Projected impacts from future warming on grapevine phenology have been modelled for two important varieties across six representative wine-growing regions in Australia. Various regional warming projections are based on a range of future greenhouse gas emission scenarios and patterns of climate change from a suite of climate models. Results are compared and contrasted regionally and the sensitivity of grapevine phenology to different climate futures is assessed. Impacts on budburst vary from region to region. Cabernet Sauvignon budburst in Coonawarra is projected to occur earlier by four to eight days in the year 2030, and by six to 11 days in 2050. Season duration (from budburst to harvest) is compressed in all regions studied and harvest is earlier in most cases. Given the highest warming scenario, harvest could be 45 days earlier in Coonawarra by 2050. Some regions may be adversely affected by the chilling requirement not being met in future warmer climates. For example, in the Margaret River region budburst is projected to be later. An important finding of this analysis is that harvest is projected to occur both earlier in the year and in a warmer climate, i.e. a dual warming impact. Harvesting in warmer temperatures can negatively impact grape quality. AbbreviationsGHG greenhouse gas; GCM global climate model

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An extensive assessment of historical trends in winegrape maturity dates from vineyards located in geographically diverse winegrape growing regions in Australia has been undertaken. Records from 44 vineyard blocks, representing a range of varieties of Vitis vinifera L., were accessed. These comprise 33 short-term datasets (average 17 years in length) and 11 long-term datasets, ranging from 25 to 115 years in length (average 50 years). Time series of the day of the year grapes attain maturity were assessed. A trend to earlier maturity of winegrapes was observed in 43 of the 44 vineyard blocks. This trend was significant for six out of the 11 long-term blocks for the complete time period for which records were available. For the period 1993-2009, 35 of the 44 vineyard blocks assessed displayed a statistically significant trend to earlier maturity. The average advance in the phenology was dependent on the time period of observation, with a more rapid advance over more recent decades. Over the more recent 1993-2009 period, the average advance was 1.7 days year, whereas for the period 1985-2009 the rate of advance was 0.8 days yr À1 on average in the 10 long-term vineyard blocks assessed for cross-regional comparison. The trend to earlier maturity was associated with warming temperature trends for all of the blocks assessed in the study.

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Accumulation of several low-molecular-weight solutes was measured in the developing floral apex, in an enclosed, elongating leaf, and in an expanded leaf of wheat plants during a 13-day period of water stress. In the apices and enclosed leaves, osmotic potential fell from - 1.2 to -4.0 MPa. The main contribution to the decline in osmotic potential during the first 3 days of stress was from an increase in the content of ethanol-soluble carbohydrate. Later, increases in the concentrations of both carbohydrates and amino acids made major contributions. Of the amino acids, the largest increases were in asparagine and proline. The enclosed tissues lost little water, although the water- to-dry matter ratio declined as a result of imported solutes. The ethanol-insoluble nitrogen content of apices remained high, and growth of apices and enclosed leaves recommenced when plants were watered after 13 days. In exposed leaves, increases in carbohydrate and amino acid contents were comparatively small, and the content of ethanol-insoluble nitrogen decreased by 50%. These leaves dehydrated within 6 days, and failed to recover when the plants were rewatered.

Needles from phosphorus deficient seedlings of Pinus radiata D. Don grown for 8 weeks at either 330 or 660 microliters CO2 per liter displayed chlorophyll a fluorescence induction kinetics characteristic of structural changes within the thylakoid chloroplast membrane, i.e. constant yield fluorescence (Fo) was increased and induced fluorescence ([Fp-FI/VFo) was reduced. The effect was greatest in the undroughted plants grown at 660 M1 CO2 L-'. By week 22 at 330 Al CO2 L-' acclimation to P deficiency had occurred as shown by the similarity in the fluorescence characteristics and maximum rates of photosynthesis of the needles from the two P treatments. However, acclimation did not occur in the plants grown at 660 Ml CO2 L-'. The light saturated rate of photosynthesis of needles with adequate P was higher at 660 pI CO2 L-' than at 330 MI CO2 L-', whereas photosynthesis of P deficient plants showed no increase when grown at the higher CO2 concentration. The average growth increase due to CO2 enrichment was 14% in P deficient plants and 32% when P was adequate. In drought stressed plants grown at 330 MI CO2 L-', there was a reduction in the maximal rate of quenching of fluorescence (RQ) after the major peak. Constant yield fluorescence was unaffected but induced fluorescence was lower. These results indicate that electron flow subsequent to photosystem II was affected by drought stress. At 660 MI CO2 L-' this response was eliminated showing that CO2 enrichment improved the ability of the seedlings to acclimate to drought stress. The average growth increase with CO2 enrichment was 37% in drought stressed plants and 19% in unstressed plants. While the influence of the increasing levels of atmospheric CO2 on plant growth has been recognized, the response of forest species under conditions of nutrient and drought stress is not well documented. P deficiency and periodic drought are commonly encountered by Pinus radiata growing in plantations in Australia and knowledge ofthe modifying effects ofthese stresses on the CO2 response could enable more realistic prediction of long term growth. The majority of CO2 enrichment studies have been short term. ' Supported by the Rural Credits Development Fund of Australia. 2Present address: Department of Biological Sciences, Stanford University , Stanford, CA 94305. These have shown that leaf photosynthesis in C3 plants is limited by the present atmospheric concentration of CO2 (340 IAI L-') because RuBP3-carboxylase catalyzes both the oxygenation and carboxylation of RuBP (13). Consequently the rate of photosyn-thesis can be increased by 30 to 50% by raising the CO2 concentration to up to 1000 MA L' or lowering the 02 to 2% (16). This increase occurs only ifelectron transport capacity is large enough to regenerate RuBP and ifthe Pi concentration in the chloroplast is maintained at a concentration which is favorable for both photophosphorylation and the synthesis of starch and sucrose (17). While the effect of electron transport dysfunction is not known, feeding of hexoses which sequest...

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Wheat plants exposed to higher than usual temperatures during ripening produced grain with weaker dough properties in glasshouse, field experiments and crop samples. In a review of Prime Hard wheat samples from 1960/61 to 1988/89, those seasons when the dough properties were particularly weak coincided with the years when the number of hours over 35�C during the grain filling period (October to December) was greatest. A five-day period of heat stress in 1988 provided an opportunity to directly investigate the effects of heat stress in the field. A weakening of dough properties was shown, for four varieties, by longer dough development times and faster breakdown in the Farinograph and also by shorter resistance to extension (at 5 cm) in the Extensograph. These (and similar changes for glasshouse grown grain) were accompanied by an increase in the proportion of gliadin (monomeric) proteins. That this increase was associated with the heat stress was shown by demonstrating increased accumulation of 14C amino acids into the gliadin fraction for heat-stressed heads in culture. These results support the hypothesis that episodes of high temperature during grain filling activate the heat shock elements of gliadin genes in wheat causing the mature grain to contain more gliadin and thus to produce weaker doughs.