scholarly journals Buried but unsafe – defoliation depletes the underground storage organ (USO) of the mesic grassland geophyte, Hypoxis hemerocallidea

2021 ◽  
Author(s):  
Craig Morris
Keyword(s):  
Growing Season ◽  
Grass Species ◽  
Underground Storage ◽  
Total Biomass ◽  
Plant Parts ◽  
Mesic Grassland ◽  
Previous Season ◽  
Carry Over ◽  
Stored Reserves ◽  
Hypoxis Hemerocallidea

Mesic grasslands in South Africa (> 650 mm a-1 MAP) are rich in herbaceous forbs, which outnumber grass species by more than 5 to 1. Many of these forbs have underground storage units (USOs), such as thickened rootstocks, rhizomes, bulbs, or corms, that provide resources (non-structural carbohydrates, minerals, and water) enabling them to resprout after dry, frosty winters, and fire. However, despite their extensive biomass and reserves ostensibly protected underground, geophytic mesic grassland forbs can be severely depleted or extirpated by chronic trampling and grazing of their aerial parts by livestock. This study examined a possible explanation for forb demise in overgrazed grassland by investigating, in a pot trial, whether the growth of forbs and the size of their USOs are negatively affected by simulated green leaf loss. In a 2x2 factorial (clipped vs. unclipped x spring regrowth in the dark vs. light), five replicate plants of Hypoxis hemerocallidea, a common mesic grassland forb that resprouts from a corm, were subject to six severe (clipped to 80 mm) defoliations during the growing season and regrown in spring under full or restricted light to measure stored reserve contribution to regrowth. Defoliated plants were resilient to defoliation during the growing season, matching the total biomass production of unclipped plants, though cutting reduced the number of leaves by ~60% and flowers by almost 85%. Spring regrowth on stored reserves equalled that from reserves plus concurrent photosynthesis, indicating the value of USOs for regrowth. However, there was a marked carry-over effect of previous season defoliation, resulting in a one-third reduction in shoot growth and 40% fewer inflorescence in spring. Crucially, corm mass was more than halved by clipping. Above-ground spring growth was linearly related to corm mass. It was concluded that buried stored reserves are not protected by recurrent disturbance to aerial plant parts and that continued diminishment of USOs under chronic disturbance by overgrazing or frequent mowing would weaken and likely eventually kill plants, reducing forb species richness. Lenient management by infrequent summer mowing or grazing at moderate stocking rates combined with periodic rotational full season resting and dormant-season burning is recommended to maintain the USOs and vigour of forbs in mesic grassland.

Grazing response strategies along a snow deposition gradient: a laboratory experiment on three grass species from Svalbard

1997 ◽  
Vol 75 (10) ◽  
pp. 1685-1691 ◽  
Author(s):  
Christina Wegener ◽  
Ann Marie Odasz
Keyword(s):  
Grass Species ◽  
Total Biomass ◽  
Response Patterns ◽  
Response Strategies ◽  
Plant Parts ◽  
Svalbard Reindeer ◽  
Grazing Response ◽  
The Cost ◽  
Deposition Gradient ◽  
Snow Deposition

The objective of this study was to determine whether Arctic grasses from different sites along a snow deposition gradient respond similarly to grazing. The effects of laboratory simulated grazing (two levels of clipping frequency, clipping height, and nutrition) on accumulated biomass of different plant parts and number of tillers were measured in the reindeer forage grasses Poa arctica R. Br. from a dry ridge habitat, Festuca rubra L. from a moist lee-side habitat, and Deschampsia alpina L. from a wet snowbed habitat in Svalbard. Both P. arctica and F. rubra increased the proportion of biomass allocated belowground at the cost of the aboveground structures in response to high clipping frequency combined with high clipping height, leaving total accumulated biomass unchanged. In D. alpina, on the contrary, the percentage of aboveground biomass increased at the cost of belowground structures in response to high clipping frequency and low clipping height. This results in higher vulnerability to clipping and reduced total biomass. These two contrasting response patterns may reflect differences in adaptations in the habitats. Stress tolerance is more important on wind-blown ridges and in lee-side habitats where the grazing season is longer. On the other hand, rapid growth is more important in the snowbed where the growing season is shorter. These strategies may be of great importance in regulating and driving the local foraging patterns of Svalbard reindeer. Key words: herbivory, Arctic, graminoids, plant strategy, forage.

scholarly journals Effect of thinning intensity on understory herbaceous diversity and biomass in mixed coniferous and broad-leaved forests of Changbai Mountain

