Browsing by Author "Shin Yabuta"

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    Effect of P-Dipping on Growth of NERICA 4 Rice in Different Soil Types at Initial Growth Stages
    (Sustainability, 2023-10-28) Emmanuel Odama; Yasuhiro Tsujimoto; Shin Yabuta; Isao Akagi; Rael Chepkoech; Ibrahim Soe; Jun-Ichi Sakagami
    Phosphorus (P) deficiency resulting from P fixation is a major constraint limiting sustainable rice cultivation in sub-Saharan Africa. Soil texture also affects P availability and use efficiency. In a factorial experiment, we evaluated the combined effect of soil texture (sand, clay loam, and clay) and P treatments P-dipping (Pdip) and two other broadcasted P fertilizer levels (Brod1 and Brod2) on the growth of NERICA 4 rice in the initial growth stages. Across all soil textures and P treatments, total plant biomass ranged from 1.06 to 4.63 g pot−1. The Pdip treatment significantly increased shoot and root biomass relative to control from 1.27 to 1.98 and 0.23 to 0.38 g pot−1, respectively. Mean photosynthetic rate values under Pdip (20.1 μmol m−2 s−1), Brod2 (19.5 μmol m−2 s−1), and Brod1 (19.3 μmol m−2 s−1) treatments showed significant 42%, 37%, and 36% increases over control, regardless of soil texture. In a striking contrast, P-dipping significantly promoted growth of root length under clay soil, but without a commensurate increase in shoot P uptake. Contrary to our hypothesis, the interactive effect of soil texture and P-dipping influenced NERICA 4 shoot and root physiological and morphological characteristics under clay loam soil texture as opposed to clay.
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    Primed Seeds of NERICA 4 Stored for Long Periods under High Temperature and Humidity Conditions Maintain Germination Rates
    (Applied Sciences, 2023-02-23) Emmanuel Kiprono Bore; Eri Ishikawa; Julie Ann Mher Alcances Libron; Keita Goto; Emmanuel Odama; Yoshihiro Nakao; Shin Yabuta; Jun-Ichi Sakagami
    Agriculture depends on the ability of seeds to survive until the next planting season under ambient conditions that may be averse to seed quality even when the seed is in a quiescent state. Seed priming invigorates seeds, but the impact on the longevity of seeds has limited its adoption. This study investigated the effect of the storage of primed rice seed on seed viability, vigor, and longevity. Three seed priming methods were employed on the rice cultivar New Rice for Africa (NERICA 4) seeds. Subsequently, the seeds were stored for 120 days at 25 ◦C and 65% relative humidity, simulating the ambient seed storage conditions of the tropics and sub-tropics. The primed seed recorded increased vigor compared to the non-primed seed until 90 days of storage. However, seed storage for 120 days reduced seed vigor and viability for all the seeds. The results indicated a significant reduction in seed vigor, increased solute leakage, generation of hydrogen peroxide, and accumulation of malondialdehyde after storage. Priming enhances cell membrane integrity and maintains seed vigor in storage at near ambient conditions long enough before reversal of its performance by the storage conditions. This assures that primed seed can either be stored until the following planting season or remain viable in the soil during delayed germination.