Trichoglume Cv Research Articles

Yield and growth features of Panicum maximum (Jacq.) var Trichoglume cv Petrie (Green Panic) under woody cover, Chaco region, Argentina

Secondary forests and shrub thickets with low suitability for cattle raising are widespread in the Chaco region (NW Argentina). Concerns about the ecological sustainability of these ecosystems favor vegetation clearing methods for improving standing forage and accessibility for livestock operations that retain native tree and shrub species, a system called ‘silvopasture’ locally. These areas are characterized by a reduction of sunlight availability if compared with treeless pastures. The objective of this research was to assess the growth rate and the effect of two harvesting intervals (15 and 30 days) on the annual yield (BM) and forage quality of Panicum maximum (Jacq.) var Trichoglume cv Petrie (Green Panic) in such a system, using two approaches: successive harvests and functional, during three growth seasons (2000–01, 2001–02 and 2002–03). Correlation of growth features of Green panic with rainfall (mm), growing degree days (°C, GDD), and soil moisture (%) at two soil depths (0–15 and 15–30 cm) was also assessed. BM varied between 3,500 and 11,500 kg dry matter ha−1. The absolute growth rate presented two annual peaks, located in early and late summer, irrespective of growth season and harvesting interval. Growth season and harvesting interval significantly affected the relative growth rate (p > F = 0.0015 and p > F = 0.0002, respectively). BM was significantly correlated with rainfall and GDD observed between sampling dates, the magnitude of the coefficients were higher for the 30-day than for the 15-day harvesting interval. Correlation between BM and soil moisture content was not significant for both soil depths. Resting periods should be longer than 30 days to maintain the stability of the grazing system.

Seasonal changes in pasture quality and diet selection and their relationship with liveweight gain of steers grazing tropical grass and grass - legume pastures in northern Australia

The variation in liveweight gain in grazing beef cattle as influenced by pasture type, season and year effects has important economic implications for mixed crop–livestock systems and the ability to better predict such variation would benefit beef producers by providing a guide for decision making. To identify key determinants of liveweight change of Brahman-cross steers grazing subtropical pastures, measurements of pasture quality and quantity, and diet quality in parallel with liveweight were made over two consecutive grazing seasons (48 and 46 weeks, respectively), on mixed Clitoria ternatea/grass, Stylosanthes seabrana/grass and grass swards (grass being a mixture of Bothriochloa insculpta cv. Bisset, Dichanthium sericeum and Panicum maximum var. trichoglume cv. Petrie). Steers grazing the legume-based pastures had the highest growth rate and gained between 64 and 142 kg more than those grazing the grass pastures in under 12 months. Using an exponential model, green leaf mass, green leaf %, adjusted green leaf % (adjusted for inedible woody legume stems), faecal near infrared reflectance spectroscopy predictions of diet crude protein and diet dry matter digestibility, accounted for 77, 74, 80, 63 and 60%, respectively, of the variation in daily weight gain when data were pooled across pasture types and grazing seasons. The standard error of the regressions indicated that 95% prediction intervals were large (±0.42–0.64 kg/head.day) suggesting that derived regression relationships have limited practical application for accurately estimating growth rate. In this study, animal factors, especially compensatory growth effects, appeared to have a major influence on growth rate in relation to pasture and diet attributes. It was concluded that predictions of growth rate based only on pasture or diet attributes are unlikely to be accurate or reliable. Nevertheless, key pasture attributes such as green leaf mass and green leaf % provide a robust indication of what proportion of the potential growth rate of the grazing animals can be achieved.

Dynamics of carbon and nitrogen in a long-term cropping system and permanent pasture system

