Identification of Candidate Genes Related to Polyploidy and/or Apomixis in <i>Eragrostis curvula</i>

This work was aimed at identifying genes that show altered expression profiles in response to changes in ploidy and/or reproductive mode (from sexual to apomictic) in the African grass Eragrostis curvula. A differential display analysis was performed on leaf and flower transcriptomes from a series of genetically related euploid plants, including tetraploid apomictic, diploid sexual, and tetraploid sexual plants. More than 100 primer combinations were used to generate 11,864 total markers, yielding 1293 differential bands. Of these bands, 11.84% to 6.74% were related to ploidy and 0.71% to 2.17% to the reproductive mode, depending on the tissue. A small percentage of bands showed similar expressions between the tetraploid apomictic and the diploid sexual plants. Expression-based similarity dendrograms were constructed. Our data suggested that ploidy is more decisive than tissue type in defining the transcriptome structure. Out of 102 fragments sequenced, 50 showed strong homology to known genes. The differentially expressed genes were mapped in silico onto maize chromosomes. Several candidates mapped within the linkage group syntenic to the Tripsacum dactyloides diplospory-governing region. The evidence indicates that expression of genes located around the diplospory-associated region may be strongly influenced by ploidy and may be silenced in the apomictic genotype. These findings are discussed in the context of diplospory molecular control and its connection with ploidy.

Genetic Variation for Grain Yield and Yield Related Traits in Tef [<i>Eragrostis tef</i>(Zucc.)Trotter] under Moisture Stress and Non-Stress Environments

Tef [Eragrostis tef (Zucc.)Trotter] is an ancient and major cereal crop in Ethiopia. Increasing tef grain yield partly requires developing cultivars that are adapted to drought stress environment. An experiment was carried out using 18 tef genotypes grown during September to December, 2010, under two water supply environments (stress during grain filling period, and non-stress) to identify genetic variation, heritability and correlations of grain yield and yield related traits. Broad-sense heritability values under respective stress and non-stress environments were grain yield (g/m2) 0.80 and 0.89, total biomass (g/m2) 0.89 and 0.73, harvest index 0.69 and 0.79, panicle weight (g/plant) 0.93 and 0.92, and seed weight (g/plant) 0.96 and 0.86. The correlations of grain yield under respective stress and non-stress environments were total biomass rp = 0.64, rg = 0.70, and rp = 0.48, rg = 0.56, harvest index rp = 0.70, rg = 0.64, and rp = 0.87, rg = 0.90, panicle weight rp = 0.98, rg = 1.00, and rp = 0.96, rg = 1.00, and seed weight/plant rp = 0.98, rg = 1.00, and rp = 0.90, rg = 1.00. The present experiment showed that either grain yield per se, or seed weight/plant could be used to improve grain yield under stress and non-stress environments.

Effect of Phosphorus Rates and Varieties on Grain Yield, Nutrient Uptake and Phosphorus Efficiency of Tef [<i>Eragrostis tef</i>(Zucc.) Trotter]

Tef [Eragrostis tef (Zucc.) Trotter] is the major cereal crop in Ethiopia. Increasing tef yield requires improving soil phosphorus (P) supply and identifying P efficient varieties. An experiment was conducted at Wenago, Ethiopia, from May to August, 2011, during the main cropping season, to investigate the role of P supply in relation to grain yield, nutrient uptake (N, P, Ca and K) and P efficiency, and to investigate varietal differences for these parameters using four P rates (0, 3, 6 and 9 g/m2 P2O5) as main plots and three tef varieties (DZ-Cr-37, DZ-Cr-82, and DZ-Cr-255) as subplots in split-plot design with three replications. For respective 0, 3, 6 and 9 g/m2 P2O5, grain yield was 84, 203, 215 and 218 g/m2, total biomass 586, 897, 971 and 1016 g/m2, and harvest index 0.14, 0.23, 0.22 and 0.22. For respective variety DZ-Cr-37, DZ-Cr-82, and DZ-Cr-255, grain yield was 194, 182 and 163 g/m2, total biomass 810, 922 and 871 g/m2, and harvest index 0.24, 0.19 and 0.18. Total plant nutrients (g/m2) for respective 0, 3, 6 and 9 g/m2 P2O5 were N 3.92, 7.95, 9.49 and 10.80, P 0.57, 1.20, 1.49 and 1.66, calcium 0.16, 0.27, 0.38 and 0.45, and K 4.45, 7.96, 9.70 and 10.50. For respective 3, 6 and 9 g/m2 P2O5, P physiological efficiency (PE) was 224, 153 and 127, apparent recovery (AR) 0.49, 0.36 and 0.28, and agronomic efficiency (AE) 92, 50 and 35. For respective variety DZ-Cr-37, DZ-Cr-82 and DZ-Cr-255, PE was 248, 130 and 126, AR 0.28, 0.44 and 0.41, and AE 68, 57 and 51. The present experiment suggests that excess P supply beyond 3 g/m2 could result in low grain yield increase and low P recovery requiring soil P assessment prior to fertilizer application. Moreover, variety DZ-Cr-37 may be incorporated in the future breeding programs for P efficiency in tef.

