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

Phosphorus efficiency in pasture species. VII. Relationships between yield and P uptake in two accessions of white clover

1991 ◽  
Vol 42 (7) ◽  
pp. 1271 ◽  
Author(s):  
GJ Blair ◽  
DC Godwin
Keyword(s):  
Root Growth ◽  
White Clover ◽  
Root Length ◽  
Dry Weight ◽  
Application Rate ◽  
P Uptake ◽  
Extension Rate ◽  
Root Extension ◽  
Root Dry Weight ◽  
P Application

Lack of data on root growth and relationships between root parameters and P uptake are major limitations to understanding and modelling P efficiency in crop and forage plants. An experiment was conducted whereby two accessions of white clover (Trifolium repens, Chiswick and Ladino) were grown in pots in a P deficient soil fertilized with a low (P5 [kg ha-1]) or high (P40) P application rate. Plants were harvested at 10, 16, 22, 28, 34 and 40 days after transplanting and tops harvested and roots recovered from the pots. Detailed measures of root members were made at 10, 16 and 22 days and these correlated with P uptake. Dry weight of tops of accessions was the same between the two rates of P until day 28. At 40 days, the tops yield of Ladino was higher than Chiswick at P40. Root dry weight increased with increasing P application rate and time from day 16 onwards. Significant differences in root growth only occurred at the 16 and 34 day harvests at P5. Ladino tended to have a greater mean P uptake over time than did Chiswick at both P levels. P uptake was found to be positively correlated with shoot and root dry weight, root length, root number, root volume and surface area, and negatively correlated with mean root diameter and mean length per root. Root extension rate at low P in Ladino was greater than that in Chiswick, which may explain the greater P uptake by Ladino at low P at later harvests in this experiment. The changes in length, diameter and number of roots in the two accessions examined in this study, with time, in response to P, reflect some form of coordination. Chiswick tended to produce many short roots whilst Ladino fewer long roots. Only small differences in P uptake per unit root length were measured, which suggest that total root length or root extension rate is the primary determinant of total P uptake in these accessions of white clover.

Ecological growth response specificity of two Douglas-fir ecotypes inoculated with coexistent beneficial rhizosphere bacteria

1994 ◽  
Vol 72 (5) ◽  
pp. 582-586 ◽  
Author(s):  
C. P. Chanway ◽  
F. B. Holl
Keyword(s):  
Seedling Growth ◽  
Seedling Emergence ◽  
Dry Weight ◽  
Douglas Fir ◽  
Rhizosphere Bacteria ◽  
Pseudomonas Aureofaciens ◽  
Root Dry Weight ◽  
Arthrobacter Oxydans ◽  
Significant Stimulatory Effect ◽  
Effect On Growth

The influence of inoculation with rhizosphere bacteria on Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedling emergence in a controlled environment and on survival and growth in the field was investigated. Seed or seedlings of interior and coastal Douglas-fir ecotypes originating from the vicinity of Williams Lake and Chilliwack, British Columbia, Canada, respectively, were inoculated with two strains of rhizosphere bacteria, Arthrobacter oxydans strain N74 and Pseudomonas aureofaciens strain K23. These strains were previously isolated from naturally regenerating Douglas-fir seedlings collected from the Williams Lake and Chilliwack sites, respectively. Seed inoculation with either strain of bacteria, K23 or N74, stimulated the rate of seedling emergence, but these effects were not ecotype specific. While inoculation did not affect germination percentage, ecotype-specific seedling growth responses were detected 13 months after field planting. Arthrobacter oxydans strain N74 significantly stimulated seedling branching and enhanced root and shoot dry weight of the Williams Lake ecotype but had no significant stimulatory effect on growth of the Chilliwack ecotype. Pseudomonas aureofaciens strain K23 significantly stimulated shoot branching and root dry weight of Chilliwack Douglas-fir but had no significant stimulatory effect on growth of that from Williams Lake. When treatments of Douglas-fir seedlings and rhizosphere bacteria that originated from the same geographic site were pooled and compared with uninoculated controls, significant increases in shoot branch number and root dry weight were also detected. No significant difference in seedling growth was detected when treatments of seedlings and bacteria that originated from different sites were pooled and compared with uninoculated controls. Based on these results, we hypothesize that plant–microbe specificity may be an important component of Douglas-fir – beneficial rhizosphere bacteria interactions in the field. Key words: Douglas-fir seedlings, emergence, growth, rhizosphere bacteria, inoculation.

scholarly journals Physiological Responses to Heat Stress Alone or in Combination with Drought: A Comparison between Tall Fescue and Perennial Ryegrass

