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1.
Pasture managers seek to balance leaf appearance with utilization to sustain sward productivity while meeting livestock nutritional needs. Achieving this in silvopasture must account for the influence of light and defoliation on tillering. We determined tiller production, as a function of light availability and clipping height, for two forage grasses adapted to cool, humid temperate conditions of the Appalachian region of the USA. Tiller production of cocksfoot (orchard grass) (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) was greatest in unshaded and least in shaded sites, irrespective of residual clipping height. Juvenile plants produced more than twice as many tillers as mature plants, with differences accentuated by site, reflecting a shift in reproductive and resource‐use strategies. Trends in tiller production were as follows: cocksfoot > tall fescue; 10‐cm > 5‐cm residual clipping height; and unshaded > partially shaded > densely shaded sites. Tiller production reaches maximum earlier in the woodlot site, regardless of species or clipping height, than at the unshaded site. Plants at the wooded site extended leaves quickly, sustaining herbage production, but had less non‐structural carbohydrate and fewer tillers. Cocksfoot, but not tall fescue, sustained leaf and tiller production in the shaded sites, suggesting that cocksfoot is suited for use in silvopasture in this region.  相似文献   

2.
Seedling tiller number is a possible selection criterion to improve seedling establishment of Altai wildrye, Leymus angustus (Trin.) Pilger, an important grass for autumn grazing of beef cattle in semiarid environments. Forty-two half-sib families selected for high seedling tiller number (HTN) and eighteen half-sib families selected for low seedling tiller number (LTN) by four cycles of divergent recurrent selection were compared with four controls, Altai wildrye cultivars Prairieland, Eejay and Pearl, and crested wheatgrass ( Agropyron desertorum (Fisch. Ex Link) Schultes), cultivar Nordan, on dryland and irrigated sites at Swift Current, Saskatchewan, Canada. Seedling tiller count, seedling height, tiller weight and seedling dry-matter yield (DMY) were determined on two plants per plot and DMY was determined for each plot for 2 years post-establishment. HTN half-sib families had more, lighter and shorter tillers than LTN half-sib families. There was a negative correlation ( r =–0·42, P  < 0·01, n =60) between seedling DMY and tiller number. HTN half-sib families had higher DMY in post-establishment years at the dryland site only. Seedling tiller number in Altai wildrye may be related to DMY at sites at which resource availability delays seedling establishment, but selection for HTN will not increase seedling DMY owing to concomitant changes in carbon allocation.  相似文献   

3.
In this study, 120–144 commercial varieties and breeding lines were assessed for grain size attributes including plump grain (>2.8 mm) and retention (>2.5 mm+>2.8 mm). Grain samples were produced from replicated trials at 25 sites across four years. Climatic conditions varied between years as well as between sites. Several of the trial sites were irrigated while the remaining were produced under dryland conditions. A number of the dryland sites suffered severe drought stress. The grain size data was analysed for genetic (G), environmental (E) and genotype by environment (G×E) interactions. All analyses included maturity as a covariate. The genetic effect on grain size was greater than environmental or maturity effects despite some sites suffering terminal moisture stress. The model was used to calculate heritability values for each site used in the study. These values ranged from 89 to 98% for plump grain and 88 to 96% for retention. The results demonstrated that removing the sources of non-heritable variation, such as maturity and field effects, can improve genetic estimates of the retention and plump grain fractions. By partitioning all variance components, and thereby having more robust estimates of genetic differences, plant breeders can have greater confidence in selecting barley genotypes which maintain large, stable grain size across a range of environments.  相似文献   

4.
Simulation models have a role in predicting and understanding the consequences of weather and management perturbations to biophysical systems. One such model is EcoMod – a biophysical simulation model of a pastoral ecosystem. It comprises a range of sub-models that form the main components of pastoral ecosystems – namely plants, soils and ruminant livestock. These component models are integrated to simulate the complex interactions occurring within such systems. The purpose of this study was to test how well EcoMod simulated the changes in growth rate and plant composition of dryland and irrigated pasture production in a temperate climate through comparison with a long-term (1966–2003) data set measured in New Zealand. The general behaviour of the modelled pastures was similar to those of the observed pastures. There was also close agreement between the measured and modelled total annual and monthly growth rates of dry matter (DM), particularly after modifying some of the parameters of plant growth to better represent the characteristics of dominant species present under dryland and irrigation pastures. There was greater discrepancy between measured and modelled pasture composition but in the case of the simulation of the dryland pasture, the proportional differences in species composition were much greater than the absolute differences in species composition. In addition to comparing the outputs of EcoMod to data from actual pasture production, model testing issues and potential sources of error between model outputs and data were also examined.  相似文献   

