Oat Floral Biology and Factors Affecting Seed Set

In India, oat is grown as fodder crop during Rabi season in north-western and central parts of the country and is now even extending to eastern region as well. The only commercially cultivated species in the genus Avena are Avena sativa, Avena nuda and Avena byzantine. Oat flowers are bit delicate when compared to other cereal floral structure and seed set is influenced by many factors during artificial hybridisation. This paper includes about floral biology of oat crop and also the various factors responsible for seed set during hybridisation viz effect of Interval Between Emasculation and Pollination, effect of temperature for seed set and any Injury to floral Parts during hybridisation.

The Effect of Age and Drought on the Recovery of Midday Leaf Hydraulics and Physiological Traits in Oat (Avena nuda)

The leaf hydraulic behavior has a significant role on species survival because plants often encounter drought. The effect of age and drought on the leaf water potential (ѰL), leaf hydraulic conductance (KL), stomatal density (SD) and size (SS), evapotranspiration (E), net photosynthetic rate (Pn) stomatal conductance (gs) and their post drought recovery in naked oat is not understood. This study investigated these facts in two naked oat cultivars, Yanmai (Ym) and Dingyou7 (Dy7). The plants were grown in pots and kept well-watered (WW) for the first ~30 days after sowing (DAS) after that for Experiment 1) the plants were kept in a rainout shelter; in a growth room and kept WW throughout. Experiment 2) the plants were grown at 40% drought to determine the effect of drought on the SD and SS. Experiment 3) the plants were grown in 40% field water capacity (FC) for ~25 days then, they were recovered from drought stress and ѰL, KL, SS, SD, E, Pn, and gs were determined. Under the drought, Ym lost KL whereas; Dy7 could maintain KL and higher midday ѰL and lower SD than Ym. The cultivar Dy7 showed maximum recovery of KL, ѰL, Pn, gs and E than Ym upon re-watering. The loss and recovery of KL, ѰL, Pn, E, gs and SD is controlled genetically in naked oat cultivars in combination with the environmental factors and the cultivar Dy7 has potential to enhance drought resistance in crops plants by genetic crop breeding. © 2021 Friends Science Publishers

First Report of Colletotrichum cereale Causing Anthracnose on Avena nuda in China

Naked oats (Avena nuda L.) is rich in protein, fat, vitamin, mineral elements and so on, and is one of the world's recognized cereal crops with the highest nutritional and healthcare value. In July 2019, leaf spot was detected on A. nuda in Zhangbei experimental station of Hebei Agricultural University. The incidence of disease is 10% to 20%. The symptoms were similar to anthracnose disease, the infected leaves had fusiform or nearly fusiform yellowish-brown spots, yellow halo around the spots. Numerous acervuli with black setae diagnostic of fungi in the genus Colletotrichum were present on necrotic lesions. To identify the pathogen, ten symptomatic leaves were collected, and only one disease spot was isolated from each leaf. Small square leaf pieces (3 to 5 mm) were excised from the junction of diseased and healthy tissues with a sterile scalpel and surface disinfested with 75% alcohol for 30s, 0.1% corrosive sublimate for 1 min, rinsed three times in sterile water. Plant tissues were then transferred on potato dextrose agar (PDA), and incubated at 25°C for 7 days. Two fungal isolates were obtained and purified by single-spore isolation method. All fungi have the same morphology and no other fungi were isolated. The aerial mycelium was gray black. The conidia were colorless and transparent, falcate, slightly curved, tapered toward the tips, and produced in acervuli with brown setae. The length and width of 100 conidia were measured and size ranged from 1.86 to 3.84 × 8.62 to 29.81 μm. These morphological characteristics were consistent with the description of Colletotrichum cereale (Crouch et al. 2006). To further assess the identity of the species, the genomic DNA of two fungal isolates (LYM19-4 and LYM19-10) was extracted by a CTAB protocol. The ribosomal DNA internal transcribed spacer (ITS) region as well as, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), and the beta-tubulin 2 (Tub2) partial genes were amplified and sequenced with primers ITS4/5, GDF/GDR, ACT-512F/ACT-783R, and T1/Bt2b, respectively (Carbone et al. 1999; Templeton et al. 1992; O'Donnell et al. 1997; Glass et al. 1995). The sequences of the ITS-rDNA region (MW040121, MW040122), the GAPDH sequences (MW052554, MW052555), the ACT sequences (MW052556, MW052551) and the Tub2 sequences (MW052552, MW052553) of the two single-spore isolates were more than 99% identical to C. cereale isolate CGMCC3.15110 (JX625159, KC843517, KC843534 and JX625186). Maximum likelihood tree based on concatenated sequences of the four genes were constructed using MEGA7. The results showed the strains isolated from A. nuda were closely related to C. cereale, as supported by high bootstrap values. A pathogenicity test of the C. cereale isolates was performed on first unfolding leaves of A. nuda. Koch's postulates were carried out with isolates by spraying a conidial suspension of 106 conidia/mL on leaves of healthy A. nuda. Four replicated pots were inoculated at a time, 10 leaves each pot, while sterile distilled water was used as the control. All treated plants were placed in a moist chamber (25°C, 16-h light and 8-h dark period). Anthracnose symptoms developed on the inoculated plants 7 days post inoculation while all control plants remained healthy. Microscopic examination showed the surface of infected leaves had the same acervuli, setae, and conidia as the original isolate. The pathogenicity test was repeated three times. C. cereale was previously reported as the causal agent of anthracnose on feather reed grass in US (Crouch et al. 2009). To our knowledge, this is the first report of C. cereale as the causal agent of A. nuda anthracnose in China.

