Bana Grass Research Articles

Reduction of FeO in Molten Slag by Solid Carbonaceous Materials for HIsarna Alternative Ironmaking Process

To investigate the use of biomass in the novel HIsarna technology, the reduction of FeO in the slag by chars produced from thermal coal (TC), charcoal (CC), and Bana grass char (BGC) was studied. A drop tube furnace coupled with a quadrupole mass spectrometer (DTF-QMS) was employed to study the injection of chars into pre-melted slag in the temperature range between 1450 °C and 1525 °C. The reduction rate was calculated from evolved gases and the extent of FeO reduction was confirmed by wavelength-dispersive X-ray fluorescence (WDXRF). The FeO reduction proceeds through two stages, starting with a rapid reduction, which is dependent on the carbon type, and followed by gradual leveling off. The reduction rate with the charcoal char (CC) was the highest, over 60 pct reduction was achieved in the first 500 seconds at 1500 °C, while ~ 50 and 40 pct achieved with TC and BGC chars, respectively, for the same reaction time. The kinetic analysis suggests that the first and second stages of the reaction can be described by the second-order (F2) and three-dimensional diffusion (D3) models, respectively. The apparent activation energy values for the first stage were 290, 229 and 267 kJ/mol for reactions with TC, CC and BGC chars, while 265, 369, and 282 kJ/mol were obtained for the second stage. Based on the experimental data and kinetic results, it can be concluded that the first stage is controlled by chemical reactions on the carbon surface, and the second stage is influenced by a mixed-controlling mechanism.

Gasification and structural behaviour of different carbon sources and resultant chars from rapid devolatilization for HIsarna alternative ironmaking process

To evaluate the potential of using renewable biomass in the novel HIsarna technology, reactivity of thermal coal (TC), charcoal (CC), Bana grass char (BGC) before and after rapid devolatilization at 1500 °C in a drop tube furnace (DTF) was investigated. Thermogravimetric (TG) was used for CO2 gasification study, and high temperature confocal scanning laser microscope (HT-CSLM), Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM) were used to characterise the morphology of all three raw carbonaceous materials and their chars produced by rapid devolatilization. CC has fastest gasification reaction before and after rapid heat treatment, and BGC raw is more reactive than TC raw but BGC 1500 °C and TC 1500 °C have very similar gasification behaviour. The reactivity index of the rapidly devolatilized char is reduced to 84.21% (BGC), 92.11% (TC) and 94.23% (CC) compared to their raw materials. This shows that BGC is more severely affected by the rapid devolatilization, and this behaviour is likely to be governed by the high ash content which will melt and cause pore blockage during heat treatment. According to HT-CSLM results the average particle sizes decreased by 28%, 24% and 20 % for TC, CC and BGC respectively. While the SEM images shown that TC has gone through significant structural changes during the rapid devolatilization, but CC and BGC maintained their parent structural shapes. The BET results indicate that TC is non-porous, but both CC and BGC contain a large number of constricted micropores with significantly larger surface area.

Delignification of Bana Grass Using Sodium hydroxide and Ozone

In this work, Bana grass, a species of Napier grass (P. purpureum × P. americanum hybrid) which contains 60.2% cellulose, 23.8% hemicellulose and 8.2% lignin, was tested in the laboratory for lignin removal or delignification. Two processes of delignification were combined. Firstly, alkali pretreatment was used to determine the best conditions for the first stage of delignification. Secondly, the selected pretreated material, which was obtained from the best conditions for the first stage, was tested with the ozonolysis process. In the first stage of alkali pretreatment, five concentrations of sodium hydroxide (NaOH) from 0.5 to 10.5 wt.% were used. This research considers the ratio of cellulose to lignin because the ratio should be high for good lignocellulose. For untreated Bana grass, the ratio of cellulose to lignin is 7.3. After the first stage of alkali pretreatment, the maximum cellulose and lignin ratio is at 12.6 with 5.5 wt.% NaOH, and the amount of lignin elimination is 5.2%. The second stage is to pretreat lignocellulose with ozone. The concentration of ozone in the experiment is 1000 mg/h, and the pretreatment time is 0–30 min. Increasing time leads to higher lignin removal, but there is still cellulose in the material. Ozone pretreatment increases the ratio of cellulose to lignin for the first stage pretreatment material to 93.8. Ozone pretreatment alone cannot eliminate lignin from Bana grass, but it is better if it reacts with a sodium hydroxide solution. A combination of alkali and ozone pretreatment gives a high ratio of cellulose to lignin. From the results of the inhibitor examination, it is found that there is no detection of acetaldehyde, but total phenolics are detected for the pretreatment condition. These toxins can be eliminated by washing with water.

