Drought severely limits the growth and development of oat (Avena sativa) seedlings. As an osmotic regulator simulating a drought environment, Polyethylene glycol (PEG) has been widely linked in response to plant drought tolerance. However, the underlying mechanism of oats’ response to PEG stress is still largely unknown. Here, we investigated the physiological and transcriptome variables of the drought-resistant oat variety DA92-2F6, and the drought-susceptible variety Longyan 3 under 15% PEG-6000 drought stress to better understand the underlying drought tolerance molecular mechanisms. The physiological results showed that except for the cell membrane permeability, the antioxidant enzyme, osmotic adjustment substance, and photosynthetic efficiency were significantly higher in the DA92-2F6 after 7 d stress. Further, 12 cDNA libraries and 123,223 unigenes were obtained by RNA-seq. A total of 33,857 differentially expressed genes (DEGs) were detected, of which two co-upregulated and three co-downregulated in four comparisons. We highlighted an analysis of the DEGs in phytohormone signal transduction pathway. The auxin, cytokinin, and brassinosteroid signaling pathways, were suppressed in Longyan 3, while abscisic acid and jasmonic acid signaling pathways were mainly activated in DA92-2F6 under drought stress. The upregulated of PP2C, ABF, SNRK2, GID1, JAZ, and MYC2 genes may enhance the drought tolerance of DA92-2F6. Taken together, these results provided a new transcript resource for the drought tolerance improvement and a reference for oat drought resistance molecular breeding.

Oat has been gaining renewed interest due to its role in a healthy human diet, in animal feed, and as a source of high value compounds with industrial applications. Nitrogen fertilization and planting density are two of the most important crop management practices that affect the formation of yield components and final yield of oat. A 2 year 3 × 5 factorial field experiment was conducted to investigate the effects of nitrogen (N) fertilizer and planting density on the flag leaf photosynthetic characteristics, grain yield, and yield components under rainfed conditions. The experiment consisted of three sowing densities (60, 180, and 300 kg·ha⁻¹) and five nitrogen fertilizer rates (0, 45, 90, 135, and 180 kg·ha⁻¹). Results showed that the grain yield was significantly (p < 0.05) correlated with the leaf net photosynthesis rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), transpiration rate (Tr), water-use efficiency (WUE), stomatal limitation value (Ls), chlorophyll content (SPAD value), leaf area index (LAI), panicle length, number of spikelets per panicle (NSP), number of grains per panicle (NGP), weight of grains per panicle (WGP), and 1000-kernel weight. Among the yield components, grain yield was driven by number of spikelets per panicle (NSP) and number of grains per panicle (NGP) at low (or high) planting density with low N supply, whereas, at high N supply, 1000-kernel weight was also an important factor for yield. Nitrogen fertilizer and sowing density had significant (p < 0.05) effects on the flag leaf photosynthetic characteristics, grain yield, and yield components of oat. The yield components increased and then decreased with the increase in nitrogen fertilizer, while they decreased with the increase in planting density. The maximum values (p < 0.05) of grain yield were observed in the nitrogen fertilization of 90 kg·ha⁻¹ and sowing density of 180 kg·ha⁻¹ treatment in both growing seasons, mainly contributing to the improved leaf photosynthesis traits (Pn, Gs, Tr, Ls, SPAD, and LAI). The combination of nitrogen fertilization of 90 kg·ha⁻¹ and sowing density of 180 kg·ha⁻¹ is suitable for oat production on a cool semiarid plateau or other agroecozones with similar environmental conditions.

Soil salinity is a major abiotic stress limiting crop production globally. Oat (Avena sativa) is an annual cereal with a strong salt tolerance, a high yield, and nutritional quality, although the mechanisms underlying its salt stress response remain largely unknown. We examined the physiological and transcriptomic responses of A. sativa seedlings to salt stress in tolerant cultivar Qingyongjiu 195 and sensitive cultivar 709. Under salt stress, Qingyongjiu 195 maintained a higher photosynthetic efficiency, antioxidant enzymes activity, and leaf K⁺ accumulation but a lower Na⁺ uptake than 709. RNA-seq revealed 6616 differentially expressed genes (DEGs), including 4265 up- and 2351 downregulated. These were enriched in pathways like plant–pathogen interaction, phenylpropanoid biosynthesis, and MAPK signaling. We specifically highlight DEGs involved in photosynthesis (chlG, CP47 psbB, COX2, LHCB) and antioxidants (trxA, GroES). Qingyongjiu 195 also appeared to enhance K⁺ uptake via KAT1 and AKT2 and sequester Na⁺ in vacuoles via NHX2. Additionally, HKT restricted Na⁺ while promoting K⁺ transport to shoots, maintaining K⁺/Na⁺. The expression levels of CAX, ACA, CML, CaM, and CDPK in Qingyongjiu 195 were higher than those in 709. Oats regulated Ca²⁺ concentration through CAX and ACA after salt stress, decoded Ca²⁺ signals through CML, and then transferred Ca²⁺ signals to downstream receptors through the Ca²⁺ sensors CaM and CDPK, thereby activating K⁺/Na⁺ transporters, such as SOS1 and NHX, etc. Our results shed light on plant salt stress response mechanisms and provide transcriptomic resources for molecular breeding in improving salt tolerance in oats.

