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Effects of Soil Moisture Regimes, Rates of Nitrogen and Phosphate Fertilizer on Yield and Quality of Pitaya (Hylocereus undatus) Fruit.
|關鍵字:||pitaya;紅龍果;soil moisture regime;nitrogen fertilizer;phosphate fertilizer;土壤水分境況;氮肥;磷肥||出版社:||農藝學系||摘要:||
土壤水分境況處理與磷肥施用量處理交感對果實總產量、結果枝數及開花數均有極顯著影響。以低土壤水分張力(0.02MPa)為灌溉起點時，果實總產量、結果枝數目及開花數對磷肥施用量之反應均較中、高土壤水分張力(0.04MPa或0.06MPa)下高，且對磷肥施用量呈二次曲線關係，分別為Y(產量) = - 28000 + 45165 X - 12940 X2(R2 = 21.4% )，推薦用量為每叢每年1.745公斤磷酐;Y(結果枝數)= - 9.3 + 47.9 X - 15.0 X2(R2 = 11.2%)，推薦用量為每叢每年1.60公斤磷酐;及Y(開花數) = - 30.5 + 68.9 X - 19.6 X2(R2 = 7.8%)，磷肥推薦最適量為每叢每年1.76公斤磷酐。
Effects of Soil Moisture Regimes, Rates of Nitrogen and Phosphate Fertilizers on Yield and Quality of Pitaya (Hylocereus undatus ) Fruit.
Field experiments were conducted form December, 1999 through 2000 to investigate the effects of soil moisture regimes (SMR), rates of nitrogen and phosphate fertilizer on yield and quality of pitaya fruit. Field experiment was held at orchard in AES of National Chung Hsing University (Wufeng, Taichung). The experiment design was a split-split plot arranged in a randomized complete block with 5 replications. Whole plots were 3 levels of soil moisture regimes (0.02, 0.04,and 0.06MPa). Subplots were 2 rates of nitrogen (1.14 and 3.36 kg/plant-yr). The sub-subplot was 3 rates of phosphate (1.29, 1.73, and 2.18kg P2O5/plant-yr). Number of fruiting cladodes and flowers, and fruit yield were recorded to study the effects of treatments on vegetative growth and fruit yield of pitaya. Panel testing for sensory evaluation was held at July 13, Sep. 1 and Oct. 6, 2000 to evaluate the quality of early, mid and late period fruits. Chemical analyses of sugar contents were also conducted at NCHU to investigate the effects of treatments on fruit quality.
Experimental results indicated that the lower soil moisture tension practiced by increasing irrigation frequency, resulted in higher fruit yield, number of fruiting cladodes and flowers. Fruit yields of 0.04 and 0.06 MPa plots were declined 36.2 %and 39.4％, respectively, than that of 0.02 MPa plots. Number of fruiting cladodes of 0.02 MPa plot was the highest (26.3 cladodes/plant). Raising soil moisture tension to 0.04 and 0.06MPa reduced number of fruiting cladodes by 22.2% and 37.4%, respectively. Number of flowers from 0.02 MPa plot was also the highest (27.39 flowers/plant). Increasing soil moisture tension to 0.04 and 0.06MPa reduced number of flowers by 36.9% and 41.3%, respectively.
Effects of phosphate significantly affected fruit yield and number of cladodes. High phosphate rate (2.18kgP2O5/plant-yr) resulted in the highest fruit yield (12982kg/ha). Lower rates of phosphate reduced fruit yield by 8.8%(1.73 kg P2O5/plant-yr) and 9.4%(1.29 kg P2O5/plant-yr), respectively.
SMR and rates of phosphate showed significant interaction on fruit yield, number of fruiting cladodes and flowers. Fruit yield, number of fruiting cladodes and flowers showed a better response to rates of phosphate application in 0.02MPa than that in 0.04 and 0.06MPa plots. The quadratic equations of response for fruit yield was Y = - 28000 + 45165 X - 12940 X2 (R2 = 21.4%, optimal input: 1.745kg P2O5/plant), number of fruiting cladodes was Y = - 9.3 + 47.9 X - 15.0 X2 (R2 = 11.2%, optimal input: 1.60kg P2O5/plant) and number of flowers was Y = - 30.5 + 68.9 X - 19.6 X2 (R2 = 7.8%, optimal input: 1.76kg P2O5/plant) to rates of phosphate under 0.02MPa irrigation starting point. Phosphate showed poor responses for growth and yield of pitaya fruits under the treatments of 0.04 and 0.06 SMR.
Fruit shape, peel color, pulp appearance and overall evaluation of early fruit were all significantly promoted in 0.06MPa plot. But qualities of mid period fruit showed poor quality in 0.06 MPa plot. When bearing mid period fruit, pitaya plants need more irrigation than bearing early period fruit. Soil moisture stress obviously degraded qualities of pitaya fruit.
Qualities of late period fruits were significantly enhanced under low rate of nitrogen application. Under high rate of phosphate application, qualities of early and mid period fruits were promoted. But late period fruits showed a high quality under mid rate of phosphate application.
Interactions between SMR and rates of phosphate significantly affected fruit quality. High soil tension with high phosphate rate resulted in high quality of early fruit. Low soil moisture tension with high phosphate resulted in better mid and late fruit quality.
Analysis of carbohydrate contents in pitaya fruits showed that excessive nitrogen reduced concentration of sucrose thus reduced sweetness score of eating quality in panel testing. Score of sweetness and sucrose content were promoted under middle rate of phosphate and low rate of nitrogen.
Because pitaya is a kind of cactus crop, growers might have an incorrect impression that irrigation should be restricted to avoid root rotting. Actually, pitaya is originated from rainforests in Central America, which is warm and moist. Although pitaya is drought tolerant, irrigation can significantly increase yield and quality under well soil drainage condition. Phosphate also significantly increased yield and quality of pitaya fruit, and irrigation can promote its availability. It is suggested that keep soil moisture tension in the orchard at 0.02 MPa as starting point for irrigation, and application of 1.75kg P2O5 per plant is essential to a high fruit yield and quality of pitaya.
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