Parthenocarpic Cucumber Cultivar Evaluation in High-tunnel Production

Fresh-consumed parthenocarpic cucumbers (Cucumis sativus) are a popular and high-value crop sold in local food markets. The parthenocarpic plant characteristics and climbing growth habit make cucumbers an ideal crop for high-tunnel production. Major types of parthenocarpic cucumbers include Beit alpha and mini, Dutch greenhouse, American slicer, and Japanese. Information regarding yield performance, plant growth, and disease resistance of the four types grown in high-tunnel conditions is limited. In this study, 16 parthenocarpic cucumber cultivars from the four major types were evaluated in high tunnels at three locations in Indiana and Illinois during Spring 2018. Plants were pruned to a single stem that was supported on a string. At all locations, the cultivars that had the most total yields were Beit alpha and mini, although their total yields were not always significantly higher than that of all the others. However, Beit alpha and mini cucumbers had high percentages of unmarketable fruit, mainly because of insect feeding damage and mechanical injuries on the skins that led to scarred fruit. Dutch greenhouse cultivars had relatively lower marketable yields at two of the three locations where there was a high percentage of misshaped fruit. ‘Tasty Green’ Japanese cucumber consistently had the lowest yields at all three locations. This cultivar also produced the most side shoot growth and, therefore, more pruning waste. The Japanese types ‘Tasty Jade’ and ‘Taurus’ had yields comparable to those of other cultivars, and they were more tolerant to two-spotted spider mites (Tetranychus urticae). However, ‘Tasty Jade’ was the cultivar most susceptible to powdery mildew (Podosphaera xanthii and Golovinomyces cichoracearum). ‘Corinto’ American slicer cucumber had relatively high yields at two of the three locations. This cultivar also had the highest percentage of marketable fruit. Information provided in the study is readily useful for growers using high tunnels when selecting parthenocarpic cucumber cultivars. It is also valuable for seed companies wishing to breed new cultivars adaptive for high-tunnel production.

Relationship between the Hormonal Balance and the Regulation of Iron Deficiency Stress Responses in Cucumber

Some studies suggest that iron (Fe) stress root responses are regulated by variations in specific plant hormones. However, this question remains unclear. A time-course experiment dealing with the relationship between the expression of the Fe-stress root responses at transcriptional (CsFRO1, CsIRT1, CsHA1, and CsHA2) and enzymatic levels [root Fe(III)-chelate reductase and plasma membrane H+-ATPase], and the variation of phytohormone concentrations in the shoot and root of Fe-starved plants have been studied in a Fe-efficient cucumber cultivar (Cucumis sativus L. cv. Ashley). The results indicate that the expression over time of the physiological Fe-stress root responses at transcriptional and enzyme activity levels are consistent with significant increases in indole-3-acetic acid root (transient) and shoot (sustained) concentrations. Fe-starvation also caused transient changes in the root concentration of abscisic acid and nitric oxide. Finally, an increase in root ethylene production and a decrease in the root concentration of some cytokinins were observed under Fe starvation, but they were not clearly timely coordinated with the expression of Fe physiological root responses.

Susceptibility level of cucumber downy mildew (Pseudoperonospora cubensis) to metalaxyl

Level of susceptibility of Pseudoperonospora cubensis isolate from Ratkovo to metalaxyl in concentrations 50, 100, 200, 400 and 800 ?g/ml was investigated. The trials were conducted on cotyledon and fully developed young leaves using cucumber cultivar Haros. Reduced level of susceptibility was detected in metalaxyl concentrations of 50, 100 and 200 ?g/ml because the intensity of sporulation in these treatments was on the same level as in control. Sporulation was also observed on developed leaves treated with metalaxyl in concentrations of 400 and 800 ?g/ml.

Performance of Mahyco Green Long and Bhaktapur Local Cucumber Cultivars at Different Sowing Dates in Mid-Hill of Nepal

An experiment was conducted in split plot design with three replications to determine the optimum date of sowing for commercial cultivation of cucumber at Lamjung Campus, Sundarbazar (750 m asl), Lamjung during December 1999 to November 2000. The cvs. Green Long and Bhaktapur Local were used in the main plot and the sowing dates in the sub-plot. Sowings were done on the 15th of the months December 1999 and February, April, June and August 2000 at an interval of two months. Manure and fertilizers were applied @ 20 t farm yard manure and 120:60:50 NPK kg/ha in all the sowings. Yield attributing characters such as plant stand, vine growth, first male and first female flowers bearing nodes, number of female flowers per plot, sex ratio and number of harvests were insignificantly different in December and February sowings. However, the periods of phenophases such as sowing to the first male and first female flowers and sowing to first harvest and last harvest were significantly longer at December sowing followed by those at February sowing. The three latter sowings showed poor performance in respect to those characters. February sowing produced significantly the highest number of marketable fruits (79.16 thousand/ha) and marketable yield (53.97 t/ha) than the earlier December and three latter sowings. The December sowing also produced significantly higher marketable yield (23.76 t/ha) than June and August sowings. Hence, the cvs. Green Long and Bhaktapur Local could not produce economic yields at April, June and August sowings at Sundarbazar (middle hill) Lamjung. Key words: Cucumber cultivar, sowing date, marketable yield J. Inst. Agric. Anim. Sci. 26:163-166 (2005)

Performance of Three Selection Cycles from Four Slicing Cucumber Populations Hybridized with a Tester

Recurrent selection has been used as a breeding method to improve traits having low heritability such as fruit yield, earliness, and fruit shape. The objective of this study was to measure the progress of recurrent selection in four slicing cucumber populations in terms of hybrid performance when crossed with a common tester. The four populations, North Carolina wide-base slicer (NCWBS), medium-base slicer (NCMBS), elite slicer 1 (NCES1), and Beit Alpha 1 (NCBA1) populations, which differed in their genetic diversity and mean performance, were developed using modified intrapopulation half-sib recurrent selection to improve fruit yield and quality. Eleven S0 families were taken randomly from each of three selection cycles (early, intermediate, and advanced) from each population. Those families were self-pollinated to form S1 families, and the S1 families were crossed to `Poinsett 76', a popular slicing cucumber cultivar. The experiment was a splitplot treatment arrangement in a randomized complete-block design with 22 replications per population, with the four populations as whole plots and the three cycles as subplots. When 10% of fruit were oversized (>60 mm in diameter), plants were sprayed with paraquat to defoliate them for once-over harvest. Plots were evaluated for total, early, and marketable yield and fruit shape. Recurrent selection for improved fruit yield and shape per se resulted in improved hybrid performance of the NCWBS and NCBA1 populations for fruit yield and shape rating when tested in the selected or nonselected environment. The NCWBS population had the largest gain (21%) in hybrid performance averaged over all traits. In addition, early yield was improved an average of 18% from early to late cycles for each population. Even though the fruit yield and shape rating of `Dasher II' was greater than the hybrid performance of each population mean for the same traits, several F1 families within each population exceeded the fruit yield of `Dasher II'.