Carbon resource sharing and rhizome expansion of Phalaris aquatica plants in grazed pastures

2005 ◽  
Vol 32 (1) ◽  
pp. 79 ◽  
Author(s):  
Brendan R. Cullen ◽  
David F. Chapman ◽  
Paul E. Quigley
Keyword(s):  
Resource Sharing ◽  
Seasonal Pattern ◽  
Soil Surface ◽  
Deep Roots ◽  
Phalaris Aquatica ◽  
Plant Parts ◽  
Grazed Pastures ◽  
Below Ground ◽  
Grazing Systems ◽  
Western Victoria

The patterns of carbon (C) resource sharing and new rhizome development in phalaris (Phalaris aquatica L. cv. Australian) were examined in grazed pastures in western Victoria. The seasonal pattern of new rhizome growth was similar under the four grazing systems tested. New rhizome production was infrequent but concentrated in winter. The phalaris plants maintained more than 1600 kg DW ha–1 of non-assimilating material beneath the soil surface (0–5 cm). Gaseous 14C was fed into plants in the field to determine if these below ground structures continued to be supported by the C assimilating tillers. The results indicated that the primary tiller does provide C to support the growth of secondary and tertiary tillers derived from its axillary buds. There was some evidence that C was exported from the fed tiller to non-assimilating plant structures. The old reproductive tiller bases (from which the assimilating tillers originate) received some C support, suggesting that this was maintained because it had deep roots attached. C export to older plant parts declined, which may lead to plant fragmentation.

Notes on Behaviour of Pemphigus betae Doane (Homoptera: Aphididae) Infected with Entomophthora aphidis Hoffm.

1958 ◽  
Vol 90 (7) ◽  
pp. 439-440 ◽  
Author(s):  
A. M. Harper
Keyword(s):  
Sugar Beet ◽  
Acyrthosiphon Pisum ◽  
Soil Surface ◽  
First Record ◽  
Department Of Agriculture ◽  
Beet Root ◽  
Pemphigus Betae ◽  
Below Ground ◽  
Sugar Beet Root ◽  
Annapolis Valley

Normally the sugar-beet root aphid, Pemphigus betae Doane, lives and feeds on sugar-beet roots below ground during the summer and fall. However, in many beet fields between Lethbridge and Monarch, Alberta, in September, 1956, a large number of these aphids were found on the soil surface and on the crowns and leaves of the plants. Many of the aphids had crawled up the plants and, even after death, remained clinging to the leaves (Fig. 1). This clinging reaction seemed similar to that of grasshoppers infected with Entomophthora grylli Fresen. Mr. R. B. Baird, Entomology Laboratory, Canada Department of Agriculture, Belleville, Ontario, identified the organism causing the disease destroying these aphids as Entomophthora aphidis Hoffm. This is the first record of this disease killing subterranean aphids in Canada. The only other reports of E. aphidis on root aphids are those of Maxson (1916) in Colorado and Charles (1941) in California. In Canada, it has been previously reported as a factor in control of the pea aphid, Acyrthosiphon pisum (Harr.), in the Annapolis Valley, Nova Scotia (MacLeod, 1953).

The impact of biomass harvesting on phosphorus uptake by wetland plants

2001 ◽  
Vol 44 (11-12) ◽  
pp. 61-67 ◽  
Author(s):  
S-Y. Kim ◽  
P.M. Geary
Keyword(s):  
Plant Biomass ◽  
Phosphorus Uptake ◽  
P Uptake ◽  
Plant Parts ◽  
Biomass Harvesting ◽  
Below Ground ◽  
The Impact ◽  
Total P ◽  
Better Than ◽  
P Removal

Two species of macrophytes, Baumea articulata and Schoenoplectus mucronatus, were examined for their capacity to remove phosphorus under nutrient-rich conditions. Forty large bucket systems with the two different species growing in two types of substrate received artificial wastewaters for nine months, simulating a constructed wetland (CW) under high loading conditions. Half of the plants growing in the topsoil and gravel substrates were periodically harvested whereas the other half remained intact. Plant tissue and substrate samples were regularly analysed to determine their phosphorus concentrations. With respect to phosphorus uptake and removal, the Schoenoplectus in the topsoil medium performed better than the Baumea. Biomass harvesting enhanced P uptake in the Schoenoplectus, however the effect was not significant enough to make an improvement on the overall P removal, due to the slow recovery of plants and regrowth of biomass after harvesting. From P partitioning, it was found that the topsoil medium was the major P pool, storing most of total P present in the system. Plant parts contributed only minor storage with approximately half of that P stored below ground in the plant roots. The overall net effect of harvesting plant biomass was to only remove less than 5% of total phosphorus present in the system.

