著者

Megumu Takahashi Yuka Nakano Hidekazu Sasaki

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.OKD-143, (Released:2018-07-07)

被引用文献数

4

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Lateral heads, which generate after the harvest of an apical head of broccoli (Brassica oleracea L. var. italica), are generally small and have a low market value. Our purpose in this study was to increase the yield of broccoli from April to May, when domestic broccoli production is low, by removing excess branches (dubbed the “L-shaping” process) and growing one or two large and marketable lateral heads with the cultivar ‘Yumehibiki’. First, we demonstrated that transplanting seedlings in late-January and early-February to a field covered by plastic mulch and tunnels enabled apical heads and marketable lateral heads to be harvested in April and May, respectively. The number of marketable lateral heads reached a maximum 81% of that of apical heads. Next, we derived the base temperature (BT; °C), effective heat unit summation (EHUS; °C·day) from transplanting to apical head harvest, and additional EHUS from apical head harvest to lateral head harvest. They were 1.76°C, 747°C·day, and 254°C·day in 2016, and 1.74°C, 675°C·day and 204°C·day in 2017, respectively. The favorable timing for transplanting to result in the highest marketable yield was estimated as when the average temperature reached 4.0°C, but was less than 7.1°C. Finally, we characterized the lateral branches that were most likely to produce marketable lateral heads. The branches that produced marketable heads showed significantly higher values for thickness of branch, length of branch, and number of leaves on branch than those that produced nonmarketable heads, although the diameters of the developing heads on the branches were not significantly higher. Further analysis revealed that the leaf area was also significantly higher in marketable lateral heads than in nonmarketable heads. Taken together, the possibility of a substantial increase in yield during the broccoli off-crop season by using L-shaped ‘Yumehibiki’ was demonstrated in this study.

著者

Kaori M. Nakajima Manato Ohishi Fumio Sato Megumu Takahashi

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-045, (Released:2023-05-31)

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In Japan, broccoli (Brassica oleracea L. var. Italica) is primarily harvested manually. Some Japanese broccoli cultivars have short stems, but these broccoli heads are more difficult to harvest, and complicate the introduction of mechanical harvesters. Therefore, research is focused on strategies to control stem length. The present study examined the effects of the plant hormone gibberellin (GA) on the morphological and agronomic traits of broccoli shoots. The broccoli cultivar ‘SK9-099’, widely distributed in Japan and characterized by a short stem, was studied. These experiments were conducted over three cropping seasons, i.e., spring (Exp. 1), summer (Exp. 2), and fall (Exp. 3), with four GA treatment plots at 0 ppm (Control), 20 ppm, 100 ppm, and 500 ppm. This study observed that, on average, GA elongated stem length from approximately 16.0 cm in the control plot to 24.7 cm in the 500 ppm plot for the three cropping seasons, without decreasing yield. In addition, GA treatment accelerated apical bud growth and shortened the overall growth period by 16 days in the 500 ppm plot compared to the control in the fall, equivalent to 20.5% of the growth period from transplantation to harvest in the latter.This study highlights several practical benefits of GA application for growers, minimizing manual harvesting labor, avoid the difficult of designing mechanical harvesters for short-stemmed cultivars, and increase field usage efficiency by shortening the growth period.

著者

Manato Ohishi Megumu Takahashi Machiko Fukuda Fumio Sato

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-022, (Released:2022-11-22)

被引用文献数

1

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The demand for broccoli (Brassica oleracea L. var. italica) is increasing for use as fresh produce and for use in the processing industry. Therefore, growth prediction technology is required for its stable production. In this study, several cultivations of experiments were conducted to clarify the critical characteristics of the parameters needed to predict the growth of broccoli in a dry matter production model. The extinction coefficient was determined based on the leaf area index and intercepted solar radiation rate. Radiation-use efficiency was demonstrated using a linear function of the accumulated solar radiation intercepted amount and the total dry weight above-ground. The distribution of dry matter to the head and stem was indicated by the sigmoid function of the accumulated average temperature. The dry matter percentage of the leaf, dry matter percentage of the head and stem, and the ratio of leaf area to the fresh weight of the leaf were represented by a power function with dry weight above-ground. The fresh weight above-ground (R2 = 0.92) and the fresh weight of the head and stem (R2 = 0.98) were highly correlated with the estimated and observed values. Verification was performed using the developed growth model. As a result, the error between the harvest date and the predicted harvest date could be forecasted to within 4 days and the error in the fresh weight of the head could be predicted with an accuracy of −0.3 ~ +7.7 g·plant−1.

著者

Megumu Takahashi Takayoshi Ohara Fumio Sato Yuka Nakano Hidekazu Sasaki

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.UTD-018, (Released:2019-02-14)

被引用文献数

4

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Axillary buds of broccoli (Brassica oleracea L. var. Italica) develop and produce lateral heads after the apical heads have been harvested; however, lateral heads are not used because of their small size, and only one apical head is generally harvested from one plant. In this study, we aimed to establish a new method to harvest two heads of 12 cm diameter from a plant by pinching the apical bud and growing two axillary buds (“V-shaping” process) in autumn cropping. First, we measured the probability of axillary bud generation (PA) at each leaf axil and calculated the integration of the PA (IPA). The PA from the 5th to 8th true leaves was especially high, and the IPA reached 4.7. Next, we investigated the period of harvest and yield of heads at different times (3rd, 5th, 7th, 9th, 11th, 13th, and 15th leaf stage) of V-shaping in Field 1 (Ibaraki Prefecture, Tsukuba City). In V-shaped plots from the 7th to 11th leaf stages, the number of marketable heads significantly increased in comparison to that of the control. It increased by 61% of that of the control at the 11th leaf stage. However, the period of harvest was delayed, and the quality of heads deteriorated by cold injury when V-shaping was conducted from the 11th stage onward. Finally, we assessed the applicability of V-shaping cultivation in other fields. V-shaping was conducted from the 9th to 11th leaf stage. The number of marketable heads increased by 69 and 62% in Field 2 (Ibaraki Prefecture, Tsukubamirai City) and Field 3 (Nara Prefecture, Uda City), respectively. However, it only slightly increased in Field 4 (Mie Prefecture, Tsu City). Comparison of cultivation conditions at these 4 fields revealed that early transplantation, to allow an approximate 300°C day increase in effective heat unit summation for harvesting before the daily minimum temperature fell below approximately 0°C, was important. In addition, improving the drainage of the field seems important, and the input of manure compost (long-term fertilizer effect) may improve the quality and yield of heads. Thus, we concluded that V-shaping cultivation enabled the harvesting of two heads by V-shaping and increased the number of marketable heads by more than 60% in a wide area.