Digitaria Species Research Articles

Some physicochemical properties of acha (digitaria exilis stapf) and iburu (Digitaria iburua stapf) grains

AbstractSome physicochemical properties of two cultivated species of Digitaria (D exilis and D iburua) were studied. Physical properties such as 1000‐kernel weight, kernel size and water absorption rate of the grains were determined. Water absorption by both cereals reached a maximum after 24 h steeping. The starch from both cereals exhibited a two‐stage pattern of swelling and solubility properties similar to other non‐waxy cereal starches. Starch from acha swelled less than iburu, 7·3 compared with 7·8 for iburu. Chemical constituents such as protein, oil, crude fibre, ash, nitrogen‐free extract and amylose were also determined. An amylose content of 280 g kg−1 was obtained for both cereal starches. Brabender amylograms obtained from starch and flour were typical of most normal, non‐waxy cereals. Maize starch had relatively higher hot‐paste and cold‐paste viscosities than starches of the two Digitaria species.

Embryological studies in some grasses and their taxonomic significance

BHANWRA, R. K., KAUR, N., KAUR, N. & GARG, A., 1991. Embryological studies in some grasses and their taxonomic significance. The species investigated are Lolium multiftorum Lam (tribe Poeae), Rostraria cristata (Linn.) Tzevlev (tribe Aveneae), Cenchrus setigerus Vahl, Digitaria abludens (Roem. et Schult.) Veld, and D. ciliaris (Retz.) Koel (tribe Paniceae). Apart from the number of microsporocytes in a median longitudinal section of each anther lobe, microsporogenesis and male gametophyte development are similar. However, members of subfamilies Pooideae and Panicoideae show marked differences in structure of the ovary, ovule and post-fertilization development. Lolium multiftorum and R. cristata vary in the structure of the dorsal ovary wall, degree of curvature in the megagemetophyte in relation to the longtitudinal axis of the ovule, and structure of the pericarp. Cenchrus setigerus is an aposporic apomict and differs markedly from species of Digitaria in this respect, in the extent of development of the inner integument and in the constitution of the dorsal ovary wall. The two species of Digitaria show minor embryological differences.

Crabgrass

Crabgrasses (Digitaria spp.), the first cultivated grains, were grown for food thousands of years before they were considered weeds. Digitaria, a genus of about 60 species, grows in the world's temperate and tropical regions. Many of the species are good forage grasses. Thirteen weedy Digitaria species infest the United States, but large crabgrass (D. sanguinalis # DIGSA) and smooth crabgrass (D. ischaemum # DIGIS) are the most common.

Digestibility and voluntary intake by sheep of five Digitaria species

Data are reported on the voluntary intake and digestibility by sheep of five species of Digitaria when grown as swards, cut at five different stages of growth and analysed for neutraldetergent solubles, hemicellulose, cellulose, lignin, N, S, Na, K, P, Ca, Mg, Si, Cu, Mn, and Zn. Digitaria setivalva was superior to the other four species in in vivo digestibility of the dry matter, organic matter and energy (5.2 percentage units), content of metabolizable energy (5.3%), voluntary intake of dry matter (8 0%) and voluntary intake of metabolizable energy (18.1 %). This superiority was associated with a higher content of digestible neutral-detergent solubles and cellulose. The metabolizable energy contents of the grasses were significantly correlated with dry matter digestibility and organic matter digestibility, content of digestible dry matter and concentrations of crude protein, neutral-detergent fibre, acid-detergent fibre, lignin and combinations of these different fractions.

Yellow Sugarcane Aphid Resistance in Selected Digitaria Germplasm1

Five Digitaria accessions, classified as resistant or susceptible to Sipha flava (Forbes) in screening trials, were studied in the laboratory to determme mechanisms of resistance, effectiveness of resistance against two geographically isolated aphid populations, and the value of resistance in reducing yield and quality losses in Digitaria species attacked by S. flava . Four accessions—P.I. 299610 and 299612, D. diversinervis (Nees) Stapf; 364357, D. frieseii Pilger; and 364523, D. longiflora (Retz.) Pers.—exhibited a high level of resistance to aphid adults and nymphs. Antibiosis appeared to be the main mechanism of resistance, based on studies with P.I. 364357. The accessions P.I. 299610, 364357, and 364523 were resistant to aphid populations from Louisiana and the Bahamas, whereas P.I. 111110, D. decumbens Stent, (pangolagrass) was highly susceptible to both populations. The level of resistance in P.I. 364357 was sufficient to prevent significant changes in dry-matter yield, prevent dry matter, and percent protein in plants receiving moderate to heavy infestations of the yellow sugarcane aphid. Yield and percent protein were significantly reduced, and percent dry matter was significantly increase in infested pangolagrass.

