Comparison of Salt Exclusion in Muscadine and Interspecific Hybrid Grapes Using a Greenhouse Screening Procedure

Bunch grapes (Euvitis) are classified as moderately salt-tolerant. However, little is known about the salt tolerance of muscadine grapes (Vitis rotundifolia). The objective of this research was to evaluate the salt exclusion capacity of muscadine grapes relative to common bunch grape rootstocks and hybrid winegrapes using a greenhouse screening assay. In two separate experiments, 31 muscadine, six bunch grape rootstocks, and five hybrid winegrape cultivars were irrigated daily with a 25-mm sodium chloride salt solution for a period of 14 d, followed by a destructive harvest to determine sodium (Na) and chloride (Cl) concentrations in root and shoot tissues. Generally, the muscadines studied exhibited a greater range of salt concentration relative to bunch grape rootstocks. Total tissue (shoot and root) salt varied by 250% and 430% across muscadines and by 180% and 190% across bunch grape rootstocks for Na and Cl, respectively. Despite the wider range, muscadine grapes expressed significantly less leaf necrosis than the bunch grape rootstocks. The most effective salt-excluding muscadines, ‘Janebell’, ‘Scuppernong’, ‘Late Fry’, and ‘Eudora’, were not distinguishable from the bunch grape rootstocks [‘Paulsen 1103’ (1103P), ‘Ruggeri 140’ (140Ru), ‘Schwarzmann’, ‘Millardet et de Grasset 101-14’ (101-14 Mgt.), ‘Millardet et de Grasset 420A’ (420A), and ‘Matador’]. Overall, there was no discernable difference between the salt exclusion capacity of muscadine and bunch grapes. The hybrid winegrape ‘Blanc Du Bois’ displayed poor Na and Cl exclusion properties but showed only moderate leaf necrosis symptoms. In both experiments, ‘Blanc Du Bois’ accumulated more than two-fold higher root and shoot concentrations of Na and Cl compared with the best-performing rootstocks (1103P, 140Ru, 101-14 Mgt.), suggesting that ‘Blanc Du Bois’ could benefit from grafting if salinity is a limiting factor.

Effect of Seed Priming with Potassium Nitrate on the Performance of Tomato

The seed industry and farmers have challenges, which include the production of poor quality and non-certified tomato seed, which ultimately results in decreased crop production. The issue carefully demands pre-sowing treatments using exogenous chemical plant growth-promoting substances. Therefore, to mitigate the above-stated problem, a series of experiments were conducted to improve the quality of tomato seeds (two cultivars, i.e., “Sundar” and “Ahmar”) and to enhance the stand establishment, vigor, physiological, and biochemical attributes under growth chamber and greenhouse conditions by using potassium nitrate (KNO3) as a seed priming agent. Seeds were imbibed in 0.25, 0.50, 0.75, 1.0, and 1.25 KNO3 (weight/volume) for 24 h and then dried before experiments. The results of growth chamber and greenhouse screening show that experimental units receiving tomato seeds primed with 0.75% KNO3 in both cultivars performed better as compared to other concentrations and nonprimed control. Significant increase in final emergence (%), mean emergence time, and physiological attributes were observed with 0.75% KNO3. Collectively, the improved performance of tomato due to seed priming with 0.75% KNO3 was linked with higher activities of total soluble sugars and phenolics under growth chamber and greenhouse screening.

New design of the device to prevent overheating the greenhouse from solar radiation in the warm period

The article describes the optimal temperature regimes for vegetable crops and discusses the existing methods of protecting the greenhouse from solar radiation during the warm period. Based on the analysis of existing devices, a new design of the greenhouse screening device, which allows reducing the temperature by 5…8 ° C is proposed.