5.
The orange wheat blossom midge, S. mosellana (Gehin) (Diptera: Cecidomyiidae), a global pest of wheat (Tritium aestivum L.), has recently invaded Montana's Golden Triangle, an important wheat producing region. Unchecked, S. mosellana populations can quickly grow to damaging levels. In this study, we document the prevalence of S. mosellana and its main natural enemy, Macroglenes penetrans (Hymenoptera: Pteromalidae), in this newly invaded area of Montana, and compared the effects of irrigated versus dryland cropping systems on S. mosellana and its parasitoid. Different approaches to monitoring S. mosellana populations were examined, including pheromone traps for adults, collection of larvae from wheat heads, and overwinter sampling of soil to measure the levels of larvae and cocoons. Adults of the M. penetrans were surveyed through daily sweep net sampling. This study demonstrated that the emergence of M. penetrans was usually well synchronized with emergence of S. mosellana as the emergence of parasitoids occurred shortly after the pest with the highest peak (90%) at 26 June and 14 July, 2015, respectively. Irrespective of sampling techniques; pheromone traps or soil sampling, no significant difference was observed in population of S. mosellana between irrigated and dryland cropping systems. In contrary, cropping systems played a significant role in the abundance of parasitoids since the irrigated fields had significantly higher population of parasitoids (five times on an average) compared to dryland cropping system. The possible implications of these findings in monitoring of S. mosellane and the establishment of M. penetrans are discussed.  相似文献   

6.
Using data from an 11-year period, total and marketable yield were related, using regression analysis, to mainstem and tuber number for five maincrop varieties (Russet Burbank, Shepody, Atlantic, Norchip, and Norland) and two early-maturing varieties (Conestoga and Carlton), at irrigated and dryland sites in western Canada. Mainstem number by itself was a poor predictor of total and marketable yield. Highly significant regressions of yield on the derived variable tuber number per mainstem were evident for all cultivars grown at the dryland sites. In general, the proportion of the total variation in yield accounted for by the regression models was much higher at the dryland than at the irrigated sites, indicating that the relationship between yield and its predictor variables was more complex for irrigated sites. While the study suggests that the use of tuber number per mainstem may be useful as an early-season predictor of tuber yield for cultivars, particularly under dryland conditions, a model using the predictor variables mainstem and tuber number will generally be superior due to the additional information it provides when competitive effects are present for light energy within the canopy or for assimilates among developing tubers. Contour plots provide a useful way to study the yield response to changes in tuber number at specific stem density levels.  相似文献   

7.
A simple potato growth model was validated in 1985 and 1986 at two dryland sites, Grand Forks, ND and Rosemount, MN, and one irrigated site, Hancock, WI. At each site, Russet Burbank potatoes were grown to maximize yield. Leaf area index and leaf, stem, root, and tuber biomass data were collected from replicated experiments every two weeks. Soil matric potentials, minimum and maximum temperatures, and solar radiation also were measured. Among sites, crop development rates and solar radiation receipts were similar, but final tuber yields differed by as much as 35 Mg/ha. Model predictions of leaf, stem, and tuber dry weights were similar to observed data both in terms of maximum values attained and seasonal development except for the experiment in Grand Forks in 1986 where the model over-estimated final tuber yield by 23 Mg/ha (115%). Soil aeration or salinity, factors not currently modeled, may account for this discrepancy. Modeled yield responses to defoliation were compared with field data from one of the experimental locations. At levels of defoliation below fifty percent, proportional yield reductions were similar between observed and modeled crops.  相似文献   

