Effect of fertilizer, root and shoot competition on the growth of Siratro (Macroptilium atropurpureum) and green panic (Panicum maximum var. trichoglume) seedlings in a native speargrass (Heteropogon contortus) sward

1985 ◽  
Vol 36 (2) ◽  
pp. 233 ◽  
Author(s):  
SJ Cook ◽  
D Ratcliff
Keyword(s):  
Seedling Growth ◽  
Seedling Emergence ◽  
Root Competition ◽  
Panicum Maximum ◽  
Leaf Production ◽  
Heteropogon Contortus ◽  
Shoot Competition ◽  
Native Grassland ◽  
Supplementary Irrigation ◽  
Macroptilium Atropurpureum

The effect of root and shoot competition and the application of fertilizer on the growth of Siratro (Macroptilium atropurpureum) and green panic (Panicum maxinzum var. trichoglume) seedlings under supplementary irrigation in an existing native grassland dominated by Heteropogon contortus was studied. The seedlings were grown in both the presence and absence of root competition and varying levels of shoot competition. Root competition was prevented by the use of steel tubes while shoot competition was varied by: clipping the native pasture to a height of either 3-5 cm or 10-15 cm every 7-10 days, leaving the native sward unclipped, and unclipped sward with wire-netting guards fitted around each seedling to prevent overtopping and facilitate light penetration. Seedling growth was assessed by determining dry weights after 29 days and also by measuring plant heights, leaf and tiller numbers and the leaf widths at 7-day intervals during this period. Application of superphosphate and nitrogen fertilizer increased the growth of both species, the initial effects being evident within 1-2 days of seedling emergence. However, at both fertilizer levels the growth of both species was primarily affected by root competition for nutrients. Where fertilizer was applied and no root competition was present heavy shading in the lower 5-10 cm of the sward canopy restricted seedling growth by reducing tiller and leaf production. The removal of shoot competition increased seedling yields fivefold whereas the removal of root competition and the removal of both root and shoot competition increased yields by 25- and 45-fold, respectively. Siratro and green panic yields were the same in the absence of root competition but Siratro yields were 11 times those of green panic where root competition was present.

Establishment of four pasture grasses and Siratro from seed oversown into dense and open speargrass pastures

1984 ◽  
Vol 24 (126) ◽  
pp. 360 ◽  
Author(s):  
SJ Cook
Keyword(s):  
Seedling Emergence ◽  
Weather Conditions ◽  
Panicum Maximum ◽  
Brachiaria Decumbens ◽  
Heteropogon Contortus ◽  
Pasture Grasses ◽  
Macroptilium Atropurpureum ◽  
Signal Grass ◽  
Native Pastures ◽  
Better Than

In two experiments, seed of Gayndah and Biloela buffel grass (Cenchrus ciliaris), green panic (Panicum maximum var. trichoglume), signal grass (Brachiaria decumbens) and Siratro (Macroptilium atropurpureum) was broadcast into a range of seedbeds imposed on native speargrass (Heteropogon contortus) pastures that had either been cleared of trees 4-5 years before sowing (C) or had the trees killed at sowing (K). The seedbeds were: untreated control (NP); mown to 3 cm before and at sowing (M); M followed by regular clipping (MD); burnt (B); B followed by regular clipping (BD); and herbicide (H). Seed was also sown into a cultivated seedbed (P) in C. The number of plants established 15-16 months after sowing was highest in the cultivated seedbed and lowest in seedbeds where competition from the native grasses was greatest. Competition was greater in C than in K, the native pastures in C having about three times more dry matter than those in K. Burning reduced competition but also reduced seedling emergence. It increased establishment slightly in K but not in C. The M and MD treatments failed to increase establishment over that of the NP control. Herbicides reduced competition and increased establishment in C and K, but only for signal grass and Siratro in C when drier conditions occurred in the second experiment. Siratro established better than the grasses in the presence of competition when weather conditions were favourable, but there was little Siratro or grass establishment when water deficits occurred soon after emergence, especially in C

Changes in Levels of Solutes During Osmotic Adjustment to Water Stress in Leaves of Four Tropical Pasture Species

1981 ◽  
Vol 8 (1) ◽  
pp. 77 ◽  
Author(s):  
CW Ford ◽  
JR Wilson
Keyword(s):  
Water Stress ◽  
Organic Acids ◽  
Osmotic Adjustment ◽  
Inorganic Ions ◽  
Arid Environment ◽  
Low Molecular Weight ◽  
Panicum Maximum ◽  
Buffel Grass ◽  
Heteropogon Contortus ◽  
Macroptilium Atropurpureum

