Untitled

Ishioka

Tachibana

et al. 2023

The spread of morning glory (Ipomoea spp.) in soybean fields in Japan has severely decreased soybean yield. Yet, current control measures do not control the proliferation of Ipomoea spp. As little is known about the flowering period and seed production among the different invading Ipomoea spp., it is challenging to create targeted control measures based on ecological characteristics. This study aimed to reveal the characteristics of the flowering phenology and seed production of four morning glory species, namely, Ipomoea coccinea L. (red morning glory), Ipomoea lacunosa L. (pitted morning glory), Ipomoea hederacea L. Jacq. var. integriuscula A. Gray (entireleaf morning glory), and Ipomoea triloba L. (three-lobe morning glory). Between 2017 and 2019, the four selected study species were grown under similar conditions of soil quality, irrigation, and environmental influences and their flowering phenology and seed data were recorded. The flowering period ranged from 36 to 40 days, and the initial flowering of I. triloba was approximately 2 weeks later than the others. I. coccinea had the highest flowering number and seed production, followed by I. lacunosa, I. triloba, and I. hederacea var. integriuscula. The fruit set-

Section: Introductionmentioning

confidence: 99%

Differences in flowering phenology and seed production of four morning glory (Ipomoea) species in Japan

Ishioka

Tachibana

et al. 2023

“…The introduction of herbicide-tolerant varieties of soybean is an effective weed management method in countries such as the United States where commercial cultivation of genetically modified soybeans is permitted and an effective control system against morning glory species using overthe-top spray application of glyphosate or glufosinate in GM soybean has been established (Culpepper, Gimenez, York, Batts, & Wilcut, 2001;Culpepper, York, Batts, & Jennings, 2000); however, this strategy is not permitted in Japan. Selective pre-emergence soil-applied herbicides are less effective against morning glory species (Crowley, Teem, Buchanan, & Hoveland, 1979;Sumiyoshi & Yasuda, 2011), and bentazone, a selective post-emergence herbicide for broadleaf, cannot control morning glory species beyond the third leaf stage (Shibuya, Asai, & Yogo, 2006). Because these are the main herbicides allowed for use in soybean fields in Japan, it is very difficult to control morning glory species chemically.…”

Section: Introductionmentioning

confidence: 99%

Chemical and cultural control of Ipomoea hederacea var. integriuscula in narrow‐row soybean in southwestern Japan

Tachibana

Homma

2021

In Japan, the spread of morning glory (Ipomoea spp.) in soybean fields has become a serious issue. To establish a control approach for Ipomoea species, this study considered the optimal system combining cultural and chemical control methods. Field experiments were conducted for 3 years to investigate the effects of no‐tillage compared with tillage seeding in narrow‐row soybean and of application timing of selective post‐emergence herbicides bentazone and fluthiacet‐methyl. The cumulative emergence of entireleaf morning glory (Ipomoea hederacea [L.] Jacq. var. integriuscula A. Gray) in no‐tillage was 25–79% of that in tillage, and the initial growth was suppressed. In no‐tillage, the dry matter weight of I. hederacea var. integriuscula was suppressed compared to tillage methods. However, in no‐tillage, initial soybean growth was inferior, and reduction of the relative photosynthetic photon flux density (RPPFD) in the soybean canopy was delayed. A combination of selective post‐emergence herbicide applications at the second and fourth trifoliate leaf stages (TLS) of soybean was most effective in I. hederacea var. integriuscula suppression. The initial growth of soybean greatly fluctuated yearly, and the period when the RPPFD became less than 50% varied at the fourth through seventh TLS. Therefore, if the initial soybean growth is good, the end of the required period for weed control can be defined as the fourth TLS. No‐tillage cultivation combined with management to promote soybean growth, such as adequate soil moisture control by subirrigation systems, may be effective in controlling I. hederacea var. Integriuscula.

Relationship between storage period and germination of Ipomoea hederacea var. integriuscula seeds under natural condition

Ishioka

Homma

2021

Morning glory (Ipomoea spp.), a problematic weed in soybean fields, is difficult to control due to its long emergence period. The intermittent germination of morning glory prolongs the emergence period, and the factors remain unclear. Therefore, we aimed to clarify the effects of different storage periods under natural conditions on germination conditions and emergence percentages of physically dormant entire‐leaf morning glory (Ipomoea hederacea var. integriuscula) seeds in the field. In 2017–2020, I. hederacea var. integriuscula was cultivated in outdoor planters. Each plant was tagged on the blooming flower peduncle to record the flowering date. The seeds of I. hederacea var. integriuscula germinated 23 days after flowering (DAF). The water content of the seeds decreased rapidly until 30 DAF, and no water absorption occurred thereafter. The germination percentage of seeds in bags outdoors was low from 45 to 210 DAF, and it increased after 270 DAF irrespective of the temperature (20–35°C). On the field surface, the shorter the period of storage in bags outdoors, the lower the cumulative emergence percentage of I. hederacea var. integriuscula. The cumulative emergence was 0% in the soil for seeds of more than 90 DAF. The survival percentage of seeds in the soil increased with the number of DAFs. Therefore, the longer the DAF of the seeds, the higher the emergence of the field and survival percentage in the soil. The long period of storage on mother plants may be one of the factors associated with the long emergence period.