Ethephon promotion of crop abscission for unshaken and mechanically shaken macadamia

Promotion of fruit abscission in macadamia, Macadamia integrifolia (Proteaceae), has potential to reduce costs associated with prolonged harvesting of late-abscising cultivars. Effects of ethephon [(2-chloroethyl) phosphonic acid] on fruit removal force and crop abscission were monitored at 3 stages of the harvest season on both unshaken and mechanically shaken trees of the late-abscising macadamia cultivar A16. Ethephon application, tree shaking, or a combination of the 2 methods, accelerated crop removal from the tree at all stages during harvest. Early harvest before natural abscission resulted in little or no difference in nut-in-shell and kernel weight, kernel recovery and kernel oil content. Delaying ethephon application or tree shaking until commencement of natural abscission resulted in greater crop removal. Fruit removal force declined naturally towards 1 kgf at this stage, and was further reduced by ethephon application. The most effective approach for harvest acceleration was to reduce fruit removal force, before tree shaking, by spraying trees with ethephon.

Fate of N-15-labelled nitrate in a wet summer under different residue management regimes in young hoop pine plantations

A field study was conducted to investigate the fate of N-15-labelled nitrate applied at 20 kg N ha(-1) in a wet summer to microplots installed in areas under different residue management regimes in second-rotation hoop pine (Araucaria cunninghamii) plantations aged 1-3 years in south-east Queensland, Australia. PVC microplots of 235 mm diameter and 300 mm long were driven into 250 mm soil. There were three replications of each of eight treatments. These were areas just under and between 1-year-old windrows (ca. 2-3 m in width) of harvesting residues spaced 15 m apart, and with and without incorporated foliage residues (20 t DM ha(-1)); the areas just under and between 2- or 3-year-old windrows spaced 10 m apart. Only 7-29% of the added N-15 was recovered from the top 750 mm of the soil profile with the leaching loss estimated to be 70-86% over the 34-day period. The N-15 loss via denitrification was 3.7-6.3% by directly measuring the N-15 gases emitted. The microplots with the incorporated residues at the 1-year-old site had the highest N-15 loss (6.3%) as compared with the other treatments. The N-15 mass balance method together with the use of bromide (Br) tracer applied at 100 kg Br ha(-1) failed to obtain a reliable estimate of the denitrification loss. The microplots at the 1-year-old site had higher N-15 immobilisation rate (7.5-24.7%) compared with those at 2- and 3-year-old sites (2.1-3.6%). Incorporating the residues resulted in an increase in N-15 immobilisation rate (24.5-24.7%) compared with the control without the incorporated residues (8.4-14.3%). These findings suggest that climatic conditions played important roles in controlling the N-15 transformations in the wet summer season and that the residue management regimes could also significantly influence the N-15 transformations. Most of the N-15 loss occurred through leaching, but a considerable amount of the N-15 was lost through denitrification. Bromide proved to be an unsuitable tracer for monitoring the N-15 leaching and movement under the wet summer conditions. (C) 2002 Elsevier Science B.V. All rights reserved.

Effect of fertilizer placement on nitrogen loss from sugarcane in tropical Queensland

This paper reports on the fate of nitrogen (N) in a first ratoon sugarcane (Saccharum officinarum L.) crop in the wet tropics of Queensland when urea was either surface applied or drilled into the soil 3-4 days after harvesting the plant cane. Ammonia volatilization was measured with a micrometeorological method, and fertilizer N recovery in plants and soil, to a depth of 140 cm, was determined by mass balance in macroplots with N labelled urea 166 and 334 days after fertilizer application. The bulk of the fertilizer and soil N uptake by the sugarcane occurred between fertilizing and the first sampling on day 166. Nitrogen use efficiency measured as the recovery of labelled N in the plant was very low. At the time of the final sampling (day 334), the efficiencies for the surface and subsurface treatments were 18.9% and 28.8%, respectively. The tops, leaves, stalks and roots in the subsurface treatment contained significantly more fertilizer N than the corresponding parts in the surface treatment. The total recoveries of fertilizer N for the plant-trash-soil system on day 334 indicate significant losses of N in both treatments ( 59.1% and 45.6% of the applied N in the surface and subsurface treatments, respectively). Drilling the urea into the soil instead of applying it to the trash surface reduced ammonia loss from 37.3% to 5.5% of the applied N. Subtracting the data for ammonia loss from total loss suggests that losses by leaching and denitrification combined increased from 21.8% and 40.1% of the applied N as a result of the change in method of application. While the treatment resulted in increased denitrification and/or leaching loss, total N loss was reduced from 59.1% to 45.6%, ( a saving of 13.5% of the applied N), which resulted in an extra 9.9% of the applied N being assimilated by the crop.

