FAO (Food and Agriculture Organization) number, type of hybrid cultivar, and type of grain. The tested samples generally showed significant (p < 0.05) differences in starch contents. Ethanol fermentation was investigated using separate hydrolysis and fermentation (SHF) as well as simultaneous saccharification and fermentation (SSF) methods The SSF method proved the most effective for the production of bioethanol, regardless of cultivar. The greatest ethanol yield (p < 0.05) was achieved with the semiflint SM Hetman cultivar (81.23% theoretical value) under the SSF process. A negative correlation (p < 0.05) between starch content and ethanol yield was demonstrated. Chromatographic analysis of the raw spirits showed that lower levels of fermentation by-products were detected for the SSF method than for SHF.

Non-structural carbohydrates characteristics of different forest layers in monsoon broad-leaved evergreen forest in Pu'er, Yunnan Province, China

Based on cluster analysis of species vertical stratification, the variations in concentration, allocation and seasonal dynamics of non-structural carbohydrates were investigated in a monsoon broad-leaved evergreen forest in Pu'er, Yunnan Province. The results showed that the concentrations of soluble sugar (3.9%) and nonstructural carbohydrates (NSC, 13.3%) were the highest in the sub-canopy. In contrast, the sugar/starch (0.76) of understory was the lowest. There was no significant difference in starch content among three forest layers. For all forest stories, the soluble sugar was mainly allocated to leaves and the roots had more starch and NSC. The soluble sugar contents in leaves and trunks of sub-canopy species were higher than canopy and understory species. There were no significant differences in soluble sugar content of twigs and roots among three different forest layers. The starch content of leaves increased with decreasing height of forest layers. In contrast, the lowest starch content (10.7%) of roots was in understory. There was no significant difference in starch content of twigs and trunks among three different forest layers. The NSC content of leaves was lower in canopy (10.7%) than that in sub-canopy (12.3%) and understory (12.0%). The lowest NSC content of roots was in understory (14.2%). The lowest sugar/starch of leaves, twigs, and trunks presented in understory, while the lowest sugar/starch of roots presented in canopy (0.79). There were dramatic seasonal variations in concentrations and components of NSC. The concentration of soluble sugar and the sugar/starch were higher in the rainy season than that in the dry season. However, the concentration of starch and NSC were higher in the dry season than in the rainy season. The variations in concentration of NSC and its components among forest layers indicated that species with different heights varied in their utilization strategies of carbon, which partly explained species coexistence.

Shrinkage of cellular food during air drying

Shrinkage of potato and carrot (cylinders and slabs) was determined during convective drying at air temperature of 25, 55 or 65 °C with air speed of 1.6 or 0.5 m/s. Initial moisture content of slab samples at different positions within the carrot root and potato tuber was determined gravimetrically and by the vacuum method at 60°C. Structure of potato slabs at exterior and center of tuber was analysed by Scanning Electron Microscope (SEM).Glass transition temperature (Tg) was approximately 50 °C for dry potato (0.021 kg/kg dm), and 40 °C for dry carrot (0.005 kg/kg dm) indicating that potato and carrot would be in rubbery state throughout drying at 65 °C. Glass transition of the samples could be observed at the end of the drying process with air temperature of 25 °C. The initial moisture content of carrot at exterior and center of root were identical. However, the center potato layers had initial moisture content higher than the exterior potato layers. SEM images showed that the cells of the exterior potato samples had smaller volume with higher starch content than the center sample, thus indicating a correlation between structure characteristics and initial solids content.For all drying conditions used in this study, shrinkage of carrot samples (cylinders and slabs) had a linear relationship with moisture content during drying. For potato, however, a change in the slope of the shrinkage curve as a function of moisture content during drying was observed for cylinder samples. For potato slabs, only those having initial moisture contents lower than 5.5 ± 0.5 kg water/kg dm showed a similar change in slope, otherwise slabs presented a straight line for the whole water content range. The air temperature and air speed had no effect on the shrinkage behaviour of both carrot and potato samples under the operation conditions used in this study. No significant impact of glass transition on shrinkage of carrot and potato samples has been found, and if any this impact would be considered minor. Differences in starch content, in structure of the cellular material and its relationship with mechanical properties of material may explain the different shrinkage behaviour observed in this work.

