Fruit maturity and storage affected the germination and seedling vigor of bell pepper (Capsicum annuum L.)ABSTRACT:
Fruit storage is beneficial to growers to avoid the exposure of fruits to adverse weather conditions and infestation by pests and diseases that may affect the seed quality. This study was conducted to evaluate the influence of fruit maturity and fruit storage on the germination and vigor of bell pepper. Fruits of California Wonder cultivar were evaluated. A storage of bell pepper fruits (green mature, half-ripe (green and red) and fully-ripe (red)) at room temperature was conducted for 0, 5, 10 and 25 days. The experiment was arranged in a Completely Randomized Design with four replications. Results showed that fruit weight was higher in green mature bell peppers without storage. However, fruit storage was advantageous due to the increase in total soluble solids and dry matter. Heavier dried seeds were obtained from fruits without storage. Half-ripe with five days of storage and fully-ripe without storage exhibited the highest germination percentage and germination index of bell pepper seeds, which was higher than the standard germination rate. However, a shorter mean germination time was observed in green mature and half-ripe fruits after five days of storage. Longer and vigorous seedlings were produced from half-ripe fruits with 25 days of storage.
Index terms:
fruit age; postharvest storage of fruits; seed quality; vigor
RESUMO:
O armazenamento de frutos é benéfico aos produtores para evitar a exposição a condições climáticas adversas e infestação por pragas e doenças que podem afetar a qualidade das sementes. Este estudo foi conduzido para avaliar a influência da maturidade dos frutos e do armazenamento dos frutos na germinação e vigor do pimentão. Frutos da California Wonder cultivar foram avaliados. Foi conduzido o armazenamento de frutos de pimentão (verde maduro, meio maduro (verde e vermelho) e totalmente maduro (vermelho)) em temperatura ambiente por 0, 5, 10 e 25 dias. O experimento foi disposto em um delineamento inteiramente casualizado com quatro repetições. Os resultados mostraram que o peso dos frutos foi maior em pimentões verdes maduros sem armazenamento. No entanto, o armazenamento dos frutos foi vantajoso devido ao aumento de sólidos solúveis totais e matéria seca. Sementes com maior matéria seca foram obtidas de frutos sem armazenamento. Frutos meio maduros com cinco dias de armazenamento e totalmente maduros sem armazenamento exibiram a maior porcentagem de germinação e índice de germinação de sementes de pimentão, que foi maior do que a taxa de germinação padrão. No entanto, observou-se um tempo médio de germinação mais curto em frutos verdes maduros e meio maduros após cinco dias de armazenamento. Plântulas mais longas e vigorosas foram produzidas a partir de frutos meio maduros após 25 dias de armazenamento.
Termos para indexação:
idade do fruto; armazenamento pós-colheita dos frutos; qualidade da semente; vigor
INTRODUCTION
Bell pepper (Capsicum annuum L.) fruits are among the fruit vegetable crops that are considered high value crops due to their importance in the livelihood of farmers and nutritional composition. The fruits are used in different culinary dishes that add flavors, aroma, and make the food colorful due to the spectrum of colors. Fruits are naturally rich in vitamin C and phenolic compounds, which are beneficial to human health (Rosa-Martinez et al., 2021). However, an essential strategy that is low-cost effective with high seed quality plays a pivotal role in the sustainable bell pepper production. Fruit storage provides a comparative advantage against retaining the fruits in the mother plant (Paul and Pandey, 2011), such as avoiding exposure to unpredictable weather conditions, and infestation of pests and disease infection. These factors affect the seed quality of bell pepper.
Studies have reported that fruit maturity significantly affected the germination and seedling vigor of crops, including bell pepper. A previous study reported that mature fruits exhibited higher germination and vigor than the green fruits (Anandalakshmi et al., 2016). Mature fruits with storage produced a higher germination (Murrinie et al., 2019). They also reported that mature fruits and storage significantly produced vigorous seedlings. Germination was higher if the fruit was more mature, and an increasing trend of germination as the fruit matures, as observed in sweet pepper (Sanchez et al., 1993). This observation concurred with a previous study that fruit storage of mature fruits (80 days after anthesis) for 7 days produced a higher germination than unstored (Colombari et al., 2021). In another report, red skin of sweet pepper (75 days after anthesis) showed high germination and vigor (Vidigal et al., 2011). These studies showed that appropriate harvesting stage and fruit storage provided essential information, especially on the seed quality of the different crops. It was reported that maximum germination and vigor are attained at physiological maturity when there is the end of seed-filling stage (Welbaum, 1999). Thus, a study on how fruit storage of three fruit maturity stages affects germination and seedling vigor of bell pepper was conducted.
