No-tillage planters for heavy-textured Alfisols in the semi-arid tropics of Australia

1996 ◽  
Vol 36 (8) ◽  
pp. 957
Author(s):  
NS Gould ◽  
DCI Peake ◽  
NP Dalgliesh
Keyword(s):  
Seedling Emergence ◽  
The Other ◽  
Soil Conditions ◽  
Research Station ◽  
No Tillage ◽  
Wet Season ◽  
Seedling Mortality ◽  
Moisture Regimes ◽  
Dry Conditions ◽  
Effective Depth

This paper provides key information on 4 no-tillage planters to facilitate adoption by fanners in northern Australia. Four commercial planters (Buffalo All-Flex Convertible slot planter, Buffalo All-Flex Compact slot planter, John Deere Max-Emerge planter and Mason Spring Release (SR) Integral planter) of contrasting design were tested in various configurations under 5 different moisture regimes during drying of a heavy-textured Alfisol at Katherine Research Station, Northern Territory, Australia (14�20'S, 132�20�E, 108 m altitude) at the end of the 1982-83 wet season. Significant differences in emergence were measured between planters and between configurations under most moisture regimes. Seedling emergence was greatest in Buffalo-Compact planter treatments, less for Buffalo-Convertible and Mason SR Integral treatments and lowest for John Deere Max-Emerge treatments. The Buffalo planters, each with an effective trash cutting coulter and narrow tine slot opener, produced consistently better results under all moisture regimes than the other 2 planters. The Mason SR Integral, with its wide tine opener, created a high incidence of clods which restricted emergence and led to increased occurrence of unimbibed seeds. Generally, for the 3 tine opener planters, the looser the soil in the furrow, the poorer the emergence. The John Deere Max-Emerge double-disc opener, whilst performing well under moist conditions, generally performed poorly when soil conditions were dry. This planter was on most occasions unable to maintain effective depth control under excessively wet or dry conditions, resulting in lower in-furrow soil moisture and significantly poorer and slower emergence than occurred with the other planters. In-furrow seed-firming presswheels, applying a contact pressure of approximately 4-5 kg/cm of presswheel tyre width, ensured better seed-soil contact and higher emergence levels than twin-inclined overfurrow presswheels. The over-furrow presswheels fitted to the John Deere Max-Emerge planter were often unable to close the slot effectively, resulting in the creation of voids and caps with resultant high seedling mortality.

Effects of seed covering treatments on the emergence and seedling growth of crisp lettuce drilled with an experimental dibber drill

1985 ◽  
Vol 105 (3) ◽  
pp. 535-541 ◽  
Author(s):  
D. C. E. Wurr ◽  
Jane R. Fellows ◽  
L. P. Bufton
Keyword(s):  
Standard Deviation ◽  
Seedling Growth ◽  
Seedling Emergence ◽  
Agricultural Engineering ◽  
Percentage Time ◽  
Moisture Regimes ◽  
Dry Conditions ◽  
Emergence Percentage

SUMMARYPelleted seed of the crisp lettuce variety Pennlake was sown on five occasions with units from either the experimental dibber drill designed by the National Institute of Agricultural Engineering or a Stanhay S870 drill. There were three dibber-drill treatments: seeds left in open holes or covered with peat–vermiculite or perlite. Seedling emergence and growth from each sowing of the four drill treatments were compared under different moisture regimes.There were large differences between drill treatments in emergence percentage, time to emergence of 50% of the seedlings which emerged (t50) and seedling weight at all sowings but there was a significant effect of drill treatment on the standard deviation of seedling emergence times at only one sowing. Of the dibber-drill treatments, only very occasionally did open holes or perlite cover give significantly better emergence than peat-vermiculite cover, which gave the most consistent results. In general, the dibber drill with peat-vermiculite cover gave significantly faster and higher emergence and heavier seedlings than the Stanhay drill. Differences in percentage seedling emergence tended to be greater under dry conditions.