8.
Alpine bluegrass (Poa alpina L.) is common in mountain areas, where it represents a valuable forage resource and is widely used for ecological restoration of disturbed landscapes. This study assessed the variation of germplasm from the Rhaetian Alps, Italy. Both seed production and morphology were examined for potential use in restoration projects and for conservation and selection purposes of local genetic resources. The effects of the ex situ growing site were also assessed in two altitude‐contrasting sites. Individual populations harboured great phenotypic diversity for all traits, including seed yield, while variation among valleys of origin was less manifest. Noticeable site‐specific population yield responses were observed, suggesting that the environment adopted for seed production may steer the choice of materials to be multiplied. The longer vegetative period in the lowland site, combined with environment‐tailored agronomic practices, contributed to better plant growth, seed yield and survival compared to the mountain site, suggesting that seed production of this Alpine species could be feasible in a lowland environment when adequate inputs were provided. One valley (Valchiavenna) displayed high average levels of seed yield and plant vigour across growing sites, indicating its possible value as a source of germplasm suitable for resowing at high altitude.  相似文献   

9.
Under terminal drought conditions, cereal varieties with limited tillering have been suggested to be advantageous, because they have fewer nonproductive tillers, thereby limiting water consumption prior to anthesis. In this study, four field trials were conducted over two growing seasons in southern Spain, under rainfed and irrigated conditions. Twenty-five genotypes were studied to evaluate the contribution of the main stem (MS) and tillers to grain yield and its components. Significant differences were found among genotypes for these contributions under non-stressed environments, but these differences were not significant under water-stress conditions. The contribution of the MS to plant grain yield was higher than that of tillers (68% vs. 32%) and was stable between years in irrigated trials. However, in the rainfed trials, MS contributed differently depending on year-to-year climate variations. Thus, under favorable weather conditions the contribution of MS to grain yield was higher than in the unfavorable year (85% vs. 59%). In irrigated environments, MS and tiller grain yield depended on the number of grains per spike, spikelets per spike, and thousand kernel weight (TKW). Under water-limited conditions, MS yield depended on the number of grains per spike and grains per spikelet, whereas the number of spikelets and TKW had less influence on MS grain yield. Furthermore, under water-stress conditions, high tillering genotypes showed yield levels similar to the genotypes with restricted tillering. Additionally, there was no significant evidence of a positive or negative effect of maximum tiller number on grain yield under rainfed conditions.  相似文献   

10.
To account for genotype x environment (G x E) interactions, sugarcane varieties are tested in multi-environment trials (METs) across multiple crop-years and seasons (early vs. late) under fully irrigated conditions in Swaziland. This study aimed to quantify the main sources of variation relevant to the MET network, identify mega-environments, evaluate adaptability of imported sugarcane varieties, and optimize resource use within the testing network. Nine varieties (eight imported Mauritian and one South African variety) were tested at two sites (Mhlume – M and Simunye – S), harvested early (E) and late (L) in the season across five crop-years in replicated (8) Latin square designs. A linear mixed model analysis of cane yield (tons of cane per ha; TCH), sucrose content (SUC%), sucrose yield (tons of sugar per ha; TSH), and fiber content (FIB%) showed that variety x season interactions were highly significant (P < 0.001) and larger than variety x site interactions for most traits. Genotype + genotype x environment (GGE) biplots revealed clustering of environments into two mega-environments by season rather than by site. Two Mauritian varieties were superior in each of the early and late mega-environments. Broad-sense heritability (H2) for all traits was larger than 0.79, with the highest value observed for FIB% (0.89). Resource optimization analysis, using variance components, suggested that future testing be conducted at a single site, across two seasons, with replicate numbers >5, and harvested across approximately five crop-years. Strong variety x season interactions should be exploited more aggressively in irrigated sugarcane selection programs.  相似文献   

11.
The aims of the experiment were to (i) test whether the higher leaf elongation rate per tiller (LERT) of Bromus stamineus D. than Lolium perenne L. at moderately low temperatures was maintained at high defoliation frequencies and (ii) explore responses in tiller dynamics during the onset of the cool season in the south‐east of the humid Pampas region in Argentina. The following treatments were applied: defoliation frequency at the 3·0‐leaf stage (i.e. one‐leaf lifespan), which is considered optimal, and higher defoliation frequency at the 1·5‐leaf stage (i.e. half‐of‐a‐leaf lifespan). The higher defoliation frequency reduced leaf elongation rate in both the species but it did not affect the leaf appearance rate. This confirms previous studies on several C3 grasses, suggesting a similar pattern of response. Changes in tiller size are proposed as a possible mechanism to explain such long‐term defoliation effects on leaf elongation rates. Responses in tiller production depended on the species considered. The higher defoliation frequency caused a reduction in site‐filling which led to lower tiller production rates in L. perenne but not in B. stamineus. Thus, B. stamineus maintained the advantage in LERT over L. perenne and its tiller production was not affected when defoliated at frequencies higher than those considered optimal.  相似文献   

