Plant Pathology Commons^™

Rooting Patterns Of Alfalfa Under Three Irrigation Treatments, D G. Lugg, A S. Abdeul-Jabbar, T W. Sammis

IGC Proceedings (1977-2023)

The research was undertaken to determine the effect of irrigation treatment on rooting patterns of alfalfa (Medicago sativa L.) over a two-year period. The experiment was conducted in.a clay loam soil at Las Cruces, New Mexico. Irrigation water was applied using a line source sprinkler system which provides a gradient of water application, and evapotranspiration (ET) was calculated from irrigation, rainfall and soil moisture data using the water balance method. Measurements were made at three locations on the gradient. Soil was sampled, using a soil tube of 7.8 cm inside diameter, in 15 cm increments to a depth in the …

Cotyledon And Leaf Development Associated With Seedling Vigor Of Six Forage Legumes, S N. Hur, C J. Nelson

IGC Proceedings (1977-2023)

Cotyledon and leaf development of six important forge legumes were compared to study their contribution to the seedling growth. Cotyledons of forage legumes expanded their size rapidly during one week after emergence, then slightly expanded until maximum size was reached and entered senescence. Larger seeds produced greater cotyledon area and speed of cotyledon expansion was closely associated with seedling growth. Earlier onset of leaf production and earlier leaf development were major determining factors for initial seedling growth. Alfalfa and red clover which have larger seeds were good in seedling vigor with larger photosynthetic area. Alsike clover and white clover with …

Effect Of Cytokinin On Lateral Bud Development In Regrowth Of Sorghum Bicolor M., H Nojima, H Oizumi, Y Takasaki

IGC Proceedings (1977-2023)

The effect of cytokinin on regrowth of Sorghum bicolor M. were examined. To determine the effect of applied cytokinin on growth of lateral buds, the lowest 10 cm portion of stems containing 6 visible lateral buds were used. The explants were cultured in the solutions of concentration of 1.0 to 15 .0 ppm cytokinin ( 6-benzyladenoprine riboside). In another, experiment, the endogenous cytokinin levels were analysed during regrowth period, using the plants grown under the shaded and non-shaded condition ( control). The length of lataral bud was the longest at the optimum cytokinin concentration of 5 ppm. The endogenous cytokinin …

Phlein Degradation In Stem Bases Of Temperature Grasses After Defoliation, Shinro Yamamoto, Yosuke Mino

IGC Proceedings (1977-2023)

The mechanism of phlein degradation in the stem bases following defoliation was studied using timothy, orchardgrass, tall fescue and Italian ryegrass. The phleinase(phlein hydrolyzing enzyme) was induced in the stem bases of all these grasses after defoliation, and the variation patterns of the activity varied with the grass species. The activity was inversely related to the phlein concentration, suggesting that the phleinase is involved in the degradation of phlein in all these grasses. The variation pattern of phleinase in orchardgrass was almost the same under different growth conditions, while that was amplified with high temperature, long day condition or N …

Winter Injury Of Alfalfa (Medicago Sativa L.) In Soil Freezing Area Of Japan, T Komatsu, J Maruyama, Y Horikawa, F Tsuchiya

IGC Proceedings (1977-2023)

In spite of the importance of alfalfa for dairy cattle, the cultivation of alfalfa is not yet expanded in eastern Hokkaido, Japan. A combined research project has been carried out, based on (1) observation of winter injury in 130 fields all over the Tokachi district from 1981 to 1983 and (2) observation of the influence of controlled snow depth during the winter 1983-1984 on regrowth of alfalfa. Tokachi was divided into three areas according to the type of winter injury, the depth of snow cover and the depth of soil frost. Both the depth of snow cover and the depth …

Relation Of Non-Structural Carbohydrate Concentration In Autumn To Wintering Ability Of Several Tropical Grasses In Southern Kyushu, K Ito, H Numaguchi, M Inosaka

IGC Proceedings (1977-2023)

In connection with the wintering ability of some tropical grasses, the relation between their growth habits in autumn and accumulation of non-structural carbohydrate (NSC) in stem during winter was examined. Seven species of tropical grasses were grown at the experimental field of Miyazaki University during 1980-1981. They were defoliated every 20th day from early summer until autumn. Tiller number and dry weight per tiller were detemined at each time of defoliation. NSC was estimated from autumn to winter. For the evaluation of regrowth following cool season, photosynthetic capacity of plant population just before the first frost and that on the …

