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1.
The chemical composition of baled silage frequently differs from that of comparable conventional silage. The extents of wilting, chopping, compaction and air infiltration potentially contribute to these differences in conservation characteristics. An experiment was organized in a 3 (0, 24 or 48‐h wilting to influence herbage dry‐matter content) × 2 (unchopped or chopped) × 2 (with or without compaction) × 2 (with or without air infiltration) factorial arrangement of treatments, to elucidate the relative effects of these factors on the conservation characteristics of ensiled grass. Dry‐matter content of herbage and infiltration of air had a greater effect on silage conservation characteristics than chopping and compaction. The main interactions were between wilting and air infiltration, wilting and compaction, and compaction and air infiltration. Air infiltration stimulated a secondary fermentation in the unwilted herbage, reflected in a large increase (P < 0·001) in clostridial activity. As wilting progressed, air infiltration facilitated yeast respiration of water‐soluble carbohydrates (WSC) and resulted in an increase (P < 0·001) in in‐silo fresh‐weight losses. Compaction reduced (P < 0·05) silage pore space and, as a result, the extent to which air could penetrate the silage mass. Compaction of the wilted herbage restricted respiration and was reflected in increased (P < 0·05) concentrations of WSC and in a reduction (P < 0·001) in fresh‐weight loss. The rapid achievement and maintenance of adequately anaerobic conditions is the primary requirement for baled silage. This study showed that failure to achieve this will lead to progressively greater losses, especially with drier herbage.  相似文献   

2.
Laboratory experiments with lucerne (Medicago sativa) have shown that maceration at cutting improves silage fermentation. Samples taken during wilting and after various ensiling periods were analysed for lactic acid bacteria (LAB) numbers and indices of silage fermentation. In Experiment 1, in which maceration was tested in unwilted and wilted lucerne, there was an additive effect of maceration and wilting on LAB numbers at ensiling, thus LAB numbers were approximately 108 colony-forming units (cfu) g?1 fresh crop for wilted, macerated forage compared with 103 cfu g?1 fresh crop for unwilted, unmacerated forage at ensiling. Initially, maceration reduced pH (P < 0·001) and increased lactic acid (unwilted comparison only; P < 0·001) and insoluble N (wilted comparison only; P < 0·001) concentrations. After 70 d ensiling, beneficial effects of maceration were associated only with the wilted silage. In Experiment 2, macerated lucerne was compared with unmacerated material, which was either ensiled after a wilting period of similar length or after wilting had proceeded to the same DM concentration as in the macerated forage. During wilting, LAB numbers were significantly higher in macerated than unmacerated forage (P < 0·05). This was also the case during the first 16 h of ensiling (P < 0·01). A decline in pH was observed earlier in macerated silage. Two days after ensiling, lactic acid concentration was higher in macerated silage (P < 0·05), but insoluble N concentration was not different. In a third experiment, unconditioned forage was compared with forages ensiled after regular conditioning or maceration. Although drying rate over 30 h was not influenced by degree of conditioning, LAB numbers during wilting increased with the degree of conditioning. In silages made from these treatments after 6 h wilting, there were no major effects on fermentation characteristics. In a fourth experiment, digestibility and voluntary intake of precision-chopped silage were measured in sheep and found not to be increased by maceration. It was concluded that maceration per se resulted in marginal improvements in fermentation; however, when maceration also increased DM concentration, fermentation was markedly improved. In these precision-chopped silages, maceration had no effect on intake or digestibility.  相似文献   

3.
Summary Potato plants, after inoculation with a South African strain of biovar 2 or a strain of biovar 3 ofPseudomonas solanacearum were grown in growth chambers at temperatures ranging from 14/16°C (dark/light) up to 25/30°C. When grown at 14/16°C or higher, plants inoculated with the biovar 2 strain developed wilting symptoms and internal symptoms on progeny tubers and the disease was transmitted by the progeny tubers. When the plants were inoculated with the biovar 3 strain, wilting symptoms developed from 18/20°C, internal symptoms on progeny tubers from 20/22°C and the disease was transmitted by progeny tubers from plants grown at 16/18°C or higher.  相似文献   

