Incubation of saline-soluble wheat β-amylase with glutenin produces an insoluble enzymatically active complex. The pH profile of the bound enzyme indicates that binding may be selective for only certain wheat amylases. Association with glutenin reduces enzyme activity, but similarity between the kinetic properties of bound and unbound β-amylase suggests that binding involves a portion of the enzyme that is remote from its catalytic site. Elevated temp. increase the activity of bound β-amylase, but the relation between activity and temp. changes at 20°C. Calculated activation energies are 11.7 kcal/mole between 4° and 20°C, and 8.8 kcal/mole between 20° and 55°C. The apparent Michaelis constant for the bound enzyme is 0.15% (w/v). Little or no active enzyme is released from the complex by disulphide-reducing agents, 0.1M NaCl, or temp. ≤55°C.

Tillering in cereals, ecologically important to plants and economically important to agronomists, is the result of the development of axillary buds into tillers. It has been shown to be affected mainly by nutrition, moisture, climate, seed size, depth of planting and species (cf. Gardner, 1942; Mitchell, 1953a, b; Aspinall 1961, 1963; Langer, 1963). Moreover, Leopold (1949) has attempted to show that axillary buds in Gramineae also suffer from correlative inhibition, although there is little evidence of apical control of lateral bud development in Gramineae. Extensive observations predominantly in dicotyledonous herbaceous plants and some tree species have shown that the fate of lateral bud development is commonly, but not necessarily, determined by the actively growing apical bud. This phenomenon, called correlative inhibition, is common in many plant species. However, the degree of sensitivity of laterals to inhibition varies greatly among different plants. Work done over the last few decades on apical dominance in relation to the influence of some hormones, nutrients, genotypes, certain physiological factors, season, age, virus infection and general vigour of plants has revealed that no single factor is adequate to explain the mechanism involved. However, hormones and nutrition are probably the main regulatory agents for tillering or branching in plant species, adapted to the prevailing climate. Very little information is available in monocotyledonous plants in relation to hormonal effects on tillering, whereas considerable work has been done in dicotyledonous plants. This discrepancy is attributable to differences in structure, especially the position of apical and lateral buds, those of dicotyledonous plants being easily accessible for investigation. It has been demonstrated that cytokinins do not only cause the initiation of lateral buds but also release those that are inhibited (cf. Thimann & Wickson, 1957, 1958). The present investigation designed as a result of these considerations with the aim of gaining information on the effects of, kinetin and carbohydrate on the growth of laterals in wheat plants. The investigation was confined to the period between the double-ridge stage and ear emergence, because there is little chance of tiller bud development after the double-ridge stage in Gramineae, as shown by various workers, although tillering may resume when the ear has emerged (cf. Leopold, 1949; Patel and Cooper, 1961; Cooper, 1948; Laude et al. 1968; Langer, 1956). In Hilgendorf '61 wheat no buds were found to grow from axillary positions beyond leaf 4 on the main stem under glasshouse conditions in plants which attained the double-ridge stage at the 5½ leaf stage. The investigation, described here was conducted in growth cabinets in which environmental conditions were controlled. The study was confined to lateral buds on the main shoot. Wheat was chosen to study the influence of kinetin on lateral growth because of the lack of information on Gramineae. The New Zealand wheat cultivar, Hilgendorf '61, was selected, since it is representative of many temperate wheat varieties grown for milling and baking.

Stripe rust often occurs as conspicuous centers of infection-"hotspots"-in early-seeded fields of young wheat in late fall in the Pacific Northwest. the significance of fall infection was established by comparing the growth and yield of plants growing within 24 such centers in eastern Washington with plants growing immediately outside. hotspot plants produced from 18.6 to 24.0% fewer tillers, from 19,6 to 25.4% less straw, and from 18.3 to 30.8% les kernels than their "healthy" counterparts.