Three tropical grasses, green panic (Panicum maximum var. trichoglume), buffel grass (Cenchrus ciliaris), and spear grass (Heteropogon contortus), and a tropical legume, siratro (Macroptilium atropurpureum), were field-grown in a semi-arid environment. One set of plants was well watered, while another set was subjected to a continuous 35-day drying cycle. Samples of specific leaves were taken at the beginning, middle and end of the drying cycle, and 1, 5 and 14 days after rewatering. The major low-molecular-weight solutes which accumulated in the grasses during water stress were the inorganic ions sodium (green panic), potassium (buffel and spear grass) and chloride (all grasses). Accumulation of these ions largely accounted for the osmotic adjustments determined from a previous study of water relations of the leaves. Concentrations of the minor constituents glucose and fructose increased only slightly in the stressed grasses, whereas levels of sucrose, the major carbohydrate component, increased substantially, particularly in spear grass. Inositol accumulated to a small extent in spear grass. Differences between the grasses were evident in the organic acid spectrum and also in changes in concentration of organic acids due to water stress. In water-stressed tissue, malate levels increased in green panic and spear grass but were reasonably constant in buffel grass. Aconitate concentrations (not detected in buffel grass) decreased in stressed green panic, but increased in spear grass. Oxalate (only trace quantities in spear grass) was a major component in green panic and buffel grass, but did not appear to vary with increase in water stress. Succinate accumulated only in stressed spear grass. The contribution of carbohydrates and organic acids to the osmotic adjustment was relatively small. Proline accumulated to varying degrees in all stressed grasses. Betaine occurred only in trace amounts in spear grass, but accumulated substantially in green panic and buffel grass. Water-stressed leaves of siratro did not accumulate inorganic ions, sugars, organic acids, proline or betaine, but pinitol levels increased. Implications of the results relating osmotic adjustment to changes in chemical composition are discussed.

Genetic variation for rate of establishment in caucasian clover

1998 ◽  
pp. 213-217
Author(s):  
K.H. Widdup ◽  
T.L. Knight ◽  
C.J. Waters
Keyword(s):  
Genetic Variation ◽  
Root Growth ◽  
Seedling Growth ◽  
White Clover ◽  
Seedling Emergence ◽  
Red Clover ◽  
Dry Weight ◽  
Cool Season ◽  
Trifolium Ambiguum ◽  
Root Dry Weight

Slow establishment of caucasian clover (Trifolium ambiguum L.) is hindering the use of this legume in pasture mixtures. Improved genetic material is one strategy of correcting the problem. Newly harvested seed of hexaploid caucasian clover germplasm covering a range of origins, together with white and red clover and lucerne, were sown in 1 m rows in a Wakanui soil at Lincoln in November 1995. After 21 days, the caucasian clover material as a group had similar numbers of emerged seedlings as white clover and lucerne, but was inferior to red clover. There was wide variation among caucasian clover lines (48-70% seedling emergence), with the cool-season selection from cv. Monaro ranked the highest. Recurrent selection at low temperatures could be used to select material with improved rates of seedling emergence. Red clover and lucerne seedlings produced significantly greater shoot and root dry weight than caucasian and white clover seedlings. Initially, caucasian clover seedlings partitioned 1:1 shoot to root dry weight compared with 3:1 for white clover. After 2 months, caucasian clover seedlings had similar shoot growth but 3 times the root growth of white clover. Between 2 and 5 months, caucasian clover partitioned more to root and rhizome growth, resulting in a 0.3:1 shoot:root ratio compared with 2:1 for white clover. Both clover species had similar total dry weight after 5 months. Unhindered root/ rhizome devel-opment is very important to hasten the establishment phase of caucasian clover. The caucasian clover lines KZ3 and cool-season, both selections from Monaro, developed seedlings with greater shoot and root growth than cv. Monaro. KZ3 continued to produce greater root growth after 5 months, indicating the genetic potential for improvement in seedling growth rate. Different pasture estab-lishment techniques are proposed that take account of the seedling growth characteristics of caucasian clover. Keywords: establishment, genetic variation, growth, seedling emergence, Trifolium ambiguum

Effects of salinity on seedling emergence and early seedling growth of Irvingia gabonensis (Irvingiaceae)

2017 ◽  
Vol 45 (2) ◽  
pp. 282-295
Author(s):  
R. Vihotogbé ◽  
C. Watson ◽  
R. Glèlè Kakaï ◽  
F. Wichern ◽  
B. Sinsin ◽  
...  
Keyword(s):  
Seedling Growth ◽  
Seedling Emergence ◽  
Early Seedling Growth ◽  
Early Seedling ◽  
Irvingia Gabonensis

Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum

1992 ◽  
Vol 43 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Mott ◽  
MM Ludlow ◽  
JH Richards ◽  
AD Parsons
Keyword(s):  
Growing Season ◽  
Close Correlation ◽  
Dry Season ◽  
Carbon Gain ◽  
Panicum Maximum ◽  
Wet Season ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Moisture Conditions ◽  
Sheath Material

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.