4.
Wilting grass prior to ensiling generally increases the dry matter (DM) intake but the effect of wilting on animal performance is still poorly understood. There is a need to improve understanding of the effects of wilting on the nutritional components and chemical composition of grass silage. This study focused on the effects of the extent and rate of wilting on N components of grass silage. Meadow grass was wilted to four DM contents (200, 350, 500, 650 g kg?1) at two different rates (fast, slow), creating a total of eight silages. Crude protein (CP) fractions were measured using the Cornell Net Carbohydrate and Protein System. Utilizable CP at the duodenum (uCP), a measure of feed protein value, was estimated using the modified Hohenheim gas test. Ruminally insoluble, undegraded feed CP (RUP) was measured using an in situ technique. Amino acid (AA) composition prior to and after rumen incubation was also investigated. Utilizable CP at the duodenum, RUP and true protein fractions B2 and B3 were increased by rapid wilting and high DM content (DM > 500 g kg?1), although the increase with DM was only mild for uCP, probably due to lower ME content in the DM‐650 silages. Non‐protein‐N decreased with increasing DM and rapid wilting. The higher RUP content from both DM‐650 silages leads to a higher total AA content after rumen incubation. Treatment also influenced the AA composition of the ensiled material, but the AA composition after rumen incubation was similar across treatments. Rapid and extensive wilting (DM > 500 g kg?1) improved protein value and reduced CP degradability. Increased uCP may result in higher milk protein yield, while reduced degradability may reduce N lost from urinary excretion. The primary effect of wilting on post‐ruminal AA supply from RUP appeared to be quantitative, rather than qualitative.  相似文献   

5.
Timothy (Phleum pratense L.) is an important forage grass used for pasture, hay and silage in regions with cool and humid growth seasons. Harvesting conditions could reduce its nutritive value, particularly with extended wilting periods. To understand how daytime or night‐time wilting influences the nutritive value of timothy, this study investigated the metabolism of non‐structural carbohydrates, including fructan and starch, together with total soluble protein and amino acid patterns in timothy plants harvested at two maturity stages (heading and anthesis) and wilted under controlled conditions for 24 h at two temperatures (15°C, 20°C) and two light regimes (darkness, light) by simulating different wilting management practices. Correlation analysis with the whole dataset showed that soluble protein, glucose and starch contents declined in plant tissues concomitantly with water loss, while amino acid, sucrose and fructose contents increased. Transient increase in amino acid content suggests that the decrease in protein content was due to proteolysis during wilting. Sucrose and fructose contents generally increased in plant tissues harvested at anthesis and wilted in light whereas they were unaffected in plants wilted in darkness. Fructan content remained stable. Fructan exohydrolase (FEH) and soluble acid invertase (INV) activities were well preserved during the first 12 h of wilting and might facilitate the fermentation process at the beginning of ensiling by supplying fructose from fructans and hexoses from sucrose to the fermentive bacteria.  相似文献   

6.
《Plant Production Science》2013,16(3):235-242
Abstract

The objective of this study was to clarify the effects of soil temperature in the stage from late tillering to panicle initiation (SI) and during the grain-filling stage (SII) on grain setting, dry matter production, photosynthesis, non-structural carbohydrate (NSC), xylem exudation and abscisic acid (ABA) levels in rice (Oryza sativa L. cv. Koshihikari). Rice plants were exposed to four different soil temperatures during SI or SII: 17.5, 25, 31.5 and 36.5°C (ST18, ST25, ST32 and ST37, respectively). The yield, yield components, grain filling and quality in SI were negatively influenced by high soil temperature of 37°C. On the other hand, there was no significant difference in those characters among temperature treatments in SII. The root/shoot ratio was smallest in the ST37 plants in both SI and SII, mainly due to their lighter root weight. At 7 days after initiation of treatment (DAT) in both SI and SII, the photosynthetic and xylem exudation rate tended to increase slightly as soil temperature increased up to 32°C. At 21 DAT, however, the photosynthetic rate was lowest in ST37, with concurrent decrease of diffusion conductance and SPAD value. In addition, decrease of NSC concentration in stem and xylem exudation rate, and increase of ABA level in leaves and xylem exudate were observed in ST37 plants at 21 DAT. These results suggested that high soil temperature before heading especially influenced yield, grain quality and plant growth. Possible mechanisms of the effect of soil temperature are discussed.  相似文献   

