الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Due to the mowing is a fundamental management for turfgrass development, the purpose of this investigation was to study the effectiveness of two growth regulating chemicals at different rates in retarding paspalum growth and evaluate their impact on paspalum visual quality as well as growth parameters with a special focus on photosynthetic pigments to determine the optimum concentrations of regulators needed and to assess the extent of damage and rate of recovery from high concentrations of these substances. To examine this, two types of plant growth regulators i.e. paclobutrazol and cycocel at different rates (50, 100, 150 mg/l for the 1st substance and 1000, 2000, 3000 mg/l for the 2nd substance) were evaluated with seashore paspalum turf during the two successive seasons of 2020 and 2021. The obtained results could be summarized as follows: Vegetative Growth Parameters and Photosynthetic Pigments Clipping fresh and dry weight (g/m2) Spraying seashore paspalum turf grown in alluvial soil or sandy soil with either paclobutrazol or cycocel led to a significant decrease in clipping fresh and dry weights, where spraying plants with cycocel caused suppression more than spraying plants with paclobutrazol. However, the plants untreated possessed the highest values, while the lowest values were recorded with plants sprayed with cycocel at a rate of 3000 mg/l followed by those sprayed with 2000 mg/l followed by those sprayed with 1000 mg/l then those sprayed with paclobutrazol at a rate of 150,100 and 50 mg/l, respectively. Photosynthetic pigments The foliar application of both paclobutrazol and cycocel caused a significant decline in the contents of photosynthetic pigments i.e., chlorophyll a and b and carotene of seashore paspalum turf grown in either alluvial or sandy soil.Under alluvial and sandy conditions, the plants untreated with plant growth regulators under study possessed the highest contents of aforementioned photosynthetic pigments, whilst the sequence order of growth regulator treatment from the most suppressing to less was as follows: Plants sprayed with 3000 mg/l cycocel> 2000 mg/l cycocel > 1000 mg/l cycocel> 150 mg/l paclobutrazol > 100 mg/l paclobutrazol > 50 mg/l paclobutrazol.It could be said that cycocel at the different rates under study had a suppression effect more than paclobutrazol at the different studied rates. Also, the obtained findings confirmed that the effect of both paclobutrazol and cycocel on the contents of the aforementioned photosynthetic pigments was consistent in the three times cuts. nNumber of days from the mowing date to reaching a height of 6 cm (N. D.) The number of days from mowing date to reaching a height of 6 cm significantly affected owing by foliar application treatments, where both paclobutrazol and cycocel led to the lateness of reaching a height of 6 cm compared with the corresponding plants untreated.Generally, in both studied seasons, the highest value of number of days was recorded when plants were sprayed with cycocel at a rate of 3000 mg/l, while the lowest one was realized with plants untreated. This trend was consistent in the three times cuts either under alluvial or sandy conditions. Also, the lateness of reaching a height of 6 cm resulted from foliar application of cycocel was greater than that of paclobutrazol. N, P, K, total carbohydrate and proline content N, P and K content The plants untreated possessed the highest values of N, P, and K (%), while the lowest values were noticed in plants sprayed with cycocel at a rate of 3000 mg/l followed by those sprayed with 2000 mg/l followed by those sprayed with 1000 mg/l then those sprayed with paclobutrazol at rates of 150,100 and 50 mg/l, respectively. The effect of both paclobutrazol and cycocel on nutrient elements i.e., N, P and K, was consistent in the three times cuts. The same trend was found concerning plants grown on both study soils taking on considering that the performance of paspalum under sandy conditions was better than that under alluvial conditions. Total carbohydrate and proline Concerning total carbohydrate (%), spraying seashore paspalum turf grown in alluvial soil or sandy soil with either paclobutrazol or cycocel led to a significant decrease in total carbohydrate content (%), where spraying plants with cycocel caused suppression more than spraying plants with paclobutrazol. However, the untreated plants possessed the highest values of total carbohydrate (%), while the lowest ones were recorded with plants sprayed with cycocel at a rate of 3000 mg/l followed by those sprayed with 2000 mg/l followed by those sprayed with 1000 mg/l then those sprayed with paclobutrazol at rates of 150,100 and 50 mg/l, respectively. In contrast, regarding seashore paspalum plant’s self-production of proline, the spraying seashore paspalum turf grown in alluvial soil or sandy soil with either paclobutrazol or cycocel led to raise the content of proline (µmol/g) in clippings fresh weight of the three cut times compared with the corresponding plants without foliar application and that to scavenge the free radicals in tissues of seashore paspalum plants resulting due to exogenous application of both paclobutrazol and cycocel stress. Root Growth Parameters The foliar application of both paclobutrazol and cycocel at all rates under study significantly suppressed the performance of seashore paspalum turf compared to the corresponding plants without foliar application (control treatment) under both alluvial and sandy conditions and this finally reflected in root traits.Spraying seashore paspalum turf grown in alluvial soil or sandy soil with either paclobutrazol or cycocel led to a significant decrease in fresh and dry weight of roots (g/m2) and root length (cm) of seashore paspalum turf, where spraying plants with cycocel caused suppression more than spraying plants with paclobutrazol. However, the plants untreated possessed the highest values of all aforementioned traits, while the lowest values were recorded with plants sprayed with cycocel at rate of 3000 mg/l followed by those sprayed with 2000 mg/l followed by those sprayed with 1000 mg/l then those sprayed with paclobutrazol at a rate of 150,100 and 50 mg/l, respectivel. CONCLUSION According to the aforementioned results of this investigation it can be concluded that both paclobutrazol and cycocel at all rates of study caused suppressed the paspalum growth and lateness of reaching a height of 6 cm and thus reducing mowing frequency. Also, it can be concluded that the performance of seashore paspalum grown on sandy soil was better than that grown on alluvial soil due to the aeration was better under sandy soil conditions. Economically, it can be recommended that the best treatment is the foliar application of paclobutrazol at a rate of 150 mg/l, and the foliar application of cycocel at a rate of 1000 mg/l may also be useful.