EMERGENCE AND SEEDLING GROWTH OF INBRED LINES OF CORN AT SUBOPTIMAL ROOT-ZONE TEMPERATURES

1987 ◽  
Vol 67 (2) ◽  
pp. 409-415 ◽  
Author(s):  
A. MENKIR ◽  
E. N. LARTER
Keyword(s):  
Zea Mays ◽  
Seedling Growth ◽  
Root Zone ◽  
Seedling Emergence ◽  
Correlation Coefficients ◽  
Dry Weight ◽  
Inbred Lines ◽  
Root Zone Temperature ◽  
Emergence Percentage ◽  
Zone Temperature

Based on the results of an earlier paper, 12 inbred lines of corn (Zea mays L.) were evaluated for emergence and seedling growth at three controlled root-zone temperatures (10, 14, and 18 °C). Low root-zone temperatures, 10 and 14 °C, were detrimental to emergence, seedling growth, and root growth of all inbred lines. Differential responses of inbred lines were observed within each temperature regime. The differences in seedling emergence among lines became smaller with increasing root-zone temperature, while the reverse was true for seedling dry weight. Simple correlation coefficients showed a significantly (P = 0.05) negative association between emergence percentage and emergence index (rate). Neither of these two emergence traits was significantly correlated with seedling dry weights. Seedling dry weights were significantly (P = 0.01) and positively associated with root dry weights. Two inbred lines exhibited good tolerance to low root-zone temperatures, viz. CO255 and RB214. A significant and positive correlation existed between emergence percentage at a root-zone temperature of 10 °C and field emergence in test with the same genotypes reported earlier. Selection at a root-zone temperature of 10 °C for a high percentage of seedling emergence, therefore, could be effective in identifying genotypes capable of germinating in cool soils. Furthermore, the significantly (P = 0.01) positive relationship between seedling dry weights at all root-zone temperatures and those from the field test suggest that strains with vigorous seedling growth in the field could be identified using low root-zone temperature regimes.Key words: Zea mays, root-zone temperature, cold tolerance

A study of root and shoot interactions between cereals and peas in mixtures

1993 ◽  
Vol 120 (1) ◽  
pp. 13-24 ◽  
Author(s):  
M. P. Tofinga ◽  
R. Paolini ◽  
R. W. Snaydon
Keyword(s):  
Relative Yield ◽  
Root Competition ◽  
Total Biomass ◽  
N Content ◽  
Total N ◽  
Resource Complementarity ◽  
Relative Yield Total ◽  
Shoot Competition ◽  
Competitive Abilities ◽  
Different Sources

SUMMARYWheat, barley and two morphologically contrasting cultivars of peas (leafy and semi-leafless) were grown in pure stands, at standard agricultural densities, and in additive mixtures of cereals with peas. The stands were grown in boxes in the field, and partitions were used to separate the effects of root and shoot interactions. The cereals and peas were either planted at the same time, or one species was planted 10 days before the other. The origin of the N present in each species was determined by applying N fertilizer labelled with 15N.Both cultivars of peas had greater shoot and root competitive abilities than wheat or barley, probably because of their larger seed size; leafy peas had greater shoot and root competitive abilities than semi-leafless peas. Sowing peas after cereals reduced their competitive ability.The relative yield total (RYT) of cereal-pea mixtures, based on total biomass, averaged 1·6 when only the root systems interacted, and 1·4 when only the shoot systems interacted, but did not differ significantly from 10 when both root and shoot systems interacted. RYT values were greater when peas were grown with wheat, rather than with barley, and when peas were sown at the same time as the cereals.Shoot competition from peas increased the N% of cereals, but substantially reduced their total N content, because biomass yield was reduced. Shoot competition from cereals had no effect on the N% of peas, and only slightly reduced their total N content. Shoot competition between cereals and peas had no significant effect upon the proportion of N derived from various sources by either cereals or peas.Root competition from peas significantly reduced both the N% and total N content of cereals. Root competition from cereals had little effect on the N% of peas, but significantly reduced their total N content and increased the proportion of N derived from rhizobial fixation from 76 to 94%. Since cereals and peas largely used different sources of N, resource complementarity for N was probably an important component of intercropping advantage, when the roots of cereals and peas shared soil resources.

