Sorghum Almum Research Articles

Control of Johnsongrass Ecotypes

Field experiments were conducted to study the effectiveness of 2,2-dichloropropionic acid (dalapon) for the control of 55 morphologically distinct ecotypes of johnsongrass (Sorghum halepense(L.) Pers.) collected throughout the United States and from several foreign countries. Ecotypes varied widely in their response to dalapon whether collected from Mississippi, from 10 other states, or from eight foreign countries. Initial control of seven ecotypes with dalapon increased 8 to 35% when nitrogen fertilization was increased from 0 to 300 lb/A. Regrowth of surviving plants was more vigorous with increased nitrogen levels so increased fertility reduced final control. Comparative differences in the susceptibility of the seven selected ecotypes to monosodium methanearsonate (MSMA) were not as great as those obtained with dalapon. Varying the rate of nitrogen fertilization had less effect on johnsongrass susceptibility to MSMA than to dalapon. Dalapon controlled sorghum almum (Sorghum almumParodi) better than johnsongrass.

Growth and Development of Johnsongrass Ecotypes

Studies were conducted on the growth and development of 55 morphologically distinct vegetative types of johnsongrass (Sorghum halepense(L.) Pers.) collected throughout the United States and from several foreign countries. Observations were made also on the growth of sorghum almum (Sorghum almumParodi) from three foreign countries. Mature leaf-blades of the different johnsongrass ecotypes varied in length from 31 to 59 cm and in width from 1.7 to 3.4 cm. Plant height and culm density varied 2 to 4-fold for the different ecotypes. Floret production varied from 87 to 352 sessile spikelets for representative panicles of the different ecotypes. The number and arrangement of branchlets within panicles also varied as did the size of various spikelet components. Sorghum almum produced much taller plants than did johnsongrass although culm density and lateral growth were less than that of johnsongrass.

Blue Grama Response to Nitrogen and Clipping under Two Soil Moisture Levels

Additional studies are needed to determine the feasibility of using sorghum almum or other high producing forage plants in seeding mixtures to help offset the initial cost of rootplowing as a brush control practice. Since rootplowing tends to destroy a certain percentage of native grasses and most rangelands, heavily infested with brush are in poor condition, reestablishment of desirable range plants is a necessity. Therefore, better methods of seedbed preparation and seeding practices in conjunction with rootplowing should be investigated.

The effect of phosphorus on the growth, chemical composition, and critical phosphorus percentages of some tropical pasture grasses

Nine tropical pasture grasses were grown in pots of a phosphate-deficient solodic soil with varying additions of phosphate. Growth responses and chemical composition of the plant tops were recorded, and from these, critical percentages of phosphorus were established. All species responded to phosphate addition. Under the conditions of this experiment Melinus minutiflora was the most responsive species and Pennisetum clandestinum the least responsive. Critical percentages of phosphorus in the tops of Melinus minutiflora, Cenchrus ciliaris, Paspalum dilatatum, Panicum maximum, Chloris gayana, Sorghum almum, Setaria anceps, Digitaria decumbens and Pennisetum clandestinum sampled at the immediate pre-flowering stage of growth were 0.18, 0.25, 0.25, 0.20, 0.22, 0.20, 0.21, 0.16, and 0.22% respectively of the dry matter. Phosphate applications decreased the concentration of plant potassium, had no significant effect on calcium, increased magnesium in most species, and in four species increased sodium. The increases in magnesium and sodium are considered to result in part from reduced potassium uptake and the plant's ability to preserve cation balance. Three species, C. gayana, P. maximum and D. decumbens, had relatively high concentrations of sodium (58, 46, and 46% of total cations respectively). In contrast S. anceps had a relatively high concentration of potassium (56 % of total cations) and low sodium (7%). Phosphate applications decreased the concentration of nitrogen, and had little effect on chloride.

Effects and interaction of lucerne and subtropical legumes in a Sorghum almum pasture