7.
《Plant Production Science》2013,16(4):460-467
Abstract

Delayed stem senescence (DSS) after pod maturation in soybean (Glycine max) lowers the quality of products in the mechanized harvest. The effects of drought and excess wet soil conditions on the occurrence of DSS were studied with special reference to remobilization of vegetative nitrogen and supply of cytokinin via xylem. Excess wet soil treatment was applied throughout the reproductive period to field-grown soybean in 2003 (Exp.1) and short-term drought stress treatment was applied during the reproductive period to pot-grown soybean plants in 2004 (Exp.2). The degree of DSS at pod maturing was evaluated by the DSS score from “1” for severe DSS to “5” for completely synchronous senescence of pods and vegetative parts. The DSS score in Exp.1 varied from 2.2 to 2.5 and that in Exp.2 from 2.8 to 3.7. Excess wet soil treatment in Exp.1 promoted the occurrence of DSS, while drought stress treatments during the periods of flowering to pod elongation, later seed-filling and seed maturing decreased it. The soybean plants that showed distinct DSS had lower ratios of seed number to vegetative dry weight at seed maturity and a lower rate of nitrogen remobilization from vegetative organs to seeds during the latter half of the reproductive period. The trans-zeatin riboside (t-ZR) level in xylem exudate tended to be higher in soybeans with severer DSS than in those normally matured in both experiments showing increased t-ZR concentration and/or higher exudation rate. These results suggest that DSS can be caused by a wet soil water condition, which lowers pod/seed number and increases vegetative organs mediated by the increased supply of cytokinin through xylem during seed-filling.  相似文献   

8.
Two experiments were carried out with grass silages cut at a leafy (Experiment 1) and a more mature (Experiment 2) stage of growth to evaluate the effect of wilting and chop length on silage intake and performance of store lambs. In each experiment, the herbage was cut with a rotary mower and was either ensiled within 24 h as unwilled silage (U) or wilted for 1–3 d (W). Each silage type was harvested with either a double-chop harvester (D) or a precision-chop harvester (P). All silages were treated with formic acid at 3 1 t?1 and were well preserved. The silages were fed ad libitum to Suffolk crossbred store lambs (twenty-four lambs per treatment) without any supplement over a period of 8 or 9 weeks. Wilting of the silages had little effect on silage intake (797 vs. 809g dry matter (DM) d?1) or on lamb performance in Experiment 1. In Experiment 2, wilting of the D silage increased silage DM intake (589 vs. 534 g DM d?1; +10%) and reduced the extent of liveweight losses. Wilting of the P silage reduced silage intake (770 vs. 791g DM d?1; -3%) and reduced liveweight gains. In Experiment 1 intakes of the D silages were 650–667g DM d?1 and just maintained lamb live weights. Intakes of the P silages were 39–49% higher than the D silages (927–968 g DM d?1) and increased liveweight gains. In Experiment 2 intakes of the D silages were 534–589 g DM d?1 and resulted in a loss in lamb live weight. Precision-chopping increased silage intakes by 31–48% (770–791 DM d?1)in Experiment 2 and improved lamb liveweight gains. Lamb performance was higher on the UP silage than on the WP silage. The rumen retention lime (RRT), estimated from the rumen contents of the lambs at slaughter and their silage intake before slaughter, was much shorter for the lambs fed on the P silages (12.6–20.6 h) than those fed on the D silages (21.4–29.3 h) in each experiment. Silage intake and liveweight gain were positively related to silage in vivo DM digestibility (DMD), whereas RRT was negatively related to DMD. However, there were distinct differences between the P and D silages in the elevation and, to a lesser extent, in the slope of the regression lines, indicating that intake of D silage was limited by factors other than the digestibility of the silage The results of this study show that the chop length of grass silage had a far greater effect on intake and on lamb performance than silage digestibility, whereas wilting had little or no effect.  相似文献   