Factors influencing germination of Scolochloa festucacea caryopses

1972 ◽  
Vol 50 (11) ◽  
pp. 2085-2092 ◽  
Author(s):  
Alan L. Smith
Keyword(s):  
Ethyl Alcohol ◽  
Seedling Growth ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Anaerobic Conditions ◽  
Factors Influencing

Germination and seedling emergence increased with increasing caryopses weight in Scolochloa festucacea. Maximum seedling survival occurred when caryopses were planted 1 cm deep. Simulation of anaerobic conditions by soaking caryopses increased seedling emergence. Seedling emergence increased after imbibed caryopses were treated in a N2 atmosphere. Emergence also was increased by soaking caryopses in 95% ethyl alcohol up to 60 min. Stratification apparently improved germination but was not a requirement. Scolochloa festucacea caryopses were more tolerant of MgCl2 than NaCl in the germination media. Optimum seedling growth occurred at 20C.

Adaptation to Water Stress of the Leaf Water Relations of Four Tropical Forage Species

1980 ◽  
Vol 7 (2) ◽  
pp. 207 ◽  
Author(s):  
JR Wilson ◽  
MM Ludlow ◽  
MJ Fisher ◽  
E Schulze
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Water Relations ◽  
Bound Water ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Panicum Maximum ◽  
Soil Drying ◽  
Buffel Grass ◽  
Heteropogon Contortus

Three tropical grasses, green panic (Panicum maximum var, trichoglume), spear grass (Heteropogon contortus) and buffel grass (Cenchrus ciliaris) and the tropical legume siratro (Macroptilium atropurpureum), were grown in plots in a semi-arid field environment. The water relations characteristics of leaves from plants subjected to a soil drying cycle were compared with those of unstressed leaves from plants in irrigated plots. Minimum water potentials attained in the stressed leaves were c. -44, - 38, - 33 and - 13 bar for the four species, respectively. The grass leaves adjusted osmotically to water stress, apparently through accumulation of solutes, so that there was a decrease in osmotic potential at full turgor (Ψπ100) of 5.5, 3.9 and 7.1 bar, and in water potential at zero turgor (Ψ0) of 8.6, 6.5 and 8.6 bar for green panic, spear grass and buffel respectively. Water stress appeared to increase slightly the proportion of bound water (B) and the bulk modulus of elasticity (ε) of the grass leaves, but it did not alter the relative water content at zero turgor (RWC0) or the ratio of turgid water content to dry weight of the tissue. The Ψπ100 and Ψ0 of stressed siratro leaves decreased by 2.5-4 bar and 3-5 bar respectively when subjected to soil drying cycles. These changes could be explained by the marked decrease in the ratio of turgid water content to dry weight of the leaf tissue rather than by accumulation of solutes. The values of RWC0 and ε for siratro leaves were not altered by stress but, in contrast to the grasses, B was apparently decreased although the data exhibited high variability. Adjustments in Ψπ100 and Ψ0 of stressed leaves of buffel grass and siratro were largely lost within 10 days of rewatering.

scholarly journals Exogenous Antioxidants Enhance Seedling Growth and Yield of Artificially Aged Cabbage and Lettuce Seeds

Horticulturae ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 274
Author(s):  
Ademola Adetunji ◽  
Sershen ◽  
Boby Varghese ◽  
Norman Pammenter
Keyword(s):  
Leaf Area ◽  
Seedling Growth ◽  
Seedling Emergence ◽  
Dry Weight ◽  
Growth And Yield ◽  
Seed Vigour ◽  
Beneficial Effects ◽  
Shoot Dry Weight ◽  
Antioxidant Defence System ◽  
Aged Seeds

Aged seeds exhibit compromised vigour in terms of germination, seedling emergence and growth, but this can to some extent be alleviated by invigoration treatments before sowing. This study aimed to investigate ageing rates and patterns in cabbage (Brassica oleraceae) and lettuce (Lactuca sativa) seeds and whether the beneficial effects of invigorating aged seeds with exogenous antioxidants translate to enhanced seedling performance. Seeds were artificially aged to 25% viability before soaking in 0.4 mM glycerol, 0.6 mM GSH and 0.2 mM trolox for cabbage, and 0.6 mM glycerol, GSH and trolox for lettuce; deionised water served as a control. After 14 days of sowing, seedling emergence percentage, mean emergence time, mean daily emergence, and time taken to 25% emergence were computed. Seedling vigour index, root and shoot dry weight, root:shoot ratio, leaf area, leaf area ratio, and leaf chlorophyll content were assessed 6 weeks after sowing. Furthermore, the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), and chlorophyll fluorescence were measured 6 weeks after sowing. Notably, ageing resulted in the loss of seed vigour and viability at higher rates in lettuce than cabbage. Seed pretreatment with glycerol promoted seedling growth in both species and shoot dry weight in lettuce, while glycerol and GSH enhanced Pn, Gs and E in lettuce. Trolox also enhanced Pn and E in lettuce. The beneficial effects of the antioxidant treatments are thought to be associated with the protection of photosystems from oxidative stress and/or stimulation of enzymes involved in photosynthesis, possibly through an enhanced antioxidant defence system during the early development stages when seedlings are particularly vulnerable to stress.

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