Patterns of seed softening and seedling emergence of nineteen annual medics during three years after a single seed crop in southern Queensland

1997 ◽  
Vol 37 (7) ◽  
pp. 767 ◽  
Author(s):  
D. L. Lloyd ◽  
G. B. Taylor ◽  
B. Johnson ◽  
K. C. Teasdale
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Farming Systems ◽  
The Other ◽  
Research Station ◽  
Hard Seed ◽  
Diurnal Cycles ◽  
Wide Range ◽  
Burr Medic ◽  
Annual Medics

Summary. To produce seed to determine the rates of seed softening of annual medics in the subtropics, 8 lines of barrel medic (Medicago truncatula), 3 lines of burr medic (M. polymorpha), 4 lines of snail medic (M. scutellata), and 1 line of each of button medic (M. orbicularis), strand medic (M. littoralis) and gama medic (M. rugosa) were grown at Warra in southern inland Queensland, in 1993. Seed of a fourth line of burr medic, a naturalised line, was harvested from Hermitage Research Station at that time. Pods were placed on the soil surface and buried at a depth of 7 cm, both in flywire envelopes and as free pods. Residual hard seed numbers were determined each year for 3 years from the envelopes, and seedlings were counted and removed from the free pods after each germination event. Patterns of softening of seeds from the same seed populations were also determined after placing them in a laboratory oven with a diurnal temperature fluctuation of 60/15° C for periods of 16, 40 and 64 weeks followed, after each time period, by 4 diurnal cycles of 35/10°C. More than 90% of the original seeds were hard. Seed softening at the soil surface ranged from 26% after 3 years in button medic to almost complete softening in the gama medic after only 2 years. Burial had little effect on the rate of softening of the button medic but about halved the rate of softening of the other lines. The barrel medics were vulnerable to losses of large numbers of seedlings which softened and germinated in January–February and the snail medics from seedlings emerging in August–December. The proportion of soft seeds recovered as seedlings in the buried compared with the surface pods was higher in the larger-seeded medics, snail and gama, and lower in the other, smaller-seeded medics. Laboratory techniques effectively ranked the medic lines for their rate of seed softening in the field and provided some insight into their seasonal patterns of seed softening. A wide range of seed softening patterns is available for fitting the requirements of various farming systems. The most appropriate pattern of softening will depend on the variability of medic seed production between years and the need for self regeneration of the medic after a cereal crop.

scholarly journals Acute zinc deficiency observed in cacao on certain soil types in Netherlands New Guinea.

1959 ◽  
Vol 7 (4) ◽  
pp. 309-316
Author(s):  
H. Schroo
Keyword(s):  
Zinc Deficiency ◽  
Root Systems ◽  
The Other ◽  
Soil Types ◽  
Soil Conditions ◽  
Wet Season ◽  
Very Old ◽  
Zn Content ◽  
Silty Loam ◽  
Leaf Symptoms

Leaf symptoms in young cacao were observed on two different soil types. On one, a very old, much leached, infertile, quartzitic silty loam, low Zn content was responsible; heavy drought which crippled the root systems made the hidden shortage acute. On the other soil, low Zn content was greatly accentuated by adverse soil conditions which impaired the uptake of Zn by the roots; high pH, excessive PO4, poor water-retaining capacity in dry weather and poor aeration in the wet season probably induced deficiency. Deficient trees recovered in 7 months with Zn sprays. (Abstract retrieved from CAB Abstracts by CABI’s permission)

A Comparative Study of the Soil Conditions favoured by certain Melolonthid and Tenebrioned Pests of Tobacco in Southern Rhodesia

1959 ◽  
Vol 50 (2) ◽  
pp. 259-263 ◽  
Author(s):  
G. H. Bünzli ◽  
W. W. Büttiker
Keyword(s):  
Life Cycle ◽  
Organic Matter Content ◽  
Matter Content ◽  
The Other ◽  
Soil Conditions ◽  
White Grub ◽  
Wet Season ◽  
White Grubs ◽  
Southern Rhodesia ◽  
The One

