Grain yield forms one of the key economic drivers behind a successful wheat (Triticum aestivum L.) cropping enterprise and is consequently a major target for wheat breeding programmes. However, due to its complex nature, little is known regarding the genetic control of grain yield. A doubled-haploid population, comprising 182 individuals, produced from a cross between two cultivars 'Trident' and 'Molineux', was used to construct a linkage map based largely on microsatellite molecular makers. 'Trident' represents a lineage of wheat varieties from southern Australia that has achieved consistently high relative grain yield across a range of environments. In comparison, 'Molineux' would be rated as a variety with low to moderate grain yield. The doubled-haploid population was grown from 2002 to 2005 in replicated field experiments at a range of environments across the southern Australian wheat belt. In total, grain yield data were recorded for the population at 18 site-year combinations. Grain yield components were also measured at three of these environments. Many loci previously found to be involved in the control of plant height, rust resistance and ear-emergence were found to influence grain yield and grain yield components in this population. An additional nine QTL, apparently unrelated to these traits, were also associated with grain yield. A QTL associated with grain yield on chromosome 1B, with no significant relationship with plant height, ear-emergence or rust resistance, was detected (LOD > or =2) at eight of the 18 environments. The mean yield, across 18 environments, of individuals carrying the 'Molineux' allele at the 1B locus was 4.8% higher than the mean grain yield of those lines carrying the 'Trident' allele at this locus. Another QTL identified on chromosome 4D was also associated with overall gain yield at six of the 18 environments. Of the nine grain yield QTL not shown to be associated with plant height, phenology or rust resistance, two were located near QTL associated with grain yield components. A third QTL, associated with grain yield components at each of the environments used for testing, was located on chromosome 7D. However, this QTL was not associated with grain yield at any of the environments. The implications of these findings on marker-assisted selection for grain yield are discussed.

Photoperiod and vernalisation genes are important for the adaptation of wheat to variable environments. Previously, using diagnostic markers and a large, unbalanced dataset from southern Australia, we estimated the effects on days to heading of frequent alleles of Vrn-A1, Vrn-B1, and Vrn-D1, and also two allelic classes of Ppd-D1. These genes accounted for ~45% of the genotypic variance for that trait. We now extend these analyses to further alleles of Ppd-D1, and four alleles of Ppd-B1 associated with copy number. Variation in copy number of Ppd-B1 occurred in our population, with one to four linked copies present. Additionally, in rare instances, the Ppd-B1 gene was absent (a null allele). The one-copy allele, which we labelled Ppd-B1b, and the three-copy allele, which we labelled Ppd-B1a, occurred through a century of wheat breeding, and are still frequent. With several distinct progenitors, the one-copy allele might not be homogenous. The two-copy allele, which we labelled Ppd-B1d, was generally introduced from WW15 (syn. Anza), and the four-copy allele, which we labelled Ppd-B1c, came from Chinese Spring. In paired comparisons, Ppd-B1a and Ppd-B1c reduced days to heading, but Ppd-B1d increased days to heading. Ppd-D1a, with a promoter deletion, Ppd-D1d, with a deletion in Exon 7, and Ppd-D1b, the intact allele, were frequent in modern Australian germplasm. Differences between Ppd-D1a and Ppd-D1d for days to heading under our field conditions depended on alleles of the vernalisation genes, confirming our previous report of large epistatic interactions between these classes of genes. The Ppd-D1b allele conferred a photoperiod response that might be useful for developing cultivars with closer to optimal heading dates from variable sowing dates. Inclusion of Ppd-B1 genotypes, and more precise resolution of Ppd-D1, increased the proportion of the genotypic variance attributed to these vernalisation and photoperiod genes to ~53%.