Genetic control of some esterase isozymes of Digitaria species, and their utility in the identification of hybrids

The use of esterase isozymes for the detection of inter- and intra-specific hybrids between five diploid accessions of the grass genus Digitaria (section Erianthae) was investigated.

Winter Hardiness in New Digitaria Germplasm1

AbstractPortions of the USDA Digitaria collection have been assessed for winter hardiness in previous studies. The objective of this study was to identify additional winter hardy Digitaria germplasm for the purpose of extending its production range as permanent pasture in the southeastern United States. This objective was accomplished by assessing plant survival for winter hardiness of 14 species and two subspecies comprising 230 accessions grown in field trials for 3 years at four locations in Florida and Georgia. Significant differential winter hardiness was exhibited among Digitaria species and among clones within species. Winter hardiness of seven species and two subspecies was significantly superior to that of the remaining seven species. The species of greatest economic value, D. decumbens Stent comprising three cultivars, is among the most winter hardy germplasm. The cultivars ‘Pangola,’ ‘Slenderstem,’ and ‘Transvala’ are among 13 clones which exhibited maximum winter hardiness. The average performance of species masked the superior winter hardiness of individual clones in some instances. These findings substantiate those reported previously and emphasize the consideration that should be given individual clones in the search for, and utilization of winter hardy Digitaria germplasm. The effect of minimum temperature on winter survival was determined. This winter hardy germplasm is being utilized in plant improvement programs, particularly in Florida. These results demonstrate the need for additional field research in an assessment of the elite winter hardy germplasm for adaptation and production capacity.

Digitaria striate virus—a rhabdovirus of grasses transmitted by Sogatella kolophon (Kirk.)

A previously undescribed rhabdovirus causing striate symptoms mainly in the Digitaria species D. decumbens (pangola grass) and D. ciliaris (summer grass) was found within a range of 18–28°S, of the Australian east coast. About 10% of individuals of the delphacid leafhopper Sogatella kolophon (Kirk.) transmitted the virus after a 24 h acquisition feed. The time between acquisition and first transmission was 5–8 days with an 8–11 day latent period before symptoms appeared in the plant. Transmission in a persistent manner was demonstrated for males and females and for nymphs and adults and through the moult to adults.The experimental host range was shown to include Avena sativa, Brachiaria miliiformis, Digitaria sanguinalis, Dinebra retroflexa, Eleusine coracana, Eleusine indica, Hordeum vulgare, Lolium multiflorum, Rhynchelytrum repens and Urochloa mosambicensis. Bullet-shaped particles 280 nm by 55 nm were readily found by electron microscopy of negatively stained sap from infected plants. The particles were often in groups and frequently showed crosss-triations, which were at a spacing of 4.2 nm and coincided with the frequency of the surface projections. Thin-section electron microscopy of infected plant tissue showed bacilliform and bullet-shaped particles in groups bounded by cytoplasmic membranes. No particles were seen within the nucleus or perinuclear space, and the particles were almost exclusively within companion cells and phloem parenchyma cells. Rhabdovirus-like particles and tubular structures were located within the brain and salivary glands of proven vector individuals, but not in healthy insects.

Laboratory Evaluation of Quality in Subtropical Grasses. III. Genetic Variation among Digitaria Species in In Vitro Digestion and its Relationship to Plant Morphology1

