An experimental study of fire and moisture stress on the survivorship of savanna eucalypt seedlings

2008 ◽  
Vol 56 (8) ◽  
pp. 693 ◽  
Author(s):  
R. J. Fensham ◽  
R. J. Fairfax ◽  
Y. M. Buckley
Keyword(s):  
Soil Moisture ◽  
Interactive Effect ◽  
Moisture Stress ◽  
Structural Development ◽  
Seedling Mortality ◽  
Detailed Understanding ◽  
Seedling Survivorship ◽  
Eastern Australia ◽  
Pastoral Management ◽  
Moisture Conditions

Eucalyptus melanophloia and E. populnea dominate large areas of savanna in eastern Australia. Under aboriginal management, fires probably occurred under a broad range of conditions, but under pastoral management, burning is avoided when soil moisture is low. This experiment subjected E. melanophloia and E. populnea seedlings to burning and moisture stress, to examine whether this change in burning regime could affect seedling survivorship. The findings suggest survivorship rates are 87–93% for unstressed seedlings with relatively large lignotubers (>12 mm2 plan area) and 56–66% for unstressed seedlings with small lignotubers. There was no substantial interactive effect between moisture stress and burning for E. melanophloia, but such an interaction was apparent for E. populnea, such that moisture stress multiplied the effect of burning. The timing of burning in relation to soil-moisture conditions may have an enduring effect on woodland structure where E. populnea is dominant. E. melanophloia seedlings are more resistant to burning, especially with moisture stress, and fire may not be limiting structural development in woodlands where this species dominates. However, a more detailed understanding of species demography is required, including the conditions required for germination, causes of seedling mortality and the time taken for seedlings to develop fire resistance in the field.

Germination, survival, and early growth of red alder seedlings in the central Coast Range of Oregon

1995 ◽  
Vol 25 (10) ◽  
pp. 1639-1651 ◽  
Author(s):  
Sybille Haeussler ◽  
John C. Tappeiner II ◽  
Brian J. Greber
Keyword(s):  
Soil Moisture ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Survival Rates ◽  
Moisture Stress ◽  
Coast Range ◽  
Seedling Mortality ◽  
Central Coast ◽  
Red Alder

Effects of forest disturbance and soil moisture levels on establishment of red alder (Alnusrubra Bong.) seedlings were studied at four sites representing a climatic moisture gradient within the central Coast Range of Oregon. On average, there was no difference in seedling emergence between recent clearcuts and second-growth forests, but emergence was much higher on mineral soil than on organic seedbeds. Emergence, on both types of seedbed, was positively correlated with spring soil moisture conditions (R2 = 0.60). Seedling survival, on the other hand, differed greatly between clearcut and forest. In clearcuts, heat and drought injuries were the primary causes of seedling mortality. In the forest, seedlings had poor vigour and quickly succumbed to pathogens, herbivores, and rain splash. First-year survival rates were strongly correlated with minimum summer soil moisture levels (R2 = 0.71). Height growth of seedlings on clearcuts (2–5 cm after 1 year; 8–23 cm after 2 years) was much slower than rates typically described for red alder. Best establishment occurred on skid trails and landings, suggesting that young seedlings may suffer less from heat or moisture stress on these heavily disturbed microenvironments.

Effects of soil moisture and temperature on seedling emergence from natural and pre-germinated onion seeds

1986 ◽  
Vol 107 (2) ◽  
pp. 249-256 ◽  
Author(s):  
W. E. Finch-Savage
Keyword(s):  
Soil Moisture ◽  
Water Availability ◽  
Seedling Emergence ◽  
Moisture Stress ◽  
Start Time ◽  
Mean Temperature ◽  
Changing Patterns ◽  
Moisture Conditions ◽  
Germinating Seeds ◽  
Germinated Seeds