Growth and nutritional evaluation of napier grass hybrids as forage for ruminants

Napier grass is a perennial, tropical C-4 grass that can produce large amounts of forage. However, low temperatures and drought stress limit its productivity and nutritive value as a forage. To overcome these limitations, pearl millet × napier grass hybrids (PMN) were developed. It was hypothesized that PMN hybrids were more drought-tolerant, produced higher yields, and had higher nutritive value than napier grass varieties. The yield and nutritive value of 4 napier grass varieties (Bana grass, Mott, MB4 and N51) and 4 PMN hybrids (PMN2, PMN3, 5344 and 4604) were determined with or without irrigation in a strip plot design in Hawaii. Hybrid PMN3 outperformed napier grass varieties and the other hybrids for yield, while 5344 showed higher nutritional content and digestibility than most other grasses. Dry matter yields during the 110-day study period ranged from 10.3 to 32.1 t/ha without irrigation and 19.6 to 55.8 t/ha with irrigation, indicating that moisture stress was limiting performance in raingrown pastures. Only hybrids PMN3 and PMN2 and variety MB4 showed significant growth responses to irrigation. Further work is needed to evaluate the hybrids in a range of environments over much longer periods to determine if these preliminary results can be reproduced over the long term. Similarly, feeding studies with animals are needed to determine if the in vitro data for digestibility are reflected in superior performance for the promising hybrids. Keywords: Biomass, cattle, in vitro digestion, nutrient content, Pennisetum , tropical grasses. DOI: 10.17138/TGFT(4)168-178

Effect of cadmium on growth, photosynthesis, mineral nutrition and metal accumulation of bana grass and vetiver grass

An experiment was conducted to evaluate the differential effects of Cd contamination on the growth, photosynthesis, mineral nutrition and Cd accumulation of bana grass (Pennisetum americanum×Pennisetum purpureum) and vetiver grass (Vetiveria zizanioides). Bana grass accumulated 48–453 and 25–208mgkg−1 in plant roots and shoots, respectively, at 15–100mgkg−1 soil Cd concentration, while vetiver grass accumulated 167–396 and 0.13–9.0mgkg−1. These results indicated that bana grass was a Cd accumulator while vetiver grass was a Cd excluder. The ratio of root to shoot biomass was significantly increased in vetiver grass, while it was unchanged in bana grass by Cd pollution. This suggests that excluders may allocate more energy to roots than shoots under Cd pollution compared to un-contaminated condition, while accumulators may allocate equal proportions of energy to roots and shoots. For bana grass, soil Cd pollution significantly decreased the concentration of Fe and Mn in roots as well as the translocation factors of Zn and K. For vetiver grass, soil Cd pollution significantly decreased the concentration of Fe in roots and had no influence on the translocation factors of Fe, Mn, Cu, Zn, Mg, K and Ca. Soil Cd pollution showed no significant effect on chlorophyll content and photosynthetic rates in either of the grasses. The water content and leaf transpiration rate were significantly increased by Cd pollution in bana grass, while they were unchanged in vetiver grass. The results indicated that the energy allocation and mineral nutrition characteristics may aid in screening suitable plant species for phytoremediation.

Nutritional characteristics and in vitro digestibility by near-infrared spectroscopy of local and hybrid napiergrass varieties grown in rain-fed and irrigated conditions