An experiment was carried out at Lawes in south-east Queensland to examine the behaviour of subtropical legumes (mixture of Glycine wightii and Phaseolus atropurpureus), of lucerne, and of all three legumes together in a Sorghum almum pasture. Two grazing regimes were imposed, both averaging almost one beast an acre a year, but one involving longer breaks between grazings. A final year of common grazing was used to obtain a better assessment of treatment effects. There was no evidence of any difference in persistence between the Nunbank and Crooble cultivars of S. almum. Initial growth of legumes was poor due to strong competition from S. almum, but in the second year they made a substantial contribution to total yield of dry matter and nitrogen, and in the following two years they also increased significantly the yield of S. almum. In general the sub-tropical legumes yielded more than lucerne, and were also more effective in increasing S. almum yields. There were only minor effects on the nitrogen content of S. almum. Lucerne and subtropical legumes were strongly competitive when sown together, in that each yielded less and had a smaller effect on S. almum than in separate mixtures with the grass ; the effects of lucerne were particularly marked. These competitive effects were less pronounced with less frequent grazing. Soil nitrogen in the 0-12 inch soil layer declined during the first two years of the pasture but increased during the following two, the accumulation occurring mainly in the surface 3 inches of plots containing legumes. Over the total pasture phase (four years), there was a small nett loss of nitrogen from the 0-12 inch layer. Volunteer species associated with a follow-up crop of Sorghum vulgare showed positive responses to residual nitrogen from lucerne but no response to subtropical legumes. It is suggested that this was associated with a slower turnover of nitrogen from lucerne root systems. There was no response in the crop itself.

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.

The in vitro digestibility of oesophageal fistula samples after washing for botanical separation

An in vitro digestibility technique was used to compare the digestibility of washed and unwashed portions of plant material collected from the oesophageal fistulas of grazing sheep. The digestibility of a washed portion was 5.5 to 8.2 digestibility units lower (P<0.05) than that of an unwashed portion of the same fistula sample. The grasses used in the study were Panicum coloratum L., Paspalurn dilatatum Poir., Eragrostis curvula Nees-var. valida Stapf., Sorghum almum Parodi, and Chloris gayana Kunth. The presence of some dry matter in the Panicum plots and the relatively low acceptability of the Eragrostis appeared to cause variation in the results due to selective grazing by the sheep. It was concluded that a correction of five digestibility units would make washed portions of fistula samples collected from grazing sheep useful in evaluating the quality of pasture species from mixed swards.

THE INTAKE AND NUTRITIVE VALUE OF FRESH, FROZEN AND DRIED SORGHUM ALMUM, DIGITARIA DECUMBENS AND PANICUM MAXIMUM

Sorghum almum, Digitaria decumbens and Panicum maximum were fed in fresh, frozen (−20 C) or dried (85° C) form to 21 wethers in metabolism cages. Neither freezing nor drying had a significant (P>0·05) effect on voluntary intake, dry‐matter digestibility or organic‐matter digestibility. Drying depressed the apparent digestibility of the nitrogen in all grasses but only in the case of D. decumbens was this significant (P<0·05). Freezing also depressed the apparent digestibility of N while both freezing and drying reduced N retention, compared with the fresh feed. None of these differences was significant.Freezing and drying are thus methods of pasture preservation that can be used to study the intake and dry‐matter digestibility of tropical pastures, but both methods may introduce bias into the measurement of N digestibility and retention.

The energy values and nutritive value indices of Digitaria decumbens, Sorghum almum, and Phaseolus atropurpureus

Two subtropical grasses, Digitaria decumbens and Sorghum almum, and one legume, Phaseolus atropurpureus (var. Siratro), cut at different ages were fed to sheep indoors to measure voluntary intake and apparent energy digestibility. Energy values of dry matter ranged from 4.11 to 4.48 kcal/g and those of organic matter from 4.47 to 4.94 kcal/g. There was a positive correlation between the energy value of organic matter and the crude protein content (r = 0.84, P < 0.01). The apparent digestibility of feed energy was correlated with species, age, and dry matter digestibility but there were significant differences between the regression equations for each species. Age was the most important factor determining the digestible energy content of the three species, and the energy value of digestible organic matter varied from 3.860 to 4.801 kcal/g. This value was positively correlated with protein content. The intake of digestible energy (kcal/kg0.75) was approximately four times as great for young cuts as for mature cuts of both grasses. Nutritive value index (N.V.I.) was closely correlated with the intake of digested energy for the three species (r > 0.998, P < 0.001), but the regression coefficient for S. almum was significantly different from those for D. decumbens and P. atropurpureus. The relative merits of the digestible energy and N.V.I. methods of expressing the energy value of pasture are discussed, and it is concluded that digestible energy is the more suitable method.

Cytological and genetical studies on hybrids between sorghum almum parodi (2n=40) and some diploid (2n=20) species of sorghum

Hybridization between S. almum (2n=40) and diploid (2n=20) species of Sorghum resulted in plants with 2n=40 and 2n=30 chromosomes. As segregation for many characters occurred in the offspring of those with 2n=40, hybrids of this type provide a means of transferring genes from the diploid to the tetraploid species of Eu-sorghum. Segregations for some genes in the progeny of these hybrids revealed heterozygosity in S. almum which may indicate that one of the ancestors of S. almum was a variety of S. vulgare very similar to the commercial grain sorghum. The triploids were only slightly fertile and the chromosome numbers of plants resulting from backcrossing to S. almum ranged from 30 to 46. Some of the plants with the higher chromosome numbers were self-fertile and segregation for genes which were present in the original diploid and tetraploid parents were observed in their off-spring. Backcrossing the triploid to the diploid parent produced fertile plants with 2n=20 and it is possible that the triploids could be used to transfer genes from the tetraploid to the diploid species of Eu-sorghum. The chromosome pairing in the triploids was similar to that expected in an autotriploid, but some non-homologous pairing was detected which may be the result of duplication of some chromosomes or chromosome segments within the genome (n=10) of S. vulgare.