On the brigalow lands of south-east Queensland, productivity of sown perennial grasses is severely limited by N availability, whereas annual crops grown on the same soil are N-sufficient. The dynamics of C and N were compared under in these soils under permanent green panic (Panicum maximum var. trichoglume cv. Petrie ) pasture and continuous cropping with grain sorghum (Sorghum bicolor). Although the sorghum system was more productive, it contained 18% less N and 29% less C. Annual flows of C and N through the soil microbial biomass were, respectively, 4500 and 240 kg ha-1 under sorghum, and 4050 and 60 kg ha-1 under pasture. Over 80% of C and N inputs to the sorghum system occurred after harvest. Under pasture, the continuous supply of residues of high C/N ratio (50-75) enabled the development of a large and active microbial biomass, which competed with the pasture plant for N, resulting in slow net mineralization of N and low levels of inorganic soil N. Under sorghum, the size of the microbial biomass was limited by C availability during the growing season. The sorghum residues had slightly lower C/N ratios (36-46), and their rapid decomposition and net mineralization of N were promoted by the fallow period and soil cultivation. Estimated annual C turnover through the soil microbial biomass was slightly faster under sorghum, and annual N turnover was around seven times faster under sorghum than under green panic. The productivity of these soils under the two management systems was controlled by the amount, quality and timing of organic matter inputs. These in turn controlled the size of the soil microbial biomass and its C and N supply, and hence the balance between immobilization and mineralization of N.

Decline in plant and animal production from ageing pastures of green panic (Panicum maximum var. trichoglume)

SummaryThe impact of age on the productivity of sown pastures of green panic (Panicum maximum var. trichoglume cv. Petrie) growing on black earth soil in south-east Queensland was measured from 1976 to 1981. During winter and spring, weaner steers grazed at 2·4 animals/ha on summer-spelled pastures which, in each year, were 1, 2, 3, 4 and 5 years old. Pastures were given 58 kg N/ha as urea each year. Live-weight gain averaged 74 kg/head on 1-year-old pasture but only 35 kg/head on 5-year-old pasture, with most of the reduction in weight gain in winter (June to August) occurring up to age 3 years, and with most of the reduction in spring (September to November) occurring for pastures older than 3 years.The decline in animal production was not caused by changes in species composition of the pasture. Rather, weight gain on older pastures was restricted by pasture quality in winter and by reduced pasture growth in spring, but not by presentation dry-matter yield. The decrease in pasture productivity seemed to be primarily due to reductions in available soil mineral N with age, since the N concentration of plant shoots decreased as a pasture aged. Tt is postulated that the immobilization of N in decomposing grass litter is a primary cause of productivity decline in ageing pastures.

The Residual Effect of P and Lime on the Performance of Four Tropical Grasses in a High P‐fixing Oxisol1

AbstractPastures sown after several years cropping may take advantage of the residual lime and P fertilizers applied earlier. A field experiment was conducted to (i) compare the potential of different grasses to use previously applied P fertilizer at two levels of applied lime and (ii) evaluate the capacity of two soil tests to predict P availability to grasses. Four grasses [Andropogon gayanusvar. bisquamulatus (Hochst) Hack] cv. Planaltina; Panicum maximumcv. Makueni; P. maximumvar. trichoglume cv. Green panic and Setaria ancepscv. Kazungula were sown on an old experimental site where P fertilizers and lime have been applied over a period of 6 years for total rates of 0, 44, 87, 131, and 175 kg ha−1of P and 4 Mg ha−1of lime. Despite the well‐known P‐fixing capacity of the soil (clayey, kaolinitic, isohyperthermic, Typic Haplustox), grasses responded markedly to residual P and lime. Andropogon and to some extent Setaria performed better than the other grasses in both, limed and unlimed plots, at low levels of applied P. Makueni performed well only on limed plots at high levels of applied P (175 kg ha−1). Available soil P and dry matter yield correlated well but the range of P availability was too small for prediction purposes. It was concluded that despite high P‐fixing capacity a large portion of residual P remained available to grasses. Soil test procedures should be improved to better reflect the P availability to grasses.

Hay conservation for cattle on winter-grazed green panic (Panicum maximum var. trichoglume) pasture in south-eastern Queensland

