Premium
Effect of Hot Water Treatments on the Quality of Rice Seed Destined for International Exchange 1
Author(s) -
Ventura Alicia Rocha,
Garrity Dennis P.
Publication year - 1987
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1987.0011183x002700020032x
Subject(s) - seedling , cultivar , germination , biology , oryza sativa , horticulture , tiller (botany) , agronomy , seed treatment , relative humidity , water treatment , biochemistry , waste management , gene , engineering , physics , thermodynamics
Hot water treatment is used to control seedborne pathogens of rice ( Oryza sativa L.) but it may adversely affect germination and seedling vigor. If cnltivars differ in sensitivity to the hot water treatment used, performance in international cultivar trials may be confounded by the differential hot water effect. We tested alternative hot water treatments within the recommended range for plant quarantine to determine their effects on the viability, vigor, and longevity of seeds of four rice cultivars differing in thermal sensitivity. Factors tested included water temperature, length of immersion period, effect of presoaking the seed, and storage conditions after treatment. Hot water treatment at 52°C for 15 rain was physiologically safe for rice seed regardless of cultivar, storage condition after treatment, or whether presoaking was practiced before the treatment. The 52°C/15‐min treatment actually increased field seedling vigor and tiller number over the untreated control. The 52°C/30‐min treatment had significant deleterious effects on the germinability of two out of four cultivars after 45 days in storage. The 57°C/15‐min treatment produced deleterious effects when the seeds were presoaked and stored under tropical room conditions (25 to 32°C/78% relative humidity). The 57°C/30‐min treatment consistently decreased seed quality in all tests and is considered an unsafe treatment for rice seed. Temperaure, exposure period, presoaking period, storage conditions, and length of storage interacted synergistically in their deleterious effects on rice seed. Safe treatments were defined in terms of all of these factors. Cultivaresponses to the various hot water treatment combinations were generally similar. The most sensitive cultivar was japonica ‘Nan Keng 32’.