scholarly journals Seed morphology and allelopathy of invasive Praxelis clematidea

2020 ◽  
Vol 48 (1) ◽  
pp. 261-272
Author(s):  
Suphannika INTANON ◽  
Buntoon WIENGMOON ◽  
Carol A. MALLORY-SMITH
Keyword(s):  
Invasive Species ◽  
Management Strategies ◽  
Soil Surface ◽  
Seed Morphology ◽  
Basic Knowledge ◽  
Agricultural Systems ◽  
Bidens Pilosa ◽  
Rubber Plantations ◽  
Plant Parts ◽  
Seed Biology

Praxelis [Praxelis clematidea (Griseb.) R.M.King & H.Rob.] is an invasive species that infests many agricultural systems globally, such as orchards, rubber plantations, and other economic crops. The purpose of this research was to study seed morphology, germination factors, and allelopathy of aboveground parts of P. clematidea. P. clematidea seeds are small, light, and possess pappi that allow them to be dispersed easily by wind or animals. Among four P. clematidea populations collected from different provinces in Thailand, the size of P. clematidea seeds ranged from 2.6 to 3.2 mm in length, 0.6 to 0.7 mm in width, and were 0.4 mm in thickness. The weight of P. clematidea seeds ranged from 0.13 to 0.21 mg. P. clematidea had about 44 to 48 seeds per head. Seeds germinated over a temperature range of 20 to 30 °C while high (45 °C) and low (10 °C) temperatures reduced germination. Maximum germination occurred when seeds were planted on the soil surface. No seedlings germinated when seeds were planted at a depth more than 1 cm. P. clematidea extracts from aerial plant parts at concentrations of 25 and 50% inhibited seedling growth of hairy beggarticks (Bidens pilosa L.). Basic knowledge of the seed biology of P. clematidea and allelochemicals can help in understanding the invasiveness and in developing management strategies for this weed.

scholarly journals Refinement of Alternate Wetting and Drying Irrigation Method for Rice Cultivation

2014 ◽  
Vol 17 (1-2) ◽  
pp. 33-37 ◽  
Author(s):  
Priya Lal Chandra Paul ◽  
MA Rashid ◽  
Mousumi Paul
Keyword(s):  
Grain Yield ◽  
Water Level ◽  
Block Design ◽  
Water Productivity ◽  
Ground Surface ◽  
Soil Surface ◽  
Ground Level ◽  
Wetting And Drying ◽  
Alternate Wetting And Drying ◽  
Below Ground

Experiments were conducted at BRRI farm Gazipur during Boro season 2010-12 to determine maximum depth of water level below ground surface in alternate wetting and drying (AWD) method. The experiment was laid out in a randomized complete block design with four irrigation treatments. The treatments of AWD method were: T1 = continuous standing water, T2 = irrigation when water level reached 15 cm below ground level, T3 = irrigation when water level reached 20 cm below ground level and T4 = irrigation when water level reached 50 cm below ground level. The experiment involved BRRI dhan28 as a test crop. The treatment T2 gave the highest grain yield (5.9 and 6.2 ton/ha) in 2010-11 and 2011-12, respectively. Maximum benefits per hectare were found Tk. 5476 and 4931 for using 807 and 880 mm water during 2010-11 and 2011-12 respectively and thus water productivity was 7.1 kg/ha-mm in T2 for both the seasons. Continuous standing (T1) water (1013 and 1100 mm) gave comparable grain yield 5.7 and 6.0 ton/ha in 2010-11 and 2011-12, respectively. Minimum water productivity was found in treatment T1 (5.6 and 5.4 kg/ha-mm) for both the seasons. Application of irrigation when water was 15 cm below soil surface was found most profitable in AWD system and the grain yield was decreased when water level was below 15 cm depth. Therefore, the recommended AWD technology could increase rice yield and save irrigation water by 25-30 percent.DOI: http://dx.doi.org/10.3329/brj.v17i1-2.20899Bangladesh Rice j. 2013, 17(1&2): 33-37

scholarly journals Effects of mycorrhizal inoculant, N:P supply ratio, and water depth on the growth and biomass allocation of three wetland plant species