MATERIAL AND METHODS
Fruit collection and preparation
The fruits of bell pepper (California Wonder cultivar) were purchased from a local grower in the City of Batac, Ilocos Norte. Green mature, half-ripe (green and red), and fully-ripe (red) fruits were harvested and separately stored under ambient conditions (30 ± 2 °C temperature; 65 ± 5% relative humidity) for 0, 5, 10, and 25 days. The study was conducted in the Postharvest and Seed Technology Laboratory room of the College of Agriculture, Food, and Sustainable Development, Mariano Marcos State University.
Seed extraction and seed drying
Seeds were extracted from different fruits after their corresponding fruit storage period and air-dried until the weight was constant. The fresh and dry seeds of every fruit were weighed and expressed in g.seeds-1.
Fruit weight and pulp dry matter
Before and after fruit storage, the fruit was weighed using a digital weighing scale. Whereas 10 g of pulp of every fruit maturity before and after storage were oven dried at 72 °C for 48 h (AOAC, 2000). Results were in g.fruit-1.
Standard germination, germination index, and mean germination time
The standard germination, germination index, and mean germination time were measured for 14 days daily following the method prescribed by ISTA (2008). Germination index and mean germination time were measured using the formula below.
Which means, n = number of germinated seeds on a specific day
d = number of days from the start of the germination test
N = total number germinated seeds by the end of the test
Shoot, root, and seedling lengths
A ruler was used to measure the shoot and root length. The sum of the shoot and root of each sample was used for the seedling length of bell pepper. These were measured 7 and 14 days after sowing. Results were expressed in cm.
Seedling vigor index (SVI)
SVI was measured by getting the product of standard germination (%) and seedling length (cm.seedling-1).
Statistical analysis
The experiment was carried out in a completely randomized design, with four replications. Analysis of variance was performed in a factorial scheme, 3 (three maturation stages) x 4 (fruit storage periods). SPSS (SPSS for Windows Version 17.0, Released 2008, SPSS Inc., Chicago, IL, USA) program was used to analyze the data. The treatment mean differences were measured using the Least Significant Difference (LSD) test.
RESULTS AND DISCUSSION
The fruit weight of bell pepper was affected by fruit maturity, storage period, and the interaction effect (Table 1). Heavier fruits were observed from green mature, and fully-ripe. As the fruit matures, the fruit weight decreases from green mature to half-ripe, but an increasing weight is observed at the fully-ripe stage. However, storage affected the fruit weight, resulting in depletion. The longer the storage period, the higher the weight loss.
On the other hand, in every fruit maturity stage, without storage was needed to avoid weight loss in green mature bell pepper (Table 2). Whereas half-ripe and fully-ripe fruits can be stored for up to five and 10 days, respectively, due to their comparable fruit weight with zero storage.
For every storage period, green mature displayed heavier fruits than the other maturity (Table 2). The three fruit maturities exhibited a similar fruit weight during the five and 10 days of storage. Whereas green mature and fully-ripe fruits showed a comparable fruit weight to the half-ripe fruits.
Fruit maturity stage, storage period, and the interaction influenced the pulp dry matter of bell fruit (Tables 1 and 3). An increasing trend in dry matter was evident from green mature to half-ripe, and no further increase beyond at half-ripe stage. There was an increasing dry matter content as the storage proceeded.
Fruits that are green mature, half-ripe, and fully-ripe need 10 and 25 days of storage to increase the pulp dry matter (Table 3). For every storage period, fully-ripe fruit had the highest dry matter among the fruit maturity. During five and 10 days of storage, half-ripe showed the highest dry matter, but no increase beyond this stage. However, longer storage, such as 25 days, the three fruit maturities had no significant variation.