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Gerong Wang ◽  
Yue Sun ◽  
Mo Zhou ◽  
Naiqian Guan ◽  
Yuwen Wang ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Mixed Forest ◽  
Growing Season ◽  
Total Biomass ◽  
Herb Layer ◽  
Simpson Index ◽  
Thinning Intensity ◽  
Ground Biomass ◽  
Below Ground ◽  
Understory Herb

Abstract Background Herbs are an important part of the forest ecosystem, and their diversity and biomass can reflect the restoration of vegetation after forest thinning disturbances. Based on the near-mature secondary coniferous and broad-leaved mixed forest in Jilin Province Forestry Experimental Zone, this study analyzed seasonal changes of species diversity and biomass of the understory herb layer after different intensities of thinning. Results The results showed that although the composition of herbaceous species and the ranking of importance values were affected by thinning intensity, they were mainly determined by seasonal changes. Across the entire growing season, the species with the highest importance values in thinning treatments included Carex pilosa, Aegopodium alpestre, Meehania urticifolia, and Filipendula palmata, which dominated the herb layer of the coniferous and broad-leaved mixed forest. The number of species, Margalef index, Shannon-Wiener index and Simpson index all had their highest values in May, and gradually decreased with months. Pielou index was roughly inverted “N” throughout the growing season. Thinning did not increase the species diversity. Thinning can promote the total biomass, above- and below-ground biomass. The number of plants per unit area and coverage were related to the total biomass, above- and below-ground biomass. The average height had a significantly positive correlation with herb biomass in May but not in July. However, it exerted a significantly negative correlation with herb biomass in September. The biomass in the same month increased with increasing thinning intensity. Total herb biomass, above- and below-ground biomass showed positive correlations with Shannon-Winner index, Simpson index and Pielou evenness index in May. Conclusions Thinning mainly changed the light environment in the forest, which would improve the plant diversity and biomass of herb layer in a short time. And different thinning intensity had different effects on the diversity of understory herb layer. The findings provide theoretical basis and reference for reasonable thinning and tending in coniferous and broad-leaved mixed forests.

scholarly journals Does Deep-Underground Storage Stimulate the Germination of Canola (Brassica napus L.) Seed?

2020 ◽  
Vol 12 (6) ◽  
pp. 23
Author(s):  
Yuxin He ◽  
Chao Liu ◽  
Heping Xie ◽  
Jingchen Wang ◽  
Yang Wang ◽  
...  
Keyword(s):  
Seed Storage ◽  
Biomass Accumulation ◽  
Underground Storage ◽  
Total Biomass ◽  
Short Term ◽  
Hypocotyl Length ◽  
Brassica Napus L ◽  
The Earth ◽  
Deep Underground ◽  
Compensatory Effect

Agriculture is a crucial area to be considered when exploring and exploiting the use of deep-underground space. We investigated the feasibility of deep-underground seed storage by keeping canola seed in either envelopes or sealed packages at four depths below the Earth’s surface (0, 240, 690, and 1410 m) at a gold mine in northeastern China. We studied the effects of storage depth and duration by conducting germination tests with the stored seed. The results showed that the rate of germination was reduced in seed stored at deeper levels and was also lower at all depths after a more prolonged period of storage. Seeds from sealed packages exhibited better resistance to the deep-underground environment than seeds kept in envelopes. However, measurements of hypocotyl lengths and biomass accumulation revealed that the germination of seeds stored in deep-underground was initially inhibited but recovered well compared with the control as the storage depth increased. The total biomass of the hypocotyl increased as the depth of seed storage deepened, indicating the existence of a compensatory effect on seed germination. The findings suggest that short-term deep-underground storage of seeds in sealed packages would improve the germination performance of cultivated canola in terms of the hypocotyl length and biomass accumulation and might be considered as a pre-sowing strategy.

FACTORS INFLUENCING INFESTATION AND INJURY OF RUTABAGAS BY ROOT MAGGOTS (DIPTERA:ANTHOMYIIDAE) IN PRINCE EDWARD ISLAND. I. FIELD STUDIES

1958 ◽  
Vol 38 (2) ◽  
pp. 188-198 ◽  
Author(s):  
D. C. Read
Keyword(s):  
Sandy Soil ◽  
Prince Edward Island ◽  
Growing Season ◽  
Field Studies ◽  
Clay Loam ◽  
High Moisture Content ◽  
High Moisture ◽  
Previous Season ◽  
Hylemya Brassicae ◽  
Root Maggot