Napiergrass can produce large amounts of biomass and its nutritive value has a significant effect on its effectiveness for animal production. However, temperature and drought stress limit its productivity. Drought-tolerant pearl millet × napiergrass hybrid (PMN) varieties were developed and produce high biomass yields. The nutritional content and digestibility of PMN is not well known, which limits its use in animal feeding. It was hypothesised that PMN hybrids are more drought tolerant and have higher nutritive value than napiergrass varieties. Four napiergrass varieties (Bana grass, Mott, MB4, and N51) and four PMN (PMN2, PMN3, 5344, 4604) were tested with or without irrigation treatment in a strip-plot design, with the objective of evaluating the nutritional value and in vitro digestibility of PMN hybrids and napiergrass. The forages were harvested on Day 110 of planting. Samples were hand chopped, oven-dried, ground to pass through a 1-mm screen and analysed for their nutrient content and in vitro digestibility using near-infrared spectroscopy. Dry matter (DM) content of PMN2 (24.3%) and PMN3 (22.9%) was significantly higher (P < 0.05) than 5344, Bana grass and N51 napiergrass varieties. No differences (P > 0.05) in acid detergent fibre, neutral detergent fibre, crude protein and metabolisable energy were found among napiergrass varieties. With no effect (P > 0.05) of irrigation, lignin content was highest (P < 0.08) in 4604 (8.2%) and lowest in 5344 (5.2%). Starch was highest (P < 0.05) in irrigated MB4 than both irrigated and non-irrigated 4604. Non-fibre carbohydrate content was highest (P < 0.05) in PMN2 (12.8%) than MB4 (8.7%). The in vitro true digestibility was significantly higher (P < 0.05) in 5344 and Bana grass (70.0% and 68.0% of DM, respectively), than PMN3 (54.5%). Rate of digestion was significantly higher (P < 0.05) in 5344 (4.9%/h) than PMN2 (2.7%/h), others were in between. Neutral detergent fibre digestibility (NDFD) of 5344 and Bana grass (56.7% and 53.2% of neutral detergent fibre, respectively) was significantly higher (P < 0.05) than PMN2 (38.0%). Although no effect of irrigation was observed, there was an interaction (P < 0.05) between variety and irrigation on neutral detergent fibre digestibility of napiergrass varieties. In conclusion, among four PMN varieties tested, PMN3 and 5344 has higher nutritional value and in vitro digestibility than PMN2 and 4604 even when grown in non-irrigated condition. Thus, PMN3 and 5344 is the preferred napiergrass variety for animal feeding, even in rain-fed farming conditions.

Fertilization Management to Optimize Yield and Quality of Bana Grass

Fertilizers containing nitrogen (N) : phosphorus (P) : potassium (K) ratios of 46:0:0, 16:20:0 and 16:12:8 were applied in combinations. Each fertilizer in both the first and the second application was provided at a rate of 75 kg ha -1 . The trial comprised 3 defoliation frequencies at 45, 55 and 65 d according to a randomized completed block design. Forage in four 1-m 2 areas in each plot was cut and weighed in the field. Crude protein content (P<0.05) and dry matter (DM) yield (P<0.01) of bana grass were greater with an application of ferti- lizer containing higher proportions of N. At only a 45 d defoliation frequency, leaf proportions (P<0.01) and the 48 h in sacco DM and neutral detergent fiber digestibility (P<0.05) were greater when the initial application of N:P:K was 16:12:8. Application of a fertilizer containing 16:12:8 10 d after cutting, followed by 46:0:0 20 d before harvesting at a 45 d defoliation frequency resulted in optimum DM yield and quality.

Production, characterization and nutritional quality of Napier grass [Pennisetum purpureum (Schum.)] cultivars in Western Kenya

Napier grass [Pennisetum purpureum (Schum.)] is the most popular perennial fodder recommended for smallholder crop-livestock farming systems in Kenya, where 80% of the national milk output is produced. The emergence of new diseases resulting in DM yield losses signals the need to develop alternatives to currently grown cultivars. Eight new cultivars (Kakamega 1, Kakamega 3, Machakos hairless, Uganda L14, Soghor Nandi L13, Kitui L7, Ex-Mariakani and Kakamega 8) were compared to four currently grown cultivars (Bana, French Cameroon, Clone 13 and Pakistan Hybrid) in the sub-humid highlands of northwestern Kenya for two growing seasons. Agronomic measurements were made on DM yield, tiller number, length, diameter and angle, leaf length, width, hairiness and colour and disease incidence. Nutritional measurements were made on leaf to stem ratio, intake, milk yields and body condition of Friesian cows. Kakamega 1, and Kakamega 3 yielded similar (p > 0.05) DM yield as Clone 13, Bana and French Cameroon, which yielded more than 16 t ha-1 and greater (p 0.05) in DM intake between Bana, Kakamega 1, Kakamega 3 and Machakos hairless. Cows feeding on Kakamega 3 and Kakamega 1 Napier grass cultivars yielded similar (p > 0.05) milk as those fed Bana grass, but more (p < 0.05) than those fed Machackos hairless. Kakamega 1 and Kakamega 3 could be used as alternatives to the currently grown Bana grass in Kenya. Key words: Napier grass, cultivars, DM, tillers, leaf, intake, milk.