Abstract Climate change projections predict that precipitation in Norway is likely to increase, and flooding and waterlogging scenarios will likely be more frequent in the future. Wheat is sensitive to waterlogging conditions, and there can be substantial yield loss due to waterlogging stress in wheat. However, there is a genetic variation in waterlogging tolerance in wheat. Screening for waterlogging tolerance in wheat has been done for many years, but the screening methodology varies with climate, soil, crop stage, and waterlogging event itself. Field screening for waterlogging tolerance in wheat is labor-intensive, time-consuming, and high cost. Here, we developed and improved a methodology to screen waterlogging tolerance in wheat in the greenhouse, which can simulate field water logging conditions. Our greenhouse waterlogging methodology using starch (0.1% m/v) is promising and creates a highly reduced environment (below -500 mV) within four days of waterlogging. Using chlorosis as a trait for evaluating waterlogging tolerance, Best Linear Unbiased Predictors (BLUPs) of twenty spring wheat genotypes tested with this methodology showed a correlation of (R=0.44) with previously obtained field data for the same trait. The developed greenhouse waterlogging method using starch (0.1 % m/v) is cost-effective, time-efficient, and labor efficient compared to field screenings. Utilizing this method, screening for waterlogging tolerance in wheat can be done within one month of waterlogging. Chlorosis percentage and recovery scale are two phenotypic traits used for screening wheat genotypes in this method. This method is promising for efficiently screening diverse wheat populations for waterlogging tolerance within greenhouse settings, with potential application in other crops. Notably, twenty spring wheat genotypes used to optimize this methodology were also collections of genotypes with contrasting haplotypes on QTL6A.2 for chlorosis. These haplotypes have significant differences (P < 0.05) for chlorosis on field waterlogging and under this greenhouse waterlogging methodology. Follow-up experiments using this methodology would be recommended in further studies on validating this QTL. Additionally, we established a cost-effective root phenotyping methodology using seed germination pouches with germination paper (dark blue grade 194) for phenotyping seminal root angle of wheat genotypes. Utilizing this method, contrasting haplotypes on QTL6A.2 for chlorosis were tested for seminal root angle, and these haplotypes were found to have significant differences in seminal root angle. This result needs verification through further experiments. Identification of candidate genes on this locus would be recommended to understand the role of seminal root angle on waterlogging tolerance. This work establishes a greenhouse-based waterlogging screening method as alternative or supplement to field screening. It shows promise for large-scale screening and QTL identification/validation for waterlogging tolerance of wheat population. Additionally, seminal root phenotyping method developed for assessing traits like seminal root angle, has potential applications in waterlogging tolerance screening as seminal root angle is proxy trait | Abstract Climate change projections predict that precipitation in Norway is likely to increase, and flooding and waterlogging scenarios will likely be more frequent in the future. Wheat is sensitive to waterlogging conditions, and there can be substantial yield loss due to waterlogging stress in wheat. However, there is a genetic variation in waterlogging tolerance in wheat. Screening for waterlogging tolerance in wheat has been done for many years, but the screening methodology varies with climate, soil, crop stage, and waterlogging event itself. Field screening for waterlogging tolerance in wheat is labor-intensive, time-consuming, and high cost. Here, we developed and improved a methodology to screen waterlogging tolerance in wheat in the greenhouse, which can simulate field water logging conditions. Our greenhouse waterlogging methodology using starch (0.1% m/v) is promising and creates a highly reduced environment (below -500 mV) within four days of waterlogging. Using chlorosis as a trait for evaluating waterlogging tolerance, Best Linear Unbiased Predictors (BLUPs) of twenty spring wheat genotypes tested with this methodology showed a correlation of (R=0.44) with previously obtained field data for the same trait. The developed greenhouse waterlogging method using starch (0.1 % m/v) is cost-effective, time-efficient, and labor efficient compared to field screenings. Utilizing this method, screening for waterlogging tolerance in wheat can be done within one month of waterlogging. Chlorosis percentage and recovery scale are two phenotypic traits used for screening wheat genotypes in this method. This method is promising for efficiently screening diverse wheat populations for waterlogging tolerance within greenhouse settings, with potential application in other crops. Notably, twenty spring wheat genotypes used to optimize this methodology were also collections of genotypes with contrasting haplotypes on QTL6A.2 for chlorosis. These haplotypes have significant differences (P < 0.05) for chlorosis on field waterlogging and under this greenhouse waterlogging methodology. Follow-up experiments using this methodology would be recommended in further studies on validating this QTL. Additionally, we established a cost-effective root phenotyping methodology using seed germination pouches with germination paper (dark blue grade 194) for phenotyping seminal root angle of wheat genotypes. Utilizing this method, contrasting haplotypes on QTL6A.2 for chlorosis were tested for seminal root angle, and these haplotypes were found to have significant differences in seminal root angle. This result needs verification through further experiments. Identification of candidate genes on this locus would be recommended to understand the role of seminal root angle on waterlogging tolerance. This work establishes a greenhouse-based waterlogging screening method as alternative or supplement to field screening. It shows promise for large-scale screening and QTL identification/validation for waterlogging tolerance of wheat population. Additionally, seminal root phenotyping method developed for assessing traits like seminal root angle, has potential applications in waterlogging tolerance screening as seminal root angle is proxy trait