9.
This review examines the response in intake of silage and animal performance after wilting of grass before ensiling. It uses data from eighty‐five published comparisons. Initial analysis identified those variables having the greatest influence on the increase in dry‐matter (DM) intake of grass silage owing to wilting. Total water loss, drying rate of the wilted material and ammonia‐N concentration of the unwilted material were the variables most closely and positively correlated to the proportional increase in DM intake as a result of wilting, with r2 values of 0·344, 0·393 and 0·240 respectively. There was little evidence of curvilinearity in any of the relationships. Stepwise regression analysis was used to identify the best multiple linear regressions for predicting the proportional increase in intake owing to wilting. Factors associated with the extent and rate of water loss in the field (total water loss and drying rate) and the quality of the unwilted material ensiled and its subsequent fermentation pattern (DM digestibility, crude protein, ammonia‐N content of unwilted silage) were the key variables in the relationship. Subsequent analysis related the increase in output of milk energy of dairy cows and liveweight gain of beef cattle to the same independent variables. This indicated that variables shown to describe the response in DM intake in the previous analysis were among those most closely related to the increases in animal performance owing to wilting of grass. To assess whether the increase in animal performance owing to wilting could be explained as a direct response to increased metabolizable energy (ME) intake of wilted compared with unwilted silages, linear relationships were derived between the increase in milk and beef production parameters and the increase in ME intake owing to wilting. From these, it was concluded that there was no clear evidence that wilting reduced the efficiency of utilization of ME in beef or dairy cattle. The present study showed that the increase in milk energy output (measured in MJ) per increase in ME intake (measured in MJ) owing to wilting was linear, with a slope of 0·19. This response from additional ME intake owing to wilting is in line with what would be anticipated when increasing ME intake by other methods.  相似文献   

10.
Effects of wilting rate and fermentation stimulators and inhibitors on protein characteristics of forages typical for organic production were assessed using traditional analytical methods and a gas production in vitro assay. The hypotheses were that the proportion of the crude protein (CP) fraction that was soluble would be lowest, and the protein feed value highest, under rapid wilting and restricted fermentation. The solubility of the CP fraction varied according to treatments and between a first and a second cut, with moderate and high content of clover respectively. It was, however, of minor importance for the protein value, both calculated as amino acids absorbed in the small intestine (AAT20) and estimated as effective utilizable crude protein (uCP04) by the in vitro assay. In ensiled herbage, AAT20 was highest in rapidly wilted and restrictedly fermented silages made from a first cut dominated by highly digestible grasses. Silages from the second cut dominated by red clover were far lower in AAT20. The in vitro assay did not separate silages according to herbage composition or wilting rate, but ranked restrictedly fermented above extensively fermented with regard to protein supply. The assay might still have caught the characteristics that determine the true protein value in vivo.  相似文献   