SummaryThe emergence of seedlings from natural, germinating and selected uniformlygerminated onion seeds was compared in a range of changing patterns of soil moisture. The timing, spread and amount of seedling emergence from seeds in all three treatments were affected by the timing of water availability in the seed bed and these effects differed between treatments.The rate of seedling emergence in all three treatments under non-limiting soil moisture conditions was correlated with mean temperature, but this relationship was obscured in irrigation treatments where water stress occurred. However, if the seed bed was moist at sowing irrespective of subsequent moisture stress the reciprocals of the time to the start, time to 50% and time to the end of seedling emergence from uniformly germinated seeds were correlated with mean temperature (r > 0·87, D.F. 27).The results show that if the seed bed is irrigated prior to sowing and soil moisture is maintained during the first 3 days following sowing high levels of seedling emergence with both predictable timing and uniformity can be achieved by sowing uniformlygerminated seeds. Seedling emergence from natural and germinating seeds was much less predictable.

The Influence of Soil Water Content on Common Cocklebur (Xanthium strumarium) Interference in Soybeans (Glycine max)

Weed Science ◽  
1989 ◽  
Vol 37 (1) ◽  
pp. 76-83 ◽  
Author(s):  
David A. Mortensen ◽  
Harold D. Coble
Keyword(s):  
Soil Moisture ◽  
Moisture Stress ◽  
Field Studies ◽  
Yield Potential ◽  
Xanthium Strumarium ◽  
Growth Responses ◽  
Node Number ◽  
Soybean Yield ◽  
Canopy Development ◽  
Moisture Conditions

Field studies were conducted in 1985 and 1986 to evaluate the stability of reciprocal interference relationships between common cocklebur and soybean under high and low soil moisture conditions. A significant soil moisture differential was established with portable rain exclusion shelters. Well-watered and drought-stressed common cocklebur reduced soybean yield 29 and 12%, respectively. Drought-stressed common cocklebur interfered with soybean over a shorter distance and the magnitude of the effect at a given distance was reduced. The reduced common cocklebur interference in drier soils was attributed to both common cocklebur and soybean growth responses to moisture stress. First, moisture stress caused greater reductions in common cocklebur canopy diameter, stem diameter, node number, and plant height than in soybean. Second, the soybean yield potential was reduced by moisture stress. The reduction in yield potential decreased the effect of the weed interference. Third, soybean canopy development was slowed, and canopy closure that occurred in about 12 weeks in well-watered soybeans never occurred in the moisture-stressed soybeans. This reduced the degree of light interference between both the common cocklebur and soybean and among the soybean plants. The results of this study indicate that the reciprocal interference relationships between common cocklebur and soybean are not stable across soil moisture conditions. The implications of unstable competitive parameters must be considered as threshold models are developed for various field crops.

Ecological Studies of the Endangered Rutidosis leptorrhynchoides. II. Patterns of Seedling Emergence and Survival in a Native Grassland

1995 ◽  
Vol 43 (1) ◽  
pp. 13 ◽  
Author(s):  
JW Morgan
Keyword(s):  
Soil Moisture ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Moisture Stress ◽  
Seedling Mortality ◽  
Themeda Triandra ◽  
Established Plant ◽  
Survival And Growth ◽  
Growth Of Seedlings

The emergence, survival and growth of seedlings of the endangered Rutidosis leptorrhynchoides F.Muell. were followed in a Themeda triandra grassland during 1991 and 1992. The effect of summer irrigation on seedling survival was also investigated. Seedling emergence occurred in both years within 2 weeks of the 'autumn break' when soil moisture rose above 20%. Ninety percent of emergence was observed within 4 weeks of the onset of germination and 87% of seedlings were within 20 cm of an established plant. No emergence was observed after 8 weeks. Thirteen percent of the 1991 cohort survived for 14 months. Mortality of most seedlings (63%) was attributed to soil moisture stress in summer. Small seedlings (Ͱ4 3 leaves) were no more susceptible to drought than larger seedlings. Seventy two percent of the 1991 cohort produced four leaves before subsequently dying. In 1992, however, most early seedling mortality was amongst cotyledonary seedlings. No seedlings flowered in their first year. Above-ground growth was slow and by 14 months, 60% of surviving seedlings had seven or fewer live leaves. Irrigation in a year of below-average rainfall had no significant effect on the survival and growth of seedlings. This suggests that seedling recruitment is not restricted to climatically favourable years (i.e. is not episodic) but rather, is potentially on-going provided suitable microsites are available for seedling survival.