Inheritance patterns in hybrids between Sorghum almum Parodi and perennial sweet Sudan grass

Juicy stem and brown plant colour are mainly tetrasomically inherited in hybrids between Sorghum almum (2n = 40) and perennial sweet Sudan grass (2n = 40). Tetrasomic inheritance is also indicated for weak midrib development and dwarf habit. The juicy stem and brown plant colour characters are linked, and the chromosomes on which these genes are situated may pair preferentially and give a 15 : 1 segregation ratio, instead of pairing at random and giving a tetrasomic segregation ratio of 35 : 1. The capacity of these chromosomes to pair preferentially may be under genetic control. It is possible that preferential pairing is part of a general diploidization process, which has led to a reduction in quadrivalent formation and increased meiotic stability in the tetraploid sorghums.

Inheritance of two seedling characters in Sorghum almum Parodi, and cross pollination within S. almum and between S. almum and S. halepense (L) Pers.

An albino seedling character in Sorghum almum Parodi was shown to be tetrasomically inherited. Segregation ratios for a pale green seedling character were very variable, and it is probable that more than one gene is involved. With the albino seedling character as a marker gene, it was found that the average natural crossing in S. almum was approximately 54% at one location and 70% at another. The maximum natural crossing between S. almum and S. halepense (L.) Pers. was 57%, but the mean was only 20%. This may indicate that some S. almum plants exhibit a degree of genetic isolation from S. halepense when these species are grown together under natural conditions.

Aneuploidy in Sorghum almum Parodi and Sorghum halepense (L.) Pers.

In four aneuploid (2n = 39) plants of Sorghum almum the odd chromosome was involved in trivalent formation at first metaphase of meiosis more frequently than it was in an aneuploid (2n = 39) plant of S. halepense. Most of the gametes of the aneuploids had 19 or 20 chromosomes. Chromosome numbers of the progenies of these plants confirmed these observations, and also showed that the aneuploid lines could be maintained although in two of the S. almum lines there was selection for female gametes with the balanced number of n = 20. S, almum and S. halepense may be autotetraploid in origin. The differences in behaviour of the odd chromosome in the aneuploids are a reflection of the different levels reached in the differentiation of two pairs of preferentially pairing and genetically different chromosomes from each group of four homologues.

Asynapsis in a Tetraploid Forage sorghum

Asynapsis was found to be associated with a recessive dwarf character in progeny derived from hybrids between Sorghum almum Parodi and perennial sweet Sudan grass. The average number of univalents at first metaphase varied from 1.5 to 38.4 per cell in the 10 plants examined. Lagging univalents usually divided or misdivided at first anaphase or telophase. In plants with a very small average number of bivalents at first metaphase, the second division of meiosis rarely occurred and the pollen grains were formed from the products of the first division. All pollen grains degenerated and the asynaptic plants were sterile.

Puccinia purpurea . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Puccinia purpurea . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Cymbopogon citratus, Sorghum almum, S. cafforum, S. halepense, S. nitens, S. nitidun, S. sudanense, S. verticilliflorum, S. virgatum and S. vulgare . DISEASE: Leaf rust of sorghum, generally occurring on older leaves when crop is maturing and in such cases causing only slight loss. Premature leaf necrosis with reduction of forage value and grain yield is reported on some highly susceptible cultivars. GEOGRAPHICAL DISTRIBUTION: Widespread, probably co-extensive with hosts and wherever sorghums are cultivated including North, South and Central America, West Indies, Africa, Australia, Fiji, Asia and Europe (CMI Map 212). TRANSMISSION: Probably by air-borne urediospores.

Cyanide formation in Sorghum almum in relation to nitrogen and phosphorus nutrition

The effects of nitrogen and phosphorus on the cyanide content of Sorghum almum Parodi, grown in the glasshouse on a phosphorus deficient soil, were investigated. Both nitrogen and phosphorus fertilizers increased the total cyanide content of plant tops; however, phosphorus dressings equivalent to 40 cwt superphosphate an acre depressed the percentage cyanide level. The effects of fertilization on cyanide production are discussed in terms of nitrogen and phosphorus uptake and plant yield.

