- |<
- <
- 1
- >
- >|
-
Seiji SHIMODA, Maki KANAYA, Yasuhiro KOMINAMI, Hiroyuki TSUJI2023 Volume 79 Issue 2 Pages 59-68
Published: 2023
Released on J-STAGE: April 10, 2023
Advance online publication: January 31, 2023JOURNAL OPEN ACCESSThe objectives of this study were to verify changes in potato tuber number and weight under climatic variations in a cool region in Japan. We investigated potato growth over a 3-year period from 2019, establishing plots with different planting times and maturity types. In 2020, early planting encountered dryness during the tuber formation period after sprouting, which significantly reduced tuber numbers. Temperature was identified as the main factor contributing to the annual variation in potato yield, largely due to unusually high temperatures during the study period. In 2021, hot and dry conditions in early summer (mid to late July) corresponded to the tuber bulking period and reduced the yield owing to light tuber weight regardless of the planting time and variety. The present study provided insights into the variability of yield components in potato by focusing on drought effects, weather, and cultivation factors, which vary substantially.
View full abstractDownload PDF (537K) -
Nobuyuki KAYABA, Ryoji SAMESHIMA2023 Volume 79 Issue 2 Pages 69-76
Published: 2023
Released on J-STAGE: April 10, 2023
Advance online publication: March 11, 2023JOURNAL OPEN ACCESSThe optimal timing of pest control is forecasted via effective accumulated temperature. We focused on the daily increment of it (Dy,i ; y and i indicate the year and day, respectively). Dy,i is usually estimated using the hourly temperature. The observed hourly temperature data are only available for the time period before the publication date (when the pest control information is released). Normals (historical data from a 30-year period) of hourly temperature have been used for the time period after the publication date, which may lead to errors in estimating Dy,i. We examined the errors caused by the use of normals and developed new methods for estimating Dy,i for the time period after the publication date: the normals of Dy,i. Simulations for the past 30 years showed that pest forecasting using the normals of Dy,i resulted in smaller errors than the existing method because it reflected diurnal temperature variations. We proposed another method for cases where high temperatures are predicted in the time period after the publication date and showed an example in which this method had better accuracy than the existing method.
View full abstractDownload PDF (1672K)
-
Hiroki OUE2023 Volume 79 Issue 2 Pages 77-84
Published: 2023
Released on J-STAGE: April 10, 2023
JOURNAL OPEN ACCESSThis study focused on stomatal conductance (gs) and electron transport rate (ETR) as one possible approach to the mechanisms of controlling canopy temperature and photosynthetic traits in rice. Three Japanese rice cultivars, Koshihikari (KH), Nikomaru (NM), and the new cultivar Himenorin (HR) developed in Ehime Prefecture were selected for the experiment. From the uppermost to the fifth leaves of five or more rice plants of each cultivar, gs and ETR were measured in situ using a handheld porometer/fluorometer. The results revealed the highest gs in HR among the three cultivars in all leaf positions from before the flag leaf extension until the maturity stage, which could be regarded as one of the advantageous mechanisms for moderating the thermal condition of the canopy with larger transpiration and supporting a higher photosynthetic level. The ETR of HR was highest among the three cultivars in most leaf positions from the heading stage to the maturity stage, which could be expected to maintain a higher photosynthetic level. These traits of gs and ETR in HR compared with NM and KH could be assessed as possible synergistic mechanisms for higher production and quality of rice with higher photosynthetic potential.View full abstractDownload PDF (1109K)
- |<
- <
- 1
- >
- >|