The Factor Analysis and Issues of Soybean Yield at Community-based Farming Corporations in Mountain Areas

The spread of morning glory (Ipomoea spp.) in Japanese soybean (Glycine max (L.) Merr.) fields has severely decreased soybean yields. Field levees are believed to be a source of this invasion. The introduction of Zoysia japonica Steud. is expected to suppress weed growth and reduce the required labor for weed management on the levees. In this study, field experiments were conducted on the soybean levees of turf (Z. japonica), bare, and weed (mainly broad leaf weeds such as white clover) from 2017 to 2019 to compare its effects on the occurrence, growth, and seed production of I. hederacea (L.) Jacq. var. integriuscula A. Gray. The canopy height in the turf levee was the lowest, and the vegetation cover rate was the highest. At the flowering and fruiting stage of I. hederacea var. integriuscula (September), the largest number of I. hederacea var. integriuscula that survived were on the turf levee; however, the plant length, dry weight, and the number of fruits were the least. Additionally, the stems of the morning glory on the turf levee were slight and spindly, and their growth and seed productivity were suppressed. Consequently, vegetation conversion to Z. japonica on the soybean field levees can be an effective strategy to suppress the colonization and growth of morning glory, thereby, improving soybean yields.

Section: Introductionmentioning

confidence: 99%

Suppression of entireleaf morning glory (Ipomoea hederacea Jacq. var. integriuscula A. Gray) growth by lawngrass (Zoysia japonica Steud.) on soybean field levees in southwestern Japan

Asami,

Fushimi,

Homma

2024

“…The global average soybean yield in 2018 was 288 kg 10 a −1 , while in Japan it was 144 kg 10 a −1 (Ministry of Agriculture, Forestry and Fisheries, 2020). One of the main causes of low soybean yield in Japan was identified as weed damage (Sakamoto et al, 2017), and morning glory species ( Ipomoea spp.) are a particularly problematic weed (Elmore et al, 1990) with the potential to reduce soybean yields by 90% when spread at a high density (Howe & Oliver, 1987).…”

Section: Introductionmentioning

confidence: 99%

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

Asami

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-

“…Compared with the global average soybean yield of 288 kg 10 a −1 in 2018, Japan's was 144 kg 10 a −1 (Ministry of Agriculture, Forestry and Fisheries, 2020). The reasons include weed damage, a decrease in soil fertility, and excess moisture injury caused by planting in upland fields converted from rice paddies (Sakamoto, Datai, & Yokomizo, 2017). Morning glory ( Ipomoea spp.)…”

Section: Introductionmentioning

confidence: 99%

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

Asami

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.