The effect of gibberellic acid and putricin application on shelf life and quality properties of Hamlin orange fruit

Dissertation for Master's Degree in Horticultural Sciences - Fruit Work

Abstract

After being separated from the mother plant, the fruit is alive and breathing and will undergo significant changes after harvesting. The storage period of fruits can be increased by optimizing environmental conditions, minimizing mechanical damage and using beneficial compounds such as gibberellins and polyamines. The life development after harvest of Hamlin orange was studied factorially in the form of a basic design of randomized complete blocks with 9 factors. In this research, the effect of gibberellic acid in concentrations of zero, 50 and 100 mg/liter and putricin in concentrations of zero, 1 and 2 mmol/liter before and after harvest on the post-harvest life and quality of orange fruits of Hamlinti Anbar cold storage was studied. Fruits treated with gibberellic acid and putricin during fruit growth (2 weeks before harvest) were stored at 8±0.5 degrees Celsius and 85±5% relative humidity for 0, 45 and 90 days. Fruit quality characteristics include fruit texture firmness, fruit weight loss, vitamin C, soluble solids, total acidity, ratio of soluble solids to total acidity, total phenol, fruit juice pH, freezing and appearance characteristics. And marketability was evaluated after 0, 45 and 90 days of storage. The pre-harvest treatment with gibberellic acid at the rate of 100 mg/L resulted in a better preservation of the firmness of the fruit tissue after 45 and 90 days of storage. 2 mM putricin maintained the pH of fruit juice after 45 and 90 days of storage. The combined use of gibberellic acid 100 mg/liter and putricin 1 mM had the best effect in maintaining the appearance and marketability after 90 days of storage. 2 mM putricin had the highest amount of vitamin C before storage and 45 days of storage, and gibberellic acid 100 mg/liter had the highest amount of vitamin C and the least decrease in the amount of vitamin C at the time of 90 days of storage. The combined use of gibberellic acid and putricin had a significant effect on the amount of total phenolic compounds in all three times before storage, 45 and 90 days of storage. The combined use of gibberellic acid and putricin generally resulted in better preservation of the quality properties of Hamlin orange fruit after 45 and 90 days of storage. The results of this research showed that the use of gibberellic acid and putrysin can be introduced as an effective strategy in the post-harvest technology of Hamlin variety oranges.

Key words: gibberellic acid, orange, putrysin, total phenol, vitamin

-1- Citrus history

Compounds are grown all over the world in subtropical climates, areas with suitable soil, sufficient humidity and if there is no frost. Citrus production areas are along a wide belt that starts from the equator and extends to 35 degrees north and south on both sides (Azeimi Tabrizi, 1369). Various citrus species are native to tropical and subtropical regions of Asia and the Malayan archipelago, and from there they have spread to other parts of the world. The main origin of all citrus species is probably the Himalayan heights in northeastern India and Burma, which as a result of seafarers' travels to Oman and Iran have been transferred to Palestine (Fatohi Qazvini, 1378; Fattohi Qazvini and Fatahi Moghadam, 1385). Theophrastus. [1] In 1310 BC, Balang and Watermelon were mentioned as the first types of citrus fruits in European civilization. Other citrus species were unknown in Europe until about 1400 AD. Some types of citrus fruits were transferred to the western regions of Asia such as Oman, Iran, and Palestine in the pre-Christian era (Daneshgar, 2006).

1-1-1-History of citrus fruits in Iran

According to historians, Alexander the Great brought one of the citrus varieties called Balang or Badrang, which originated from the southern regions of China to India. It was observed in Iran in 330 BC. The introduction of citrus fruits in Iran, including the Balang species, has a history of about 400 years (Daneshgar, 2006). According to historical references, Iran was the gateway for the exit of citrus fruits from Asia to other parts of the world. Since the Safavid era, in terms of the traffic of Portuguese ships in the south of Iran, orange seeds were available to the people of the south and cultivated (Fatohi Qazvini, 1378; Fattohi Qazvini and Fatahi Moghadam, 1385; Daneshgar, 1386).Then its seeds were brought from the south to the north of the country about 300 years ago and cultivated in Khorram Abad neighborhood of Tankabon city. Since then, especially since the beginning of 1300 AH, different species and cultivars of citrus fruits were imported into Iran (Fatohi Qazvini and Fatahi Moghadam, 1385). In 2010, there were 7604431 hectares, which produced 105532587 tons of citrus fruits (oranges, tangerines, lemons, grapefruits). In the analysis of citrus producing countries separately, it is clear that China, Brazil, Nigeria, Mexico, and the United States rank first to fifth in terms of cultivated area, while Brazil, the United States, China, Mexico, and Spain are ranked first to fifth in terms of production. Iran is one of the major citrus producing countries. According to the latest statistics published by FAO, in 2018, the cultivated area of ??citrus fruits in Iran is 288,108 hectares and the production amount is 4,462,438 tons and the average yield is 17.9 tons per hectare. And Iran ranks eighth among citrus producing countries both in terms of the amount of production and the cultivated area.

According to the report of the World Food and Food Organization (FAO), the total production of oranges in the world in 2010 is 66.4 million tons, of which 3.36 million tons are used for fresh consumption and 1.30 million tons are used for processing.

1-3- Important areas of citrus cultivation in the world

Citrus grows well in latitudes of 35-40 degrees in the northern and southern hemispheres in tropical and subtropical climates. But commercial citrus fruit can be found in areas with temperatures above -7°C (Davis and Albrigo, 1994). According to Yelensky[3] in 1985, the five climate zones for citrus cultivation in the world are as follows:

1- Humid coastal areas such as Japan, the Black Sea coast, New Zealand, where cold-resistant cultivars such as Japanese tangerine are based on three-leaf oranges. It is cultivated.

2- Subtropical areas that have a Mediterranean climate, such as Spain, Italy, Australia, Lebanon and coastal areas of California. Areas that do not have frost and are suitable for cultivating orange and lemon cultivars.

3- Dry semi-tropical areas include the deserts of southeastern California and Arizona, which is a part of Texas. The fruits produced in these areas have a good appearance and are suitable for fresh consumption.

4- Subtropical humid areas that include Florida, part of China, India, South Africa, Argentina and Brazil. Fruits in these areas have thin skin and good color quality. The amount of extract and soluble solids is high, although the fruits produced in these areas are suitable for fresh consumption, but regions such as Florida and Brazil, having large processing industries, basically produce concentrated extract. (Srivastava and Shym, 2002) Climatic restrictions have caused more density of citrus orchards in the areas of Chabaksar to Nowshahr and Amol to Behshahr (Fatohi Qazvini and Fatahi Moghadam, 1385). undergo significant postharvest changes. Fruit shelf life can be extended by optimization of environmental conditions, minimization of mechanical damage and application of natural chemical materials such as polyamines and gibberellins. This study in factorial design based on randomized complete block.