Reserve carbohydrates are critical for herbage yields, productivity as well as management strategies of bush tea (Athrixia phylicoides DC). This study was conducted to evaluate carbohydrate accumulation in response to pruning seasons (summer, autumn, winter, and spring) involving different organs grown under different conditions and to determine mean dry matter production of bush tea. Three separate parallel trials were conducted under wild, field, and glasshouse conditions. Seasons and different growing sites were considered as treatments. Treatments for all controlled trials (field and glasshouse) consisted of seasonal pruning (winter, spring, summer, and autumn). Trials were arranged using a randomized complete block design with 25 single plants as replicates per treatment. Seasonal responses revealed that winter had the highest starch (145.0 mg·g−1) in the stems and reserve carbohydrates (480.6 mg·g−1) in the roots, whereas in the roots sugar (400.6 mg·g−1) was highest in summer. The highest significant root reserve carbohydrates occurred in winter (594.6 mg·g−1) and the lowest in autumn (fall) (313.3 mg·g−1). Bush tea plants pruned during winter had the highest overall reserve carbohydrates in the stem (598.7 mg·g−1). Under glasshouse conditions, the highest dry matter production was observed in December (midsummer) (170 g per plant); while in field-grown plants in the same month dry matter production was 400 g per plant. Therefore, the best time to maximize production of bush tea is during the spring and summer seasons.
Fhatuwani N. Mudau, Ambani R. Mudau, Mpumelelo Nkomo, and Wonder Ngezimana
Ambani R. Mudau, Puffy Soundy, and Fhatuwani N. Mudau
Manipulation of microenvironments by means of photoselective nettings is widely used to improve the productivity and quality of high-value vegetables. The aim of this study was to investigate the effect of photoselective nettings on growth, productivity, and postharvest quality attributes of baby spinach. Baby spinach cv. Ohio was grown from seeds, and the trial was repeated. Plants were planted in an open field (control) and under closed nets, viz., black, pearl, yellow, and red nets. At harvest, baby spinach leaves were subjected to 4, 10, and 20 °C storage temperatures for 12 days. Crops grown under black nets and stored at 4 °C retained higher level of antioxidant activity (0.23 g·kg−1), whereas the least level of antioxidant activity was observed in baby spinach grown under red and yellow shade nets (0.01 g·kg−1). Similar trend was evident with flavonoid content where baby spinach leaves grown under black nets maintained high level of flavonoids at 4, 10, and 20 °C during storage period compared with other shade nets and the control. The study control showed a better potential in retaining antioxidant activity over red and yellow shade nets. Results showed that black shade nettings have the potential to reduce water loss, decay incidents, and maintain flavonoid content and antioxidant activity followed by pearl and yellow nets.
Ambani R. Mudau, Puffy Soundy, Hintsa T. Araya, and Fhatuwani N. Mudau
The aim of the current study was to determine the influence of modified atmospheric pressure on the quality of baby spinach during storage. Treatments consisted of control [(normal air) (78% N2; 21% O2)], modified atmosphere (MA) (5% O2; 15% CO2; balance N2), storage temperature (4, 10, and 20 °C), and number of days after storage (0, 3, 6, 9, and 12). Parameters recorded are gas composition, weight loss, sensory quality, minerals and trace elements (Mg, Fe, and Zn), flavonoids, and antioxidant activity. The results of this study demonstrated that in the headspace gas there was overall reduction in O2 and increase in CO2 levels over the storage period. After 6 days of storage, all samples in normal air irrespective of the storage temperature were found to fall short of acceptable marketability with regard to visual appearance. The total antioxidant activity and flavonoids were well maintained under controlled atmosphere (CA) at 4 °C when stored for 9 days.
Ambani R. Mudau, Puffy Soundy, Hintsa T. Araya, and Fhatuwani N. Mudau
Spinach is an annual, cool-season, green leafy vegetable that in temperate areas can be grown year-round. However, different seasons can influence the quality and shelf life of the produce. The objective of this study was to investigate the influence of different seasons on the quality of baby spinach leaves during growing and postharvest storage. The study was initiated in early Nov. 2013 and culminated toward the end of Oct. 2014, then was repeated from Nov. 2014 until Oct. 2015. A 4 × 5 × 3 factorial experiment was laid out in a randomized complete block design with four replicates per treatment. The treatments were arranged as follows. In autumn, winter, spring, and summer, leaves were kept up to 12 d at three different temperatures: 4, 10, and 20 °C. Parameters recorded are weight loss, leaf length, total flavonoids, and antioxidant activity. Results of the study demonstrate that the level of antioxidants in winter remained stable during storage, specifically at 4 °C, followed by autumn and spring. In contrast, the summer season reflected the worse potential of retaining a level of antioxidants compared with the other seasons. On day 12, at a storage temperature of 4 °C, winter maintained 0.55 mg·g–1 dry weight (DW), whereas autumn, spring, and summer had 0.41, 0.40, and 0.11 mg·g–1 DW, respectively. In conclusion, it is recommended that baby spinach growers consider winter, autumn, and spring for growing baby spinach to manage the quality favorably during the postharvest storage period in South Africa.
Ambani R. Mudau, Mpumelelo M. Nkomo, Puffy Soundy, Hintsa T. Araya, Wonder Ngezimana, and Fhatuwani N. Mudau
Spinach (Spinacia oleracea) is a member of the Amaranthaceae family. Baby spinach leaves have a very high respiration rate, thus postharvest quality is affected mostly by tissue decay and the development of off-odors. Thus, this study was conducted to investigate the influence of storage temperature and time on the postharvest quality of baby spinach. Baby spinach leaves were harvested 36 days after planting and subsequently stored at 4 and 22 °C for 0, 2, 4, 6, 8, 10, or 12 days. Thereafter, the leaves were incubated for 72 hours at 40 °C to dry. Minerals, trace elements, total phenols, total carotenoids, flavonoids, and antioxidant activities were measured. Concentration of magnesium (Mg), zinc (Zn), and iron (Fe) were declined after 8 days of storage at 4 °C, while at 22 °C they declined after 2 days of storage. Mg, Zn, and Fe revealed a similar trend with significantly higher carotenoids found up to 6 days in storage at 4 °C, while at 22 °C the carotenoid levels declined after only 2 days. Total phenolic compounds gradually decreased in samples stored at 4 °C. However, samples stored at 22 °C showed a rapid decrease after 4 days. Both total antioxidant activities and vitamin C content showed a similar trend, with the content remaining constant at 4 °C and decreasing after 6 days, whereas the total antioxidant activities and vitamin C for leaves stored at 22 °C decreased immediately after 2 days. Results demonstrated that quality of baby spinach deteriorates as storage time and temperature increase.