The effects of stocking rate and hay conservation on liveweight gains of weanling Hereford cattle grazing a green panic (Panicum maximum var. trichoglume cv. Petrie) pasture in winter and spring only were measured over seven years. A 2 x2 factorial experiment included stocking rates of 1 .5 and 2 . 5 animals/ha, with and without hay conservation. Protein supplementation using a mixture of cottonseed meal and urea was an additional treatment in two winters. Stocking rate had little effect on pasture yields at the start of grazing or on hay yields. The mean liveweight gains per animal at stocking rates of 1 . 5 and 2.5 animals/ha were 69 and 50 kg, respectively, on non-conserved pasture, and 86 and 54 kg on conserved pasture. Liveweight gain response to conservation was greater at the lighter stocking rate and appeared due to greater accessibility of higher quality pasture in situ rather than to feeding of hay per se. At the light stocking rate, little or no hay was required. Feeding protein produced 6 kg more liveweight gain per animal during the supplementation period in the two winters but this advantage disappeared by the end of grazing. Liveweight gain per hectare decreased with increased stocking rate in both hay and no-hay groups in the first and third year, decreased in the hay group only in the second year and increased in both groups in the last four years of the experiment. The benefit from making and feeding hay was small and the economics of the practice would depend on alternative uses for excess hay.

Performance of grazed creeping-rooted lucernes on two soils in central Queensland

The creeping-rooted lucernes (Medicago falcata x M. sativa), cv. Walkabout and breeder's line ECRS 1, were compared with M. sativa cvv. Hunter River and Siro Peruvian for persistence and production under dryland conditions on alluvial and solonetz soils at Biloela and Theodore in central Queensland. The lucernes were sown with green panic (Panicum maximum var trichoglume cv. Petrie) and were grazed intermittently by cattle. Established lucerne populations were similar on each soil, but varied among lines in the range 25-55 plants/m2, with creeping-rooted lucernes having the lowest. Persistence on the two soils differed markedly; after two years, populations had decreased to between 7-22 plants/m2 on the alluvial whereas less than 3 plants/m2 remained on the solonetz. Survival of both creeping-rooted lines was inferior to that of Hunter River on both soils, but only significantly (P < 0.01) so on the alluvial soil. Dry matter yields from the creeping-rooted lines on the solonetz soil during the first year were similar and averaged 2.6 t/ha, compared with Hunter River, 3.4 t/ha, and Siro Peruvian, 6 t/ha.

Effects of shading on the growth and nitrogen content of green panic and Siratro in pure and mixed swards defoliated at two frequencies

A study was made of the effect of illumination at 100, 60 and 40% of sunlight on the growth of Macroptilium atropurpureum cv. Siratro and Panicum maximum var. trichoglume cv. Petrie (green panic) in pure and 50150 mixture swards, dcfoliated every 4 (D4) 01 8 (D8) weeks. The plants were grown without nitrogen fertilizer on a soil of moderate nitrogen status. Shading to 60 and 40% of full sunlight increased the shoot yield of green panic in pure sward by 30 and 27% respectively in the D8, but reduced it in the D4 treatment by 3 and 14%. Shade (40% full sunlight) reduced the shoot yield of Siratro in pure swards by 38 and 33 % in the D4 and D8 treatments. Nitrogen accumulation in green panic was markedly improved by shading: the increase in shoot nitrogen yield in pure sward under 60 and 40% light levels was 29 and 32% for the D4 and 45 and 76 % for the D8 treatment. All plant fractions of green panic increased in percentage nitrogen with increasing shade. The nitrogen yield of Siratro in pure sward declined with shading in proportion to dry weight. Shaded green panic swards had a higher leaf area index, better distribution of leaf area with height, and lower light extinction coefficients. The individual leaves had greater photosynthetic activity than those from the full sunlight swards. Shade-grown Siratro swards had a lower leaf area index and their leaves had a lower photosynthetic potential than in the full sunlight treatment. Nodulation was reduced under shade. Competition between green panic and Siratro was most severe in relation to shoot yield, and was accentuated by shading, frequent defoliation, and time. The proportion of Siratro in the mixture declined from 40 % initially to as low as 4-6 %. The extra competitiveness of the tropical grass, green panic, under shade in this experiment was due to a substantially increased ability to accumulate nitrogen and also to changes in canopy structure. In soils of markedly different nitrogen status or with nitrogen fertilizer the shade response might be modified.

