Agronomy and Crop Sciences Commons^™

The Regulation Of Winter Growth Of Temperate Pasture Grasses, D R. Kemp

IGC Proceedings (1977-2023)

Temperate pasture grass growth rates are lowest in winter and limit the number of stock that can be carried through the year on many farms. Field studies of the regulation of pasture growth in winter showed that the earlier a grass intiates reproductive development the greater is the mean pasture growth rate through winter. A 5 to 10 fold variation in winter growth rates between a range of genera and ecotypes was simply related to the time of onset of reproductive development. Prospects for improving winter pasture growth by selecting for early flowering outlined.

Italian Ryegrass Response To Allelopathic Effects Of Stubble-Residues From Several Tropical Grasses, Y Takahashi, S Uozumi, S Ono, Y Yoden

IGC Proceedings (1977-2023)

The laboratory experiments with aqueous extracts of 11 tropical grass stubble-residues allowed an examination of the allelopathic effects of the extracts on seed germination and early growth of Italian ryegrass (Lolium multiflorum, cv. Minamiwase, Abbr. as IRG). Germination of IRG was generally found to be reduced with an increase in concentration of the residue extracts. Extracts of African millet (Eleusine coracana), Guinea grass (Panicum maximum, strain GR-171) and setaria (Setaria anceps, cv. Nandi and Kazungula) were very inhibitory to the germination of IRG at a high concentration (4g dried stubble/lOOml) ; whereas …

Relationship Between Germination Tests And Field Emergence Of Perennial Warm-Season Forage Grasses, F H. Hsu, C J. Nelson

IGC Proceedings (1977-2023)

Perennial warm-season forage grasses can be valuable components of forage systems to improve animal performance in summer, but they are difficult to get established. Therefore, two germination tests and two field experiments were conducted to determine relationships between seed germination and field emergence. Chilled and unchilled seed of big bluestem (Andropogon gerardi Vitman), caucasian bluestem ( Bothriochloa caocasica (Prin.) C. E. Hubb.), indiangrass ( Sorghastrum nutans (L.) Nash.), and switchgrass (Panicum virgatum L.) were germinated at different temperatures. Unchilled seed were planted in the field near Columbia, MO., at approximately 2-week intervals from early April to late June in …

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) …