Triple Cropping Systems of Spring Maize, Tropical Grass of Teff (<i>Eragrostis tef</i>) and Winter Cereal Crops to Combine Total Digestible Nutrient Yield with Protein Concentration in Southern Kyushu, Japan

It is ordinarily common for forage production in southern Kyushu to adopt a double cropping system, composed of summer forage crops (e.g. maize and sorghum) cultivated from late March to early September, and winter grass crops (e.g. Italian ryegrass (IR) and oat) from mid-October to the following May. However, if high total digestible nutrient (TDN) production is aimed to introduce winter cereal crops (e.g. wheat and barley) as a replacement of IR, it is necessary to cultivate tropical grass, which has a rapid-growth potential with high crude protein (CP) concentration in a switching period between summer and winter crops. In this study, teff (Eragrostis tef) was tried to evaluate as a candidate crop in the switching period. Yield and quality of two types of triple forage cropping system were determined under maize-teff-barley and maize-teff-wheat in the first and second year, respectively. Compared with the normal year, summer temperature was higher and summer and winter precipitations were lower in the first year, while no climatic disorder was observed in the second year. Even though dry matter yield of teff was minimal in the present system due to weed damage, CP concentration was the highest among crops and TDN yields of the present cropping system tended to be higher in the second year with no drought stress than in the conventional maize-IR system in the region.

Proximate analysis: Relative feed values of various forage plants for ruminants investigated in a semi-arid region of Punjab, Pakistan

The experimental site “Sial Morr Sugar mill, District Sargodha” Punjab, Pakistan was selected to carry out present investigation. The forage samples of Eragrostis pilosa, Dactyloctenium aegyptium, Parthenium hysterophorus and Calotropis procera were collected from the three sites held in this area. The forage samples were cleaned with distilled water to rinse dust particles and other impurities. These forage samples were air dried, oven dried and ground for the assessment of proximate analysis. Proximate analysis procedures including the percentage of moisture content, crude protein, ash contents and crude fiber in the sample were determined by the Association of Official Analytical Chemists methods. The CP contents among different plant species ranged from 8.1% to 26.2% at all sites. The lowest CP value was found in Eragrostis pilosa at site III while the highest CP contents in Dactyloctenium aegyptium at site II. The CP content showed significant (p < 0.05) result among all species at all sites. There was consistence pattern of increase and decrease found during all plant species at all sites. Generally, CP concentration averaged high at site II. Our CP contents are above the critical value. Considering the overall percentage of moisture composition, it was highest at site II. However, the moisture was found more in Calotropis procera at site II. The Dactyloctenium aegyptium had the least moisture content of 3.9% while the highest water content of 7%. Ash contents varied from 7.2% to 17.9% among various plant species at all sampling sites. The lowest ash contents were recorded in Dactyloctenium aegyptium at site III. At site II, ash contents were highest in Eragrostis pilosa. The differences between ash contents of various plant species were significant (p < 0.05) at all sampling site. Generally, the ash contents were higher at site II. Crude fiber contents differed significantly (p Parthenium hysterophorus had greater crude fiber contents at site II while the lowest value of CF found in Dactyloctenium aegyptium at site I. The differences were significant between all plant species other than the Specie I at all sites. The values ranged from 1.2% to 4.1%. It was highest in Parthenium hysterophorus (4.1%) at site I and least in Dactyloctenium aegyptium (1.2%) at site III. Maximum ether extract value was achieved at site I.

Ecological adaptation strategies of annual plants in artificial vegetation-stabilized sand dune in Shapotou Region

Taking annual plant Eragrostis poaeides in the artificial vegetation-stabilized sand dune in the Shapotou Experimental Research Station as example, study has been done on the adaptation strategies of annual plants to random environment through fixed quadrat observations of population changes and fixed plant determinations of individual growth, seed germination,population dynamics, spatial distribution pattern of population, competition and regulation. During the growing season, the survival rate of annual plants depends on the precipitation intensity and precipitation duration which activate the germination of seeds. The optimal germination strategy of annual plants in this habitat during the growing season appears as continuous germination under suitable conditions. Such continuous germination is an adaptive characteristic of annual plants to random environment. In addition, the variation processes of population size and regulation mechanism of E. poaeoides are studied. Statistical results of natural population in four consecutive years show that water condition in the habitat is the leading factor affecting the population dynamics of E. poaeoides. During the establishment period E. poaeoides had a higher death rate, but in the middle to later period they could survive stably. Due to the limitation of soil moisture, the competition among individuals for water inevitably led to self-thinning phenomena. Under very arid condition, the survival curve of annual herbs entirely appears as Deevey Ⅲ type (C type), but under relatively adequate precipitation condition, the survival curve appears as intermediate type. The strategy of life history obviously appears as r-strategy. Plant species of r-strategy often occurs in the early succession stage of the communities. In the relatively adequate and evenly-distributed rainfall years, E. poaeoides population exhibited a density-dependent, i. e., survival rate increased with decrease in population density. The main pattern to regulate the population number for the intraspecific competition is to regulate the highly variable initial density into a final density with narrow variation range.