Effect of different concentrations of phytostimbiostimulant application on growth, yield, and postharvest attributes of Cherry Tomatoes

Abstract

Tomatoes can be regarded as important economic crops worldwide. They can enhance food security and alleviate poverty due to its numerous health benefits possess. The production of tomatoes in South Africa is finite, it has been mainly sustained through the usage of hydroponics, plastic channels, fertilizers and biostimulants. However, the usage of moringa based biostimulants on tomatoes remains underexplored. There is no scientific literature on the effects of different concentrations of Phytostim® biostimulant on growth, yield, and postharvest attributes. Phytostim® biostimulant is an agro agricultural input that is organic and safe technology. It is a moringa-based biostimulant constituted from 22 amino acids. Phytostim® is a newly commercially available product that can enhance crop vigour and nutrient use efficiency. Therefore, the aim of this research was to investigate scientific information on the effects of different concentrations of Phytostim® biostimulant on growth, yield, and post-harvest attributes of tomatoes ‘Roma’. The specific objectives of the study were to: (1) To evaluate the effect Phytostim® biostimulant different concentrations on ‘Roma’ tomato cultivar growth and yield. (2) to assess whether the application of Phytostim® biostimulant at different concentrations affect postharvest attributes in tomatoes cultivar ‘Roma’. Therefore, to achieve the above objectives the following procedures were taken: To achieve objective 1: four-week-old seedlings of tomato were transplanted in the microplot in an open field for a period of 12 weeks. The experiment was laid out in completely block randomised design consisting of eight treatments which were different concentrations of Phytostim® biostimulant (0, 0.1, 0.5, 1, 2, 2.5, 3 and 4%, while 0% was control) replicated three times. Irrigation with 250 mL of tap water was performed whenever there was a status of ‘dryness. Data was subjected to one-way analysis of variance (ANOVA) and Duncan’s Multiple Range Test (DMRT) was used for separating means using the Statistix 10.0 software package. Different concentrations of Phytostim® biostimulant were foliar applied in an interval of 14 days during the entire growing period. The growth attributes which included plant height, leaf length, and stem diameter were taken on a weekly basis. At harvest, yield components including the number of fruits per plant, diameter, size, and fresh weight of the fruits, were recorded. The effect of different concentrations of Phytostim® biostimulant significantly influenced (p<0.05) the growth and yield attributes of tomato. The study revealed that on the growth attributes Phytostim® biostimulant increased the stem diameter by 12 mm, plant height was increased by 95 cm, leaf length by 3.5 cm at the concentration of 0.1 %. On the yield attributes, Phytostim® biostimulant increased size of the fruits by 60 mm, diameter of the fruits by 56 mm, number of fruits per plant by 26 and fresh weight of the fruits by 51 g at the concentration of 0.1%. To achieve objective 2: fresh tomato fruits were harvested at pink stage and each treatment combination consisted of twenty-six fruits from green biotechnology of research centre and excellent (GBRCE). The treatments consisted of 8 pre harvest different concentrations of Phytostim® biostimulant (0, 0.1, 0.5, 1, 2, 2.5, 3 and 4%, while 0% was control) laid in complete randomised design (CRD). Samples of six tomato fruits per treatment (Phytostim® biostimulant concentrations) were stored for 0, 5, 10, and 15 days) in a retailer box at ambient condition. The fruits were stored for 0,5,10 and 15 days for the assessment of percentage weight loss, firmness, pH, colour and total soluble solids (TSS). The parameters were assessed at an interval of 5 days and oven dried at 40 º C for 48 hours for analysis of nutritional composition which were protein and mineral elements. The results revealed that the effects of different concentrations of Phytostim® biostimulant significantly influenced (p<0.05) postharvest attributes and nutritional composition. Percentage weight loss gradually increased as days of storage increased. Percentage weight loss in 0.1 % concentration was 3.38 % at day 0 and 14.00 % at day 15. Firmness had a decline throughout the storage period. Firmness in 0.1% concentration was 5.5 N at day 0 and 1.6 N at day 15. TSS increased as days increased, whereby in 0.1 % it was 4.2 % at day 0 and 7.7 % at day 15. pH values were acidic for all the treatments throughout the storage, whereby in 0.1 % concentration it was 4.0 at day 0 and 4.53 at day 15. At the end of storage period, the fruits maintained a good colour quality, in 0.1 % concentration it was (h° = 24.58 and a*= 18.46). The results obtained revealed that percentage weight loss, firmness, TSS, pH and colour of tomatoes cultivar ‘Roma’ were significantly (p<0.05) influenced by different concentrations of Phytostim® biostimulant. However, the results showed that all the postharvest attributes were enhanced at 0.1 % concentration Phytostim® biostimulant compared to control and other Phytostim® concentration. The concentration of 0.1% can extend shelf-life of tomato fruits with 15 days. Furthermore, the study showed that different concentrations of Phytostim® biostimulant significantly (p<0.05) influenced the nutritional composition including protein and minerals (Mg, Ca, Fe, K, Zn, Cu, P and Na). The nutritional compositions were enhanced at 0.1% concentrations of Phytostim® biostimulant as compared to the control and other concentrations of Phytostim® biostimulant. In this regard it can be concluded that the concentration of 0.1% can be effectively used by farmers as an eco-friendly and cost-effective method to prolong shelf life of tomato and enhance its nutritional composition. Therefore Phytostim® biostimulant can be adopted by small- and large-scale farmers as a safe method to prolong shelf life and produce quality fruits without harming the environment.