The potential of integrated marketing in increasing adoption of land rehabilitation practices in northwest New South Wales,Australia

Land degradation is a major threat to the productivity of agricultural land in Australia, and on the soils used for growing wheat (Triticum aestivum) soil erosion and fertility decline are serious problems. A study financed jointly by NSW Agriculture, Grains Research and Development Corporation (GRDC) and agribusiness looked at the effectiveness of using integrated marketing to increase adoption of dryland lucerne (Medicago sativa) in rotations in northwestern NSW as a means to rehabilitate degraded wheat soils. At the time of the study, average wheat and protein yields were declining. Integrated marketing, with heavy reliance on television advertising, was run during Summer 1992 and Autumn 1993. Approximately 750 wheat growers, located around Moree in NSW comprised the target group. A similar number of comparable farmers from around Dalby in southern Queensland, who were not exposed to the promotional campaign, formed the control group. Farmers were surveyed by mail just before and 18 months after the campaign. While the results were compounded by severe drought during the study time, as well as by other constraints, the data suggest none the less the value of this approach in getting farmers to change their practices. One in six wheat growers in the target area were aware of the free information kit available via the advertised 1800 number or freepost mail coupon; one in twelve obtained the kit. Television was the most influential media in eliciting a response, followed by the Australian Grain Magazine. The results suggested that the campaign did in fact engender the desired change. The study highlights the possible role integrated marketing may play in rural Australia, whether the subject dealt with is agricultural, environmental or other, not because of any novelty value, but because of the technique itself. © 1998 John Wiley & Sons, Ltd.     

Anatomy and compositional variation within potatoes

Re-examination of the histological development of the potato tuber supports Artschwager’s view that tuber growth is predominantly due to enlargement of the perimedullary zone and is of procambial origin. Pith (medulla) and cortical regions are differentiated from the ground or fundamental meristem derived from the apical meristem of the stolon apex, even before tuberization has been initiated. The procambium gives rise to external phloem, primary xylem, internal phloem and associated parenchyma, and likewise to interfascicular parenchyma. Those parenchyma cells so formed inwardly to the xylem “ring” contribute to the growth of the perimedullary zone. The sequence of tissue origins is diagrammed and discussed from the viewpoint of modern concepts of histogenesis.     

Cell size in Russet Burbank potato tubers with various levels of nitrogen and soil moisture tensions

Russet Burbank potatoes were grown at levels of added nitrogen of 0, 135, and 270 kg/ha and soil moisture tensions (SMT) of 0.5 and 1.0 atm. With all combinations, there was a consistent gradient of larger to smaller starch-storage parenchyma cells from stem end to bud end of mature tubers. Stem and bud ends of tubers grown at a SMT of 0.5 atm with N had smaller cortical and pith (innermost medullary or water-core) cells than did ends of tubers grown without N. Perimedullary tissues of bud ends of tubers receiving N likewise contained smaller cells than did corresponding tissues of tubers grown without N. No pronounced differences in cell size were found in tissues from the midsections. In bud-end tissue of tubers grown at a SMT of 1.0 atm, there were no consistent differences in cell size with respect to N levels. However, pith, perimedullary, and cortical tissues of the midsections and stem ends of tubers receiving N had smaller cells than did corresponding tissues from tubers without N. The different patterns of cell size in tubers grown at different SMT indicate that the effects of N may be influenced by soil moisure.     

Host–strain mediated selection for an effective nitrogen-fixing symbiosis between Trifolium spp. and Rhizobium leguminosarum biovar trifolii

We have previously reported significant strain–host incompatibility between the microsymbiont Rhizobium leguminosarum biovar trifolii and Trifolium spp. related to geographic and phenological barriers. Additionally, we have shown that an effective symbiosis between strains of R. l. trifolii and clover was established despite the soil harbouring ineffective R. l. trifolii capable of nodulating the host. We termed this “selection” for effective symbiosis. This paper reports glasshouse-based experiments to validate and further explore this in situ selection phenomenon. The effect of cell density and strain ratio at the time of inoculation, as well as soil pH, were investigated on two hosts (Trifolium purpureum and Trifolium polymorphum) that were each exposed to one microsymbiont capable and one incapable of N₂ fixation. In co-inoculation experiments at a cell density of 10⁴ cells/mL, each host nodulated solely with its effective strain, even when this strain was outnumbered 100-fold by the ineffective strain. However, the selection process ceased when the effective strain was outnumbered 1000-fold. At higher basal cell concentrations of 10⁵–10⁸ cells/mL, selection for WSM1325 to form effective nodulation on T. purpureum was evident, but was significantly reduced as the ratio of ineffective cells in the inoculum increased above 4-fold. The results indicate that the selection mechanism is highly dependent on the basal rhizobial cell density. Soil pH did not significantly alter the process, and both strains grew at similar rates and formed nodules at similar rates. A preliminary investigation into the genetic backgrounds of WSM1325 and WSM2304 revealed that although their 16S rRNA sequences were identical, they have considerable differences in their symbiotic and chromosomal replicons through examination of atpD, GSII and nodD sequences.     

Cell wall thickness during growth of domestic and foreign potato cultivars

During growth of Russet Burbank tubers from less than 100 to over 250 g, thickness of parenchyma cell walls nearly doubled (1.9X) to slightly over 1 μ. Although affecting cell size at harvest maturity, different levels of N fertilizer and soil moisture had little influence on wall thickness. Wall thickness in Kennebec and Norchip increased to 0.9μ (1.7X), and in White Rose to slightly under 0.8 (1.2X). During the same growth, cell size nearly doubled in Russet Burbank. Cells of Kennebec, Norchip and White Rose averaged smaller than those of Russet Burbank at harvest maturity. Wall thickness and cell size showed similar relationships in foreign cultivars. Wall thickness in European varieties Bintje and Pimpernel was comparable to that of White Rose. Thickness in Atjimba closely approached that of Russet Burbank, and in Kamarz was similar to that of Norchip. Among South American cultivars, Doré had unusually thick walls (1.36μ), whereas those in Fruitella and Papa Bianca were between those of Norchip and White Rose. Bintje was comparable to domestic cultivars in tuber size, but all other foreign cultivars studied had medium to small tubers. Doré had unusually large cells for a small tuber. Differences in wall thickness may be due to differences in amounts of cell wall material, to differences in hydration properties of pectic components, or to combinations of both. Independently of wall thickness, the many primary pit fields in parenchyma walls may be a limiting factor in wall strength. The very thin pit membranes consist mainly of cellulosic microfibrils formed early in cell growth.