Effect Of Drought On Leaf Senescence And Forage Quality Of Three Temperate Grasses, S Bittman, G M. Simpson, Z Mir

IGC Proceedings (1977-2023)

This study was conducted to compare the effect of a period of drought on leaf senescence, protein yield and P concentration in smooth bromegrass (Bromus inermis Leyss.) (Br), crested wheatgrass (Agropyron cristatum (L.) Gaertn. spp. pectinatum (Bieb.) Tzvel.) (CW g) and Altai wildrye (Leymus angustatus (Trin.) Pilger) (Awr ). Susceptibility to drought in terms of leaf water potential, senescence, and nutritive quality, was greatest in CWg, intermediate in Br, and least in A Wr. Drought induced less sencence in vegetative than in floral tillers in CW g and Br; the ability of A Wr to maintain its quality …

Flowering And Seed Production Of Macroptilum Atropurpureum Cv. Siratro As Influenced By Water Stress, L Kowithayakorn, L R. Humphreys

IGC Proceedings (1977-2023)

Siratro (Macroptilium atropurpureum) was grown in soil beds with a controlled water table in the glasshouse, or in the field at Khon Kaen, northeast Thailand. A gradient in leaf water potential (L WP) was evident as water stress developed, the youngest leaves exhibiting lower L WP than older leaves bearing pods. But density was reduced during the drying phase to -10 or -15 bar, but showed a persistent increase for up to 8 weeks following rewatering relative to plants having a constant water table. The ratio of floral to total buds was independent of treatment. Inflorescence density exerted the …

The Effect Of Moisture Stress On Mimosine Content Of Leucaena Leucocephala, R A. Bray, Jan Hoekstra

IGC Proceedings (1977-2023)

To investigate the effect of moisture stress on mimosine contect in Leucaena Leucocephala, seedlings of cv. K8 were grown in pots in a glasshouse. One set was watered to field capacity, and another watered to just above wilting, and harvested after 6, 9, 12, or 14 days stress. Moisture stress increased mimosine content dramatically, both in newly expanded and in older leaves. Mimosine content in stressed leaves remained relatively content with age (in contrast to leaves of control plants), providing another possible example of slower ageing due to moisture stress. Because of the close relationship between leaf age and mimosine …

Soil And Plant Water Relations On A Wooded Grassland In Kenya, M J. Trlica, R D. Child, E K. Maranga

IGC Proceedings (1977-2023)

Field studies of soil and plant water potential as related to transpiration losses of water from grass and shrub species were conducted through a wet and dry season on a wooded grassland in Kenya. Seasonal patterns of leaf conductance and transpiration indicated that deep rooted shrubs utilized more water per unit leaf area than did the dominant grass Digitaria macroblephara. Several shrub species continued to transpire water throughout most of the dry season. Shrub use of deep soil water resources, combined with selective grazing of grasses, may help explain why shrub encroachment into grasslands within Kenya has become a …

Adaptive Co2 Fixation And Nitrate Assimilation In Portulaca Oleracea, N K. Chang, H B. Kim

IGC Proceedings (1977-2023)

The intercellular relationships between leaves and stems for pathways of CO2 and nitrate assimilation were investigated in Portulaca oleracea growing under the natural environmental conditions. The number of stomata was 3,275cm-2 in leaves, while the stomata could not be observed in stems. Stomata! resistance in leaves of the young purslane was high at night and low in daytime. The difference between the highest and the lowest acidity was the greatest at the 2nd node of the intact plant. The order of the node having the highest acidity was changed as the leaves were detached from the top to the bottom. …

Characteristics Of Photosynthesis, Transpiration And Water Use Efficiency Of C3 And C4 Grass Leaves, W Agata, Y Kawamitsu, S Hakoyama, P B. Kaufman

IGC Proceedings (1977-2023)

Characteristics of photosynthesis and transpiration were examined with attached leaves of eight C3 and fourteen C4 grasses under different light conditions. On the basis of these data, water use efficiency, leaf conductance and intercellular CO2 concentration were also calculated. Light saturation point and maximum photosynthetic rate of C4 grasses were higher than those of½ grasses. The light response curve of transpiration was similar in both grasses. However, the values of C3 grasses were higher than those of C4 grasses at a broad range of light intensity. Water use efficiency of both grasses increased rapidly with increasing in light intensity till …

A Measurement Of The Sap-Flow Velocity Using The Heat Pulse Method In Several Forage Crops, K Tateno

IGC Proceedings (1977-2023)

This paper reports a heat pulse method for measuring water flux in the stem and its application to investigation of plant-water relationships in Japanese millet (Echinochloa utilis Ohwi et Yabuno), sorghum (Sorghum bicolor L. Moench) and maize (Zea mays L.).