HortScience ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 682-686 ◽  
Author(s):  
Yiwei Jiang ◽  
Bingru Huang
Keyword(s):  
Heat Stress ◽  
Root Growth ◽  
Water Content ◽  
Perennial Ryegrass ◽  
Tall Fescue ◽  
Control Level ◽  
Photochemical Efficiency ◽  
Dry Weight ◽  
Cool Season ◽  
Root Dry Weight

Heat and drought are two major factors limiting growth of cool-season grasses during summer. The objective of this study was to compare the effects of heat stress alone (H) or in combination with drought (H+D) on photosynthesis, water relations, and root growth of tall fescue (Festuca arundinacea L.) vs. perennial ryegrass (Lolium perenne L.). Grasses were exposed to H (35 °C day/30 °C night) or H+D (induced by withholding irrigation) in growth chambers for 35 days. Soil water content declined under H+D for both grasses but to a greater extent for fescue than for ryegrass. Declines in canopy net photosynthetic rate (Pn), leaf photochemical efficiency (Fv/Fm), and leaf relative water content (RWC) and the increase in electrolyte leakage (EL) were much more severe and occurred earlier for ryegrass than fescue subjected to both H and H+D and for both species than under H+D then H. Evapotranspiration (ET) rate increased to above the control level within 3 or 6 days of H and H+D for both species, but fescue had a higher ET rate than ryegrass at 3 and 6 days of H and 6 days of H+D. Root dry weight and viability in all soil layers decreased under H and H+D for both species. However, fescue had higher root dry weight and viability than ryegrass in the 20-40 cm layer under H and in both the 0-20 and 20-40 cm layers under H+D. The results indicated that maintenance of higher Pn, Fv/Fm, ET, RWC, and root growth and lower EL would help cool-season turfgrass survive summer stress, and that their characteristics could be used for selecting stress tolerant species or cultivars.

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

Third generation progress in breeding white clover for resistance to root-knot nematode

1996 ◽  
Vol 6 ◽  
pp. 163-166
Author(s):  
J. Van den Bosch ◽  
C.F. Mercer
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Egg Production ◽  
Control Method ◽  
Dry Weight ◽  
Third Generation ◽  
Root Knot Nematode ◽  
Root Dry Weight ◽  
Wide Range ◽  
Meloidogyne Sp

Root-knot nematode (Meloidogyne sp.) reduces growth and nutrition of white clover (Trifolium repens L.) in New Zealand, and breeding resistant cultivars (with low galls per gram of root) is the preferred control method. Resistant and susceptible selections were bred from a wide range of white clover lines for three generations. In the third generation there were significant differences between seed lines from the selections for number of galls, root dry weight, visual growth score and galls/gram of root dry weight. Resistant selections had 43% of the susceptible selections' galls per gram, and 50% of the number of galls. Germplasm showing resistance to Meloidogyne spp. in the USA showed partial resistance to the local Meloidogyne sp. Two resistant and two susceptible genotypes were also compared for nematode egg production; resistant genotypes had a mean of 3,460 eggs/plant, compared to 25,030 for susceptible genotypes. Keywords: breeding, Meloidogyne sp., resistance, rootknot nematode, screening, selection, Trifolium repens, white clover

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.

Germination Ecology of Milkweedvine (Morrenia odorata)

Weed Science ◽  
1984 ◽  
Vol 32 (6) ◽  
pp. 781-785 ◽  
Author(s):  
Megh Singh ◽  
Nagi Reddy Achhireddy
Keyword(s):  
Seed Germination ◽  
Osmotic Stress ◽  
Root Growth ◽  
Seedling Growth ◽  
Shoot Growth ◽  
Seedling Emergence ◽  
Germination Percentage ◽  
Planting Depth ◽  
Germination Ecology ◽  
Optimum Ph

The germination of milkweedvine (Morrenia odorataLindl. ♯3MONOD) seed at 20 or 25 C was unaffected by a 12-h photoperiod. The 12-h photoperiod, however, decreased germination by 50% at 15 C. No germination occurred at 35 C regardless of photoperiod. By alternating 35 C for 12 h with 20 C for 12 h, the germination percentage was 57%. Seedling growth was maximum at alternating temperatures of 30/20 C. Optimum pH for germination and seedling growth was 7 and germination did not occur at pH levels below 6. Seed germination declined steadily at osmotic stress below −0.12 MPa; no germination occurred at −0.5 MPa. Seedling growth was not influenced by osmotic stress down to −0.18 MPa. Germination percentages of seeds kept under aerated water and nonaerated water were similar, but the seedling growth was greater in aerated water. Seedling emergence was maximum from depths of 0.5 to 2.5 cm, but no seedling emerged from 0 or 10 cm. Planting depth was negatively correlated (r = −0.7) with shoot growth but positively correlated (r = +0.98) to root growth.