The races of maize (Zea mays L.) which are cultivated in the highlands of central Mexico at altitudes above 2000 m include Palomero Toluqueño, Cónico, Arrocillo Amarillo, Chalqueño, and Cacahuacintle. This complex of races is of ancient origin and has a distinct plant morphology, karyotype, and isozyme frequency compared to other types of maize except, possibly, some races from the highlands of Guatemala. It is adapted to cool areas with mean growing season temperatures between about 12.5 and 17.0 °C and is superior to maize from temperate, mid‐altitude tropical, and lowland tropical regions for seedling emergence, photosynthetically‐based growth, and ability to continue grain filling at low temperatures. It also has better frost and hail tolerance, but is poorly adapted to high temperatures. It can emerge from sowing as deep as 0.25 m, and is resistant to rust caused by Puccinia sorghi Schw. With the support of the Mexican government, hybrids and improved open‐pollinated cultivars have been derived from these races. CIMMYT is conducting a breeding program based on these races for tropical highlands worldwide, but with the inclusion of other germplasm to improve grain yield and agronomic traits, especially resistance to lodging. These programs have shown excellent prospects for improving grain yield and agronomic traits in highland tropical environments. Research from New Zealand suggests that this germplasm resource has potential for raising grain yields in cool, temperate environments.

Roots play a key role in plant growth regulation. It is well described that the below-ground plant architecture has a significant impact on plant performance under abiotic constraints and maintains stability under increased grain load (Lynch, 2013). Although loci influencing root traits have been shown to affect grain yield and agronomic performance (e.g., Canè et al., 2014), knowledge about the genetic control of root growth in major grain crops is limited. Here, we demonstrate that VERNALIZATION1 (VRN1), a key regulator of flowering behavior in cereals (Deng et al., 2015), also modulates root architecture in wheat and barley. Our discoveries provide unexpected insight into underground functions of a major player in the flowering pathway.

Data from advanced breeding experiments between 1985 and 1994 were used to determine the effects of region, year and environment on the quality of canola grown across Victoria. Estimates from these unbalanced data were made using residual maximum likelihood. Environmental effects were large relative to cultivar effects for oil and protein content, while the reverse occurred for glucosinolate content. High oil contents (and low seed protein contents) were correlated with cooler spring temperatures and higher spring rainfall. Oil contents were lowest, on average, in canola grown in dry years, or from the hotter regions, such as the Mallee, and were highest in canola from the cooler, wetter regions, such as south-western and north-eastern Victoria. Fatty acid composition varied with year and region. Means for saturated fatty acid content averaged 6.4 0.1%. The oleic acid content averaged 60.3 0.4% and was higher in canola grown in central Victoria and the Wimmera, and in most years, in north-eastern Victoria compared with other regions. Low temperatures and low rainfall reduced oleic acid content. Linoleic acid content averaged 19.7 0.3% and linolenic acid averaged 10.4 0.3%, with the content of these fatty acids negatively correlated with the content of oleic acid. Erucic acid levels were below 0.6% in all regions.

Glutenins and gliadins are the major components of the storage protein in wheat and make a significant contribution to dough rheology and baking quality. Qualitative differences in these proteins are known to be important for dough rheology, particularly for glutenins, but much less is known about quantitative differences, especially as influenced by field environment. Flour protein, the proportion of glutenin and gliadin in flour protein, loaf volume, and the dough rheological characters dough development time, dough breakdown, dough extensibility, and maximum dough resistance (Rmax) were determined for 7 cultivars grown in 15 diverse environments. The proportion of glutenin in flour protein was highly dependent on cultivar, whereas, although cultivar was still important, environmental variation was greater than cultivar variation for gliadin. Environmental variation was greater than cultivar variation for the dough rheological characters. Across environments, the proportion of gliadin increased with increasing flour protein, whereas the proportion of glutenin decreased. An index of accumulated temperatures above 30˚C during the first 14 days after anthesis explained a significant proportion of the increase in gliadin, and, to a lesser extent, the decrease in glutenin. Increasing Rmax and dough development time, and more rapid dough breakdown, were also associated with this index. The rate of increase of Rmax with the temperature index was greater for cultivars with the Glu-D1a allele than those with the Glu-D1d allele, suggesting that the relative performance of cultivars with different alleles at this locus depends on environment.