An investigation was made to determine the factors governing the distribution pattern of the larvae of certain species of Melolonthids and Tenebrionids; these are known to be serious pests of tobacco plants in Southern Rhodesia.Observations were made on mixed populations of the white grubs, larvae of Anomala exitialis Pér. and Schizonycha profuga Pér. (MELOLONTHINAE), on the one hand, and on those of the false wireworms, larvae of Psammodes similis Pér. and P. scrobicollis (Fhs.) (TENEBRIONIDAE), on the other.It was found that the habitats favoured by white grubs had a higher clay, silt and organic matter content than those favoured by false wireworms. This was indicated by the darker brown colour of the soil; the clay ratio of the soils of the two types of habitat was as 1 to 0·725 and the nitrogen ratio as 1 to 0·524, respectively.Heavy infestations of tobacco fields are associated with 60,000 white grubs or 1,500 false wireworms per acre. The white grubs complete their life-cycle in one year, the larvae obtaining the food requirements necessary for their develop ment in the 4 to 5 months of the wet season. The false wireworms have a two-year life-cycle, the active feeding stages of the larvae being spread over 18 to 21 months, comprising both wet and dry seasons.The infestations by the two classes of insect do not overlap in space to any great extent but are governed by the nature of the soil, the white grubs favouring areas in which the soil has a higher nutrient value and the false wireworms areas where the soil is poorer.Reference is made to parasitisation of white-grub larvae in two areas, where the soil had an abnormally high nitrogen content, by a species of Tiphia in the one area and by entomogenous fungi in the other.False wireworms have not been found to be similarly attacked under field conditions.

scholarly journals The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland

2021 ◽  
Vol 14 (1) ◽  
pp. 3-8
Author(s):  
Philip W. Tipping ◽  
Melissa R. Martin ◽  
Jeremiah R. Foley ◽  
Ryan M. Pierce ◽  
Lyn A. Gettys
Keyword(s):  
Biological Control ◽  
Population Dynamics ◽  
Seedling Recruitment ◽  
Additional Treatment ◽  
Seed Rain ◽  
The Other ◽  
Melaleuca Quinquenervia ◽  
Biological Control Agents ◽  
Seedling Mortality ◽  
Sapling Growth

AbstractThe potential of Melaleuca quinquenervia (Cav.) S.T. Blake to reinvade cleared areas was evaluated over a 13-yr period that included two wildfires and the introduction of biological control agents. The first wildfire occurred in 1998 and was followed by a mean of 591.5 recruited seedlings m−2. Recruits from that fire were cleared 7 yr later in July 2005 for a second experiment to evaluate seedling recruitment into cleared areas. Seed rain, seedling recruitment and mortality, and sapling growth rates were measured in four plots located around individual large reproductive trees. A second natural wildfire in 2007 burned through those plots, leading to increases in seed rain followed by a pulse in recruitment of 21.04 seedlings m−2, 96.5% fewer than after the 1998 fire. Recruits in half of the plots around each tree were then treated with regular applications of an insecticide to restrict herbivory by biological control agents, while herbivory was not restricted in the other half. There was no difference in seedling mortality between treatments 1,083 d post-fire (2007) with 96.6% seedling mortality in the unrestricted herbivory treatment and 89.4% mortality in the restricted herbivory treatment. Recruits subjected to the restricted herbivory treatment grew taller than those in the unrestricted herbivory treatment, 101.3 cm versus 37.4 cm. Many of the recruits were attacked by the biological control agents, which slowed their growth. Although solitary M. quinquenervia trees retain some capacity to reinvade areas under specific circumstances, there was a downward trend in their overall invasiveness at this site, with progressively smaller recruitment cohorts due to biological control agents. Land managers should prioritize removing large reproductive trees over treating recently recruited populations, which can be left for many years for the biological control agents to suppress before any additional treatment would be needed.

scholarly journals Limnology of Merbok estuary, Kedah, Malaysia

2015 ◽  
Vol 41 (1) ◽  
pp. 13-19
Author(s):  
Kaniz Fatema ◽  
Wan Maznah Wan Omar ◽  
Mansor Mat Isa
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Suspended Solids ◽  
Total Suspended Solids ◽  
Quality Parameters ◽  
The Other ◽  
Wet Season ◽  
Hand Temperature ◽  
Do Concentration ◽  
Merbok Estuary