The growth and activity of winter wheat roots in the field: the effect of sowing date and soil type on root growth of high-yielding crops

1984 ◽  
Vol 103 (1) ◽  
pp. 59-74 ◽  
Author(s):  
P. B. Barraclough ◽  
R. A. Leigh
Keyword(s):  
Winter Wheat ◽  
Root Growth ◽  
Grain Yield ◽  
Dry Weight ◽  
Sowing Date ◽  
Thermal Time ◽  
Regression Equations ◽  
Root Dry Weight ◽  
Significant Difference ◽  
Distribution Of Roots

SummaryThe effect of sowing date on root growth of high-yielding crops (8–1 It grain/ha, 85% D.M.) of winter wheat (Triticum aestivum L. cv. Hustler) was measured at Rothamsted and Woburn in 1980 and 1981. Roots were sampled by coring on five occasions and changes in root dry weight and length were determined. The average growth rate between March and June was about 1 g/m2/day (200 m/m2/day), over 5 times that measured between December and March. Increases in root weight or length with time were generally exponential to anthesis when the crops had 101–172 g root/m2 (20–32 km/m2). September-sown wheat had more root than October-sown wheat at all times, but whereas early differences in length were maintained throughout the season, root weights converged between March and June. Overall, there was no significant difference in root dry-matter production between sites at anthesis, but there was a substantial difference between years. Differences in root growth between crops were reduced by plotting the amount of root against either the number of days from sowing or accumulated thermal time. Using che latter, root growth between December and June was reasonably linear although there was some indication of a lag below 500 °C days. Regression equations obtained for the relationships between root growth and accumulated thermal time also fitted previously published data and may provide general descriptions of root growth with time.Roots of September-sown crops reached 1 m depth by December but those of October-sown crops were not detectable at this depth until April. For most crops the distribution of roots with depth was reasonably described by an exponential decay function, with over 50% of the roots in the top 20 cm of soil at all times. At Woburn in 1981, a plough-pan restricted roots to the upper soil horizons for most of the season but apparently had little effect on the total amount of root produced. For one of the experimental crops an empirical mathematical function describing the distribution of roots with depth and time is presented.Using the data from this and previously published studies, the relationship between grain yield and the amount of root at anthesis was investigated. Total root length was positively correlated with grain yield but nonetheless similarly yielding crops could have different-sized root systems. Total root dry weight was poorly correlated with grain yield.

scholarly journals Phytotoxic Activity ofOcimum tenuiflorumExtracts on Germination and Seedling Growth of Different Plant Species

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
A. K. M. Mominul Islam ◽  
Hisashi Kato-Noguchi
Keyword(s):  
Root Growth ◽  
Seedling Growth ◽  
Plant Extracts ◽  
Dry Weight ◽  
Italian Ryegrass ◽  
Test Species ◽  
Barnyard Grass ◽  
Phytotoxic Activity ◽  
Isolation And Characterization ◽  
Shoot And Root Growth

Phytotoxic activity ofOcimum tenuiflorum(Lamiaceae) plant extracts was investigated against the germination and seedling growth of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), Italian ryegrass (Lolium multiflorum), barnyard grass (Echinochloa crus-galli), and timothy (Phleum pratense) at four different concentrations. The plant extracts at concentrations greater than 30 mg dry weight equivalent extract mL−1reduced significantly the total germination percent (GP), germination index (GI), germination energy (GE), speed of emergence (SE), seedling vigour index (SVI), and coefficient of the rate of germination (CRG) of all test species except barnyard grass and GP of lettuce. In contrast, time required for 50% germination (T50) and mean germination time (MGT) were increased at the same or higher than this concentration. The increasing trend ofT50and MGT and the decreasing trend of other indices indicated a significant inhibition or delay of germination of the test species byO. tenuiflorumplant extracts and vice versa. In addition, the shoot and root growth of all test species were significantly inhibited by the extracts at concentrations greater than 10 mg dry weight equivalent extract mL−1. TheI50values for shoot and root growth were ranged from 26 to 104 mg dry weight equivalent extract mL−1. Seedling growth was more sensitive to the extracts compared to seed germination. Results of this study suggest thatO. tenuiflorumplant extracts have phytotoxic properties and thus contain phytotoxic substances. Isolation and characterization of those substances from this plant may act as a tool for new natural, biodegradable herbicide development to control weeds.

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