Effects of environmental and plant factors on foliar freezing resistance in tropical grasses. I. Precondition factors and conditions during freezing

The foliar freezing resistance of Setaria anceps cv. Narok and Panicum maximum var. trichoglume cv. Petrie was studied under controlled freezing in the laboratory. Maximum foliar hardening in both species was achieved in 8 days at a night temperature of 10°C or less. A reduction in relative humidity from 100 to 79 % during freezing at –5°C caused 80 and 88 % decreases in foliar damage (as measured by percentage foliage death) in P. maximum and S. anceps respectively. Reducing the cooling rate during a freezing cycle significantly increased the amount of foliar damage to both species but there was no significant effect of reheating rate. An increase in freezing duration from 0.5 to 4 hr increased foliar damage by 35 and 58 % at –2.5° and by 45 and 36 % at –3.5° in S. anceps and P. maximum respectively. Phosphorus and potassium applications had no effect on frost damage, but increased nitrogen application rates and nitrogen concentrations in the tissues were related to greater frost damage. A decrease in plant water status prior to frosting caused a significant decrease in foliar frost damage in P. maximum. Except for atmospheric humidity, a decrease in the minimum freezing temperature by 2° had a larger effect on foliar damage than had other plant or environmental factors. S. anceps demonstrated a greater frost tolerance than P. maximum in all experiments.

Response of some tropical grasses to molybdenum application

The response to Mo application of Panicum maximum var. trichoglume cv. Gatton (panic), Cenchrus ciliaris cv. Biloela (buffel) and Setaria sphacelata cv. Nandi (setaria) was studied at three rates of NO3 supply in pots containing soil that was severely Mo deficient for tropical legumes. There were no growth responses of these grasses to Mo, except for a marginally significant effect in panic at the highest NO3 treatment at the first harvest. These results are compared with Mo responses of legume/grass mixtures in the field and published data showing large growth responses of some temperate grasses to Mo. Application of Mo had no effect on total N concentrations of grass tops but markedly decreased NO3-N concentrations in buffel. Setaria had a greater ability to take up Mo than the other grasses and this was associated with the lower NO3 levels in this species. Critical Mo concentrations for growth of all grasses were below 0.02 p.p.m.

Growth and Digestibility of Grasses : 1. Pattern of tiller appearance and their relative weight as yield components in green panic (Panicum maximum var. trichoglume cv. Petrie)

Growth and Digestibility of Grasses : 1. Pattern of tiller appearance and their relative weight as yield components in green panic (Panicum maximum var. trichoglume cv. Petrie)

Leaf water potentials of pasture plants in a semi-arid subtropical environment

Leaf water potentials (�1) were measured on pasture plants at the Narayen Research Station in southern Queensland. The main findings were: 1. There were marked differences between species in the value of �1, measured during drought. Lucerne (Medicago sativa cv. Hunter River) and buffel grass (Cenchrus ciliaris cv. Biloela) usually showed a lower (i.e. more negative) �1 than Siratro (Macroptilium atropurpureum cv. Siratro), when they were grown together in a mixed pasture. Siratro seemed to possess a useful degree of drought avoidance. High drought resistance was observed in buffel grass; this was attributed to its tolerance of water stress. Green panic (Panicum maximum var. trichoglume cv. Petrie) was found to have as low a �1 as lucerne during drought when the two species were grown with Siratro in a mixed pasture. 2. The plants were under severe water stress before all the available water was removed from the deeper soil horizons. 3. �1 was lower in nitrogen-fertilized buffel grass or spear grass (Heteropogon contortus), than in the corresponding unfertilized controls. 4. The vapour-exchange and dye-marker densiometric methods gave different values for �1 in buffel grass, green panic and Siratro; the vapour exchange technique recorded lower, i.e, more negative figures than the other method when the plants were under severe water stress. The two methods gave similar values for lucerne. The relation between the values obtained for buffel grass by the two methods was affected by nitrogen fertilization. The reaction of sown pasture plants to drought at Narayen is discussed.

Tissue testing for assessing the phosphorus status of green panic, buffel grass and setaria

The possibility of using phosphorus concentrations in different parts of pasture grasses for diagnosing their phosphorus status was studied. Critical phosphorus concentrations using youngest expanded leaves of green panic (Panicum maximum var. trichoglume cv. Petrie), buffel grass (Cenchrus ciliaris cv. Biloela), or setaria (Setaria sphacelata cv. Nandi) were found to be almost identical to those assessed from the whole tops. Critical phosphorus concentrations in green panic and setaria decreased with age of plant, and for whole tops of green panic were : 0.55 per cent in plants with three to four leaves on the primary shoot, 0.32 per cent in plants with four to five leaves on the primary shoot and 0.1 5 per cent in plants with six to seven leaves on the primary shoot. Values in the whole tops of setaria were: 0.46 per cent (four leaves), 0.36 per cent (five leaves), 0.24 per cent (six leaves) and 0.14 per cent (seven leaves). A similar decline with stage of growth was observed when youngest expanded leaves were used to estimate critical phosohorus concentrations in setaria