2005 ◽  
Vol 83 (9) ◽  
pp. 1117-1125 ◽  
Author(s):  
Lauchlan H. Fraser ◽  
Larry M. Feinstein
Keyword(s):  
Biomass Allocation ◽  
Water Depth ◽  
Soil Surface ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Nutrient Supply ◽  
Wetland Plant ◽  
Below Ground ◽  
Root:Shoot Ratios ◽  
Water Depths

In the greenhouse, we investigated the growth and biomass allocation of three juvenile wetland species ( Carex tribuloides Wahl., Phalaris arundinacea L., and Rumex orbiculatus Gray) under three different water depths (–4, 0, and +2 cm relative to the soil surface), three N:P supply ratios (1:30, 1:1, 30:1), and two mycorrhizal inoculant treatments (arbuscular mycorrhizal (AM) fungi present, absent). After 6 weeks, the plants were harvested, separated to above- and below-ground parts, oven-dried, and weighed. The mycorrhizal inoculant significantly increased plant growth and reduced root:shoot ratios. At an N:P supply ratio of 30:1, plants with AM fungi had significantly greater biomass than those plants without AM fungi. However, at 1:1 N:P supply ratio, plants without AM fungi had greater biomass. Plants without AM fungi had higher root:shoot ratios at 0 and –4 cm water depth than plants with AM fungi. In general, C. tribuloides had the lowest growth, and unlike P. arundinacea and R. orbiculatus, was not affected by the water depth treatment. Growth of the wetland plants was limited more by nitrogen than by phosphorus. Our results suggest that at high N:P nutrient supply ratios and non-flooded conditions the growth of wetland seedlings can benefit by being inoculated with AM fungi.

Grazing system and stocking rate effects on the productivity, botanical composition and soil surface characteristics of alfalfa-grass pastures

1997 ◽  
Vol 77 (4) ◽  
pp. 669-676 ◽  
Author(s):  
J. D. Popp ◽  
W. P. McCaughey ◽  
R. D. H. Cohen
Keyword(s):  
Soil Surface ◽  
Surface Characteristics ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Forage Production ◽  
Basal Cover ◽  
Grazed Pastures ◽  
Litter Cover ◽  
Grazing System ◽  
Stocking Rates

A 4-yr experiment was conducted (1991 to 1994) near Brandon, MB, to determine the effects of grazing system (continuous and rotational) and stocking rate [light (1.1 steers ha−1); heavy (2.2 steers ha−1)] on the productivity, botanical composition and soil surface characteristics of an alfalfa (Medicago sativa L.; approximately 70%), meadow bromegrass (Bromus biebersteinii Roem & Schult.; 25%) and Russian wild ryegrass [Psathyrostachys juncea (Fisch.) Nevski; 5%] pasture. Grazing season length was shorter (P < 0.05) for cattle in continuously compared with rotationally stocked pastures in 1991, while in 1993 and 1994 it was shortest (P < 0.05) in heavily stocked continuously grazed pastures. Carrying capacity (steer days ha–1) was greater (P < 0.05) in heavily stocked rotationally grazed pastures compared with other treatments in 1991, 1993 and 1994. In 1992, it was greater (P < 0.05) in heavy than light stocking rate treatments for both rotationally and continuously grazed pastures. Cattle usually gained more (P < 0.05) per day (kg d−1) and during the season (kg hd−1) at light than at heavy stocking rates, while total liveweight production (kg ha−1) was greater (P < 0.05) at heavy than at light stocking rates. Forage production and disappearance did not differ (P > 0.05) within grazing systems and stocking rates from 1991 to 1993, but in 1994, production and disappearance were greater (P < 0.05) at heavy than at light stocking rates. Mean seasonal herbage mass available and carry-over were greater (P < 0.05) in lightly stocked pastures than heavily stocked pastures from 1991 to 1994. After the first year of grazing, the proportion of alfalfa increased (P < 0.05), while grasses declined (P < 0.05) within all grazing treatments. In subsequent years, a trend was observed, where alfalfa declined and grasses increased in all pastures, except those stocked heavily and grazed continuously, which by 1994 had the greatest (P < 0.05) percentage of alfalfa. As years progressed, increases (P < 0.05) in basal cover concurrent with declines in bare ground were recorded on all grazing treatments, while litter cover often did not differ (P > 0.05) within either grazing system or stocking rate, except in 1992, when basal cover was lowest (P < 0.05), while litter cover was greatest (P < 0.05) on lightly stocked continuously grazed pastures compared with other treatments. Stocking rates were a key factor to optimizing individual animal performance and/or gain per hectare on alfalfa grass pastures, however differences in the effect of continuous and rotational stocking on pasture productivity were minimal. Key words: Alfalfa, grazing, stocker cattle, production