11.
The effect of spreading mown perennial ryegrass (Lolium perenne) herbage over the total ground area on water loss during field-wilting was compared with leaving herbage in swaths (three swaths put together into one, occupying 0·18 of ground area) in three experiments. Spread crops were not tedded during wilting but were rowed up immediately before harvest. In all experiments, conventional silage-making equipment was used on a field scale. Feeding value was assessed with lactating dairy cows and growing heifers (Experiment 1) and sheep (Experiment 3). The periods of field wilting were 48 h (Experiment 1), 24 h (Experiment 2) and both 24 h and 48 h (Experiment 3). Spreading the crop was associated with larger increases in loss of water in all three experiments compared with leaving grass in swaths. Losses of dry matter (DM) during wilting were similar in Experiment 2 but were higher for the swathed crop wilted for 48 h than for 24 h in Experiment 3. Spreading resulted in restricted fermentations associated with higher crop DM contents at ensiling. In Experiment 1 the concentrations of DM, ash and water-soluble carbohydrate in silage were higher (P < 0·001) for spreading the crop and the concentrations of crude protein and neutral-detergent fibre were lower (P < 0·05) than for swathed material. In Experiment 3, spreading was associated with higher concentrations of water-soluble carbohydrates and ethanol and lower concentrations of fermentation acids, ammonia-N and neutralizing value in silage. Voluntary DM intake of silage by dairy cows and heifers was higher for spread than for swathed material (P < 0·05), but in Experiment 3 (sheep) there were no significant differences between treatments in voluntary intake of DM. The increased intake by dairy cows of silage from spread herbage was reflected in increased concentrations of milk fat (P < 0·01) and protein (P < 0·05) but not in milk yield (P > 0·05). It is concluded that spreading herbage during field wilting prior to ensiling accelerates water loss and has the potential to improve the feeding value of the ensiled product.  相似文献   

12.
Macrophomina phaseolina is the causal agent of charcoal rot disease, which attacks many plant species, including those in the Cucurbitaceae. The fungus is frequently isolated from wilted melon and watermelon plants in Israel. Nevertheless, the role of M. phaseolina in disease progress and induction of wilting or yield reduction in watermelons and melons is not clear and not similar. Precise disease identification is important in order to suggest effective control measures. The objective of the current study was therefore to investigate disease progress and document its damage in watermelon and melon. Watermelons and melons were seeded in a field naturally infested with M. phaseolina and in the greenhouse in 10-L pots containing dune sand. Plants were inoculated at 35 days of age using two methods: drenching with macerated fungus around the crown area or stabbing the lower stem with an M. phaseolina-infested toothpick. Disease progress was documented in the field and in the greenhouse. Plant colonization and symptom development were more pronounced in melon than in watermelon. Large lesions and significant internal rotting developed in melon plants inoculated by the two methods in both field and greenhouse. In watermelon, however, no lesions or internal rotting were observed. Disease effect on melons and watermelons was observed only in the field, a short time before harvest, and was expressed as partial wilting and significant loss of shoot and fruit fresh weight similarly to disease appearance under natural infection. No wilting of melons or watermelons was observed in the greenhouse experiment.  相似文献   

13.
Summary

Laboratory tests were conducted to determine the effect of a microbial inoculant on the stomatal response of maize leaves (Zea mays L.). The microbial inoculant investigated is known as Effective Microorganisms or EM and consists of a mixed culture of naturally occurring, beneficial microorganisms. Research has shown that EM applied to soils and plants can improve soil properties and enhance the growth, yield and quality of crops. The exact mechanisms or modes-of-action of how EM cultures elicit beneficial effects on plant growth and metabolism is not known. However, it is likely that some of these cultures can synthesize phytohormones (i.e., auxins and others) or growth regulators that stimulate plant growth. Consequently, the effects of EM and partial illumination on stomatal response of intact and excised maize leaves were evaluated. Potted plants were dried to the wilting point and rehydrated with either a 1:100 dilution of EM and water or water alone applied to the soil. Sudden illumination of plants maintained in the dark showed that the leaf stomata of the EM-treated plants opened more rapidly than water-treated control plants. When leaves were excised and subjected to dehydration, the stomata closed more slowly (i.e., remained open longer) for the EM-treated plants compared with the water-treated control plants. There was no effect of EM on cuticular conductance in any of the experiments. The results of this study indicate that EM cultures contains bioactive substances that can significantly affect leaf stomatal response.  相似文献   

