Low-altitude aerial imaging, an approach that can collect large-scale plant imagery, has grown in popularity recently. Amongst many phenotyping approaches, unmanned aerial vehicles (UAVs) possess unique advantages as a consequence of their mobility, flexibility and affordability. Nevertheless, how to extract biologically relevant information effectively has remained challenging.Here, we present AIRMEASURER, an open-source and expandable platform that combines automated image analysis, machine learning and original algorithms to perform trait analysis using 2D/3D aerial imagery acquired by low-cost UAVs in rice (Oryza sativa) trials.We applied the platform to study hundreds of rice landraces and recombinant inbred lines at two sites, from 2019 to 2021. A range of static and dynamic traits were quantified, including crop height, canopy coverage, vegetative indices and their growth rates. After verifying the reliability of AirMeasurer-derived traits, we identified genetic variants associated with selected growth-related traits using genome-wide association study and quantitative trait loci mapping.We found that the AIRMEASURER-derived traits had led to reliable loci, some matched with published work, and others helped us to explore new candidate genes. Hence, we believe that our work demonstrates valuable advances in aerial phenotyping and automated 2D/3D trait analysis, providing high-quality phenotypic information to empower genetic mapping for crop improvement.

complement to storage. One popular form of seed enhancement is priming which contains a hydrate-dehydrate process before sowing to invigorate seeds and promote germination 13 , hence its name "priming" which means promotion at the start. Seed deterioration as a result of ageing is attributed to the imbalance in the reductive /oxidative (redox) state caused by the accumulation of reactive oxygen species (ROS) which accelerate viability loss 8,14-16. Antioxidant priming has been shown to be effective in removing ROS 17 , boosting antioxidant enzymes 17 , and, through inhibition of lipid oxidation, increasing cell membrane integrity (CMI) as measured by electrical conductivity (EC) 18. The antioxidant effect is achieved by holding the seed in a hydrated state before radicle protrusion 19. This state is to make full use of antioxidant enzymes and antioxidants to scavenge ROS 6 and to apply exogenous antioxidants during priming 20. During storage the seed is dehydrated and antioxidant enzymes are inactive 21. Antioxidant priming is therefore beneficial to the activation of antioxidant system. However, its exact role in subsequent storage, indicated by post-priming seed survival, is much more ambiguous 6. One probable reason is that it promotes radicleprotrusion during which a seed loses its desiccation tolerance 22 and therefore suffers cell membrane injury during desiccation 21. In practice there is hardly any standard for priming as a method to prolong seed longevity 20. Could antioxidant priming act as a regular method of boosting seed longevity, and if so, when should a seed lot be primed? Priming has been found to be more likely to benefit seeds at the vulnerable stage 6. Our question was whether would antioxidant priming prolong or abbreviate the resistant stage? Would it decelerate viability loss? To better understand the exact role of antioxidant priming, antioxidant 15 and oxidant priming were applied to rice seeds to study post-priming survival. Rice is the model species for cereals and ranks third in the world's crop production, following maize and wheat. It is also the staple food in tropical or subtropical areas where temperatures are high. Without cold storage, environments for seed preservation are inclement and seed enhancement can be more useful. The original germination percentage (GP) of rice (Nipponbare, NPB) seeds in this study was already 97%, hard to improve. So, priming could only benefit seeds through prolonging the resistant stage or decelerating viability loss rather than increasing GP. Two hypotheses were proposed: (1) ageing resistance significantly declines as a result of storage before GP decreases; (2) antioxidant priming increases ageing resistance at high GP and decelerates viability loss. This study sought to discover an optimal time point for seed priming against viability loss, which can be generalized to other species and circumstances of storage and perhaps extended to be incorporated with other types of seed enhancement. Results Seed longevity under AAA responded negatively to t...

BackgroundSeed viability monitoring is very important in ex situ germplasm preservation to detect germplasm deterioration. This requires seed-, time- and labor- saving methods with high precision to assess seed germination as viability. Although the current non-invasive, rapid, sensing methods (NRSs) are time- and labor-saving, they lack the precision and simplicity which are the virtues of traditional germination. Moreover, they consume a considerable amount of seeds to adjust sensed signals to germination percentage, which disregards the seed-saving objective. This becomes particularly severe for rare or endangered species whose seeds are already scarce. Here we propose a new method that is precise, low-invasive, simple, and quick, which involves analyzing the pattern of dehiscence (seed coat rupture), followed by embryonic protrusion.ResultsDehiscence proved simple to identify. After the trial of 20 treatments from 3 rice varieties, we recognized that dehiscence percentage at the 48th hour of germination (D(48)) correlates significantly with germination rate for tested seed lots. In addition, we found that the final germination percentage corresponded to D(48) plus 5. More than 70% of the seeds survived post-dehiscence desiccation for storage. Hydrogen peroxide (1 mM) as the solution for imbibition could further improve the survival. The method also worked quicker than tetrazolium which is honored as a fast, traditional method, in detecting less vigorous but viable seeds.ConclusionWe demonstrated the comprehensive virtues of dehiscence method in assessing rice seed: it is more precise and easier to use than NRSs and is faster and more seed-saving than traditional methods. We anticipate modifications including artificial intelligence to extend our method to increasingly diverse circumstances and species.Electronic supplementary materialThe online version of this article (10.1186/s13007-018-0334-3) contains supplementary material, which is available to authorized users.

Wetland degradation is a source of anxiety and is more severe in cold regions than other areas. The soil seed bank acts as a propagule source for revegetation to affiliate the restoration of degraded wetlands. However, the effects of this approach are controversial and depend on the traits of the seed bank and its interactions with the environment. The seed bank in an alpine fen meadow was studied to determine its exact role in revegetation. The surveyed shore of a Tibetan lake, Gahai Lake, was divided into three sites under different levels of grazing pressure. Each site was separated into six transects along a water‐depth gradient to collect soil cores to determine the pattern of biodiversity through a germination experiment in a greenhouse. After an analysis of heterogeneity‐related diversity, partitioning of 58 discovered species indicated that 39.5 could be contributed to beta‐diversity, which was mainly contributed to water depth. Overgrazing (0.607 sheep unit/acre, November—March) decreased seed bank diversity in many respects, especially through decreasing spatial heterogeneity and homogenizing biota. A lightly grazed, well‐protected site had not only the highest beta‐diversity and species abundance but also the highest inter‐site species turnover rate compared with other sites under moderate grazing intensity. Despite the lack of target species, the seed bank serves as (i) a species‐rich pool; (ii) an extant legacy seed source for sustaining heterogeneity and floristic diversity; and (iii) an ecological indicator, and its effect can be reinforced by appropriate grazing practices (multiple intensity) and hydrological modifications. Copyright © 2016 John Wiley & Sons, Ltd.

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