الفهرس 
Effect of Postharvest Treatments with Jasmonic Acid and Chlorpropham on Sprouting, Quality, and Storability of Potato TubersOnly 14 pages are availabe for public view
 |  | from | 109 |  |  |
| | | from | 109 | | |
Abstract
The present study was suggested as an attempt to investigate the effects of immersion potato tubers with chlorpropham and jasmonic acid, as well as, their interactions on physical and Chemical characteristics, as well as, sprouting and storability of potato tubers cv. Diamant which were harvested at its commercial maturity stage from a private farm at Kom Hamada, Behira Governorate, Egypt and then stored under cold storage.
The selection of tubers were based on its size (medium weight tubers approximately 100-150 gm), and the absence of physical injuries, mechanical damage and diseases infection. Tubers were packed in net plastic boxes (15 kg/ box) and surface-disinfected with 2% sodium hypochlorite for 2-4 minutes and then rinsed with tap water and air-dried.
The dried potato tubers were immersed in solutions containing chlorpropham (CIPC) at 0, 50, 75 and 100 ppm (CIPC0, CIPC1, CIPC2 and CIPC3, respectively) and jasmonic acid (JA) at 0, 0.001, 0.01 and 0.1 Mm JA/l (JA0, JA1, JA2 and JA3, respectively) either alone or in combinations for 20 minutes. The control treatments were dipped in tap water for 20 minutes. After that, the tubers were dried and cured in dark for one week at 20°C and 75% RH. The total number of the treatment combinations was (4x4=16 treatments). After curing, the tubers were placed in the dark cold storage room for long-term storage (140 days) at (10±1°C) and 85±5% relative humidity (RH) to evaluate their influence on shelf life of potato tubers.
A random sample of potato tubers were selected to determine physico-chemical characteristics before cold storage period (initial storage day) and every 28 days interval (6 storage periods) during cold storage
The experimental layout is a split plot system in completely randomized design (CRD) with three repetitions. The concentrations of chlorpropham and jasmonic acid distributed in the main and sub plots, orderly. The experimental unit were represent by 16 boxes )15 kg each). The experiment was performed in May 2017 season.
The obtained results could be summarized as follows:
1. Changes of Physico-chemical characteristics during long term storage
1.1. Regardless the application of CIPC or JA concentrations, the values of physical characteristics after the five tested period; 28, 56, 84, 112 and 140 days from cold storage tended to change as follows; hardness, dry matter content and PH seemed to slightly decline as compared to their initial values. However, virtual density, L/D percentage seemed to
99
maintain their values from elevation or declining. additionally, TSS exhibited higher mean values than their initial ones.
1.2. Concerning the changes in chemical characteristics after cold storage, it was noticed that tuber’s content of starch, TTA, vitamin C and total carbohydrates followed the same magnitude of all the five tested periods; 28, 56, 84, 112 and 140 days from storing, where, these traits exhibited lower mean values than their initial values before storage. Meanwhile, total, reducing and non-reducing sugars tended to be elevated compared with their initial values.
2. Effect of chlorpropham
2.1. Hardness and virtual density were, significantly, increased due to dipping potato tubers into CIPC solution at the rate of 75 ppm or 100 ppm compared to the lowest concentration CIPC1 (50 ppm). However, tuber’s L/D percentage, dry matter content and PH value did not appear to be significant by applying various CIPC concentrations. The highest significant mean values of TSS obtained by immersion potato tubers in CIPC at the rate of 50 ppm or the untreated control.
2.2. Starch, non-reducing sugars and total carbohydrate contents of tubers did not differ significantly as a result dipping tubers into CIPC at different concentrations. However, using CIPC2 (75 ppm) gave the highest values of TTA and vitamin C. Meanwhile, the highest mean values of total and reducing sugars were recorded by immersing tubers in CIPC at the rate of 50 ppm followed by the untreated tubers.
3. Effect of jasmonic acid
3.1. Hardness, dry matter content and PH value of potato tubers showed a significant increase due to applying tubers with JA at the rate of 0.01 mM/l (JA2), followed by 0.1 mM/l (JA3), whereas, the lowest one was recorded at the concentration 0.001 mM/l (JA1) and the untreated control. On the other side, both virtual density and L/D percentage did not significantly show any clear trend by using various JA concentrations. It was, also, noticed that the highest mean value of TSS was recorded in tubers immersion with JA at 0.001 mM/l (JA1) or the untreated tubers.
3.2. Increasing the dipping concentration of JA up to 0.01 mM/l was associated with significant increments in starch, TTA and total carbohydrates and also significant decreases in total, reducing and non-reducing sugars contents. Tuber’s vitamin C content, however, did not reflect any significant difference due to JA concentrations.