1). The velocity of sap-flow in the stem, evaluated by the heat pulse method, was closely ralated to the water loss due to transpiration measured in weight units. Linear relationships and positive correlations were observed in all species between sap-flow velocity and transpiration rates.

2). Japanese millet had similar pattern in the diurnal courses of the sap-flow …

The Response Of Photosynthesis In Digitaria Eriantha (Steud) Subsp. Eriantha To The Application Of Different Forms And Concentrations Of Nitrogen, M M. Wolfson, C F. Cresswell

IGC Proceedings (1977-2023)

Digitaria eriantha (Steud) subsp. eriantha plants were grown under controlled conditions and treated with different forms and concentrations of nitrogen in order to determine its effect on photosynthetic activity. Single leaf and whole plant net photosythetic rates were meaured and appeared to vary according to the units in which the activity was expressed. Although single leaf photosynthesis was measured on young leaves, near the meristematic tip, the rates had decreased to very low levels by the fourth of month of treatment, irrespective of the mode of expression used. A similar trend was observed when the whole plant net photosythetic rates …

The Effect Of Form And Concentration Of Nitrogen Supply On Photosynthetic Temperature Optima And Light Saturation Levels In Selected C4 Photosynthetic Grasses, C F. Cresswell, Dawn Prophet

IGC Proceedings (1977-2023)

The influence of increased nitrogen supply on the carbon dioxide gas exchange characteristics of indigenous C4 photosynthetic grasses and Zea mays L. were determined in this study. The grasses investigated were Themeda triandra Forsk, Hyparrhenia hirta (L) Stapf. and Eragrostis curvula (Schrad) Nees. Previous studies had established that the carbon dioxide compensation point increased beyond the levels usually associated with C4 photosynthetic plants, within 24h of increasing the nitrogen supply either as nitrate, or as ammonium nitrogen (Grossman and Cresswell, 1974). In this study the increased supply of nitrogen resulted in a shift of both the temperature optima as well …

Co2 Exchange Of The Abovegrass And Belowground Components Of Kleingrass (Panicum Coloratum L.) During Drought In The Northern Chihuahuan Desert, William B. Sisson

IGC Proceedings (1977-2023)

The effect a 52 day drought had on the die! whole-plant carbon balance of kleingrass (Panicum coloratum L.) growing in the northern Chihuahuan desert was determined. Whole-plant CO2 inputs (photosynthesis) and outputs (belowground and aboveground respiration) were measured on day 52 of the drought (June 23, 1981) and 2 days following 1.12 cm of precipitation that occurred on June 24, 1981. Although net photosynthesis rates were severely depressed on June 23, a positive whole-plant carbon balance was determined prior to and following the rain. On a whole-plant basis,.002 g C/g DW/day was gained on June 23 and .015 g …

Differences In Leaf Anatomy And Vegetative Growth Of Panicum Species In The Dichotomiflora Group, Ryu Ohsugi, Takao Murata

IGC Proceedings (1977-2023)

The Dichotomiflora group of the genus Panicum includes two leaf anatomical variations of NAD-malic enzyme (ME) type C4 species; one with choroplasts centrifugally arranged in Kranz cells (chlorencymatous bundle sheath cells) and the other with chloroplasts centripetally arranged in Kranz cells (hereafter referred to as NAD-ME(F) and NAD-ME(P) species, respectively). We examined various characteristics related to leaf anatomy and vegetavive growth to clarify the differences between two type species. NAD-ME(F) species had a paradermally longer Kranz call and had higher percentage of Kranz call area to total cross-sectional leaf blade area than NAD-ME(P) species. At the 6th-7th leaf stage, NAD-ME(F) …

Khon Kaen Stylo: The First Commercial Cultivar Of Pasture Legume In Thailand, Anake Topark-Ngarm

IGC Proceedings (1977-2023)

During 1976-1982 various experiments were conducted to test and identify the pasture legume which may replace Towns ville sty lo used in pasture improvement program for Northeast Thailand. A seed lot of Stylosanthes humilis CPI 61674 introduced from Australia was selected and purified through 2 cycles of bulk method of selection at Khon Kaen University. This accession was evaluated in various agronomic aspects with emphasis on resistance to anthracnose disease, tolerance to heavy grazing and persistence under farmer's village situation. Major results from the evaluations indicated that the S. humilis CPI 61674 when compared to Townsville stylo or Verano stylo, …

