Physiological performance and fruit quality of noni (Morinda citrifolia L.) cultivated in different agro-climatic zones of Fiji
From Firenze University Press Journal: Advances in Horticultural Science
R. Prakash, School of Agriculture, Geography, Environment, Ocean and Natural Sciences, The University of South Pacific
A. Jokhan, School of Agriculture, Geography, Environment, Ocean and Natural Sciences, The University of South Pacific
R. Gopalan, School of Agriculture, Geography, Environment, Ocean and Natural Sciences, The University of South Pacific
R.D. Singh, School of Agriculture, Geography, Environment, Ocean and Natural Sciences, The University of South Pacific
A.V. Prasad, School of Agriculture, Geography, Environment, Ocean and Natural Sciences, The University of South Pacific
Noni (Morinda citrifolia L.) is a tropical evergreen perennial plant with large elliptical leaves and a compound fruit (Nelson and Elevitch, 2006). Noni is native to is native to Southeast Asia and Australia and has a pantropical distribution (Nelson, 2003; Pandiselvi et al., 2019) The plants are significant source of traditional Polynesian medicine. The fruits range from 410 cm in length and about 34 cm in diameter and are the most commonly used parts. The fruit has a broad range of nutraceutic and therapeutic potentials (ChanBlanco et al., 2006; Mahantesh et al., 2018; Almeida et al., 2019; Inada et al., 2020). Noni fruit products have become quite popular in the area of health care due to its biologically active compounds and high antioxidant potential. Commercial noni farming occurs in most tropical countries and is now growing in the Pacific Islands. Growing noni under rain fed conditions are highly beneficial in tropical countries where rainfall is abundant with good volcanic soil (Nelson and Elevitch, 2006). Most countries, however, have their own agroclimatic zones where certain crops perform well. Agroclimatic zone is the characterization of an area based on its climatic parameters that are suitable for agriculture (Parry et al., 1988). Farming in agroclimatic zones ensures that a crop is ecologically viable together with being economically profitable. Amin et al. (2004), lists some agroclimatic parameters as rainfall, maximum and minimum temperature, humidity, evapotranspiration, maximum possible sunshine hours and wind speed. Crop growth and agricultural productivity are primarily affected by all climatic elements, whether its effects occur singly or in combination (Parry et al., 1988; Mittler, 2006). Precipitation, temperature and solar radiation have a direct effect on key plant metabolic processes such as photosynthesis and respiration while humidity is crucial for regulating transpiration and plant water balance. Suboptimal values of precipitation, temperature, light intensity and relative humidity can result in crop yield reduction and product quality (Ferrante and Mariani, 2018). Noni is renowned for tolerating a wide range of climatic conditions in its habitats. According to Nelson (2003), noni is found from 1 m to 800 m above sea level growing in a wide range of soils (infertile soils, acidic and alkaline soils) in its natural habitats. The mean annual rainfall range is from 2504000 mm, and mean annual temperature range is from 20oC to 35oC. Noni plants can survive dry seasons with less than 40 mm of rainfall for at least 3 4 months depending on plant size and age and its surrounding temperature and humidity (Nelson, 2003). According to Nelson and Elevitch (2006), in cultivation, about 5001500 mm annual rainfall that evenly spreads over the year is ideal for obtaining high yields. In wet areas where the annual rainfall is up to 4000 mm/year, the yield of noni is high, but the fruits are usually very watery, less sweet and tend to have much slower and uneven ripening while in drier areas fruits are much sweeter with rapid and even ripening (Nelson and Elevitch, 2006). Under cultivation, noni has been found to be a very low maintenance plant which requires low irrigation and fertilizer. Since noni’s commercial market firmly bases its adverts on high antioxidant properties, noni growers must ensure that good plant growth and high fruit yield also accompanies fruits with high antioxidant properties. Antioxidants can be enhanced in fruits by changing some cultivation practices once the specific environmental effects on fruits are known (Dumas et al., 2003; Wang, 2006). Major antioxidants, both enzymatic and nonenzymatic protect higher plant cells from oxidative stress damage that usually occurs when the plants undergo environmental stresses. Antioxidant properties of noni are highly associated with the nonenzymatic phenolic compounds (Dussossoy et al., 2011). The nonenzymatic antioxidants in plants are mainly comprised of ascorbic acid, glutathione, αtocopherol, carotenoids, phenolics, flavonoids, and amino acid cum osmolyte proline. Due to their essential role in protection and development, high levels of nonenzymatic antioxidants are usually expected in plants undergoing adverse environmental stress hence noni’s antioxidants may be elevated under stressful conditions. Growers often make the cultivation environments ideal and stressfree for plants which are likely to lower the antioxidant capacity of the fruits. Hence apart from increasing the plant growth and fruit yield, it is also important to know what kind of environmental conditions would enhance the antioxidant levels in the noni fruits. This study examined the growth and physiological performance of noni plants cultivated in Fiji’s three different agroclimatic zones and compared its growth, fruit production and yield together with its antioxidant properties. The study implicates how noni’s cultivation environment can be altered to enhance the antioxidant production together with maintaining the overall productivity.
DOI: https://doi.org/10.36253/ahsc-14019
Read Full Text: https://oaj.fupress.net/index.php/ahs/article/view/14019
