Highlight:A genome-wide association study with rice revealed a wide range of natural variation to ozone stress and identified candidate loci affecting nine traits of physiological and agronomical importance.

Water stress (WS) during spike development strongly affects final grain yield and grain quality in cereals. Proline, an osmoprotectant amino-acid, may contribute to alleviating the effects of cell and tissue dehydration. We studied five spring barley genotypes contrasting in their drought response, including two introgression lines, S42IL-143 and S42IL-141, harboring a Pyrroline-5-carboxylate synthase1- P5cs1 allele originating from the wild barley accession ISR42-8. We tested the hypothesis that barley genotypes harboring a wild allele at P5cs1 locus are comparatively more drought-tolerant at the reproductive stage by inducing proline accumulation in their immature spikes. At the booting stage, we subjected plants to well-watered and WS treatments until physiological maturity. Several morpho-physiological traits had significant genotype by treatment interaction and reduction under WS. Varying levels of genotypic proline accumulation and differences in WS tolerance were observed. Spike proline accumulation was higher than leaf proline accumulation for all genotypes under WS. Also, introgression lines carrying a wild allele at P5cs1 locus had a markedly higher spike and leaf proline content compared with the other genotypes. These introgression lines showed milder drought symptoms compared with elite genotypes, remained photosynthetically active under WS, and maintained their intrinsic water use efficiency. These combined responses contributed to the achievement of higher final seed productivity. Magnetic resonance imaging (MRI) of whole spikes at the soft dough stage showed an increase in seed abortion among the elite genotypes compared with the introgression lines 15 days after WS treatment. Our results suggest that proline accumulation at the reproductive stage contributes to the maintenance of grain formation under water shortage.

A vigorous root system in barley promotes water uptake from the soil under water-limited conditions. We investigated three spring barley genotypes with varying water stress responses using rhizoboxes at the seedling stage. The genotypes comprised two elite German cultivars, Barke and Scarlett, and a near-isogenic line, NIL 143. The isogenic line harbors the wild allele pyrroline-5-carboxylate synthase1-P5cs1. Root growth in rhizoboxes under reduced water availability conditions caused a significant reduction in total root length, rooting depth, root maximum width, and root length density. On average, root growth was reduced by more than 20% due to water stress. Differences in organ proline concentrations were observed for all genotypes, with shoots grown under water stress exhibiting at least a 30% higher concentration than the roots. Drought induced higher leaf and root proline concentrations in NIL 143 compared with any of the other genotypes. Under reduced water availability conditions, NIL 143 showed less severe symptoms of drought, higher lateral root length, rooting depth, maximum root width, root length density, and convex hull area compared with Barke and Scarlett. Within the same comparison, under water stress, NIL 143 had a higher proportion of lateral roots (+30%), which were also placed at deeper substrate horizons. NIL 143 had a less negative plant water potential and higher relative leaf water content and stomatal conductance compared with the other genotypes under water stress. Under these conditions, this genotype also maintained an enhanced net photosynthetic rate and exhibited considerable fine root growth (diameter class 0.05–0.35 mm). These results show that water stress induces increased shoot and root proline accumulation in the NIL 143 barley genotype at the seedling stage and that this effect is associated with increased lateral root growth.

Modelling and multiple linear regression were used to explore the reason for low maize yield in the Atebubu-Amantin and West Mamprusi Districts of Ghana, West Africa. The study evaluated maize yields on twenty farms against measures of soil fertility, agronomic attributes and soil water availability. Correlations between yield, soil fertility, rain, crop density, and weed biomass, were low, and no single factor could explain the low yields. A 50-year virtual experiment was then set up using the Agricultural Production Systems Simulator (APSIM) to explore the interactions between climate, crop management (sowing date and nitrogen fertilization) and rooting depth on grain yield and nitrate (NO3-N) dynamics. The analysis showed that a lack of optimal sowing dates that synchronize radiation, rainfall events and nitrogen (N) management with critical growth stages explained the low farm yields.