AbstractIn vitro organic matter digestion procedures (IVOMD) were used to evaluate a wide range of Digitaria spp. (digitgrass) breeding lines at three stages of maturity, across 11 field replications of one genotype, and as full‐sib families evaluated at two locations and with two fertilizer treatments. Observations were made on the effect of flowering culms and stem microanatomy on digestibility. Information on the variation in digestibility among digitgrass hybrids and factors which may affect digestibility would be useful in selecting promising genotypes early in a breeding program.At 3, 5 and 7‐week regrowth, IVOMD ranged respectively from 69.8 to 77.7, 56.6 to 68.4 and 50.7 to 64.0% on different lines. Lines lower in digestion at 3‐week re‐growth were lower at 5 and 7 weeks, and lines initially higher in digestion usually remained higher at all three harvests. Eleven field replications of a clonally propagated genotype did not differ significantly, nor did three laboratory replications per sample. Significant differences in IVOMD were detected not only among hybrid families, but also within some of the families (among full sibs).A factorial analysis was performed on IVOMD data on five hybrid families. Significant differences in digestion among genotypes, families, levels of fertilization, and location were observed. The genetic portion constituted the greatest single component of the total variance. The range in IVOMD was 53.9 to 76.3% among genotypes and 57.8 to 73.1% among families. Genotype IVOMD correlated directly with family mean for each harvest. A highly significant negative correlation (r = −0.81) was found between percent IVOMD and percent seed stalks. Micro‐scopic examination revealed that genotypes with low digestion showed more evidence of secondary cell wall thickening in nodal regions of the stem than did those genotypes with high digestion.

Drought Tolerance in Digitaria

Selected clones of 10 Digitaria species were evaluated for drought tolerance in field trials. Grasses were established by vegetative propagation during the wet season. Observations on survival and growth were made at intervals throughout the 25-month duration of the trial. Approximately one-third of the plants failed to survive, with greatest losses occurring during the period of minimum rainfall. Significant differences in survival among species were found; for example, Digitaria decumbens Stent and Digitaria valida Stent are superior to Digitaria diversinervis (Nees) Stapf and Digitaria swazilandensis Stent. Differential performance of clones within species is demonstrated by two accessions; i.e., USDA P.I. 111110 (Digitaria decumbens Stent) and USDA P.I. 299795 (Digitaria setivalva Stent). Pangola grass and select clones of other Digitaria species may be established by vegetative propagation in rainfall belts of 20 to 30 inches per annum with reasonable assurance of success.

Seed Dormancy in Two Species of Digitaria from Africa1

Dormancy in seeds of Digitaria milanjiana (Rendle) Stapf and D. pentzii Stent was investigated by germination tests in the laboratory over a 12‐month period. By using intact, dehulled, clipped and chemically treated seeds, dormancy was found to be due to the need for a period of after‐ripening in dry storage and to effects exerted by palea aml lemma. The caryopsis itself after‐ripens upon storage for 4 to 5 months, and removal of palea and lenmm from 4‐ to 5‐month‐old caryopses results in almost complete germination. Good germination can be obtained in seeds stored for shorter periods of time either by removing the seed coat, pericarp and endosperm or by treating dehulled seeds with gibberellic acid.

Studies on hybrids in Digitaria II. The F1 plants, Digitaria ciliaris HERS. x D. ischaemum MUHL.

1. The hybridization was carried out. amohg three species of Digitaria, and F1 seeds were obtained from D. ciliaris PERS. (2n=54) X D. ischaemum MUHL. (2n=36). The average crossability was about 28% in two years. 2. Although the F1 seeds were smaller than the mother seeds, and the number of days necessary for germination was irregular and larger than that of the parents, their rate of germination was about 66%No viable seeds were obtained in the reciprocal cross. 3. As the F1 plants were not vigorous, many of them died in the younger stage owing to the high temperature of the midsummer. The growth of F1 plants was poor as compared with that of the parents. Many of the morophological characters of F1 jwere resembling with those of the mother plant. 4. F1 plants were almost cornpletely pollen sterile with 0.26% of apparently normal pollen, and the anther did not dehisce. Therefore, no F2 seed was obtained by self, open and back cross pollinations.

Cytogenetical Studies on forage plants. (II) : Chromosome numbers and some Specific characters in Japanese native species of Digitaria.

Chrornosome number was determined from the three species of Digit(zria. The results are summarized in Tab.1. From the results hitherto obtained it can be properly assumed that a polyploid series, diploid, tetraploid and hexaploid are existent and the basic chromosome number may be 9. As the chromosome behaviour in meiosis of PMCS was quite normal and three species possess distinct character istics, morphological and ecological (Tab. 2), authors suppose that allopolyploidy may be possible more in Digitaria.