No abstract

Okra (Abelmoschus esculentus L. Moench) is a popular vegetable grown in most parts of Sri Lanka. Farmers and home gardeners purchase seeds in packed-form from retail outlets. However, quality problems are frequently reported, especially claiming low field germination even with the laboratory-tested and certified seeds. Quality parameters namely, percentage germination , moisture, field emergence and vigour index analysis were used to determine the effect of different storage environmental conditions on seed longevity of two okra varieties during a two-year storage period, from March 2016 to March 2018. Seeds in triple-laminated packets stored in four contrasting environments, namely, low temperature storage conditions (17 °C and 60-65% RH); three geoenvironmental conditions namely; Gannoruwa (Mid Country Wet Zone), Kundasale (Mid Country Intermediate Zone), and MahaIlluppallama (Low Country Dry Zone) displayed varied behavior in seed quality parameters respective of the variety. It was apparent that germination test alone does not represent the full potential of field emergence. Results of the present study revealed that when field emergence and vigour are also taken in to account, both varieties of okra seed (with initial germination and moisture of ca. 94% and ca. 10%) can be stored under ambient conditions at Gannoruwa, Kundasale or MahaIlluppallama for a maximum period of 12 months, without compromising the seed quality. The seeds stored under low temperature conditions (i.e. 17 °C), maintained the seed germination over 75% for a period of 24 months.

Bean is a popular vegetable grown in most parts of Sri Lanka. Farmers and home gardeners purchase seeds in packeted form retail outlets. However, quality problems are frequently reported, especially on low field germination. Quality parameters namely, percentage germination, field emergence, seedling length, vigour index and chlorophyll fluorescence analysis were used to determine the effect of different storage environmental conditions on seed longevity of two bean varieties during a two-year storage period, 2016 to 2018. Seeds in triple-laminated packets stored in four contrasting conditions; low temperature storage conditions (Tem. 5oC, 65% RH); three geo-environmental conditions namely, Gannoruwa (mid country wet zone), Kundasale (mid country intermediate zone), and Mahailuppallama (low country dry zone) showed varied behavior in seed quality parameters respective of the variety. It was apparent that germination test alone does not represent the full potential of field emergence. Results of the present study revealed that when field emergence and vigour are also taken in to account, both varieties of bean seeds can be stored under ambient conditions at Gannoruwa, Kundasale or MahaIlluppallama for a maximum period of 12 months, without compromising the seed quality. The seeds stored under low temperature conditions (i.e. 5 °C), maintained the seed germination over 75% for a period of 24 months.

Tomato is one of the most commonly growing vegetable crops among the farmers in Sri Lanka. Standard laboratory germination of tomato seeds fulfills the regulatory requirements of seed marketing. However, poor field performance is an overwhelming problem to farmers. Present study was focused on the longevity of two varieties of tomato seeds as affected by their quality characters (percentage germination, moisture, field emergence and vigour index, seed protein and carbohydrate contents) including seed health (exposure of Clavibacter michiganensis subsp. Michiganensis (CMMV), Spotted wilt virus (TSWV) and Leaf curly top virus (LCTV)) under four different storage environmental conditions during a one-year long storage study. Seeds were packed in triple-laminated aluminum packets (TLA) and stored in low temperature storage conditions (17±1 °C and 65% RH) and in ambient conditions in Gannoruwa, Kundasale, and MahaIlluppallama that represent the three agro-ecologically zones; Mid Country Wet Zone (MCWZ), Mid Country Intermediate Zone (MCIZ) and Low Country Dry Zone (LCDZ) respectively. Seed quality parameters displayed varied responses depending on the variety. Physiological changes that occur in seeds due to temperature, RH, changes in proteins and carbohydrate content, CMMV and TSWV during storage were manifested as reduction in seed germination, field emergence and vigour index. However, none of the seedling carried LCTV and therefore its effect on seed quality parameters could not be assessed. The seeds could be stored for ca. 29 months at low and constant temperatures and RH conditions without compromising local seed germination standards compared to ambient storage in the three environments. CMMV and TSWV detected in all seed samples indicated potential threats to tomato farmers in Sri Lanka.

Bean and okra are common vegetables cultivated in the most regions of Sri Lanka.  The seeds of these crops are mainly stored in cold storage as bulk before releasing retail lots to sales outlets. Commercial growers and gardeners buy seeds in bulk or in packages at retail stores. Although certified seeds are frequently tested by the seed testing laboratories, they do not guarantee the maximum field emergence. Certified seed lots of two pole bean varieties, ‘Keppetipola Nil’ (KN) and ‘Bandarawela Green’ (BG) and two okra varities,’MI-5’ and ‘Haritha’ were stored in poly sack and polypropylene bags under controlled temperature (17±1 °C) and relative humidity (RH) (52-55%) over a two-year period. Bulk seeds of bean and okra varieties packed in polypropylene and poly sack bags depicted a high germination percentage throughout the storage period for two years. Seed quality parameters, seed germination, seed moisture, field emergence and vigour index significantly varied with the storage duration and declined in varieties. Significant differences in moisture, field emergence and vigour index were recognized as affected by the packing materials in all varieties except MI-5. Both Poly sack and polypropylene packing materials were found suitable to maintain viability at the minimum seed certification standards for two years of storage period. Poly sack was more appropriate than polypropylene to keep viability for more than 2 years of storage under low temperature and RH condition. These findings would help seed handlers including seed producers and seed sellers to store crop seeds between growing seasons in the tropical environment.