In order to explore the preliminary effect of 1-MCP application at seedling stage on the growth effect and yield of open field cucumber, this experiment conducted cultivation experiments on three application periods (leaf spraying at one leaf stage, 2 days before planting, spraying after the third harvest), two treatment times (one treatment, two treatment), and two management methods (removing the first and second female flowers, and conventional management). The results showed that in the open field cucumber cultivation experiment, the application of 1-MCP at seedling stage could promote the growth of cucumber, and the T4 treatment was the best, and the second treatment was better than the first treatment; T4 (0.35 mL 1-MCP + treatment 2 days before colonization + after the third harvest + routine management) treatment scheme had the best effect.
Cucumber Variety ‘Drite L108’ (Cucumis sativus L. Cv. Derit L108) was selected as the test material. In the solar greenhouse, different days (1, 3, 5, 7, 9 d) of light (PAR < 200 µmol·m-2·s-1) and normal light conditions were designed with shading nets to observe the growth indexes of cucumber plants and the changes of antioxidant enzyme activities in leaves. The results showed that: (1) continuous low light increased the SPAD (relative chlorophyll) value of cucumber leaves and decreased the net photosynthetic rate. The longer the continuous low light days are, the smaller the net photosynthetic rate of cucumber leaves and the worse the photosynthetic recovery ability would be. (2) The plant height, stem diameter and leaf area per plant were lower than CK, and the above indexes could not return to the normal level after 9 days of normal light recovery; the yield and marketability of cucumber fruit decreased under continuous low illumination. (3) The activities of SOD (superoxide dismutase) and POD (peroxidase) in cucumber leaves increased, the activities of CAT (catalase) first increased and then decreased, and the content of MDA (malondialdehyde) continued to increase. The longer the days of continuous light keep, the more seriously the cucumber leaves were damaged by membrane lipid peroxidation. After continuous light for more than 7 days, the metabolic function of cucumber leaves was difficult to recover to the normal level.
Dormancy is a state of lack of germination/sprouting in seed/tuber although required conditions (temperature, humidity, oxygen and light) are provided. Dormancy is based on hard seed coat dormancy or lack of supply and activity of enzymes (internal dormancy) necessary for germination/sprouting. Dormancy is an important factor limiting production in many field crops. Several physical and chemical pretreatments to production material (seed/tuber) are carried out for overcoming dormancy. Physical and physiological dormancy can be found together in some plants and this event makes it difficult to provide high frequency healthy seedling growth. Whereas, emerging of all production material (seed, tuber) sown/planted and forming healthy seedling are prerequisites of plant production.
In order to explore the application of the new integrated intelligent spore capture system developed in China in the prediction of cucumber downy mildew and cucumber powdery mildew, the main working parameters of the integrated intelligent spore capture system, such as the presence or absence of air cutting head, the height of air collection port and the time of air collection, were optimized by identifying the morphology of captured spores in the case of natural disease in the field. The relationship between the disease index of cucumber downy mildew and cucumber powdery mildew in greenhouse and the amount of spores captured was analyzed through the dynamic monitoring of disease and spores. The results show that when the air cutting head is not installed, the height of the air collection port is 70 cm, and the period of 10: 00–10: 30 was beneficial to the capture of spores. The disease index of cucumber downy mildew and cucumber powdery mildew had a strong positive correlation with the total amount of spores captured for 7 consecutive days. Continuous monitoring of cucumber downy mildew sporangia and rapid increase in the number is a predictor of the occurrence or rapid increase of cucumber downy mildew. The conidia of cucumber powdery mildew were not detected before the disease onset, and the number of conidia captured was still small at the peak of the disease. The research shows that the integrated intelligent spore capture system is suitable for the prediction of cucumber downy mildew, but there are still some problems in the prediction of cucumber powdery mildew.
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