Climatic conditions for seedling recruitment within perennial grass swards in south-eastern Australia

2012 ◽  
Vol 63 (4) ◽  
pp. 389 ◽  
Author(s):  
R. Thapa ◽  
D. R. Kemp ◽  
M. L. Mitchell
Keyword(s):  
Soil Moisture ◽  
New South ◽  
Perennial Grass ◽  
New South Wales ◽  
Climatic Conditions ◽  
South Eastern ◽  
South Wales ◽  
Eastern Australia ◽  
Moisture Conditions ◽  
South Eastern Australia

Recruitment of new perennial grass plants within existing grassland ecosystems is determined by seed availability, suitable microsites, nutrients and climatic conditions, water and temperatures. This paper reports on the development of criteria to predict recruitment events using modelled soil moisture conditions associated with recruitment of species in five field experiments at Orange (Phalaris aquatica), Trunkey Creek (Austrodanthonia spp.), and Wellington (Bothriochloa macra) in central New South Wales, Australia, and the frequency of those conditions during the past 30 years. Recruitment events were recorded when a rainfall event (median 68 mm across the three sites) kept the surface volumetric soil moisture (0–50 mm) above the permanent wilting point for at least 15 continuous days, allowing for, at most, two ‘dry days’ in between. A key finding from our study is that rainfall events creating favourable soil moisture conditions for seedling emergence typically occurred in the second half of February, sometimes extending to early March. Previously it was thought that recruitment would more likely occur through autumn, winter, and spring when rainfall in southern Australia is more reliable. The 30 years’ data (1975–2004) showed that the P. aquatica site had a median of 20 continuous moist days each year in February–March, whereas, there were 16 and 10 days for the Austrodanthonia and B. macra sites, respectively. The probabilities of exceeding seven or 15 continuous days of moist surface soil were 98% and 78% at the P. aquatica site, 91% and 49% at the Austrodanthonia site, and 73% and 30% at the B. macra site, and indicated that some recruitment is possible in most years. These analyses were extended to several sites across New South Wales, Victoria, and Tasmania to estimate the frequency with which recruitment could occur within natural swards. Across these sites, the probabilities of exceeding seven continuous days of soil moisture were >55% and of exceeding 15 continuous days were lower, which showed that suitable climatic conditions exist during late summer–early autumn across south-eastern Australia for a recruitment event to occur. Future research may show that the criteria developed in this paper could have wider regional application.

Soybean (Glycine max) Response to AC 263,222 and Chlorimuron as Influenced by Soil Moisture

1995 ◽  
Vol 9 (3) ◽  
pp. 553-560 ◽  
Author(s):  
Larry J. Newsom ◽  
David R. Shaw
Keyword(s):  
Soil Moisture ◽  
Field Experiments ◽  
Sprinkler Irrigation ◽  
Moisture Stress ◽  
Yield Reduction ◽  
Moisture Regime ◽  
Natural Rainfall ◽  
Moisture Regimes ◽  
Ac 263,222 ◽  
Moisture Conditions

Field experiments conducted in 1992 and 1993 evaluated differential response of 20 soybean cultivars to POST application of AC 263,222 or chlorimuron, as influenced by soil moisture. Natural rainfall was supplemented with overhead sprinkler irrigation to achieve three moisture regimes: excessive (12.5 cm/wk), optimum (5 cm/wk), and low (non-irrigated). Chlorimuron and AC 263,222 injured soybean. Excessive moisture did not increase soybean injury with chlorimuron for any of the cultivars tested compared to optimum moisture; however, 17 of 20 cultivars were injured more by AC 263,222 in combination with excessive moisture than optimum moisture. AC 263,222 reduced the height of five cultivars. Photosynthetic rate of several cultivars was reduced by both AC 263,222 and chlorimuron. Neither herbicide affected the number of nodes per main stem or seed weight; however, pod numbers were reduced for several cultivars with both herbicides. In the low moisture regime, AC 263,222 delayed the maturity of 18 of 20 cultivars with ‘Hutcheson’ maturity delayed 7.1 d. Excessive moisture when combined with AC 263,222 reduced yields for 12 cultivars, compared to five cultivars with chlorimuron. Under optimum moisture conditions, AC 263,222 reduced the yield of 10 cultivars, whereas chlorimuron reduced the yield of 9 cultivars. Low moisture stress only resulted in a yield reduction with 3 cultivars treated with AC 263,222.