Cytological And Morphological Characteristics Of The Genus Chloris, H Nakagawa, H Sato

IGC Proceedings (1977-2023)

Chromosome number, method of reproduction and morphological characteristics were investigated in 14 species of the genus Chloris including Rhodes grass. Chromosome numbers of the Chloris species were 2n = 20 (gayana, roxburghiana, pilosa and virgata), 40 (gayana, pycnothrix, acicularis, radiata, polydactyla, divaricata and barbata), 80 (ciliata and distichophylla), 100 (castilloniana) and 120 (truncata). Method of reproduction was studied by embryo sac analysis. Embryo sacs of all tested species had eight nuclei, indicating sexuality. Selfed seed set indicated that Rhodes grass is cross-pollinated and the other species are self-pollinated. Cluster analysis …

Allelopathic Effects Of Tall Fescue On Germination And Seedling Growth Of White Clover Genotypes, G A. Rederson

IGC Proceedings (1977-2023)

Tall fescue (Festuca arundinacea Schreb.) and white clover (Trifolium repens L.) are commonly grown together in pastures of the southeastern USA. Allelopathy of tall fescue may reduce white clover germination and growth during establishment of the legume. The objective of this study was to determine if white clover genotypes differ in germination and initial growth in extracts of tall fescue leaves. Agar containing leaf extracts from tall fescue was used to test the germination and root growth of forty white clover genotypes. Significant differences were found between the genotypes for percent germination and root length score. Root length score …

Field Performance Of Tall Fescue Selected For Leaf-Area Expansion Rate, C J. Nelson, D A. Sleper, J H. Coutts

IGC Proceedings (1977-2023)

Several morphological characters have been associated with yield of forage grasses. Our objective was to evaluate field performance of four generations of tall fescue (Festuca arundinacea Schreb.) that had been selected for differences in leaf area expansion rate (LAE). Yield of reproductive growth at two locations was influenced very little by selection for high LAE, despite a reduction in density of both reproductive and vegetative tillers. Conversely, selection for high LAE led to an increased yield of vegetative regrowth due to higher leaf elongation rate (LER) and higher weight/tiller (WIT) for vegetative tillers that more than offset a decreased …

Palatability And The Organoleptic Characteristics Of The Cultivars And Hybrids Of Tall Fescue (Festuca Arundinacea), J Scehovic

IGC Proceedings (1977-2023)

The studies of alimentary'behaviour of sheep in a trough cafeteria showed important differencies in palatability among several cultivars and hybrids of tall fescue. Currently, except for some possible hypotheses, the palatability remains the least understood factor in evaluation of feeding value of grass. In order to explain these differencies of palatability, we studied 7 cultivars and hybrids of tall fescue, the palatability of which was previously established with sheep. The studied cultivars were harvested in 6 cuts on plots sown in 4 replications. One part of the collected plant material was pressed to extract juice, another part was frozen and …

Near Infrared Reflectance Spectroscopy Screening Of Astragalus Species For Nitro-Toxins, M D. Rumbaugh, D H. Clark, R C. Lamb

IGC Proceedings (1977-2023)

The potential of near infrared reflectance spectroscopy for the prediction of nitro-toxin concentrations in 55 Astragalus species was evaluated. A calibration equation based on 90 plant samples selected to represent the range of concentrations of the 55 test species was verified on all remaining samples. The correlation coefficient, r= 0.77, indicated that the technique would be of value for the first cycle of a selection program to reduce nitro-toxin concentrations. The more exact measurements provided by conventional chemical analyses would probably be necessary in advanced cycles of selection if differences among plants or populations were smaller than those detectable by …

Callus Induction And Plant Regeneration From Inflorescence Segments Of Pangola Grass, Y K. Cheng

IGC Proceedings (1977-2023)

Young inflorescences of pangola grass, (Digitaria decumbens Stent), CV. A24, were cultured on half strength of Murashige and Skoog's (MS) medium supplemented with various concentrations and combinations of2,4-dichlorophenoxyace­tic acid (2,4-D), naphthaleneacetic acid (NAA) and kinetin to find the optimum medium for callus induction and plant regeneration. Callus tissue was initiated from the intercalary meristems of the spikelet base or rachis of the cultured inflorescences on either 2,4-D or NAA medium. Calluses were induced 6 days after culturing in 4mg/1 2,4-D and 2mg/1 kinetin medium. Plantlets were obtained in 5 days after calluses were transplanted on MS medium not supplemented …