The fresh and dry weights of seeds were influenced by the fruit maturity, storage period, and interaction effect (Tables 1, 4, and 5). Heavier fresh weight of seeds was observed with earlier fruit maturity and without storage. The dry weight of seeds was higher in half-ripe fruits and without storage. Green mature seeds may contain a higher amount of water content than the other fruit maturities, as compared to half-ripe and fully-ripe.
In general, a higher fresh weight was obtained without storage for the three fruit maturities (Table 4). However, three fruit maturities in every storage period had a similar fresh weight, but a storage of 25 days showed that green mature displayed a heavier fresh weight than the other fruit maturities. The result indicates that to obtain a heavier fresh weight green mature stage of the bell pepper is considered with and without storage.
Irrespective of storage period, except for 25 days, either half-ripe or fully-ripe can be used to obtain a higher dry weight of seeds (Table 5). Heavy dry weight of seeds may indicate a higher dry matter accumulated. It was reported that an increase of dry weight occurred in Stage 2 of the seed development process, which reaches the physiological maturity where an increase of the dry weight no longer evident (Bewley and Nonogaki, 2017). This indicates that half-ripe fruits produced a higher dry weight because there was no longer significant increase in the dry weight at fully-ripe stage. Moreover, no fruit storage is needed to increase the dry weight because fruit storage showed a decrease in the seed dry weight (Table 1). Moreover, results signify that more mature fruits, such as half-ripe and fully-ripe, provided enough nutrients for the seeds from the mother plant.
Storage for five days was needed for the half-ripe bell pepper fruits to provide a higher germination percentage, which is more than 85% (as the standard) (Figure 1A). More than five days of storage showed no significant increase. Whereas for the fully-ripe, storage was no longer needed because of the similarity with five and 10 days of storage. It was observed that storage was required for the green mature to produce higher germinated seeds, but it did not show a higher germination rate than the standard (85% germination). It signifies that fruit storage was not enough to make the seeds develop and mature enough to produce a higher germination rate. Hence, green mature is not recommended for the farmers, even how long the storage will be. However, half-ripe with a maximum of five days storage and fully-ripe with 0 and 10 days storage are recommended. For fully-ripe fruit, 10 days of storage is recommended, as the germination percentage was similar to that of unstored and five-day storage. Storing the fruits up to 25 days for the half-ripe will provide the chance to avoid the unpredictable weather conditions and infestation/infection of pests/diseases. Across the fruit storage period, half-ripe fruit had a higher germination rate than the green mature and fully-ripe. Similar results were reported by other authors (Anandalakshmi et al., 2016; Vidigal et al., 2011) and a subsequent fruit storage positively improved germination, as concurred by a previous report (Colombari et al., 2021; Murrinie et al., 2019). In every storage period, half-ripe and full-ripe fruits produced a higher germination percentage as compared to green mature fruits during five and 10 days of storage. Whereas during 25 days of storage, half-ripe exhibited a higher germination rate than fully-ripe. This indicates that subsequent fruit storage using the half-ripe stage of fruits proved to produce a higher germination of bell pepper seeds. Thus, based on the above results, a subsequent storage of half-ripe fruits can be recommended to the farmers.
The standard germination (A), germination index (B), and mean germination time (C) of the different fruit maturity stages before and after fruit storage of bell pepper. Bars with different letters in lowercase and uppercase are significantly different at P≤0.05 level among fruit maturity in every storage period and among storage periods in every fruit maturity, respectively, using the Least Significant Difference test.
An interaction effect was observed on the GI (Figure 1B). In green mature, an increase in GI was observed with a longer storage period up to 10 days. Five days of storage were beneficial for the half-ripe because longer than this period did not increase the GI, and a decline was observed with 25 days of storage. However, for fully-ripe, no storage is needed to obtain a high GI, but a storage of 10 days showed a similarity between these storage periods. The fluctuating GI may be due to the accumulation of abscisic acid (ABA) during seed development, wherein this plant hormone is responsible for seed dormancy, resulting in a low germination rate. ABA regulates the dormancy and germination (Zheng et al., 2024). A high and low ABA promotes seed dormancy and germination, respectively. Moreover, during seed formation, ABA controls key events, such as the deposition of storage reserves, the prevention of precocious germination, and the induction of primary dormancy (Kermode, 2005). Furthermore, it was reported that the essential role of ABA during early seed development is to maintain the embryos in a developmental state until they become fully formed and have accumulated sufficient reserves to provide better germination. Kermode (2005) further discussed that ABA biosynthesis in the embryo and surrounding seed tissues permits the continuation of maturation, including storage protein synthesis and storage lipids. This report may relate to the current study that during fruit storage in fully-ripe fruit for five days there could be ABA biosynthesis that resulting in the accumulation of a high amount of this plant hormone, which may inhibit the germination of seeds. However, a positive impact may be observed, such as avoidance of viviparous germination during fruit storage. But a further investigation is needed to analyze the ABA content of the seeds used in the study.