scholarly journals The effect of short-term vs. long-term soil moisture stress on the physiological response of three cocoa (Theobroma cacao L.) cultivars

2020 ◽  
Vol 92 (2) ◽  
pp. 295-306 ◽  
Author(s):  
Wiebke Niether ◽  
Alexandra Glawe ◽  
Katharina Pfohl ◽  
Noah Adamtey ◽  
Monika Schneider ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Theobroma Cacao ◽  
Moisture Stress ◽  
Biochemical Response ◽  
P Value ◽  
Severe Drought ◽  
Seedling Mortality ◽  
Short Term ◽  
Soil Moisture Stress

Abstract Understanding water stress signaling mechanisms and screening for tolerant cocoa cultivars are major challenges when facing prolonged dry and rainy seasons in cocoa-producing areas. While abscisic acid (ABA) and proline are supposed to enhance drought tolerance in cocoa, the role of polyamines remains unclear. The aim of this study was to investigate the biochemical response and phenological adaptation of cocoa (Theobroma cacao) on different soil moisture conditions, with a focus on short-term (20 days) and long-term (89 days) stress conditions, and to compare the performance of three cocoa cultivars. In a split plot design with four blocks, cocoa seedlings of an international high-yielding cultivar (TSH-565) and two locally selected cultivars (IIa-22 and III-06) from the drought-exposed Alto Beni region, Bolivia, were arranged in pots under a roof shelter (cultivar: three levels). The seedlings were exposed to strong (VERY DRY) and moderate (DRY) soil moisture deficits, water logging (WET) and regular irrigation (MOIST) that served as a control (moisture: four levels). We examined the growth performance and the levels of ABA, proline, and polyamines in the leaves. Growth was reduced already at a moderate drought, while severe drought enhanced seedling mortality. Severe drought increased the levels of ABA by 453% and of proline by 935%, inducing a short-term stress response; both compounds were degraded over the long-term period. The polyamine concentration was unrelated to soil moisture. The cocoa cultivars did not differ in their biochemical response to soil moisture stress (proline: p-value = 0.5, ABA: p-value = 0.3), but the local cultivar III-06 showed a stronger height growth increment than the international cultivar TSH-565 (237%, p-value = 0.002) under drought conditions.

scholarly journals Evaluation of Maize (Zea mays L.) Hybrids for Economic Heterosis under Different Soil Moisture Regimes at North Eastern Plain Zone of India

2020 ◽  
pp. 55-67
Author(s):  
Ashok Singamsetti ◽  
J. P. Shahi ◽  
P. H. Zaidi ◽  
K. Seetharam ◽  
Kartik Madankar ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Grain Yield ◽  
Agricultural Research ◽  
Moisture Stress ◽  
Maize Hybrids ◽  
Waterlogged Condition ◽  
Lattice Design ◽  
Standard Heterosis ◽  
Moisture Conditions ◽  
Positive Heterosis