Examinations of more than 100 rutabaga fields per year, from 1951 to 1955, showed that Hylemya brassicae (Bouché) was the only species of root maggot that injured rutabagas in Prince Edward Island. H. liturata (Mg.) (= H. trichodactyla (Rond.)), H. cilicrura (Rond.), and Muscina stabulans (Fall.) were associated with H. brassicae but did not injure the roots. H. brassicae flies [note Whitcomb (12) for illustrations] began to emerge from overwintered puparia early in June in sandy soil areas and late in July in clay loam areas. Heavy texture and high moisture content of soils were closely correlated with the delay in emergence. The flies laid their eggs near rutabaga plants, usually in crevices in the soil, and upon hatching the larvae entered and fed on the roots. Larvae generally entered the roots at a depth of one inch or more below the surface of the soil. In general, early-planted rutabagas in sandy soil areas and late plantings in clay loam areas were severely damaged by larvae of H. brassicae, whereas late plantings in sandy areas and early plantings in clay loam areas were lightly infested. However, in the sandy soil areas where all of the rutabaga crops were harvested early in August damage was relatively light. Also, fields isolated by other rutabaga fields from sources of infestation such as storage bins and infested rutabaga crops, of either the current or the previous season, were usually slightly damaged. Use of barnyard manure increased H. brassicae infestations early in the season but did not significantly influence the damage caused during the whole growing season.

Fermentation kinetic, chemical composition, organic matter degradation and metabolisable energy of three non-cultivated pastures located in the central plateau of Mexico

2009 ◽  
Vol 2009 ◽  
pp. 92-92
Author(s):  
A A Rayas-Amor ◽  
P Dorward ◽  
T Rehman ◽  
F L Mould ◽  
O A Castelan-Ortega
Keyword(s):  
Economic Benefit ◽  
Nutritive Value ◽  
Growing Season ◽  
Production Costs ◽  
Grass Species ◽  
Organic Matter Degradation ◽  
Central Plateau ◽  
Maize Stover ◽  
Resource Poor ◽  
Metabolisable Energy

Approximately 80% of all production costs are related to the purchase of forages and other feeds in dairy enterprises in Mexico. Resource poor, smallholder (campesino) systems are heavily reliant on the use of maize stover, noncultivated/cultivated grass species and weeds to feed their dairy cattle, thus a nutritional understanding of local forage resources would be of considerable economic benefit. The objective of this study was to determine the nutritive value of non-cultivated pastures (NcP) across the growing season.

scholarly journals   Effect of elevated CO2 and temperature on phosphorus efficiency of wheat grown in an Inceptisol of subtropical India

2012 ◽  
Vol 58 (No. 5) ◽  
pp. 230-235 ◽  
Author(s):  
Manoj-Kumar ◽  
A. Swarup ◽  
A.K. Patra ◽  
J.U. Chandrakala ◽  
K.M. Manjaiah
Keyword(s):  
Grain Yield ◽  
Dry Weight ◽  
P Uptake ◽  
Utilization Efficiency ◽  
Phosphorus Efficiency ◽  
Total Biomass ◽  
P Efficiency ◽  
Plant Parts ◽  
P Fertilizer ◽  
P Utilization

In a phytotron experiment, wheat was grown under two levels of atmospheric CO<sub>2</sub> [ambient (385 ppm) vs. elevated (650 ppm)], two levels of temperature (ambient vs. ambient +3&deg;C) superimposed with three levels of phosphorus (P) fertilization: 0, 100, and 200% of recommended dose. Various measures of P acquisition and utilization efficiency were estimated at crop maturity. In general, dry matter yields of all plant parts increased under elevated CO<sub>2</sub> (EC) and decreased under elevated temperature (ET); however, under concurrently elevated CO<sub>2</sub> and temperature (ECT), root (+36%) and leaf (+14.7%) dry weight increased while stem (&ndash;12.3%) and grain yield (&ndash;17.3%) decreased, leading to a non-significant effect on total biomass yield. Similarly, total P uptake increased under EC and decreased under ET, with an overall increase of 17.4% under ECT, signifying higher P requirements by plants grown thereunder. Although recovery efficiency of applied P fertilizer increased by 27%, any possible benefit of this increase was negated by the reduced physiological P efficiency (PPE) and P utilization efficiency (PUtE) under ECT. Overall, there was ~17% decline in P use efficiency (PUE) (i.e. grain yield/applied P) of wheat under ECT. &nbsp;

Compositional changes over four years for binary mixtures of grass species grown with white clover

2005 ◽  
Vol 85 (2) ◽  
pp. 351-360 ◽  
Author(s):  
D. B. McKenzie ◽  
Y. A. Papadopoulos ◽  
K. B. McRae ◽  
E. Butt
Keyword(s):  
White Clover ◽  
Tall Fescue ◽  
Principal Component ◽  
Growing Season ◽  
Kentucky Bluegrass ◽  
Repeated Measurements ◽  
Grass Species ◽  
Growth Stages ◽  
Meadow Fescue ◽  
Reed Canarygrass