An evaluation of Bana grass, Greengold and Pennaris. I. Intake by sheep and production characteristics

An evaluation of Bana grass, Greengold and Pennaris. I. Intake by sheep and production characteristics

Poor germplasm management complicates the effective utilisation of Napier and Bana grass

Poor germplasm management complicates the effective utilisation of Napier and Bana grass

Ecological rehabilitation and phytoremediation with four grasses in oil shale mined land

Vetiver grass ( Vetiveria zizanioides), bahia grass ( Paspalum notatum), St. Augustine grass ( Stenotaphrum secundatum), and bana grass ( Pennisetum glaucum × P. purpureum) were selected to rehabilitate the degraded ecosystem of an oil shale mined land of Maoming Petro-Chemical Company located in Southwest of Guangdong Province, China. Among them, vetiver had the highest survival rate, up to 99%, followed by bahia and St. Augustine, 96% and 91%, respectively, whereas bana had the lowest survival rate of 62%. The coverage and biomass of vetiver were also the highest after 6-month planting. Fertilizer application significantly increased biomass and tiller number of the four grasses, of which St. Augustine was promoted most, up to 70% for biomass, while vetiver was promoted least, only 27% for biomass. Two heavy metals, lead (Pb) and cadmium (Cd) tested in this trial had different concentrations in the oil shale residue, and also had different contents and distributions in the four grass species. Concentrations of Pb and Cd in the four grasses presented a disparity of only 1.6–3.8 times, but their uptake amounts to the two metals were apart up to 27.5–35.5 times, which was chiefly due to the significantly different biomasses among them. Fertilizer application could abate the ability of the four species to accumulate heavy metals, namely concentration of heavy metals in plants decreased as fertilizer was applied. The total amount of metals accumulated by each plant under the condition of fertilization did not decrease due to an increase of biomass. In summary, vetiver may be the best species used for vegetation rehabilitation in oil shale disposal piles.

The Effect of Pre-wilting and Incorporation of Maize Meal on the Fermentation of Bana Grass Silage

An experiment was conducted to investigate the effects of pre-wilting Bana grass (Pennisetum purpureum x P. americanum) herbage under sunny conditions for 0, 6, 18, 24, 32 and 48 h and ensiling it with maize meal. Four levels of maize meal (viz., 0, 5, 10 and 15% on fresh weight (Fw) basis) were tested. The experiment had a split-plot design. Wilting increased the concentration of water soluble carbohydrates (WSC) significantly (p 0.001) from 250 to 620 g⋅kg -1 , between 0 and 48 h respectively. The concentration of fermentation end-products decreased (except butyric acid) and pH increased when the period of wilting increased, indicating that fermentation was restricted. In particular, lactic acid content declined from 50.8 to 26.2 g⋅kg -1 ⋅DM (p<0.01) and the residual WSC contents of silage increased from 2.7 with fresh herbage to 18.1 g⋅kg -1 ⋅DM with 48 h of wilting (p<0.001). Rapid wilting for 24 h, to a DM of 450 g⋅kg -1 was optimum since important increases in pH, residual WSC and DMD occurred at this level of wilting. Acetic acid, butyric acid and ammoniacal-N contents were lowest with 24 h of wilting. There were no significant interactions between length of wilting and the incorporation of maize meal. Wilting had a greater influence on fermentation than the incorporation of maize meal. Addition of maize meal facilitated fermentation by increasing forage DM content and reducing effluent production. In addition, the maize meal increased DMD. It was concluded that maize meal should generally be incorporated at a level of 5% on fresh weight basis. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 6 : 843-851)

The Effect of Harvesting Interval on Herbage Yield and Nutritive Value of Napier Grass and Hybrid Pennisetums

