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  • Author or Editor: Dong-Hyuk Ahn x
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Large fluctuations in fruit set and fresh yield are issues associated with the production of sweet pepper. Fluctuations in fresh yield (i.e., flush) result in improper labor distributions and price fluctuations for growers. Modeling the fruit set is a promising way to improve the profits of growers and allow the arrangement of labor distribution and logistics. Therefore, this study aimed to develop a model for predicting the short-term yield changes of sweet pepper by integrating two sub-models: one model for predicting the production of total dry matter and one model for predicting the individual fruit growth. We hydroponically grew four sweet pepper cultivars (Artega, Nagano, Nesbitt, and Trirosso) in a greenhouse to investigate the accuracy of the proposed model. Comparisons between observed and predicted fresh yields showed that the peaks and troughs of fresh yields were accurately predicted, regardless of cultivar differences. The average root mean square error between them was within the range of 0.24 to 0.39 t⋅ha−1⋅d−1. Therefore, growers will be able to predict short-term yield changes of sweet pepper by obtaining coefficients for predicting the production of total dry matter and fruit growth curve of the cultivar scheduled to be cultivated.

Open Access

We investigated the relationships among the fruit set, dry matter production, and source-to-sink ratio of sweet pepper (Capsicum annuum) plants grown in a greenhouse. We quantified daily fruit sink strength per stem (st) at m days after transplanting (SSTm_st) by modeling the fruit growth curve. The daily total dry matter production (TDMm_st) was calculated and defined as the source strength. During an experiment lasting ≈250 days, the fruit set ratio [number of fruit harvested/number of flowers (FSRm)] decreased significantly with increases in both the weekly average SSTm_st from 9 days before anthesis (DBA) to 13 days after anthesis (DAA) and the weekly average fruit number (FRNm_st) from 9 to 1 DBA. FSRm increased significantly with increases in both the weekly average TDMm_st from 1 to 13 DAA and the weekly average source-to-sink ratio [source strength/fruit sink strength (SSRm_st)] from 5 DBA to 13 DAA. During the whole experimental period, significant positive correlations with FSRm were observed for TDMm_st and SSRm_st, and significant negative correlations with FSRm were observed for SSTm_st and FRNm_st. FSRm increased until approximately the time when the weekly average SSRm_st at 1 to 7 DAA (anthesis to 156°C⋅d−1) ranged from 1.0 to 4.0; then, it showed a saturation curve at SSRm_st values more than 4.0 (R 2 = 0.81). These results suggest that it is possible to moderate the fluctuations in sweet pepper yield by monitoring the SSRm_st and the number of fruit set.

Open Access

To investigate the influence of morphological changes in individual leaves of tomato on light interception and dry matter (DM) production, we altered leaf shape by trimming leaflets of young or mature leaves of the Dutch cultivar Gourmet and the Japanese cultivar Momotaro York. Young leaves 5-cm long were trimmed of their first and second leaflets from the leaf apex. Mature leaves were similarly trimmed at ≥71 days after transplanting (DAT). The individual leaf area (LA) of intact ‘Momotaro York’ leaves was significantly larger than that of ‘Gourmet’. Light–photosynthesis curves of the cultivars were almost identical. Mature-trimmed plants of both cultivars had a smaller individual LA and a smaller leaf area index (LAI), and a greater light-extinction coefficient (LEC). Although there was no significant difference in light-use efficiency (LUE) (i.e., DM production per unit intercepted solar radiation) in ‘Gourmet’ between trimming stages, LUE of ‘Momotaro York’ was decreased significantly by young-leaf trimming. Trimming of young leaves significantly decreased the LEC in ‘Gourmet’ but increased it in ‘Momotaro York’. Although leaf trimming would be impractical for commercial cultivation, these results may provide with a clue for breeding for yield improvement.

Free access