Kentucky bluegrass, meadow fescue, orchardgrass, tall fescue, timothy, and reed canarygrass were seeded in all possible two-grass combinations with white clover in conventional and underseeded barley treatments using a split-plot design at the Western Agriculture Centre near Pynn’s Brook, NL. The objectives were: (1) to assess dry matter yield (DMY) of two binary grass species when sown with white clover in mixtures under a system with cuttings at similar crop growth stages as rotational grazing and to assess the effect of underseeding to barley on this system; (2) to identify mixtures that enhance herbage distribution throughout the grazing season; and (3) to assess the sward dynamics over successive cropping seasons. The composition of the binary grass mixtures with white clover affected seasonal DMY, seasonal herbage distribution, and sward dynamics over the production years. Orchardgrass in mixtures decreased DMY, shifted the herbage distribution toward early season, and competed with other species. Timothy composition of the stand showed the largest decline over the 3 production years, whereas white clover declined in mixtures with bluegrass, orchardgrass, or tall fescue. Meadow fescue and reed canarygrass with white clover was the most productive mixture with excellent persistence and good yield distribution over the growing season. Orchardgrass was the least compatible species in the mixtures; it dominated first growth and contributed the least to biomass production in later years. Both bluegrass and reed canarygrass performed well in mixtures over the 3 production years; bluegrass appeared to enhance the performance of the other species during summer regrowth whereas reed canarygrass was superior in the later part of the growing season. Underseeding with barley did not affect white clover yield in any production year but detrimentally affected the yield of orchardgrass and meadow fescue in mixtures, and their seasonal distribution. Key words: Bluegrass, orchardgrass, meadow fescue, tall fescue, timothy, reed canarygrass, repeated measurements, principal component analysis, herbage DM distribution, species competition

scholarly journals Fate of nitrogen-15 in the subsequent growing season of greenhouse tomato plants (Lycopersicon esculentum Mill) as influenced by alternate partial root-zone irrigation

RSC Advances ◽  
2017 ◽  
Vol 7 (55) ◽  
pp. 34392-34400 ◽  
Author(s):  
Maomao Hou ◽  
Fenglin Zhong ◽  
Qiu Jin ◽  
Enjiang Liu ◽  
Jie Feng ◽  
...  
Keyword(s):  
Lycopersicon Esculentum ◽  
Root Zone ◽  
Growing Season ◽  
Tomato Plants ◽  
Residual Nitrogen ◽  
Greenhouse Tomato ◽  
Lycopersicon Esculentum Mill ◽  
Crop Uptake ◽  
Previous Season ◽  
Fate Of Nitrogen

Alternate partial root-zone irrigation has profound impacts on the crop uptake of residual nitrogen originated from the previous season.

Regeneration of Canada Thistle (Cirsium arvense) from Intact Roots and Root Fragments at Different Soil Depths

Weed Science ◽  
2013 ◽  
Vol 61 (2) ◽  
pp. 277-282 ◽  
Author(s):  
Mette Goul Thomsen ◽  
Lars-Olav Brandsæter ◽  
Haldor Fykse
Keyword(s):  
Cirsium Arvense ◽  
Total Biomass ◽  
Layer By Layer ◽  
Canada Thistle ◽  
Soil Layers ◽  
Plant Parts ◽  
Shoot Number ◽  
Two Factors ◽  
Intact Root ◽  
Intact Roots

In the present field study, the capability of Canada thistle to develop shoots from intact roots and root fragments at different soil depths was studied. The experiments were performed on four sites with high-density Canada thistle, with three or four replications per treatment. At each site, the soil in the plots was removed layer by layer (to 30 or 40 cm, depending on the site), within a 1 by 1-m quadrat, and spread out on a plastic sheet. All roots and other plant parts were removed, and the soil was either replaced without any root material (two sites), or the roots of the thistles were cut into 10-cm-long fragments and replaced into the source holes (two sites). The measured variables were shoot number and biomass. The number of shoots of Canada thistle decreased with increasing depth (P < 0.001) and increased with time. Additionally, the two factors interacted (P < 0.001) such that shoot development was slower from greater depths. Roots from ≤ 20 cm depth produced higher biomasses than did roots from below 20 cm depth. Replacement of root fragments did not affect the amount of biomass produced. It was concluded that the intact root system contributed considerably more to the total biomass produced by Canada thistle than did the root fragments in the upper soil layers.

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