Screening a set of tomato parental lines and their hybrids for resistance to early blight (Alternaria solani) by detached leaf method

Nine parental lines and 18 hybrids derived by crossing them in Line × Tester fashion were screened against the early blight pathogen Alternaria solani along with a resistant, susceptible and a commercial check in the form of Arka Rakshak, IIHR2202 and Abhinava respectively. Parental lines and the resistant and susceptible checks were screened over two seasons and results obtained were almost similar with the line IIHR1816 exhibiting resistance with the disease severity of 25 % in both the trials, while the line IIHR977 was found to be resistant in the first season with PDI of 25 % and moderately resistant in the second season with the slightest increase in the disease severity up to 25.6 %. None of the hybrids were found to be resistant except, whereas about eight hybrids were found to be moderately resistant. IIHR2892 x IIHR2853 was found to be highly susceptible with severity of 68.75 %, which is on par with the susceptible check IIHR2202 (70.50 %). The results obtained from the detached leaf method of screening should be confirmed by the field or greenhouse screening methods before using them in further breeding programmes.

Detached-Leaflet Evaluation of Tomato Germplasm for Late Blight Resistance and Its Correspondence to Field and Greenhouse Screenings

Breeding for disease resistance requires efficient techniques for screening large plant populations. Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of tomato (Solanum lycopersicum) worldwide, and there is a great interest in developing cultivars with resistance to this pathogen. Screening for LB resistance is commonly conducted under field or greenhouse conditions using whole plants. In a previous study, we demonstrated correspondence between field and greenhouse screening of tomato for LB resistance. Here, we report the use of a detached-leaflet assay for such screening. Seventy-two genotypes from two tomato species, varying in degree of resistance and susceptibility to LB, were evaluated in two replicated experiments for response to LB in a detached-leaflet assay, and the results were compared with those previously obtained from field and greenhouse screening of the same genotypes. There were significant (P < 0.001) positive correlations between replications (average r = 0.75) and experiments (average r = 0.72), suggesting that the detached-leaflet experiments were consistent. Further, there were significant (P < 0.001) positive correlations between responses in the detached-leaflet assay and those from field (r = 0.82) and greenhouse screenings (r = 0.84), suggesting reliability of the detached-leaflet assay. The results indicate the utility of the detached-leaflet assay for evaluating tomato for LB resistance, which may facilitate screening of large breeding populations.

Wheat takeall lessons learned during a search for effective biological control

Takeall (causal agent Gaeumannomyces graminis var tritici) is one of the most important soilborne diseases of wheat Greenhouse screening of microorganisms for disease suppression was conducted using a targeted approach that focused on the fungal genus Trichoderma In spite of indications of disease suppression in preliminary assays effective biocontrol was not observed in subsequent tests Explanations for this apparent loss of disease suppression could include insufficient numbers of potential biocontrol agents screened during the selection process or the issue of falsepositive (type 1 error) results

A Rapid Greenhouse Screening Method to Identify St. John’s Wort (Hypericum perforatum) Accessions Resistant to Colletotrichum gloeosporioides

Anthracnose is a major production constraint for st. john’s wort (Hypericum perforatum L.) caused by the fungus Colletotrichum gloeosporioides (Penz.). A greenhouse screening method based on mortality was developed to eliminate accessions susceptible to anthracnose in the early stage of breeding for resistant cultivars. The mortality of 22 accessions of st. john’s wort artificially inoculated with a strain of C. gloeosporioides was highly correlated between three greenhouse experiments (r = 0.799 to 0.923), even when done at two different places. The response of the greenhouse screening was equally highly correlated to the mortality in the field tested at two sites naturally infested with C. gloeosporioides (r = 0.700 to 0.865) but less well correlated with the mortality at a third field site (r = 0.495 to 0.672). Yield of st. john’s wort was highly correlated with mortality (r = –0.747 to –0.846) at all three field sites, but a significant interaction between accession and site was observed. Therefore, an improvement of anthracnose resistance of st. john’s wort should be based on a greenhouse screening of seedlings followed by multiple-site field testing of adult plants.