The photoperiod sensitivity gene Ppd-D1 and the vernalisation genes Vrn-A1, Vrn-B1, and Vrn-D1 are known to contribute to optimal adaptation to specific environments. Diagnostic molecular markers for detecting important alleles of these genes are now available, including for 2 distinct spring alleles of Vrn-A1 (a and b). As a first step for determining the relative importance of these alleles, they were characterised in Australian cultivars released from the late 19th until the early 21st Century. The photoperiod-insensitive Ppd-D1a allele did not occur in the Australian cultivars we assessed until after the release of cultivars containing CIMMYT germplasm in 1973. Thereafter, this allele became common; however, cultivars with an alternative, presumably photoperiod-sensitive, allele have continued to be released for all parts of the Australian wheatbelt, including for latitudes less than 28°S. In contrast to other parts of the world, Vrn-A1b was frequent in cultivars released during the first 70 years of the 20th Century and is still present in modern cultivars. Before the use of CIMMYT germplasm, the spring allele of Vrn-B1 and the winter allele of Vrn-D1 were common. Four major combinations of alleles of these major genes were identified in modern cultivars: first, those similar to WW15 (Anza), with the Ppd-D1a allele, the spring Vrn-A1a allele, and winter alleles at Vrn-B1 and Vrn-D1; second, those similar to Spear or Kite, with the alternative, photoperiod-sensitive allele at Ppd-D1, the spring Vrn-A1a allele, the spring Vrn-B1a allele, and the winter allele at Vrn-D1; third, those similar to Pavon F 76, with the Ppd-D1a allele, the winter allele at Vrn-A1, and the spring alleles at Vrn-B1 and Vrn-D1; fourthly, those similar to Gabo, with the winter allele at Vrn-A1, the spring allele at Vrn-B1, the winter allele at Vrn-D1, but the Ppd-D1a allele. Other combinations were found, including those for winter cultivars and those for early heading cultivars. A hypothesis was suggested for the facultative cv. Oxley. Evidence was presented to suggest that modern full-season cultivars head ~1 week earlier in a Mallee environment than cultivars from the late 19th Century.

Improvements in malting quality are important if barley from south-eastern Australia is to remain competitive on export markets. Grain is desired that will produce high levels of malt extract and diastatic power but has moderate levels of grain protein. To examine cultivar and environmental effects, especially nitrogen (N) fertilizer, on levels of malting quality parameters and their correlations, seven cultivars of barley were grown in a fallow and pea stubble rotation with five levels of N fertilizer in the Wimmera region of Victoria in 1990 and 1991. The first season was relatively dry and warm, while the second was wetter and cooler. Grain yield and malt extract were markedly lower in 1990 than 1991, and grain protein concentration, grain screenings and diastatic power were significantly higher. Grain protein and diastatic power increased almost linearly with increasing N application, with a higher rate of increase in 1990 than in 1991. Malt extract declined almost linearly with increasing N application, but the change in rate of decline between seasons was less than the change of rate of increase of grain protein. Environmental correlations between protein concentration and malt extract, and between malt extract and diastatic power, were negative. They were close to -1.0 when the environmental factor varying was restricted to N fertilizer, but were of a smaller absolute magnitude when seasons and rotations were also allowed to vary. In contrast, genotypic correlations were of intermediate magnitude. Broad-sense heritabilities for malt extract and diastatic power were relatively high, even with such contrasting seasons. This indicates that it should be possible to develop cultivars for south-eastern Australia which have high malt extract and high diastatic power at low protein levels. However, applications of N fertilizer that raise grain protein concentration will reduce malt extract, with the effect much greater in drier, warmer seasons.