Synthesis beyond limit

<p>Rice production needs to increase in the future in order to meet increasing demands. The development of new improved and higher yielding varieties more quickly will be needed to meet this demand. However, most rice breeding programmes in the world have not changed in several decades. In this article, we revisit the evidence in favour of using rapid generation advance (RGA) as a routine breeding method. We describe preliminary activities at the International Rice Research Institute (IRRI) to re-establish RGA on a large scale as the main breeding method for irrigated rice breeding. We also describe experiences from the early adoption at the Bangladesh Rice Research Institute. Evaluation of RGA breeding lines at IRRI for yield, flowering time and plant height indicated transgressive segregation for all traits. Some RGA lines were also higher yielding than the check varieties. The cost advantages of using RGA compared to the pedigree method were also empirically determined by performing an economic analysis. This indicated that RGA is several times more cost effective and advantages will be realized after 1 year even if facilities need to be built. Based on our experience, and previous independent research empirically testing the RGA method in rice, we recommend that this method should be implemented for routine rice breeding in order to improve breeding efficiency.</p

Proposed routes of Salamaua to Wau Road [cartographic material] /

Map 237 from Ferguson Collection.; Map shows four proposed routes from Salamaua to Wau, Papua New Guinea. Relief shown by hachures.; Signed: W. Ramsay McNicoll.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.map-f237

Evaluating the Performance and Opportunity Cost of a Smart-Sensed Automated Irrigation System for Water-Saving Rice Cultivation in Temperate Australia

Irrigated rice is the largest user of precious global water reserves. Adoption of water-saving irrigation practices is limited by the associated increased labor demand compared to flooded rice cultivation. Automated gravity surface irrigation systems have shown the potential to deliver significant labor savings in traditional flooded rice; however, widespread adoption does not seem apparent. Furthermore, previously designed systems have not been capable of irrigation control during both ponded and non-ponded periods. This study aimed to evaluate the performance of an automated irrigation system for rice with features not previously developed, provide direction for future systems and analyze the opportunity cost (the value of other on- or off-farm activities that could be conducted with that time) of time associated with automated irrigation. The automated irrigation system was found to successfully control 23–31 flush-irrigation events per bay per season in a 9-bay border-check aerobic rice field for 2 seasons. In addition, successful water control was achieved in a traditional drill-sown field with 4 flush irrigations followed by 15 weeks of permanent flooding. Labor savings of 82–88% during the flush-irrigation events and 57% during the ponding period were achieved with automation when compared to manual irrigation. However, the opportunity cost of the saved time was found to comprise the greatest benefit. Changing the analysis from using a flat “cash” cost of time to using opportunity cost of time reduced the payback period from seven to four years at the traditional ponded-rice site. In the more labor-intensive aerobic rice site, the payback period was reduced from three years to one year when accounting for the opportunity cost of time as opposed to only the direct costs. Whilst the payback period is site-dependent and cultivation method-dependent, these case studies demonstrate that automated gravity surface irrigation can enable novel water-saving practices in rice and provide substantial economic benefits

Replication Data for: Leaf emergence, tillering, plant growth, and yield in response to plant density in a high-yielding aerobic rice crop

The traditional transplanted and flooded rice cropping system is threatened by water shortage and labor cost increase in many Asian countries and is currently evolving toward direct-seeded and water-saving systems. However, yield penalties generally accompany this evolution and ongoing research targets their mitigation. In a previous research, slower plant development rate was observed in aerobic crops, possibly caused by the increased plant density. This possible factor was tested in experiments conducted at IRRI’s farm, Los Banos, Philippines, in 2012 and 2013. One elite variety was direct-seeded at three plant distances (6, 10, and 20 cm × 20 cm) and sprinkler-irrigated to keep the soil water potential above−10 kPa. Weekly measurements were made to dissect crop and plant physiological differences. Data from previous experiments on tillering in the greenhouse of four varieties and in fields in aerobic and flooded conditions were added to strengthen the results from the current experiment. The last upper leaves of the main stem appeared faster at higher plant density, thus increase plant density was not the cause for the slower leaf appearance in aerobic than in flooded crops. Plants at higher plant density also had earlier panicle initiation, earlier earing, and 0.8 leaf less than plants at low density. The number of outgrowing tillers was linked to the number of leaves on the main stem by a variety-specific relationship that is independent from plant density and water management. Tiller density was regulated by the cessation of the outgrowth of tillers triggered by the onset of stem elongation at 20-cm plant distance and occurred earlier at shorter distances probably in response to the high root density. Grain yields were significantly higher at higher plant density (6-cm and 10-cm plant distances) and correlated with a higher tiller density. Thus for aerobic crops, seedling density higher than 50 plants per sq meter remains the way to get high yields for the type of variety used in this study

Potential distribution of the invasive mite Tetranychus evansi (Tetranychidae) in the Mediterraean region

Predicting the potential geographical distribution of a species is particularly useful for pests with strong invasive abilities. Tetranychus evansi, possibly native of South America, is a spider mite recognized as a pest of solanaceous crops. This mite is considered as an invasive species in Africa and Europe and has been recorded in many parts of the world. To define the potential global distribution of the species, a CLIMEX model distribution was developed using: i) South American records, ii) laboratory life‐history parameters and iii) exotic records. The model results fitted the known distribution of T.evansi Except for some dry locations host plants develop only with irrigation. High temperatures, dry and wet stresses play a role in limiting the spread of the mite in the tropics, Whereas in a large part of North America and Europe, the distribution of T.evansi appears to be limited essentially by cold stress. A distribution map is provided for the global potential distribution of T.evansi. The Mediterranean region is of particular interest because it is the main area where tomato is grown in open fields in Europe. According to the model, the Mediterranean region will be colonized in exorably by the pest. However, model results indicate a mite distribution being limited to coastal areas

Integrated nutrient–weed management under mechanised dry direct seeding (dds) is essential for sustained smallholder adoption in rainfed lowland rice (Oryza sativa L.)–Corrigendum

In the above mentioned article, the corresponding author's present address was omitted from the corresponding author information. The corresponding author information should read. On page 7, in Table 2, the decimal points have been mistakenly omitted in column 'Yields for transplanted rice', making the figures 100 times what they should be. This should be the same order of magnitude as the 'Yields for DDS rice'; about 2.0 t/ha'. The corrected Table 2 is displayed below. (Table Presented)