Oat is a main feed crop in high- altitude areas of western China, but few studies have been done on its silage making. The aim of this study was to evaluate the effect of silage additives on fermentation, aerobic stability, and nutritive value of different oat varieties (OV) grown in the Qinghai–Tibet Plateau of China. Two OV (Avena sativa L. cv. Longyan No.1 (OVL1) and Avena sativa L. cv. Longyan No.3 (OVL3)) were planted in a randomized complete block design, harvested at early dough stage with 32.6% and 34.1% DM, respectively. The fresh material was chopped to 2-cm length and treated with additives (0, Sila-Mix (MIX), Sila-Max (MAX) in a 2 × 3 factorial arrangement of treatments with three replicates. Both additives contained a mixture of lactic acid bacteria and supplied a final application rate of 2.5 × 10⁸ of lactic acid bacteria per kg of fresh forage weight. After 60 d of ensiling, the number of lactic acid bacteria in treated silages was about 10-fold greater than the control and generally resulted in a lower pH and ammonia-nitrogen (P < 0.001), greater total acids and ratios of lactic acid/acetic acid (P < 0.001), and DM recovery (P = 0.028). Treatment with additives also decreased (P < 0.001) the number of yeasts, which resulted in marked (P < 0.001) improvements in aerobic stability with the effect being greatest with MAX. Both additives improved (P ≤ 0.036) the 48-h in situ DM digestion in OVL1, but not in OVL3 (P ≥ 0.052). Treatment with both additives also increased (P ≤ 0.003) NDF digestion in OVL1 while it was improved (P < 0.001) only by MAX in OVL3. In contrast, the additives did not affect (P ≥ 0.088) in situ hemicellulose digestion in OVL1, but it was improved (P = 0.048) by MIX and further improved (P = 0.002) by MAX in OVL3. Treatment with MAX improved yields of digestible DM and digestible NDF in both varieties. Dry matter recovery was not affected (P = 0.121) by variety. Compared to CTRL, silage treated with MAX had a greater (P = 0.015) DM recovery (96.7% vs. 93.9%). Inoculation improved (P < 0.001) aerobic stability. The MAX was the most effective for both varieties, while MIX was intermediate and was more effective in OVL3 than OVL1 silage. The results also showed that in Qinghai–Tibet Plateau, compared to OVL1, OVL3 resulted in greater (P ≤ 0.002) yields of digestible nutrients; specifically, treated with MAX improved silage fermentation efficiency, DM recovery, and provided excellent aerobic stability for feeding to ruminants.

A field grazing experiment was conducted in Jingtai County, Gansu Province, China, from 2003 to 2010. The grazing intensity treatments included light grazing (LG, 0.45 sheep unit/ha), moderate grazing (MG, 0.75 sheep unit/ha), heavy grazing (HG, 1.50 sheep unit/ha), and no grazing (NG). Soil physical, chemical, and biological properties were measured. The results showed that, with increasing grazing intensities, the concentrations of total nitrogen, available nitrogen, organic matter, available phosphorus, available potassium, urease, catalase, and alkaline phosphatase in the soil decreased significantly with LG being mostly the greatest (P < 0.05). Soil bulk density for HG and NG was greater than that for LG and MG (P < 0.05). The concentrations of copper, manganese, and zinc were lower than their critical levels for plant growth, whereas iron was greater than its critical level. Correlation and principal component analyses revealed that soil trace elements were the secondary principal component compared with the primary elements, i.e., soil moisture, bulk density, etc.

Background: Drought is a significant condition that restricts vegetation growth on the Tibetan Plateau. Artemisia wellbyi is a unique semi-shrub-like herb in the family Compositae, which distributed in northern and northwest of Tibetan Plateau. It is a dominant species in the community that can well adapt to virous environment stress, such as drought and low temperature. Therefore, A. wellbyi. has a potential ecological value for soil and water conservation of drought areas. Understanding the molecular mechanisms of A. wellbyi. that defense drought stress can acquire the key genes for drought resistance breeding of A. wellbyi. and provide a theoretical basis for vegetation restoration of desertification area. However, they remain unclear. Thus, our study compared the transcriptomic characteristics of drought-tolerant “11” and drought-sensitive “6” material of A. wellbyi under drought stress. Results: A total of 4875 upregulated and 4381 downregulated differentially expressed genes (DEGs) were induced by drought in the tolerant material; however, only 1931 upregulated and 4174 downregulated DEGs were induced by drought in the sensitive material. The photosynthesis and transcriptional regulation differed significantly with respect to the DEGs number and expression level. We found that CDPKs (calmodulin-like domain protein kinases), SOS3 (salt overly sensitive3), MAPKs (mitogen-activated protein kinase cascades), RLKs (receptor like kinase), and LRR-RLKs (repeat leucine-rich receptor kinase) were firstly involved in response to drought stress in drought tolerant A. wellbyi. Positive regulation of genes associated with the metabolism of ABA (abscisic acid), ET (ethylene), and IAA (indole acetic acid) could play a crucial role in the interaction with other transcriptional regulatory factors, such as MYBs (v-myb avian myeloblastosis viral oncogene homolog), AP2/EREBPs (APETALA2/ethylene-responsive element binding protein family), WRKYs, and bHLHs (basic helix-loop-helix family members) and receptor kinases, and regulate downstream genes for defense against drought stress. In addition, HSP70 (heat shock protein70) and MYB73 were considered as the hub genes because of their strong association with other DEGs. Conclusions: Positive transcriptional regulation and negative regulation of photosynthesis could be associated with better growth performance under drought stress in the drought-tolerant material. In addition, the degradation of sucrose and starch in the tolerant A. wellbyi to alleviate osmotic stress and balance excess ROS. These results highlight the candidate genes that are involved in enhancing the performance of drought-tolerant A. wellbyi and provide a theoretical basis for improving the performance of drought-resistant A. wellbyi.