12.
为给小麦长势的遥感监测提供依据,利用多种植被指数对比分析了水浇地和旱地春小麦不同生育期冠层光谱及叶绿素含量的变化,并建立了不同地类春小麦叶绿素含量的最佳估测模型。结果表明,春小麦叶绿素含量在整个生育期呈先升后降趋势,且水浇地高于旱地。春小麦冠层光谱在可见光波段表现为阳坡和双面坡地>阴坡地>水浇地,而在近红外区域反之。在起身期-乳熟期,春小麦叶绿素含量分别与二次修正土壤调节植被指数和植被衰老反射率指数的相关性最好;在拔节-扬花期,水浇地和阴坡地的叶绿素含量分别与绿度植被指数和修正归一化差异指数相关性最好,阳坡和双面坡地则与二次修正土壤调节植被指数的相关系数最大。利用相关性最好的植被指数模拟春小麦叶绿素含量,水浇地在起身-扬花期宜用抛物线模型,乳熟期则适合用乘幂模型,且各模型r和检验r均大于0.88,拟合程度较高;阴坡、阳坡和双面坡地起身期适用指数模型,其余时期适合抛物线模型。  相似文献   

13.
Under dryland conditions of the Texas High Plains, maize (Zea mays) production is limited by sparse and erratic precipitation that results in severe water stress particularly during grain formation. When plant populations are reduced to 2.0–3.0 plants m−2 to conserve soil water for use during grain filling, tillers often form during the vegetative growth and negate the expected economic benefit. We hypothesized that growing maize in clumps spaced 1.0 m apart would reduce tiller formation, increase mutual shading among the plants, and conserve soil water for grain filling that would result in higher grain yield. Studies were conducted during 2006 and 2007 at Bushland, TX. with two planting geometries (clump vs. equidistant), two irrigation methods (low-energy precision applicator, LEPA, and low-elevation spray applicator, LESA) at three irrigation levels (dryland, 75 mm and 125 mm in 2006; and dryland, 50 mm and 100 mm in 2007). For dryland plots in 2007, clump plants had only 0.17 tillers (0.66 tillers m−2) compared with 1.56 tillers per plant (6.08 tillers m−2) for equidistant spacing. Tillers accounted for 10% of the stover for the equidistant plants, but less than 3% of the grain. Clump planting produced significantly greater grain yields (321 g m−2 vs. 225 g m−2 and 454 g m−2 vs. 292 g m−2 during 2006 and 2007, respectively) and Harvest Indexes (0.54 vs. 0.49 and 0.52 vs. 0.39 during 2006 and 2007, respectively) compared with equidistant plants in dryland conditions. Water use efficiency (WUE) measurements in 2007 indicated that clumps had a lower evapotranspiration (ET) threshold for initiating grain production, but the production function slopes were 2.5 kg m−3 for equidistant treatments compared to 2.0 kg m−3 for clump treatments. There was no yield difference for method of irrigation on water use efficiency. Our results suggest that growing maize in clumps compared with equidistant spacing reduced the number of tillers, early vegetative growth, and Leaf Area Index (LAI) so that more soil water was available during the grain filling stage. This may be a useful strategy for growing maize with low plant populations in dryland areas where severe water stress is common.  相似文献   

14.
The morphogenetic responses of individual tillers and the composition of tiller populations throughout regrowth in response to all combinations of two post‐grazing heights (35 and 45 cm) and two pre‐grazing conditions (95% and maximum canopy light interception during regrowth – LI95% and LIMax) were studied in swards of elephant grass (Pennisetum purpureum Schum. cv. Napier) from November 2011 to April 2012. Swards were subjected to the same treatments from January 2011 until measurements began, to enable them to adapt to the defoliation regimes. Treatments were allocated to experimental units (850 m2 paddocks) according to a 2 × 2 factorial arrangement in a randomized complete block design, with four replications. The total number of tillers (basal + aerial) was similar for both LI pre‐grazing targets. However, there was a change in the preferential growth pathway used by plants characterized by modification in the proportion of tiller classes in plant population. Swards managed with the LIMax target had a smaller population density of basal tillers and used the recruitment of aerial tillers as the main growth pathway. Although effective for maintaining stable rates of leaf elongation and senescence, such a strategy resulted in greater tiller death. Additionally, stem elongation, a consequence of the competition for light under those circumstances, resulted in differences in sward herbage mass and morphological composition with potential implications for herbage feeding value.  相似文献   

