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The eects of water stress on physiological attributes of drought-sensitive (Kalyansona) and drought-tolerant (C-306) wheat cultivars were studied in a pot experiment. Water stress was imposed by withholding irrigation at boot and anthesis stages. Leaf water potential, leaf osmotic potential and leaf turgor potential (measured with 1 1 pressure chamber and osmometer), as well as leaf diusive resistance, leaf transpiration rate and leaf-to-air transpiration gradient (measured with a steady-state porometer) were measured diurnally. Growth and yield parameters were recorded after harvesting of the crop. Triplicate data were analysed using a completely randomized design and correlations amongst these parameters were computed. Water stress was found to reduce diurnal leaf water potential and leaf osmotic potential in both the genotypes but leaf osmotic potential was signi®cantly higher in the droughttolerant cultivar C-306 than in the drought-sensitive cultivar Kalyansona. Positive turgor was recorded in both the genotypes under water stress and non-stress conditions. Water-stressed plants showed signi®cantly lower turgor potential than control plants. In diurnal observations, water-stressed plants exhibited signi®cantly higher leaf diusive resistance in both genotypes at both stages. The diusive resistance of C-306 was predominantly higher than that of Kalyansona. Water stress decreased leaf transpiration rate at both stages but the reduction was higher at the anthesis stage. The leaf-to-air temperature gradient was much higher in C-306 than in Kalyansona at the boot stage but at the anthesis stage genotypic variation was non-signi®cant. The capacity to maintain cooler foliage was lower at the anthesis stage than at the boot stage in both the cultivars. Shoot dry weight, number of grains, test weight 2 2 , grain yield, biological yield and harvest index decreased to a greater extent when water stress was imposed at the anthesis stage, while imposition of water stress at the boot stage caused a greater reduction in plant height and number of tillers. Similarly, water stress caused a smaller reduction in growth, yield and yield attributes in C-306 than in Kalyansona.In general, the correlation coecient of grain and biological yield with water potential and its components was positive and highly signi®cant. Similarly, turgor potential was also correlated positively and signi®cantly with grain yield at both the stages, but with biological yield it was signi®cant only at the anthesis stage. A negative and signi®cant correlation was obtained for diusive resistance and leaf-to-air temperature gradient with grain yield at the boot and anthesis stages. The rate of transpiration was also positively and signi®cantly correlated to grain and biological yields at both the stages. Amongst the yield attributes, number of leaves and number of tillers were positively correlated at the anthesis stage, whereas leaf area and shoot dry weight were signi®cantly correlated with grain and biological yields at both the stages.

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Previous work identified the wild barley (Hordeum vulgare ssp. spontaneum) accession CPI-71284-48 as being capable of limiting sodium (Na(+)) accumulation in the shoots under saline hydroponic growth conditions. Quantitative trait locus (QTL) analysis using a cross between CPI-71284-48 and a selection of the cultivated barley (H. vulgare ssp. vulgare) cultivar Barque (Barque-73, a moderate Na(+) excluder) attributed the control of the Na(+) exclusion trait from CPI-71284-48 to a single locus on the short arm of chromosome 7H, which was named HvNax3. The locus reduced shoot Na(+) accumulation by 10-25% in plants grown in 150 mM NaCl. Markers generated using colinearity with rice and Brachypodium, together with the analysis of introgression lines and F(2) and F(3) families, enabled HvNax3 to be mapped to a 1.3-cM interval. Genes from the corresponding rice and Brachypodium intervals encode 16 different classes of proteins and include several plausible candidates for HvNax3. The potential of HvNax3 to provide a useful trait contributing to salinity tolerance in cultivated barley is discussed.

An adaptive threshold element is able to "learn" a strategy of play for the game blackjack (twenty-one) with a performance close to that of the Thorp optimal strategy although the adaptive system has no prior knowledge of the game and of the objective of play. After each winning game the decisions of the adaptive system are "rewarded." After each losing game the decisions are "punished." Reward is accomplished by adapting while accepting the actual decision as the desired response. Punishment is accomplished by adapting while taking the desired response to be the opposite of that of the actual decision. This learning scheme is unlike "learning with a teacher" and unlike "unsupervised learning." It involves "bootstrap adaptation" or "learning with a critic." The critic rewards decisions which are members of successful chains of decisions and punishes other decisions. A general analytical model for learning with a critic is formulated and analyzed. The model represents bootstrap learning per se. Although the hypotheses on which the model is based do not perfectly fit blackjack learning, it is applied heuristically to predict adaptation rates with good experimental success. New applications are being explored for bootstrap learning in adaptive controls and multilayered adaptive systems.