Opalescence in Australian-grown pecan kernels: Occurrence and causes

Opalescence is an unattractive browning of the interior of the pecan kernel compared to the white interior of normal kernels. The discoloration is due to the presence of free oil, resulting from decompartmentalization in the endosperm of opalescent,pecans. Using a subjective scoring system, approximately 70% of Australian-grown pecan kernels tested were found to exhibit opalescence to some degree. Evaluation of kernels for opalescence during the harvesting-processing chain showed that opalescence first becomes evident in kernels after mechanical cracking. Opalescent kernels were found to have lower levels of calcium and higher amounts of oil compared to nonoptalescent kernels. Differential scanning calorimetry showed that kernels do not freeze at -18 degreesC.

Identification of micronutrient deficiency of wheat in the Peshawar Valley, Pakistan

A field experiment was conducted to study the effect of micronutrients, zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), boron (13) and a commercial fritted micronutrient product called Zarzameen, on the yield and the yield components of wheat (Triticum aestivum L.), in the Peshawar valley, Pakistan. Different combinations of Zn, Cu. Fe. Mn, B, and Zarzameen were applied at the rate of 4.0, 2.0, 5.0, 2.0, 1.0 kg ha(-1) and 1.0 kg ha(-1), respectively, along with a basal dose of 100 kg ha(-1) nitrogen(N), 75 kg ha(-1) phosphorus (P) and 50 kg ha(-1) potassium (K). The fertilizer treatments (macro- and micronutrients) increased wheat dry matter, grain yield, and straw yield significantly over an unfertilized control. Soil tests for B and Zn were increased both at boot and harvesting stage, and Fe at boot stage, with the addition of micronutrients. Plants without B had showed classical B deficiency symptoms at grain formation stage, but not at vegetative stage. Boron concentration in the dry matter of wheat plants increased with the addition of the B fertilizer in the soil. Boron deficiency was not observed in plants containing >4 mg B kg(-1) at the boot stage, or in soils containing > 1.4 mg kg(-1) hot water soluble B.

The 2000 Ogura Lecture: Olfactory neural cells: An untapped diagnostic and therapeutic resource

Objective. This is an over-view of the cellular biology of upper nasal mucosal cells that have special characteristics that enable them to be used to diagnose and study congenital neurological diseases and to aid neural repair. Study Design: After mapping the distribution of neural cells in the upper nose, the authors' investigations moved to the use of olfactory neurones to diagnose neurological diseases of development, especially schizophrenia. Olfactory-ensheating glial cells (OEGs) from the cranial cavity promote axonal penetration of the central nervous system and aid spinal cord repair in rodents. The authors sought to isolate these cells from the more accessible upper nasal cavity in rats and in humans and prove they could likewise promote neural regeneration, making these cells suitable for human spinal repair investigations. Methods: The schizophrenia-diagnosis aspect of the study entailed the biopsy of the olfactory areas of 10 schizophrenic patients and 10 control subjects. The tissue samples were sliced and grown in culture medium. The ease of cell attachment to fibronectin (artificial epithelial basement membrane), as well as the mitotic and apoptotic indices, was studied in the presence and absence of dopamine in those cell cultures. The neural repair part of the study entailed a harvesting and insertion of first rat olfactory lamina propria rich in OEGs between cut ends of the spinal cords and then later the microinjection of an OEG-rich suspension into rat spinal cords previously transected by open laminectomy. Further studies were done in which OEG insertion was performed up to 1 month after rat cord transection and also in monkeys. Results: Schizophrenic patients' olfactory tissues do not easily attach to basement membrane compared with control subjects, adding evidence to the theory that cell wall anomalies are part of the schizophrenic lesion of neurones. Schizophrenic patient cell cultures had higher mitotic and apoptotic indices compared with control subjects. The addition of dopamine altered these indices enough to allow accurate differentiation of schizophrenics from control patients, leading to, possibly for the first time, an early objective diagnosis of schizophrenia and possible assessment of preventive strategies. OEGs from the nose were shown to be as effective as those from the olfactory bulb in promoting axonal growth across transected spinal cords even when added I month after injury in the rat. These otherwise paraplegic rats grew motor and proprioceptive and fine touch fibers with corresponding behavioral improvement. Conclusions. The tissues of the olfactory mucosa are readily available to the otolaryngologist. Being surface cells, they must regenerate (called neurogenesis). Biopsy of this area and amplification of cells in culture gives the scientist a window to the developing brain, including early diagnosis of schizophrenia. The Holy Grail of neurological disease is the cure of traumatic paraplegia and OEGs from the nose promote that repair. The otolaryngologist may become the necessary partner of the neurophysiologist and spinal surgeon to take the laboratory potential of paraplegic cure into the day-to-day realm of clinical reality.