Group recommendation has attracted wide attention owing to its significance in real applications. One of the big challenges for group recommendation systems is how to integrate individual preferences of each group member and attain overall preferences for the group. Most of the traditional group recommendation solutions regard group members as equal participants and assign a same weight to each member. As a result, performance of this type of recommendation methods is not as good as expected. To improve the performance of group recommendation, a novel group recommendation model via Self-Attention and Collaborative Metric Learning (SACML) is presented in this paper. With the employment of Self-Attention mechanism, the SACML model can learn the similarity interactions between group members and services and decide a different weight for different group member. Based on these weights, group preferences for services can be generated by the aggregation of group members' preferences and the group's own preference. Similar metric space between group and services is obtained via collaborative metric learning with the group preferences and positive and negative services' features. Group recommendation is finally implemented based on the obtained metric space. Simulation has been conducted on CAMRa2011 and Meetup datasets, and experimental results show that the proposed SACML model has better performance in comparison with those baseline methods.

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<p><strong>Abstract.</strong> Unmanned Aerial Vehicles (UAVs) are increasingly used, and open new opportunities, in agriculture and phenotyping because of the flexible data acquisition. In this study the potential of ultra-high spatially resolved UAV image data was investigated to quantify lodging percentage, lodging development and lodging severity of barley using Structure from Motion techniques. The term lodging is defined as the permanent displacement of a plant from the upright position. Traditionally lodging quantification is based on observations that need, and vary with observers in the field. An objective threshold approach was proposed in this study to improve the accuracy in lodging determination. Across breeding trials, manual reference measurements and UAV based lodging percentage showed a very high correlation (R²&amp;thinsp;=&amp;thinsp;0.96). In addition, the multi-temporal lodging percentage development was used to estimate the recovery rate and to determine the influence of different lodging events. Based on the parameter lodging percentage an approach was developed that allowed the assessment of lodging severity, an information that is important to estimate the yield impairment. Lodging severity can be used for insurance applications, precision farming and breeder research. This trait, together with differentiated recovery are novel traits next to lodging severity that will aid the selection for genetic lines.</p>

1516 With about 70% of yam tuber been water, yield is critically affected during bulking as a result 17 of onset of temporal drought. As a consequence of climate change, farmers who are into 18 Dioscorea rotundata (white yam) production for local and international market lose their 19 investments mainly due to erratic precipitation, drought spells culminating into low yields of 20 just 12t/ha compared to the potential of about 22-49t/ha depending on the variety. Innovative 21 land uses technologies with higher and sustained productivity for yam production are 22 imperative. This study verifies improved agronomic package for sustainable yam production 23 in yam growing areas in the forest -savannah transition zone of Ghana during the 2015 and 24 2016 cropping seasons. The improved agronomic package included use of ridging as seedbed, 25 seed treatment before planting, fertilizer application at a rate of 30:30:36 N:P 2 0 5 :K 2 0 kg/ha 26 plus 15 kg/ha Mg and 20 kg/ha S as MgSO 4 and the use of minimum stakes (trellis; 30-50% 27 less number of stakes used by farmers staking). This was compared with farmers' practice 28 which consisted of mounding, no fertilizer application and no seed treatment. The results 29 revealed significant (P ≤ 0.01) yam yields of more than 60% difference between the improved 30 agronomic practice and farmers' practice from Ejura, Atebubu and Kintampo yam growing 31 communities. Adoption of improved agronomic practices does not only sustain yam 32 production and address deforestation but also provide higher returns on investments 33 promoting climate resilience by small holders. Key Words35 Climate smart agriculture, Fertilizer, Improved technology, Seed treatment, Trellis staking, 36 Yam 37 38 Background 39 2 40 In Ghana, crops are already experiencing heat stress, drought spells, several pests and 41 diseases outbreak and shorter growing crop duration as a consequent of the changing climate 42 (1). Thus, a potential catastrophe for smallholder farmers and the millions of people who 43 regularly grow rain-fed full season crops such as yam, cocoyam, rice etc.(2-5). Choices about 44 what to grow are often dictated by the ability of the rainfall regime to support moisture for 45 plant growth (6). One way around this would be to breed for varieties with shorter crop 46 maturity durations or management interventions that build on the resilience of cropping 47 production systems to reduce shocks if the shocks from the climate change cannot be done 48 away with. Evidence suggests that climate smart agriculture can make a contribution to 49 mitigation by supporting more efficient use of fertilizers, weed management and reduced 50 staking options in yam production (1,7,8). 51 Yam, an important staple food crop across West Africa is a major non-traditional export 52 crop in Ghana contributing to about 16% of the National Agricultural Gross Domestic Product 53 (9,10). However, there are a number of challenges that hamper the production and 54 productivity of yam. Predominantly amongst them are; inade...