A 6 (accession)×5 (cutting interval) factorial experiment was conducted over two years to investigate the effect of stage of growth on herbage production, nutritive value and water soluble carbohydrate (WSC) content of Napier grass and Napier grass xPearl millet hybrids (hybrid Pennisetum). The purpose of the experiment was to determine the optimum stage of growth to harvest the Pennisetums for ensilage. Two Napier accessions (SDPP 8 and SDPP 19) and four hybrid Pennisetum (SDPN 3, SDPN 29, SDPN 38 and Bana grass) were compared at five harvest intervals (viz. 2, 4, 6, 8, and 10 weeks). Basal fertilizers were similar in all treatment plots, although nitrogen (N) top-dressing fertilizer was varied proportionately, depending on the harvesting interval. The application was based on a standard rate of 60 kg N/ha every six weeks. Stage of growth had significant effects on forage yield, WSC content and nutritive value of the Pennisetums. Herbage yields increased in a progressively linear manner, with age. Nutritive value declined as the harvesting interval increased. In particular, crude protein content declined rapidly (p<0.001) from 204 g kg - 1 DM at 2 weeks to 92 g kg - 1 DM at 8 weeks of growth. In vitro dry matter digestibility decreased from 728 to 636 g kg - 1 DM, whilst acid and neutral detergent fibre contents increased from 360 and 704 to 398 and 785 g kg - 1 DM, respectively. Rapid changes in nutritive value occurred after 6 weeks of growth. The concentration of WSC increased in a quadratic manner, with peaks (136-182 g kg - 1 DM) at about 6 weeks. However, the DM content of the forage was low (150-200 g DM kg - 1 ) at 6 weeks. Therefore, it was concluded that Pennisetums should be harvested between 6 and 7 weeks, to increase DM content and optimize herbage production without seriously affecting nutritive value and WSC content. Accessions SDPN 29 and SDPP 19 appeared to be most suited for ensilage. It was suggested that WSC content should be incorporated as a criterion in the agronomic evaluation and screening of Pennisetum varieties.

Dry Matter Intake, Digestibility and Milk Yield by Friesian Cows Fed Two Napier Grass Varieties

The objective of this study was to compare two varieties of Napier grass (Bana Napier grass vs French Cameroon Napier grass) and to determine whether feed intake, digestibility, average daily gain (ADG) and milk yield of lactating Friesian cows from fresh cut Bana Napier grass was greater than from French Cameroon Napier grass, using a completely randomized design. Results show that Bana Napier grass had similar percent dry matter (DM), ash and gross energy (GE) to French Cameroon. Bana grass had higher percent crude protein (CP) and lower fiber fractions, acid detergent fibre (ADF), neutral detergent fibre (NDF) and lignin compared to French Cameroon. Overall the forage quality was marginally higher in Bana Napier grass compared to French Cameroon. The DM and NDF intake expressed as a percentage of body weight (BW) were similar in both Napier grass types. Both grasses had similar digestible DM and energy. Bana had higher digestible CP but lower digestible ADF and NDF than French Cameroon. Bana Napier was not different from French Cameroon when fed as a sole diet to lactating cows in terms of low DM intake, milk yield and a loss of BW and condition. To improve the efficient utilization of both Napier grass varieties, a supplement capable of supplying 1085-1227 g CP/d and 17.0-18.0 Mcal ME/d is required for cows to support moderate gains 0.22 kg/d and 15 kg 4% fat corrected milk/d.

Identification of superior pearl millet by napier hybrids and napiers in Zimbabwe

During 1988 and 1989, over 200 pearl millet [Pennisetum glaucum (L.) R. Br.] by napier grass (Pennisetum purpureum Schum) hybrids were developed by SADC/ICRISAT in Zimbabwe to provide superior pearl millet by napier hybrids especially for semi-arid rainfed regions. Eighteen such pearl millet by napier hybrids (SDPN), 20 napiers (SDPP), and two checks, Bana grass (pearl millet x napier hybrid), and Green Gold Harare (Panicum sp.) were evaluated at Aisleby (irrigated) and Lucydale (rainfed) locations during 1990/92. There were six cuttings (over 12 months) at Aisleby, and seven cuttings (over 16 months) at Lucydale. Among pearl millet by napier hybrids, SDPN 29 produced the highest total dry matter (DM) yield over cuttings at both locations. SDPN 29 produced 38 t total DM yield ha-1 (38% more than the best check, Bana grass) at Aisleby, and 12.5 t total DM yield ha-1 at Lucydale (39% more than the best check, Bana grass). Based on green fodder yield, DM yield, crude protein %, and in-vitro DM digestibility, two hybrids, SDPN 3 and SDPN 29 were selected and the cuttings were supplied to several hundred farmers in Zimbabwe. Among napiers, SDPP 19 and SDPP 10 were the highest yielding entries. During the dry period (April to October) at Lucydale, both SDPNs and SDPPs plants continued to grow and some entries produced DM yields of over 600 kg ha-1 per cut. This is the period when the forage is most needed. There were no significant differences for total DM yield over cuttings between highest yielding SDPP and highest yielding SDPN at both locations. The variation in napiers for different traits suggests that the napiers can be improved for forage quality and yield.