Water quality in three different stations of Merbok estuary was investigated limnologically from October, 2010 to September, 2011. Water temperature, transparency and total suspended solids (TSS) varied from 27.45 - 30.450C, 7.5 - 120 cm and 10 -140 mg/l, respectively. Dissolved Oxygen (DO) concentration ranged from 1.22-10.8 mg/l, while salinity ranged from 3.5-35.00 ppt. pH and conductivity ranged from 6.35 - 8.25 and 40 - 380 ?S/cm, respectively. Kruskal Wallis H test shows that water quality parameters were significantly different among the sampling months and stations (p<0.05). This study revealed that DO, salinity, conductivity and transparency were higher in wet season and TSS was higher in dry season. On the other hand, temperature and pH did not follow any seasonal trends.Bangladesh J. Zool. 41(1): 13-19, 2013

scholarly journals Effects of water absorption on the mechanical properties of hybrid natural fibre/phenol formaldehyde composites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sekar Sanjeevi ◽  
Vigneshwaran Shanmugam ◽  
Suresh Kumar ◽  
Velmurugan Ganesan ◽  
Gabriel Sas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Water Absorption ◽  
Hybrid Composites ◽  
Phenol Formaldehyde ◽  
Natural Fibre ◽  
The Other ◽  
Fibre Reinforcement ◽  
Dry Conditions

AbstractThis investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m2) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.

Nutritional factors associated with seasonal population increase of cacao thrips, Selenothrips rubrocinctus (Giard) (Thysanoptera), on cashew, Anacardium occidentale

1963 ◽  
Vol 53 (4) ◽  
pp. 681-713 ◽  
Author(s):  
R. G. Fennah
Keyword(s):  
Amino Acids ◽  
Water Stress ◽  
Amino Acid ◽  
Acid Concentration ◽  
Leaf Tissue ◽  
The Other ◽  
Amino Acid Concentration ◽  
Population Increase ◽  
Bearing Surface ◽  
Wet Season

The feeding of the cacao thrips, Selenothrips rubrocinctus (Giard), on cashew, Anacardium occidentale, one of its host plants in Trinidad, West Indies, is considered in relation to the annual period of maximum population increase on this host and to the choice of feeding sites on individual leaves. On trees observed for three years, populations regularly increased during the dry season, from a low level in December and January to a peak in April or May, and then rapidly declined during the wet season. Even when thrips were most abundant, some trees were free from attack, and this could not be attributed to protective morphological features, to specific repellent substances in the leaf, or to chance. S. rubrocinctus was found to feed on leaves that were subjected to water-stress and to breed only on debilitated trees: the evidence suggested that the adequacy of its supply of nutrients depends on the induction of suitable metabolic conditions within the leaf by water-stress.Both nymphs and adults normally feed on the lower, stomata-bearing surface of the leaf, but in a very humid atmosphere only a weak preference is shown for this surface and if, under natural conditions, it is exposed to insolation by inversion of the leaf, the insects migrate to the other surface. Since the thrips were shown to be indifferent to bodily posture, the observation suggests that their behaviour is governed primarily by avoidance of exposure to undue heat or dryness and only secondarily by the attractiveness of the stomata-bearing surface.Leaves of cashew tend not to become infested while still immature, and become most heavily infested, if at all, soon after they have hardened. Breeding does not occur on senescent leaves. The positions of feeding thrips are almost random on leaves under abnormal water-stress, but otherwise conform to certain patterns that mainly develop in fixed sequence. On reversal of an undetached leaf and consequent transfer of thrips from one surface to the other, there is no appreciable change in their distribution pattern or the apparent acceptability of the substrate. Changes of pattern were readily induced by injury to the plant during a period of water-stress and less easily, or not at all, when water-stress was low. Injury of areas of the leaf by heat was followed by their colonisation by thrips, and partial severance of branches by increased attack on their leaves.Leaves detached from uninfested trees invariably became acceptable for feeding within four hours. During this period, leaf water-content declined and the ratios of soluble-carbohydrate content and α-amino acids to fresh-leaf weight fell slightly and rose considerably, respectively. In the field, the latter ratio was invariably higher for infested than for uninfested leaf tissue, even on portions of the same leaf. If the nutrient value of leaf tissue is determined by the rate at which α-amino acids are extractable through a stylet puncture, the observed change in acceptability for feeding following plucking may be accounted for by the increase in α-amino-acid concentration. Feeding that is restricted on any one tree to the margins of local leaf injuries during prolonged high water-stress and totally absent when stress is low can be correlated with an α-amino-acid content in the living marginal tissue that is high or low, respectively. The ability of thrips to establish themselves and breed on leaves of a particular tree in the dry season and their failure to do so on leaves of the same tree in the wet season conforms with the greater or less amino-acid concentration occurring in the leaf at these respective times.