14.
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 .  相似文献   

15.
To develop an in vitro assay method for bacterial wilt resistance in potato, resistant and susceptible standard genotypes were grown in vitro, and different conditions of inoculation with Ralstonia solanacearum phylotype I/biovar 4 were examined. The optimal condition was the inoculation of 6–8 leaf stage plants with a bacterial concentration of 102 CFU ml?1 and an incubation temperature of 28 °C. Evaluation of stem wilting was more reliable than that of leaf wilting. Using this method, nine genotypes with different resistance levels in the field were evaluated. Lower disease indices were obtained for genotypes with high resistance levels in the field, suggesting that this assay is useful for evaluating bacterial wilt resistance in a controlled environment.  相似文献   

16.
乙烯响应转录因子(AP2/ERF)家族在植物逆境胁迫与物质合成中有重要功能,其成员TaERFL1a参与了小麦响应非生物胁迫过程,然而其在淀粉合成中的功能尚不清楚。本研究利用大麦条纹花叶病介导的基因沉默技术(barley stripe mosaic virus-virus induced gene-silencing,BSMV-VIGS),在田间条件下抑制 TaERFL1a基因在小麦籽粒中的表达,通过测定灌浆期间籽粒内该基因的表达量、成熟籽粒产量性状和淀粉性状,探究TaERFL1a在小麦籽粒淀粉合成中的功能。结果发现,在接种后23 d,接种BSMV-VIGS- TaERFL1a植株籽粒内 TaERFL1a基因表达水平降低了86.5%; TaERFL1a基因沉默植株成熟籽粒的粒长、粒宽、千粒重和淀粉含量分别降低了5.22%、12.70%、9.53%和5.43%; TaERFL1a基因沉默植株的籽粒淀粉粒排列疏松且数量减少。这些结果表明TaERFL1a转录因子在小麦灌浆期间的籽粒淀粉合成中发挥了重要作用。  相似文献   

17.
崔娟  李旋  许喆  唐佳威  董莉环  吴磊  史树森 《玉米科学》2017,25(5):141-144,151
柳叶刺蓼是吉林省春玉米田的恶性杂草,严重危害玉米生长发育,降低玉米产量。在大田条件下采用添加柳叶刺蓼密度系列试验和拟合函数关系模型方法,研究柳叶刺蓼与玉米的竞争关系。结果表明,在柳叶刺蓼的竞争干扰下,玉米株高、茎粗、穗长、单穗重、百粒重及产量均随柳叶刺蓼密度的增加而降低,空秆率增加。幂函数y=2.947x~(0.855)能较好地拟合玉米产量损失与柳叶刺蓼密度之间的关系(R~2=0.983;F=287.355;P=0.000 1)。玉米田柳叶刺蓼人工除草的经济阈值为3.97~5.02株/m~2,90%莠去津可分散粒剂或20%氯氟吡氧乙酸乳油化学防除柳叶刺蓼的经济阈值分别为0.45~0.58和0.53~0.67株/m~2。  相似文献   

18.
Hydraulic resistance in plants is one of the most important factors responsible for changes in leaf water potential that is an indicator of plant water stress. Although the hydraulic resistance to passive water transport (Rpa) is a robust index in paddy rice (Oryza sativa), measurement is both time-consuming and labour-intensive. Here, we describe on a quick method to measure hydraulic resistance to osmotic water transport (Ros) by measuring the xylem sap exudation rate and osmotic water potential. In a greenhouse experiment, Ros responded significantly to soil temperature, but under field conditions soil temperature varied considerably less than air temperature. In the field experiment, Ros of six rice cultivars at two growth stages was strongly positively correlated with Rpa. We conclude that measuring Ros could be used to evaluate root water transport capacity in paddy rice under conditions with adequate soil water.  相似文献   