Two β-amylase genes, OsBAM2 and OsBAM3, are involved in starch remobilization in rice leaf sheaths

To identify mechanisms of starch degradation in rice leaf sheaths at the post-heading stage, we investigated the function of OsBAM2 and OsBAM3, which encode plastid-targeted active β-amylase isoforms, in starch remobilization in leaf sheaths. The starch content in the second leaf sheaths below the flag leaf (the third leaf sheaths) peaked at the flag leaf emergence stage and gradually decreased until 15 days after heading. The mRNA levels of OsBAM2 and OsBAM3 in the third leaf sheaths increased from the flag leaf emergence stage to the heading stage when the starch content began to decrease. However, these mRNA levels did not always remain high during post-heading. Overexpression of OsBAM2 or OsBAM3 markedly repressed starch accumulation in the third leaf sheaths, showing that OsBAM2 and OsBAM3 function in starch degradation in rice leaf sheaths. In contrast, no significant differences in starch content in the third leaf sheaths were detected between knockdown plants of OsBAM2 or OsBAM3 and non-transgenic wild-type plants. Our results suggest that reduced expression of the individual genes, OsBAM2 or OsBAM3, does not result in excess accumulation of starch in the leaf sheaths, probably because of the complementary function of another gene or the action of other genes encoding starch-degrading .

Physicochemical and antioxidant composition of fresh peach palm (Bactris gasipaes Kunth) fruits in Costa Rica

Summary The variability of the physicochemical composition, carotenoid and polyphenol contents and hydrophilic antioxidant capacity of fresh peach palm (Bactris gasipaes) fruit was studied with a view to its exploitation as a potential source of bioactive compounds. The variability present in five batches of peach palm fruit obtained from two regions in Costa Rica: Tucurrique (T) and Pérez Zeledón (PZ), was studied. Significant differences were found for fruit weight, length and width amongst the batches studied. The moisture, fat and protein contents of the Tucurrique fruit were significantly lower than those from Pérez Zeledón. No significant difference in starch content was found between any of the batches of peach palm fruit studied. In terms of antioxidant compounds, the total carotenoid content ranged between 109 and 202 µg β-carotene equivalents/g dry weight (dw), while the total polyphenol content varied from 54 to 106 mg gallic acid equivalents (GAE) /100 g (dw). Both these components presented variability amongst the five batches. The antioxidant capacity was determined by the ORAC method and only the PZ 3 sample presented significant differences from the other four batches. The average hydrophilic antioxidant capacity was 37 ± 7 µmol of Trolox equivalents (TE)/g (dw). Overall, the peach palm fruit showed potential to be used in the development of functional foods since the variability of the raw peach-palm fruit, determined by applying a principal component analysis, showed that some characteristics of this fruit were not affected by harvest time and showed no differences between the batches from the two areas.

Overexpression of ADP-glucose pyrophosphorylase (IbAGPaseS) affects expression of carbohydrate regulated genes in sweet potato [Ipomoea batatas (L.) Lam. cv. Yulmi

ADP-glucose pyrophosphorylase is crucial in starch metabolism. The open reading frame of IbAGPaseS gene is comprised of 1539-base pairs and encodes a polypeptide of 512 amino acid residues. The deduced IbAGPaseS protein sequence was homologous with that of other AGPase proteins of various plant species. Also, the IbAGPaseS gene appears to be a member of multiple gene families and further, the differences in the copy numbers among the ten cultivars were considered to lead to differences in starch contents. IbAGPaseS was expressed in whole tissues and revealed high activity in thick-pigmented roots and developing tuberous roots. RT-PCR analysis indicated that the main role of IbAGPaseS is starch biosynthesis accumulating sink tissues during sweet potato root development. The IbAGPaseS cDNA was introduced to sweet potato under the control of the CaMV 35S promoter using Agrobacterium-mediated gene transfer techniques, thereby affecting the expression levels of carbohydrate regulated genes and sporamin gene. These results suggest that IbAGPaseS affects carbohydrate gene regulation.

