الفهرس 
Contentsيوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
5-SUMMARY AND CONCLUSION : Studies on the effect of some treatments which reduce the injury of high temperature on yield and its quality for sweet pepper crop under late season. In nature, plants often face the challenge of severe environmental conditions such as high-temperature stress that exert adverse influences on plant growth and development causing considerable losses in the crop productivity. So, two field experiments were carried out at a private farm located in Khelala Village, Bilqas District, Dakahlia Governorate, Egypt, during the two successive summer seasons of 2018 and 2019 to investigate the effect of some treatments which reduce the injury of high temperature on sweet pepper grown in late summer season. Three different levels of covering plants by net shading (50, 63 and 75%), two different planting distances (30, 40 and 50 cm) and two foliar spray rates of potassium silicate (750 and 1500 ppm) and control treatment were investigated. Nine treatments were arranged in a randomized complete block design with three replications. The results obtained could be summarized as follows: 1. Vegetative Growth characteristics. The covering plants by net shading at 75% is the superior treatment compared to other treatments, while the control treatment gives the lowest values of all growth parameters in the both seasons, except the number of branches/plant at 60 days period in the first season which gives the lowest value with covering plants by net shading (50 %) followed by control treatment, such effect was the same during the both investigated seasons. 2. Chemical Composition of Plant Foliage. There are a significant increase of values of N, P and K percentages in leaves of sweet pepper plants due to all investigated treatments compared to control treatment (untreated plants) which gives the lowest values of N, P and K (%) in leaves at all growth stages, where 75% shade is the superior treatment at two growth stages (60, 90 days after transplanting), while, planting distance 30 cm gives the highest values of N, P and K percentages in leaves of sweet pepper plants at 120 days after transplanting. 3. Fruit Setting and Falling Percent. The plants sprayed with potassium silicate at rate of 1500 ppm give higher fruit setting % in the both studied seasons. On the other hand, the less falling % is recorded when distance between cultivated plants is 50 cm in the first season, while the less falling % in the second season is recorded at 1500 ppm K2SiO3. In the first season, all treatments, except shade 50 % and shade 63 % treatments give fruit setting % more than control treatment and falling % less than control treatment, where shade 50 % and shade 63 % treatments record the lowest fruit setting and the highest falling percent compared to other treatments. In the second season, all treatments, except shade 50 % only, give the highest fruit setting % and lowest falling % compared to control treatment, where shade 50 % records the lowest fruit setting (20.13 in the second season) and the highest falling percent (79.87 % in the second season) compared to other treatments. 4. Fruit Physical and Chemical characteristics. Regarding to fruit physical characteristics i.e. fruit length, diameter and flesh thickness and some fruit chemical characteristics i.e. N, P and K (%), vitamin C and TSS of sweet pepper plants at three different stages from transplanting (after 60, 90 and 120 days) of sweet pepper plants as affected by different treatments, all treatments in the both seasons have a significant increase compared to control treatment . On the other hand, covering plants by net shading at 75% is the superior treatment, while the control treatment gives the lowest values in the both seasons. 5. Early, Mid and late yield as number of fruits and fruit weight. All treatments show a positive effect on early, mid and late yield as fruit weight and number of fruits, where the values at all investigated treatments significantly increase compared to control treatment (T9),while T8 treatment (1500 ppm K2SiO3) is the superior treatment compared to the others. This trend was realized under both seasons. The highest values of all aforementioned yield traits are recorded with spraying 1500 ppm K2SiO3 followed by spraying 750 ppm K2SiO3 followed by planting distance 50 cm then 75% shade, while the control treatment gives the lowest values of all aforementioned yield traits in the both seasons. 6. Total yield as number of fruits and fruit weight per plot and feddan. All treatments show a positive effect on total yield as number of fruits and fruit weight per plot and feddan of sweet pepper plants, where the values at all investigated treatments significantly increase compared to control treatment (T9),while T8 treatment (1500 ppm K2SiO3) is the superior treatment compared to the others. This trend was realized under both seasons. The highest values of total yield as number of fruits and fruit weight per plot and feddan of sweet pepper plants are recorded with spraying 1500 ppm K2SiO3 followed by spraying 750 ppm K2SiO3 followed by planting distance 50 cm then 75% shade, while the control treatment gives the lowest values of total yield as number of fruits and fruit weight per plot and feddan of sweet pepper plants traits in the both seasons. CONCLUSION : Generally, according to the obtained results, all investigated treatments positively affected on most studied parameters as compared to control treatment, where covering plants by net shading at the level of 75% gave the best values of all studied traits. Also, planting distance (50 cm) gave the best values of all studied traits as compared to (30 and 40 cm). As well as foliar application with K2SiO3 at rate of 1500 ppm led to increasing growth and flowering parameters, yield and its components. It can be concluded that, shading at the level of 75% with plants spacing (50cm) and foliar application of K2SiO3 at rate of 1500 ppm twice (at period of 45 days from transplanting and flowering stage) may be very beneficial to improve the growth of sweet pepper plants and obtain the highest fruits quality under high temperature stress.