Comparative trails with Sorghum almum and other forage sorghums in south-east Queensland

Results from trials with 46 different forage sorghums indicate that the Crooble variety of Sorghum almum and Krish (a selection from a hybrid between S. halepense and S. roxburghii) are superior to all the others in yielding ability and persistence in south-eastern Queensland. All characters investigated in S. almum showed considerable variability, and improvement of some by further breeding and selection should be possible. Palatability and ease of seed identification may be improved by selection following hybridization with perennial sweet sudan grass.No source of resistance to leaf diseases was found in S. almum.

Animal production from a Sorghum almum pasture in south-east Queensland

A grazing experiment on Sorghum almum pastures, one of which received 200 lb nitrogen an acre a year, as urea, was carried out at Lawes in south-east Queensland. Pastures were grazed continuously at three set stocking rates : 1 beast to 1 1/2 acres, 1 beast per acre, and 2 beasts per acre. Grazing commenced 3 1/2 months after sowing and continued for two years. Mean liveweight production over the whole period at the medium stocking rate of one beast per acre was 0.92 lb a head a day. Production was closely related to stocking rate : gain per head decreased and production per acre increased as stocking rate increased. Nitrogen fertilizer increased animal production at the heaviest stocking rate. Seasonal pattern of animal production was influenced by stocking rate, but, in general, a winter--early spring period of small gains or losses of weight was followed by a rapid increase in late spring--early summer, with the rate of gain decreasing from mid-summer onwards. This followed the seasonal pattern of pasture production : little or no production over the cool dry winter, but high yields of forage during summer. No close relation was detected between liveweight gain and green forage available in the period of rapid increase in liveweight. During the phase of declining pasture and animal production, liveweight increment was related to available pasture expressed as green material minus S. almum stem. Crude protein content of unfertilized S. almum varied from 15 per cent for green material in spring to 2.5 per cent for the dry forage available in winter. Urea increased both yield and protein content.

Nitrogen fertilizer responses of pasture grasses in south-eastern Queensland

The results are reported of field experiments with nitrogen-fertilized pasture grasses at Samford and D'Aguilar in south-eastern Queensland. The main findings were :- 1. Nitrogen applied as urea or ammonium sulphate increased the annual yield of dry matter under mowing from 1,000- 5,000 lb up to 10,000-20,000 lb an acre, and rates of fertilizer in excess of 400 lb of elemental nitrogen an acre a year were required ,for maximum grass yields during favourable seasons. 2. Ammonium sulphate, applied at rates up to 400 lb N/acre/year, had relatively little effect on the percentage of nitrogen in Rhodes grass (Chloris gayana Kunth.), Paspalum dilatatum Poir., and P. commersonii Lam., cut three times a year. Rates of urea above those required for maximum growth markedly increased the percentage nitrogen content of a Sorghum almum Parodi-blue couch (Digitaria didactyla Willd.) mixture. 3. In an experiment with Rhodes grass, P. dilatatum and P. commersonii, nitrogen recovery rose with increasing rates of ammonium sulphate. At 70 lb N/acre/year the average nitrogen recovery by Rhodes grass was 10 per cent; at 400 lb N/acre/year it was 47 per cent. 4. The residual effects of ammonium sulphate, measured on Rhodes grass during the growing season following two years of fertilization, were very small indeed. 5. Use of nitrogen fertilizers sometimes caused marked changes in the botanical composition of the sward.

Performance of pasture grasses in mixtures with Townsville lucerne at Katherine, N.T

At Katherine, N.T., between 1959-60 and 1961-62, the performance of Townsville lucerne alone and of mixtures of Townsville lucerne with Gayndah buffel grass, Biloela buffel grass, birdwood grass, and Sorghum almum was compared at three frequencies of wet-season cutting. The two most satisfactory mixtures, Townsville lucerne with Gaynahh buffel and birdwood grass, differed little in performance. Over three years, their average dry matter production exceeded that of Townsville lucerne alone by 45 per cent, but average nitrogen production was not appreciably greater than that of the pure legume pasture. Biloela buffel grass is considered to be an unsuitable companion grass for Townsville lucerne because of its competitive power. After three years, the dry matter contribution of the legume in Biloela buffel mixtures was only 18 per cent under the most favourable cutting treatment. The Sorghum almum mixture gave the highest dry matter yield in the first year, but the grass did not survive well, and by the third year the pasture was mainly Townsville lucerne. Sorghum almum may be useful in providing bulk in the early years of an intended pure legume pasture. The role of a perennial grass component in Townsville lucerne pastures is discussed.