Analysis Of Seed Production In Relation To Climatic Conditions In Tall Fescue Varieties, Shigeru Suzuki

IGC Proceedings (1977-2023)

Resulting from extensive efforts of breeding, our new registered varieties of forage crops show excellent performance in forage production under proposed areas of recommendation, but in general there are problems for seed production. In order to raise seed production or to find out better environments a regional seed production trial including several forage species was attempted. Under wide range of natural conditions, plant characteristics especially panicle and seed properties were recorded besides seed yield for two to three harvest years. Because response of these traits in relation to environmental conditions of experimental sites was of primary concern, soil conditions and …

Effect Of Management On Seed Recovery And Seed Yield Of Bromus Willdenowii, K R. Brown, M P. Rolston

IGC Proceedings (1977-2023)

Prairie grass (Bromus willdenowii) is a relatively new, large seeded herbage grass species. Management factors for seed production were studied in 8 trials at two locations. Seed yields increased as sowing rate was increased from 7 .5 to 30 kg/ha. Nitrogen fertilizer increased seed yields, and seed recovery from 24.3 to 34. 7 seeds per 100 florets. High seed yields of 2000 kg/ha can be harvested, and two harvests in the same season are possible. Spring sown crops produce economic yields of 740 to 1460 kg/ha in the first summer. Harvest losses can be high (29 to 50% …

Influence Of Irrigation Frequency During Bloom On Lucerne Seed Yield On A Shallow Duplex Soil In South-Eastern Australia, A J. Taylor, V L. Marble

IGC Proceedings (1977-2023)

During bloom, lucerne (Medicago sativa L.) was subjected to different irrigation frequencies based on accumulated Class A 1 Pan evaporation (Epan) to determine the 1 irrigation requirements on a shallow duplex soil. Seed yields ranged from 528 kg ha- on the driest treatment to 1105 kg ha- on the treatment irrigated on the lowest Epan interval. The components of yield which correlated with seed yield were top growth, number of sterns, number of racemes with pods,.and the number of seeds per pod. In order to produce high seed yields, lucerne has a high requirement for water during bloom and on …

Burning, Cutting And The Structure Of Seed Yield In Brachiaria Decumbens, W W. Stur, L R. Humphreys

IGC Proceedings (1977-2023)

The management of post-harvest residues of seed crops of signal grass (Brachiaria decumbens cv. Basilisk) was studied at Mt. Cotton, southeast Queensland. Cutting and burning using moderate (4-8 t ha-1) fuel loads gave similar seed yields to cutting and removing residues, but a higher fuel load which increased fire duration decreased tiller and inflorescence density and seed yield. Tiller density was negatively related to the duration of the interval between cutting and burning. Cutting close to ground level and removing litter increased tiller density. Tillering virtually ceased 25 days after cutting or burning when floral initiation had occurred, and …

Reproductive Development Of Two Desmodium Cultivars, R L. Ison

IGC Proceedings (1977-2023)

Reproductive development of Desmodium uncinatum cv. Silverleaf and D. intortum cv. Greenleaf was investigated in the field in Bali, Indonesia. Sites of varying altitude and thus temperature regimes, separated by only 45km at latitude 8°30'S, enabled investigation of the effects of temperature x photoperiod interactions on flowering and seed production of these cultivars. Floral initiation and flowering of Silver leaf on March 22 and April 14 respectively was independent of site but this cultivar was poorly adapted to the low, warmest site where it did not survive. Floral initiation of Greenleaf at the coolest high site on March 30 was …

Validity Of Breeding For A Female Bias In The Dioecious Buffalograss (Buchloe Dactyloides), James A. Quinn

IGC Proceedings (1977-2023)

Efforts to develop varieties of buffalograss (Buchloe dactyloides) with more females (up to 70%) than males have been based on the assumptions that 1) the female is a better forage plant, and 2) a female bias will result in greater seed production. These hypotheses are currently being tested in both field and greenhouse evaluations, using a wild population from the Oklahoma panhandle and a cultivar ofTexas-Oklahoma-Kansas origin. For both populations, males and females did not differ significantly, either in total biomass or in relative biomass allocation to stolons or reproductive culms. Field observations produced no evidence for sex-linked …