Journal of Taiwan Agricultural Research

Author:Chwen-Ming Yang*, Cheng-Wei Liu, Kai-Ying Chiu, Kai-Yue Chen, Ying-Chun Chen, Ya-Ching Teng, Hui-Ping Lo, and Yi-Jing Chen

Abstract:

     A field experiment was carried out at an Organic Farm of Mingdao University, Pitou Township, Changhua County. Two field management practices, agricultural unmanned aerial vehicle (or agricultural drone; T) and traditional human labor (CK) for biopesticide spraying and fertilization, were compared to evaluate the differences in the growth and production of organic broccoli. According to the preliminary results of Fall Crop in 2021, there were no significant differences between the two management practices in plant height, stalk length, stalk circumference, leaf number, leaf area, and leaf area index. All traits followed a similar trend as the growth progressed, indicating that the T-managed practice did not cause a significant growth lag in the investigated growth traits relative to those of the CK practice. There was generally no significant difference between the two practices in the fresh weight and dry weight of leaves, stalks, and the whole plant along plant development. Both practices used hand weeding to remove weeds that emerged on the furrows of the field plots. It showed that the furrows with CK practice 19 d after seedling transplanting had a higher weed population. After that, no difference was found between the two practices, and the weed population gradually decreased with the expansion of the broccoli plant size. From the counts of insects caught by yellow (Y) and blue (B) sticky paper traps hanging around the plots of the field, it was shown that counts of insects caught by Y paper traps were greater than that of the B paper traps in the plots of both practices. The average counts of insects caught by each Y paper trap were higher in plots of CK, while the average counts of insects caught by each B paper trap were higher in plots of T. There was no significant difference in the total counts of insects caught by Y plus B paper traps between two management fields. In the first harvest of flower heads (I, 12/17/2021), no difference was found in the average values of the length of flower stalks between practices. In the second harvest (II, 12/24/2021), the average value of the length of flower stalks of T (23.49 ± 0.34 cm) was longer than that of CK (22.20 ± 0.51 cm). The pooled data of two harvests also showed that T (23.46 ± 0.54 cm) had a higher value than CK (22.46 ± 0.54 cm). When the longest diameter of harvested flower heads were compared, the average value of T (19.36 ± 1.11 cm) was higher than that of CK (17.36 ± 0.40 cm) in the first harvest, but not in the second harvest, nor in pooled data of two harvests. By the regression analyses between the fresh weight of flowerheads and the length of flower stalks of pooled data, there exists no relationship in both the first- and the second-order regression models. However, the regression between fresh weight of flower heads and longest diameter of flower heads showed a significant linear relationship, in both CK (R² = 0.415, P < 0.0001) and T (R² = 0.229, P < 0.0001). With pooled data of two harvests, results indicated that T practice (8,047 ± 1,213 no. ha^-1) collected more flower heads than CK practice (5,506 ± 711 no. ha^-1), as well as in the yield of fresh flower heads, 3,956 ± 639 kg ha^-1 for T and 2,531 ± 544 kg ha^-1 for CK. Comparing the percentage distributions of different levels (fresh weights) of flower heads collected in two harvests of both management fields, from level 1 to level 8 (from small to large), it was shown that CK practice collected more flower heads of level 1–3 in the first harvest and level 2–5 in the second harvest. For T practice, it collected more flower heads of levels 2–5 and levels 3–4 in the first and the second harvests, respectively. With pooled data, CK practice collected most the flower heads in levels 1–5, 94.29% in total, while T practice had most flower heads in levels 2–5, a total of 90.50%. As a result, under the conditions of this experiment, compared with the traditional human labor management practice, the agricultural drone management practice may produce flower heads with larger sizes and fresh weights.

Key words:Agricultural unmanned vehicle, Agricultural drone, UAV, Organic broccoli, Production

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