CARBOHYDRATE METABOLISM IN INFLORESCENCES OF EPIDENDRUM IBAGUENSE

The purpose of this work was to determine changes in the carbohydrate content and sucrolytic activity in flower structures of Epidendrum ibaguense. Inflorescences were harvested at the different stages of development: 0 – mature closed bud, 1 – fully opened flower, 2 – senescence onset (red petals and twisted red labellum), 3 – wilted and senescent flower. Levels of total soluble sugar, reducing and non-reducing sugars and starch, as well as acid and alkaline invertase and sucrose synthase activities were determined. In inflorescences at the stage 3 the consumption of carbohydrates was observed during their postharvest life, as both carbohydrate types decreased along with time. The levels of soluble sugars, non-reducing sugars and starch did not differ over time in the inflorescence at stages 0, 1 and 2. Reducing sugar content decreased in flowers at stages 0, 1 and 3. No significant difference in starch content was detected among stages 0 to 2; starch showed an increase in senescing flowers. Soluble acid invertase was the main enzyme active throughout flower ageing. Sucrose synthase activity was kept low, with a relative increasing during senescence, which coincided with the highest levels of starch. In conclusion, carbohydrate metabolism varied along with the stage of development and the postharvest life of inflorescences of E. ibaguense.

Starch degradation in rumen fluid as influenced by genotype, climatic conditions and maturity stage of maize, grown under controlled conditions

Starch is the major component of maize kernels, contributing significantly to the feeding value of forage maize when fed to ruminants. The effects of genotype, climatic conditions and maturity stage on starch content in the kernels and on in vitro starch degradability in rumen fluid were investigated. Kernels of six maize genotypes, differing in amylose content and vitreousness, grown under three contrasting day/night temperature regimes during grain filling, and harvested at different maturity stages from two greenhouse experiments were investigated. Starch content was measured using an enzymatic method and the gas production technique was used to assess starch degradation in rumen fluid of dairy cows. The extent of starch degradation at different incubation times (6, 12 and 20h) was calculated from measured gas production data (6, 12 and 20h, respectively) and a published equation. Gas production (ml gas/g OM) showed a positive linear relationship with starch content in the kernels up to a certain level of starch accumulation. At each maturity stage, whole kernel and starch degradation in rumen fluid depended on the genotype (P<0.0001), growing conditions (P<0.0001), starch content (P<0.0001) and starch amount (P<0.0001) in the kernels. While starch content increased with advancing maturity, starch degradation similarly increased up to a certain level of starch content. In vitro starch degradation of the maize kernels in rumen fluid was affected by the starch composition, e.g. amylose and amylopectin content. Starch degradation was inversely related to the amylose content and vitreousness. Higher starch degradation was observed in the waxy (no amylose) and non-vitreous genotypes. The highest starch degradation was observed when plants were grown at intermediate temperatures in both experiments. The difference in starch degradability of each genotype at the same accumulated thermal time, i.e. maturity stage, was due to differences in grain filling rate, caused by the different temperature regimes. This effect of genotype and climatic conditions was consistent for all incubation times (P<0.0001). Rumen in vitro starch degradation is significantly influenced by genotypic, differences in starch content of the maize kernels and their growing conditions.

Yield and properties of ethanol biofuel produced from different whole cassava flours.

The yield and properties of ethanol biofuel produced from five different whole cassava flours were investigated. Ethanol was produced from five different whole cassava flours. The effect of quantity of yeast on ethanol yield, effect of whole cassava flour to acid and mineralized media ratio on the yield of ethanol produced, and the physical properties of ethanol produced from different cassava were investigated. Physical properties such as distillation range, density, viscosity, and flash point of ethanol produced differ slightly for different cultivars, while the yield of ethanol and electrical conductivity of ethanol from the different cassava cultivars varies significantly. The variation in mineral composition of the different whole cassava flours could also lead to variation in the electrical conductivity of ethanol produced from the different cassava cultivars. The differences in ethanol yield are attributed to differences in starch content, protein content, and dry matter of cassava cultivars. High yield of ethanol from whole cassava flour is best produced from cultivars with high starch content, low protein content, and low fiber.