Kangaroos and feral goats as economic resources for graziers: Some views from south-west Queensland

Fifteen years ago it was proposed that the conversion of kangaroos from a pest to an economically valuable resource would allow graziers to reduce the numbers of domestic stock and thereby lower total grazing pressure. Since then, little progress towards this goal has been achieved. This is believed to be due mainly to the low prices obtained for kangaroo products. A survey of graziers in south-west Queensland was carried out to discover their opinions on kangaroos as a potential economic resource. Questions on the harvesting of feral goats were also included in the survey because of the contrast this industry provides to kangaroo harvesting in terms of grazier involvement. The results of the survey are discussed in relation to resource ownership rights; kangaroo product prices and marketing; and competition within the kangaroo harvesting industry. They show that while low kangaroo product prices do act as a disincentive to graziers, other administrative, legal and institutional factors are also important impediments to their entry to the industry. It is concluded that until the focus of attention widens to include consideration of these as well as just market factors, little progress will be made towards integrating graziers into the kangaroo harvesting industry.

Influence of planting date, method of handling and seed size on supersweet sweet corn seed quality

A supersweet sweet corn hybrid, Pacific H5, was planted at weekly intervals (P-1 to P-5) in spring in South-Eastern Queensland. All plantings were harvested at the same time resulting in immature seed for the last planting (P-5). The seed was handled by three methods: manual harvest and processing (M-1), manual harvest and mechanical processing (M-2) and mechanical harvest and processing (M-3), and later graded into three sizes (small, medium and large). After eight months storage at 12-14degreesC, seed was maintained at 30degreesC with bimonthly monitoring of germination for fourteen months and seed damage at the end of this period. Seed quality was greatest for M-1 and was reduced by mechanical processing but not by mechanical harvesting. Large and medium seed had higher germination due to greater storage reserves but also more seed damage during mechanical processing. Immature seed from premature harvest (P-5) had poor quality especially when processed mechanically and reinforced the need for harvested seed to be physiologically mature.

Vps20p and Vta1p interact with Vps4p and function in multivesicular body sorting and endosomal transport in Saccharomyces cerevisiae

Vps4p (End13p) is an AAA-family ATPase that functions in membrane transport through endosomes, sorting of soluble vacuolar proteins to the vacuole, and multivesicular body (MVB) sorting of membrane proteins to the vacuole lumen. In a yeast two-hybrid screen with Vps4p as bait we isolated VPS20 (YMR077c) and the novel open reading frame YLA181c, for which the name VTA1 has recently been assigned (Saccharomyces Genome Database). Vps4p directly binds Vps20p and Vta1p in vitro and binding is not dependent on ATP-conversely, Vps4p binding to Vps20p is partially sensitive to ATP hydrolysis. Both ATP binding [Vps4p-(K179A)] and ATP hydrolysis [Vps4p-(E233Q)] mutant proteins exhibit enhanced binding to Vps20p and Vta1p in vitro. The Vps4p-Vps20p interaction involves the coiled-coil domain of each protein, whereas the Vps4p-Vta1p interaction involves the (non-coiled-coil) C-terminus of each protein. Deletion of either VPS20 (vps20Delta) or VTA1 (vta1Delta) leads to similar class E Vps(-) phenotypes resembling those of vps4Delta, including carboxypeptidase Y (CPY) secretion, a block in ubiquitin-dependent MVB sorting, and a delay in both post-internalisation endocytic transport and biosynthetic transport to the vacuole. The vacuole resident membrane protein Sna3p (whose MVB sorting is ubiquitin-independent) does not appear to exit the class E compartment or reach the vacuole in cells lacking Vps20p, Vta1p or Vps4p, in contrast to other proteins whose delivery to the vacuole is only delayed. We propose that Vps20p and Vta1p regulate Vps4p function in vivo.