Differences in Physiological Responses of Two Oat (Avena nuda L.) Lines to Sodic-Alkalinity in the Vegetative Stage

Sodic-alkalinity is a more seriously limiting factor in agricultural productivity than salinity. Oat (Avena nuda) is a salt-tolerant crop species and is therefore useful in studying the physiological responses of cereals to alkalinity. We evaluated the differential effects of sodic-alkalinity on two naked oat lines, Caoyou1 and Yanke1. Seedlings of the two lines were exposed to 50 mM alkaline salt mixture of NaHCO3 and Na2CO3 (18:1 molar ratio; pH 8.5) for 2 weeks in a soil environment. Sodic-alkalinity exposure led the assimilation of abundant Na+ at similar concentrations in the organs of both lines. However, Caoyou1 showed much stronger growth than Yanke1, exhibiting a higher dry weight, total leaf area, and shoot height under sodic-alkalinity. Further analysis showed that Caoyou1 was more sodic-alkalinity tolerance than Yanke1. This was firstly because of differences in the oxidative stress defense mechanisms in leaves of the two lines. Antioxidant enzyme activities were either slightly elevated (catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GP), glutathione reductase (GR)) or unaltered (superoxide dismutase (SOD)) in Caoyou1 leaves, but some enzyme (SOD, GPOX, GR) activities were significantly reduced in Yanke1. AnAPX1 transcript levels significantly increased in Caoyou1 under sodic-alkalinity conditions compared with Yanke1, indicating its better antioxidant capacity. Secondly, the related parameters of Mg2+ concentration, phosphoenolpyruvate carboxylase (PEPC) activity, and AnPEPC transcript levels in the leaves showed significantly higher values in Caoyou1 compared with Yanke1. This demonstrated the effective utilization by Caoyou1 of accumulated HCO3− in the irreversible reaction from phosphoenolpyruvate to oxaloacetate to produce inorganic phosphorus, which was elevated in Caoyou1 leaves under alkalinity stress. Overall, the results demonstrated that the greater sodic-alkalinity tolerance of Caoyou1 is the result of: (1) maintained antioxidant enzyme activities; and (2) a higher capacity for the phosphoenolpyruvate to oxaloacetate reactions, as shown by the higher PEPC activity, Mg2+ concentration, and total phosphorus concentration in its leaves, despite the lower soil pH.

PECULIARITIES OF NAKED OAT GRAIN AS A CEREAL CULTURE

Archaeological excavations show that oats were known as early as the Bronze Age, from about 1500-1700 BC. According to various historical data, the homeland of the oat culture forms is Southern Europe, Northeast China and Mongolia. The first archeological findings of oat grain were discovered in Germany and date back to the I-VI c. In Kievan Rus oats began to grow from about the VI. For many centuries, oats have been an important feed and foof grain,and with the beginning of the twentieth century there is an increase in its use in agriculture and processing. Widespread products of oat processing in different countries of the world are groats, cereals, flour and food bran, in addition to traditional products produce instant cereals, muesli, various intended semi-finished products. Oats are also widely used in other industries: it is additionally used in the production of beer, oat milk, ice cream, bread, cookies, baby food, etc. In Ukraine, oats are grown mainly as ancillary technical culture. The area of crops is from 5000 to 6000 km2. The main production is concentrated in Polissia and Forest-Steppe, mainly spring oats are grown, to a lesser extent semi-winter and winter forms. According to the State Statistics Service of Ukraine, the gross grain harvest in the last 5-7 years has increased and is at the level of 458 ... 616 thousand tons of grain per year. Over the past 20 years, oat production in Ukraine has been declining, due to the fact that most of it is grown for cereals, with a relatively small crop yield and high cultivation costs, even with the use of state-of-the-art agrotechnology. About 60,000 tonnes of oats are used annually to meet the needs of the domestic groats industry. Breeders have received new grains that have increased nutritional and technological value. Considering new varieties of oats, it is possible to distinguish naked forms of Avena nuda (naked oats). In the world, naked oats is a valuable crop that has a consistently high nutritional value that allows it to be used in various industries. This type of oat is derived by the method of individual selection from a cross-hybrid population. The variety of this oat is inermis, morphologically different from the hull varieties by the structure of the spikelets, which determines the peculiarities of its quantitative and qualitative indicators The peculiarity of naked oats is the absence of flower hulls firmly bound to the grain surface (20 ... 40% in oat hulled forms), which significantly improves its properties. The hulls in the naked varieties are soft, do not cover the grain very tightly and are almost completely separated in the process of grain harvesting and threshing.