Estimating above- and below-ground macrophyte production in Scirpus tidal marshes

1988 ◽  
Vol 66 (2) ◽  
pp. 368-374 ◽  
Author(s):  
Jean-François Giroux ◽  
Jean Bédard
Keyword(s):  
Standing Crop ◽  
Belowground Biomass ◽  
Tidal Marshes ◽  
Optimal Size ◽  
Lawrence Estuary ◽  
Plant Parts ◽  
Peak Standing Crop ◽  
Below Ground ◽  
The Difference ◽  
St Lawrence Estuary

Different methods to estimate primary production of Scirpus marshes of the St. Lawrence estuary were compared. Quadrats 25 × 25 cm and cores 10 cm in diameter were found to be the optimal size to sample above- and below-ground standing crops, respectively. Ash content for different plant parts of various species was measured to obtain more accurate estimates of organic matter. A series of allometric equations relating stem height and mass were developed to estimate aerial standing crop from permanent nondestructively sampled plots. This method, however, overestimated standing crop compared with the destructive (harvest) method. The relationship between the above- and below-ground standing crop was also determined for the dominant species and used to predict belowground biomass without destructive sampling. Finally, the Smalley method provided the best estimates of net annual above- and below-ground production when losses attributed to decomposition were not considered. For less intensive studies, however, the methods based on peak standing crop and on the difference between maximum and minimum biomass would yield good approximations of above- and below-ground production.

The biology of a landlocked form of the normally catadromous salmoniform fish Galaxias maculatus (Jenyns). III. Structure of the gonads

1972 ◽  
Vol 23 (1) ◽  
pp. 17 ◽  
Author(s):  
DA Pollard
Keyword(s):  
Single Case ◽  
Seasonal Pattern ◽  
Histological Structure ◽  
Testicular Development ◽  
Teleost Fishes ◽  
Female Fish ◽  
Gonadal Maturation ◽  
Galaxias Maculatus ◽  
History Of ◽  
Western Victoria

Changes in the gross morphology and histological structure of the gonads of a landlocked form of Galaxias maculatus inhabiting Lake Modewarre, south-western Victoria, are described in relation to the seasonal pattern of gonadal maturation outlined in a previous paper on the life history of this fish. Macroscopic changes in the gross morphology of the gonads are classified as to seven arbitrary maturity stages, these approximately corresponding, in the case of the male, with seven histological stages of testicular development. Nine stages of oocyte development in the ovaries of female fish are also outlined, and a single case of synchronous abnormal hermaphroditism is described. The above findings are then discussed in relation to those of previous studies on the gonads of a variety of teleost fishes, and in particular a number of other forms also belonging to the order Salmoniformes.

scholarly journals Effect of fertilization on below-ground plant mass of submontane Polygono-Cirsietum meadow

Beskydy ◽  
2013 ◽  
Vol 6 (1) ◽  
pp. 33-42
Author(s):  
Petr Holub ◽  
Ivan Tůma ◽  
Karel Fiala
Keyword(s):  
Primary Productivity ◽  
Root Biomass ◽  
Net Primary Productivity ◽  
Growing Season ◽  
Dry Mass ◽  
The Czech Republic ◽  
Plant Parts ◽  
Below Ground ◽  
Turn Over ◽  
Different Levels

We assessed below-ground net primary productivity (BNPP) in the wet submontane Cirsium meadow occurred in the highland region of the Czech Republic. Effect of four different fertilization levels on BNPP was estimated in 1992. At the beginning of the growing season (April 29), total dry mass of rhizomes, roots and total below-ground plant parts of unfertilized stand reached 177, 1478 and 1657 g.m-2, respectively. Their living parts formed 42 % of their total dry mass. In comparison with unfertilized stands, however, the greatest accumulation of dry mass of rhizomes (504 g.m-2), roots (1503 g.m-2) and total below-ground dry mass (2008 g.m-2) was reached after application of 90 kgN.ha-1. Similarly, the highest BNPP values for living (435 g.m-2.yr-1) and total below-ground dry mass (351 g.m-2.yr-1) were calculated for the stand affected by the same amount of fertilization. These data show how variable role grasslands can play in accumulation and turn over of root biomass due to different levels of fertilization.

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