15.
《Plant Production Science》2013,16(4):430-441
Abstract

The objectives of this study were to identify the growth parameters involved in determining the number of spikelets on an individual tiller (ST) and to elucidate how ST is determined in rice (Oryza sativa L.). We examined the correlation of ST with the dry weight (DWT), leaf area (LAT), and the amount of nitrogen (NT) at heading for individual tillers grown under different conditions that were expected to affect spikelet production. In 1999, the japonica rice cultivars “Mineasahi” (short-duration), “Hinohikari” (intermediate-duration), and “Akebono” (long-duration) were transplanted in a paddy field on two different dates (EARLY and LATE). In 2000, Hinohikari was grown under three different treatments (gibberellic acid application, nitrogen topdressing, and thinning of hills at panicle initiation) and without treatment (control). Covariance and partial correlation analyses indicated that ST was positively and essentially correlated with DWT rather than with LAT and NT. The regression of ST on DWT was stable within each cultivar regardless of the treatment, year, tiller order, and number of differentiated spikelets. The slope of the regression was the steepest in the short-duration cultivar. These results suggest that the steep slope is desirable for high-yielding cultivars with large panicles. We conclude that ST is mostly determined by dry matter production of an individual tiller regardless of the number of differentiated spikelets. We present a diagram showing the relationship between dry matter production and the number of differentiated, surviving, and degenerated spikelets on an individual tiller.  相似文献   

16.
Rotational stocking theoretically enables regrazing of regrowth, but regrowth may be limited in xerophytic vegetation. We tested the hypothesis that regrowth would be slow and fixed in Hesperostipa comata (a caespitose, drought‐tolerant grass), while growth would be flexible in Pascopyrum smithii (a rhizomatous, less drought‐tolerant grass) under increasing defoliation and moisture, by assessing tiller growth rates, population dynamics and plant yield on marked plants in a Dry Mixed Grass prairie. Plots were clipped in late summer to simulate a deferred control, or intermittently during the growing season (May–August) at high intensity–low frequency (HILF), low intensity–high frequency (LIHF) or high intensity–high frequency and crossed with two water treatments (ambient and addition) in both a xeric upland and a mesic lowland. Growing season defoliation increased tiller growth rates of P. smithii in the upland, whereas HILF and LIHF reduced growth in the lowland. All defoliation regimes increased tiller growth for H. comata. Tiller populations of H. comata increased with frequent defoliation, while tiller populations of P. smithii decreased regardless of defoliation regime. Frequent defoliation, regardless of intensity, reduced yield relative to the deferred control for both grasses. While water addition consistently increased growth rates and reduced differences in tiller number among defoliation treatments, the regrowth of both grasses remained similar under varied defoliation with ambient moisture. High moisture conditions also promoted regrowth more in P. smithii compared to H. comata. In summary, neither grass species displayed an inherently fixed or flexible tiller or plant yield response in response to defoliation or moisture.  相似文献   

17.
A field study was undertaken between April 2003 and May 2004 in southern Tasmania, Australia to quantify and compare changes in herbage productivity and water‐soluble carbohydrate (WSC) concentration of perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under a defoliation regime based on leaf regrowth stage. Defoliation interval was based on the time taken for two, three or four leaves per tiller to fully expand. Dry‐matter (DM) production and botanical composition were measured at every defoliation event; plant density, DM production per tiller, tiller numbers per plant and WSC concentration were measured bimonthly; and tiller initiation and death rates were monitored every 3 weeks. Species and defoliation interval had a significant effect (P < 0·05) on seasonal DM production. Prairie grass produced significantly more (P < 0·001) DM than cocksfoot and ryegrass (5·7 vs. 4·1 and 4·3 t DM ha?1 respectively). Plants defoliated at the two‐leaf stage of regrowth produced significantly less DM than plants defoliated at the three‐ and four‐leaf stages, irrespective of species. Defoliation interval had no effect on plant persistence of any species during the first year of establishment, as measured by plant density and tiller number. However, more frequent defoliation was detrimental to the productivity of all species, most likely because of decreased WSC reserves. Results from this study confirmed that to maximize rates of regrowth, the recommended defoliation interval for prairie grass and cocksfoot is the four‐leaf stage, and for perennial ryegrass between the two and three‐leaf stages.  相似文献   