Voluntary intake and quality of diet selected by cattle grazing bana grass, kikuyu and forage sorghum

Bana grass (Pennisetum purpureum x P. amerieanum) was compared with kikuyu (P. clandestinum) and forage sorghum (Sorghum bicolor) with respect to quality of samples ;elected by four oesophageally fistulated steers. Hand-cut samples of the three forages were also compared with fistula samples for certain quality parameters. No significant difference (P ≥ 0,05) was found between IVDOM and N content of hand-cut and fistula samples, but ADF and NDF values differed significantly (P ≤0,01). Grazing significantly (P ≤0,05) reduced the leaf: stem ratio of the pastures. Changes in this ratio were, however, not consistent among the different species over different periods. Kikuyu contained more N throughout the growing season than bana grass or sorghum (P ≤0,01), while the IVDOM of sorghum was less (P ≤0,01) than that of bana grass and kikuyu. Seasonal trends were significant on occasions. Kikuyu contained less cell wall (NDF) (P ≤0,05) than bana grass and sorghum but the disappearance of NDF from nylon bags only differed significantly between kikuyu and sorghum. Organic matter intake (faeces voided measured by faecal bags) was consistently in the order of bana grass > sorghum > kikuyu, with a significant (P ≤0,05) difference between bana grass and kikuyu. It was concluded that the general assumption in the literature that hybrid Pennisetum species based on Napier are soft and palatable, may be true for bana grass as well

Effect of temperature and solar radiation on the development of dry matter and attributes of elephant grass (Pennisetum purpureum Schum.)

Nineteen accessions of elephant grass (Penniseturn purpureurn) were grown in a long-day photoperiod at 5/10, 18/13, 21/16, 27/22, 33/28 and 36/3l�C day/night temperatures during spring, summer and autumn in the Canberra phytotron. The temperature optimum for dry matter production was 33/28�C, and the magnitude of dry matter production was dependent on the solar radiation received; the low radiation levels in autumn reduced yields of advanced plants. Except at the lowest temperature, cumulative yield was associated with cumulative radiation. Rate of stem elongation was highest at 33/28�C under the spring and summer radiation regimes. Under autumn radiation conditions, rate of elongation was highest at 27/22�C. Rate of leaf appearance and leaf area per plant were linearly related to temperature and were little affected by radiation level. Rate of tiller production showed two maxima, at 18/13-21/16�C and at 33/28-36/31�C, and the maximum temperature was dependent on radiation level. The accessions Q5083, Bana grass and Taiwan consistently produced high yields throughout the range of temperatures tested. The results are discussed in relation to accession performance in the field.

Effects of ensiling or drying on five forage species in western Kenya: Zea mays (maize stover), Pennisetum purpureum (Pakistan napier grass), Pennisetum sp. (bana grass), Impomea batata (sweet potato vines) and Cajanus cajan (pigeon pea leaves)

Tropical livestock production systems are enhanced when surplus wet season feeds can be preserved for use during dry seasons. For this reason, new locally feasible preservation methods were tested on locally available feeds at Maseno in western Kenya. Values for the chemical composition of fresh, dried and ensiled maize stover, napier grass, bana grass, sweet potato vines and pigeon pea leaves were compared. Silage and hays preserved nutrients with equal efficiency, except for sweet potato vine silages. The sweet potato silages suffered a shift of protein into the acid detergent insoluble fraction, representing a loss of 37 g plant crude protein per kg silage dry matter. Only 15 g crude protein per kg dry matter was damaged when sweet potato vines were dried.