Establishment of green panic as influenced by type, amount, and placement of vegetative mulch

Establishment of green panic (Panicum maximum var, trichoglume cv. Petrie), was measured after sowing beneath mulches of sawdust, native pasture hay, barley straw, Dolichos lablab stubble and sorghum stubble. Long, chaffed, or milled materials, all applied at 2500, 5000, or 10,000 kg ha-1 were tested. Comparisons were made with a control (no mulch) in two experiments on a self-mulching clay at Gayndah, south-eastern Queensland. Seedling emergence with all surface mulches was superior to the control and to emergence from sowing into mulch incorporated in the surface soil. Optimum rates of mulch for emergence approached 5000 kg ha-1 but varied between experiments and with mulch types. Reducing mulch particle size did not consistently improve emergence relative to long straw. In a third experiment, seedling emergence at 42 days after irrigation was directly related to the proportion of area covered by mulch irrespective of the arrangement of mulch bands. Seedling yield followed trends in plant density. Practical implications of the results are discussed.

The digestibility and voluntary intake of six varieties of Panicum

The digestibility and voluntary intake of P. coloratum CV. Kabulabula, P. coloratum var. Makarikariense CV. Burnett and C.P.I. 13372, P. maximum var. trichoglume CV. Petrie Green Panic, P. maximum cv. Coloniao guinea grass and Hamil were measured with sheep in metabolism pens. Each grass was cut eight to ten times at different growth stages and times of the year. Varieties differed (P<0.01) in their dry matter and organic matter digestibility but the maximum mean difference between varieties was only 2.8 and 3.4 per cent respectively. There were large differences in voluntary intake between grasses. P. maximum cv. Hamil had a voluntary intake 50 and 27 per cent greater than P. coloratum cv. Kabulabula when both had p dry matter digestibility of 50 and 60 per cent respectively. Voluntary intake of digestible organic matter of P. maximum CV. Hamil was 26 per cent higher than that of P. coloratum CV. Kabulabula. The higher intake of P. maximm occurred despite its having higher silicon percentages than P. coloratum. It was concluded that because of the biased relation between intake and digestibility selection of grasses on the basis of digestibility determinations alone could be a misleading guide to their nutritional value.

Animal production on sown and native pastures on brigalow land in southern Queensland during drought

Liveweight gains of six yearling steers grazing on each of four introduced grasses, each with lucerne, were compared with those from native pasture and native pasture plus forage oats, on a weakly solonized brown clay loam of moderate fertility in the brigalow region of southern Queensland. The pastures were grazed continuously for three years (1963 to 1965) at set stocking rates during the worst drought known from 87 years of local records. At the height of the drought in 1965 the sown pastures supported animals as far into the drought as did the two native pasture treatments at half the stocking rate. Sorghum almum (CV. Crooble) and Rhodes grass (Chloris gayana CV. Pioneer) died late in the drought and did not re-establish after rain, whereas buffel grass (Cenchrus ciliaris CV. Nunbank) and green panic (Panicm maximum var. trichoglume CV. Petrie) survived. Standing dry matter in the pastures was less than 1,000 lb dry matter an acre for much of the life of the experiment. At a stocking rate of one bullock to 2.3 acres S. almm gave the highest average gain per head in the first full year of grazing (462 lb per head), but this was only significantly better (P<0.05) than the gain from buffel grass, and not significantly better than the gains (at one bullock to 4.6 acres) on native pasture (415 lb per head) and native pasture plus oats (390 lb per head). Rainfall in the first year was 18 inches. In the remaining two years, with 13 and 8 inches of rain respectively, there were no significant differences between the sown pastures until the S. almum and Rhodes grass died. Native pasture plus oats (681 lb per head) and native pasture (424 Ib per head) gave the greatest gain per head in 1964, but not per acre because of the lower stocking rate.