A new Species of Cicadulina, China (Homoptera, Jassidae) injurious to Maize in Tanganyika Territory

1936 ◽  
Vol 27 (2) ◽  
pp. 251-252 ◽  
Author(s):  
W. E. China
Keyword(s):  
New Species ◽  
Distinct Species ◽  
The Gambia ◽  
The Other ◽  
Colour Pattern ◽  
Streak Virus ◽  
Research Station ◽  
Two New Species ◽  
A New Species

The genus Cicadulina was established in 1926 (Bull. Ent. Res. 17, p. 43) to hold a new species, C. zeae, China, injurious to maize in Kenya Colony. Later (Bull. Ent. Res., 19, 1928, p. 66) it was shown that Balclutha mbila, Naude, recorded as transmitting the virus of streak disease of maize in Natal, also belonged to this genus, and two new species C. arachidis and C. similis were described from the Gambia, where they were reported as injurious to ground-nut and suspected of transmitting the virus of the rosette disease of that plant. Since that time Dr. H. H. Storey of the Amani Research Station has been investigating the possibility of transmission of the streak virus of maize by C. zeae. In attempting to breed strains capable of transmission of the disease certain crosses were made which showed conclusively that he was dealing with two distinct species. These species he was able to separate on the colour pattern of the abdomen. Dr. Storey has now sent to me material of both these species and a study of the genitalia corroborates his finding. One, of course, proved to be C. zeae, the other is new and I therefore propose to dedicate it to the discoverer.

scholarly journals Prevalence and risk factors of mastitis in dairy cows

1970 ◽  
Vol 26 (2) ◽  
pp. 54-60 ◽  
Author(s):  
MA Rahman ◽  
MMU Bhuiyan ◽  
MM Kamal ◽  
M Shamsuddin
Keyword(s):  
Risk Factors ◽  
Dairy Cows ◽  
Dairy Farms ◽  
Clinical Mastitis ◽  
Dry Season ◽  
The Other ◽  
Wet Season ◽  
Lactating Cows ◽  
California Mastitis Test ◽  
Control Programmes

Identification of risk factors is important for the design of control programmes for mastitis in cows. Information about farms and management was collected at a farm visit. California Mastitis Test (CMT) was performed to assess sub-clinical mastitis, and cows, udder and milk were examined for clinical mastitis. A total of 347 lactating cows from 83 farms in the dry season (November - February) and 388 lactating cows from 89 farms in the wet season (June - October) were studied. The overall prevalence of mastitis was 19.9% and 44.8% in dry and wet seasons, respectively. The prevalence of mild mastitis was 17.3% and 40.7%, whereas that of moderate mastitis was 2.6% and 4.1% in dry and wet seasons, respectively. The prevalence of mastitis was higher (P<0.01) in wet than in dry season. On average, 18.7% quarters had mastitis during the wet season and 6.9% in the dry season. In the dry and wet seasons, respectively, 63.9% and 11.2% had completely dry floors, and the prevalence of mastitis was 22.6% and 30.0%. On the other hand, 88.8% and 36.1% of 83 farms had partly or completely wet and soiled floor and the prevalence of mastitis was 40.0% and 59.5% in the dry and wet seasons, respectively. Udder cleanliness, milk yield and peri-parturient diseases significantly (P<0.01) increased the risk of mastitis. The prevalence of mastitis is regarded as quite high. Dry and clean floor to keep cow's udder and teat clean would help control mastitis in the dairy farms of Bangladesh. DOI: 10.3329/bvet.v26i2.4951 Bangl. vet. 2009. Vol. 26, No. 2, 54-60

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