19.
Herbage, predominantly perennial ryegrass (Lolium perenne) grown in Northern Ireland, was harvested at four dates from June to October 1996 (H1, H2, H3 and H4). At each harvest approximately one-fifth of the grass harvested was artificially dried and pelleted (G). The remainder of the grass was either wilted for 28–52 h (W), depending on the weather conditions, or ensiled directly, i.e. unwilted (UW). Within the W and UW treatments an inoculant or formic acid additive was applied to the herbage before ensiling. After a minimum ensiling period of 10 weeks, sixty steers, mean initial live weight 432 (s.d. 37) kg, were offered the twenty forages in a four-period partially balanced changeover design experiment. Each period was of 2 weeks’ duration. Dry-matter (DM) intakes were recorded daily, with intakes in the second week of each period used in the statistical analysis of the data. The digestibility of each of the forages was also determined in vivo using four castrated male sheep per silage. Wilting increased the DM content of the silage and the pH, the largest increase in DM content occurring at the second harvest. On average, wilting proportionally increased silage DM intake by 0·21 compared with the unwilted silage (P < 0·001), but the intake of the wilted silage was not significantly different from that of the artificially dried and pelleted grass (P > 0·05). The intake of the wilted silage was higher than that of the unwilted silage at each harvest, the proportional increases being 0·22 (P < 0·001), 0·41 (P < 0·001), 0·19 (P < 0·001) and 0·05 (P > 0·05) at harvests H1, H2, H3 and H4 respectively. Treatment of the grass with formic acid before ensiling resulted in a proportional increase in silage intake of 0·08 compared with the inoculant-treated silage (P < 0·05). Compared with the inoculant-treated silage, formic acid increased silage intake by 0·08, 0·02, 0·14 and 0·10 at harvests H1 (P > 0·05), H2 (P > 0·05), H3 (P < 0·01) and H4 (P < 0·05). The results of this study indicate that the effect of wilting on silage intake varies across different harvests and additive treatments. The difference in response to wilting across different harvests is mainly a result of the prevailing weather conditions during wilting.  相似文献   

20.
Regrowth of 3- and 4-month old (‘young’ and ‘old’ respectively) sheep's burnet [Sanguisorba minor ssp. muricata (Spach) Briq.] was studied under limiting and non-limiting moisture conditions in a glasshouse. Moisture deficits were imposed by using a single cycle of withholding moisture until first wilting. Plants of each age were defoliated severely at three levels which represented approximately 80–100% canopy removal. These levels were based on the proportion retained of the eight most mature leaves on each plant and were referred to as complete [0% residual leaf area (rLA)] and partial [50% rLA (four leaves) and 100% rLA (eight leaves)] defoliation. Vegetative growth and total non-structural carbohydrate (TNC) levels were studied. Leaf number (0-8 leaves), area (0-115 cm2) and dry weight (0-1·0 g) differed (P < 0·05) between defoliation intensities at the start of regrowth, while stubble (1·2 g) and root (12.·6 g) dry weights were similar. Soluble sugars [< 6% dry matter (DM)] and starch (< 1% DM) occurred in leaf, stubble and root. Old plants were morphologically and physiologically more developed than young plants. For example, stubble (2·0 g) and root (21·5 g) dry weights of old plants were greater (P < 0·05) than those of young plants (04 and 3·7 g respectively). Defoliation intensity had a major effect on regrowth, with completely defoliated plants at the final harvest having leaf numbers (forty-nine leaves) and areas (235 cm2) almost twice those of partially defoliated plants. Stubble soluble sugar levels (38% DM) were lower than those of partially defoliated plants (5·5% DM), and it was suggested that these contributed to regrowth. Moisture regime had a negligible influence on plant growth. However, plants in the dry regime had soluble sugar levels 1·4 (stubble) -1·7 (roots) times higher than those watered adequately, which suggested that plants adjusted to the water depletion. The effects of plant age on regrowth were similar for most characters, but the larger and physiologically more mature old plants would probably be more tolerant of successive defoliations.  相似文献   

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