18.
The physiology of tiller death in grasses.   总被引：2，自引：0，他引：2  
A reproducible method of causing tiller death on individual ryegrass (Lolium perenne L., cv. S23) plants is described. This was achieved by subjecting whole plants grown previously for 7 weeks in full light (100%) and full nutrient (100%) to either light stress (17.5% or 2.5%) or nutrient stress (10% or 0%) or various combinations of light and nutrient stress. Detailed records were made of tiller appearance, position and weight, and the probability of tiller death was calculated. Analysis of each plant indicated that the smallest tiller, which was often, but not always the youngest, was the most vulnerable when the whole plant was stressed. Tiller position was relatively unimportant in determining survival. The results are discussed in relation to tiller mortality in natural populations and crop communities.  相似文献   

19.
为明确秋季耕作方式对旱地麦-玉二熟体系小麦籽粒产量形成的影响,于2019年6月至2021年6月,在豫西典型旱作麦-玉二熟区的洛阳市孟津区小浪底镇明达村,选择前茬夏玉米免耕的田块,设置秋深松、秋免耕和秋旋耕3种耕作方式,分析了不同秋季耕作方式下两个试验年度的小麦籽粒产量及其构成因素和穗部性状以及2020-2021年度的小麦群体茎蘖数、孕穗后的旗叶净光合速率（Pn）和干物质积累转运特性。结果表明,秋季耕作方式对小麦产量、穗部性状、旗叶Pn和干物质积累转运特性均有显著的调节作用。与秋旋耕相比,秋深松的小麦茎蘖数除返青期外均显著增加,穗数增加5.74%~16.06%;秋深松虽然对小麦旗叶Pn无显著影响,但提高灌浆中后期的旗叶SPAD值,显著改善了干物质积累转运特性,从而使千粒重增加,其中2019-2020年度使穗长和小穗数分别提高7.50%和9.42%,最终使籽粒产量提高9.77%~19.09%。秋免耕后,小麦孕穗和抽穗期的叶片Pn、返青至开花期的干物质积累量、花前干物质转运量及其对籽粒产量的贡献率也较秋旋耕均显著降低,而花后干物质对籽粒产量贡献率提高7.35个百分点,从而保证了籽粒产量无显著下降。与秋免耕相比,秋深松下不同生育时期的茎蘖数均显著增加,孕穗至灌浆中后期的叶片Pn,灌浆中后期的旗叶SPAD值,返青-成熟期的干物质积累量,花前干物质转运量、转运效率及其对籽粒产量的贡献率分别提高7.16%~18.41%、10.27%、12.25%~19.97%、42.19%、4.02个百分点和11.95个百分点,其中2019-2020年度穗长和小穗数分别增加7.50%和8.41%,穗数和籽粒产量分别提高16.74%~17.63%和10.31%~23.63%。综上,秋深松不仅可增加小麦穗数,而且可改善旗叶光合及干物质积累转运特性,进而提高籽粒产量,是旱地麦-玉二熟区实现小麦高产的耕作方式。  相似文献   

20.
Brachiaria and Cynodon are two of the most important pasture grasses worldwide. Computer model simulations can be used to study pasture species growth and physiological aspects to identify gaps of knowledge for genetic improvement and management strategies. The objective of this research was to compare the performance relative to calibrated parameters of the CROPGRO‐Perennial Forage Model (CROPGRO‐PFM) for simulating three different species (“Marandu” palisadegrass, “Convert HD 364 ® ” brachiariagrass and “Tifton 85” bermudagrass) grown under similar management. The field experiment consisted of two harvest frequencies, 28 and 42 days, under irrigated and rainfed conditions. Data used to calibrate the model included regular forage harvests, plant‐part composition, leaf photosynthesis, leaf area index, light interception and plant nitrogen concentration. The simulation of biomass production of the three grasses presented d‐statistic values higher than 0.80, RMSE ranging from 313 to 619 kg/ha and ratio observed/simulated ranging 0.968 to 1.027. Harvest frequency treatments of 28 and 42 days were well simulated by the model. A sensitivity analysis was conducted to evaluate the most influential parameters needed for model calibration and to contrast the grasses, showing that the differences among the three grasses are mostly driven by plant‐part composition and assimilate partitioning among plant organs.  相似文献   

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