An interaction effect between fruit maturity and storage period was observed (Figure 1C). At zero storage, half-ripe and fully-ripe had similar MGT. At five and 10 days of storage, the half-ripe had the lowest MGT among the three different maturities. However, at 25 days of storage, green mature had the lowest MGT. Despite green mature having the lowest MGT at 25 days of storage, it had the lowest germination percentage (Figure 1A), which was lower than 85% germination. Results indicate that to obtain a higher germination of bell pepper seeds and faster germination, either 5 or 10 days of fruit storage of half-ripe fruit is recommended.
Interaction effects on shoot, root, and seedling lengths were observed. Fruits that were green mature had longer roots and seedlings with storage for five days (Figure 2A and 2C). No elongation of roots beyond this storage period. Whereas half-ripe and fully-ripe displayed longer roots and seedlings without storage. Irrespective of storage, half-ripe fruits produced longer roots than the other fruit maturity.
The root length (A), shoot length (B), seedling length (C), and seedling vigor index (D) of the different fruit maturity stages before and after fruit storage of bell pepper. Bars with different letters in lowercase and uppercase are significantly different at P≤0.05 level among fruit maturity in every storage period and among storage periods in every fruit maturity, respectively, using the Least Significant Difference test.
On the other hand, green mature fruit stored for five days produced longer shoots than a prolonged storage period (Figure 2B). An increase in shoot length in half-ripe was observed with a longer storage period of 25 days. Whereas no significant elongation of shoots in fully-ripe fruits was observed. Half-ripe fruits from five to 25 days of storage showed a longer shoot than the other maturity stages. However, an interaction effect was also observed in the seedling vigor index of bell pepper (Figure 2D). Without the storage of bell pepper fully-ripe fruits exhibited vigorous seedlings than the half-ripe fruits. In every storage period, particularly 5, 10, and 25 days, half-ripe fruits produced vigorous seedlings than the fully-ripe. There was a decrease in the seedling vigor index beyond the half-ripe stage. It was observed that fruit storage improved the seedling vigor index, which was observed in green mature for 5 days, half-ripe for 25 days, and fully-ripe for 10 days.
A maximum dry weight was observed in half-ripe fruit (equally red and green in color of fruits) without storage, but it did not produce a higher germination (Figure 1A). Thus, a maximum germination was observed in fully-ripe (red fruits) if no storage was employed. However, if half-ripe fruits with storage of 5 days produced a higher germination rate. Therefore, 5 days of storage of half-ripe fruit is needed to produce a higher germination because of no significant increase in germination. The color of bell pepper can be used to predict the seed germination. This was also reported by a previous study that black fruits produced a higher seed germination than the red fruits (Fang et al., 2023). Another study also reported that more mature fruits displayed a higher germination (Silva et al., 2022).
Thus, the farmers have the option either to use the half-ripe with storage up to 25 days or the fully-ripe without storage. But with the consideration of avoiding the environmental factors affecting seed quality, half-ripe fruits with subsequent fruit storage are recommended.
CONCLUSIONS
Fruit maturity and storage improved the germination and seedling vigor of bell pepper. More than 85% of germination was obtained from half-ripe and fully-ripe fruits with and without five days of storage, respectively. But half-ripe with, either 5 or 10 days of fruit storage, was beneficial to obtain a faster germination rate. However, 25 days of fruit storage are needed to produce taller with vigorous seedlings using half-ripe fruit maturity.
ACKNOWLEDGEMENTS
The authors would like to thank the Mariano Marcos State University for supporting the study.
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Additional data will be made available by the authors upon reasonable request.