The present experiment was conducted to understand the effect of soil moisture status on the economic or standard heterosis in fifty maize hybrids for grain yield and flowering traits.  The trials were planted at Agricultural Research Farm, Banaras Hindu University, Varanasi in alpha-lattice design with two replications. The analysis of variance revealed the significant differences for grain yield and flowering related traits such as days to 50% anthesis, days to 50% silking and anthesis-silking interval under all the moisture conditions including optimal, managed drought and managed waterlogging conditions. Significant amount of heterosis was observed over the selected check P3502 for all the traits under study; however, the magnitude and direction varied with traits and with soil moisture level. For days to 50% anthesis, hybrids ZH17192, VH112926, VH123021, ZH114250, ZH16929 and ZH16930 were showed significant negative heterosis under all the moisture conditions that explained earliness under both moisture-stress and normal conditions. Among the tested hybrids, VH123021 and ZH16929 were recorded significant negative standard heterosis for flowering traits; and significant positive heterosis for grain yield under all the three moisture conditions. Six hybrids under drought, seven hybrids under optimal and two hybrids under waterlogged condition showed positive standard heterosis for grain yield. Further evaluation of these hybrids at multi-locations and multi-year is advisable to confirm the promising findings observed in our study. This study could be valuable for development of climate-resilient maize hybrids.

scholarly journals ROOTSTOCK GROWTH AFFECTED BY CROPPING LEVEL UNDER LOW SOIL-MOISTURE CONDITIONS IN SEYVAL GRAPEVINES

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 761C-761
Author(s):  
M. McLean ◽  
S. Howell ◽  
J.A. Flore ◽  
A.J.M. Smucker
Keyword(s):  
Soil Moisture ◽  
Moisture Stress ◽  
Relative Strength ◽  
Root Penetration ◽  
Carbohydrate Partitioning ◽  
Video Recordings ◽  
Water Plant ◽  
Below Ground ◽  
Moisture Result ◽  
Moisture Conditions

Both berries and roots of grapevines are powerful carbohydrate sinks. However, during periods of soil-moisture stress, the relative strength of these two sinks is not known. This experiment was conducted to evaluate interrelationships between differing crop loads on carbohydrate partitioning for above and below-ground tissues. Root development, depth, and rate of turnover were determined by quantifying root images from video recordings taken to depths of 75 cm at two week intervals throughout the growing season. Two-year old own rooted Seyval grapevines, and Seyval grafted to 5-BB and Seyval, were grown under a rain exclusion shelter and provided with 10 or 2.5 liters of water/plant/week. Treatments were cropping level, either 0 or 6-clusters/vine. Shoot length, number of mature nodes, and dry leaf weight of vines under high cropping level were significantly reduced compared to vines growing under the low cropping level; so was root number and depth of root penetration. These data suggest that conditions of low soil moisture result in carbohydrate partitioning in favor of the clusters at the expense of the roots.

scholarly journals Virulence of Leptographium serpens on Longleaf Pine Seedlings Under Varying Soil Moisture Regimes

Plant Disease ◽  
2008 ◽  
Vol 92 (11) ◽  
pp. 1574-1576 ◽  
Author(s):  
G. Matusick ◽  
L. G. Eckhardt ◽  
S. A. Enebak
Keyword(s):  
Soil Moisture ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Moisture Stress ◽  
Lesion Size ◽  
Severe Drought ◽  
Seedling Mortality ◽  
Pine Seedlings ◽  
Moderate Drought ◽  
Pinus Spp

Recently, Leptographium serpens has been recovered from the roots of declining and dead longleaf pine (Pinus palustris) in stands associated with various abiotic stresses. Although most data suggest that L. serpens is pathogenic to various Pinus spp., there is little known of its virulence on longleaf pine or its relationship with abiotic stress in causing disease. These trials examined the effects of L. serpens infection coupled with drought stress. Trials began with wound inoculations of bareroot longleaf pine seedlings in spring 2006 and 2007 at the seedling stress facility at Auburn University. Soon after inoculation, seedlings were also subjected to adequate moisture, moderate drought, or severe drought. Sixteen weeks after inoculation, longleaf pine survival, L. serpens virulence, and seedling growth characteristics were measured. Longleaf pine seedlings inoculated with L. serpens had 33% mortality (138/420) which was significantly greater than nonwounded control seedlings (22%, 47/211). Survival and lesion size on longleaf pine suggests that L. serpens is moderately pathogenic to longleaf pine seedlings. Separately, moisture stress associated with low soil moisture also contributed to seedling mortality. Results suggest that L. serpens infection and moisture stress commonly experienced by southern pines act independently to stress longleaf pine.

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