Editorial: Seed Science and Technology. Volume 49 Issue 3 (2021)

This issue of Seed Science and Technology is a good reflection of the wide scope of the field of study. Species of interest include major cultivated crops as well as wild and native species. Likewise, research topics span a wide array of subjects relevant to those interested in basic seed biology, production, testing, ecology, conservation and biodiversity. Understanding basic mechanisms of seed dormancy and germination remains a major topic of interest. Seed quality and its attributes are also of particular interest, as evidenced by research articles on seed vigour, health, genetic purity and physical characterisation.

LED Light Pre-Treatment Improves Pre-Basic Seed Potato (Solanum tuberosum L. cv. Golden King) Production in the Aeroponic System

Production of plants under artificial light conditions is an innovative and smart concept to grow food year-round in any location. However, pre-basic seed potato production in the greenhouse from LED pre-treated seedlings under an aeroponic system is a new and creative idea. Therefore, the objective of the study was to optimize the effect of LED pre-treatment and determine the best LED spectral composition on growth performance and tuberization of potato plants. Potato variety ‘Golden King’ was treated under 9 LED light spectra for 30 days—L1 (natural light), L2, (R:B), L3 (R:B:G), L4 (R:B:FR), L5 (R:B:G:FR), L6 (R:B:G:FR:UV), L7 (R:B:FR:UV), L8 (R:B:W:FR), and L9 (R:B:W:FR:UV) under 300 µmol m−2 s−1 photosynthetic photon flux density (PPFD), 23/15 °C (day/night) temperature, and 70% relative humidity. The study revealed that growth characteristics and tuber number for plants were increased most by the light spectrum L4 (R:B:FR). Furthermore, photosynthetic pigments increased in L4, L7, and L8, while TSC and sucrose accumulated more in L1 treatment. In contrast, higher seed tuber fresh weight was recorded in L8, L9, L4, and L7. Overall, it can be concluded that potato seedlings pre-treated with the L4 (R:B:FR) LED spectral composition performed best for growth, establishment, and tuberization.

Institutionalizing Quality Declared Seed in Uganda

Farmer-led seed enterprises can produce good quality seed and market it. However, for them to thrive, they need a conducive policy and regulatory framework that is inclusive and less stringent than existing regulatory frameworks. One way to provide a more enabling environment for farmer-led enterprises is through the Quality Declared Seed (QDS) production and marketing system. In Uganda, this seed class is specifically introduced for farmer-led enterprises to produce and market quality assured seed of crops and varieties not served by the private sector. The class is anchored in the Ugandan National Seed Policy and its seed regulations and its operationalization plan. We identified a combination of three strategies that enabled the QDS class to be incorporated into the National Seed Policy. These were: (i) to generate evidence to demonstrate that local seed businesses (farmer groups) can produce and market quality seed; (ii) to engage stakeholders towards an inclusive seed policy; and (iii) to develop a separate QDS regulatory framework. By 2021, institutionalization has reached a critical mass. Areas of attention for full institutionalization are the decentralization of inspection services, awareness and demand creation for quality seed, increasing the number of seed producers, and solving shortages of basic seed (starting material for producing seed).

Pectobacterium parmentieri (black leg disease of potato).

Pectobacterium parmentieri is a bacterial pathogen of potato present in Europe since the 1960s. The bacterium was earlier classified as Pectobacterium carotovorum. After reclassification of P. carotovorum subsp. carotovorum SCC3193 to P. wasabiae and later on to P. parmentieri, several studies devoted to identification of pectinolytic bacteria in international collections and identification of the strains isolated from infected potato plants have indicated that this bacteria commonly occurs in several regions of Europe, Canada, USA, New Zealand and South Africa. P. parmentieri can cause symptoms of blackleg and soft rot on potato tubers. These diseases are usually a consequence of latent infection of seed potatoes. In the majority of countries pre-basic and basic seed tuber potatoes intended for the production of seed tuber crops should be free of Pectobacterium spp. and Dickeya spp. P. parmentieri is not present on any international or national alert lists.

Characteristics and yield of basic seeds of native potato (Solanum goniocalyx) obtained in temporary immersion bioreactor under greenhouse conditions

The characteristics and yield of basic seeds of two native Peruvian potato varieties "Peruanita" and "Amarilla Tumbay" (Solanum goniocalyx), obtained in temporary immersion bioreactors under greenhouse conditions, were evaluated in order to obtain quality seeds in a continuous and sustainable way to guarantee farmers' production and to meet national demand. For this purpose, microtubers and cuttings obtained by temporary immersion bioreactors (TIB) were cultivated in an area of 240 m2 at 3.201 masl, a completely randomized block design was applied with a bifactorial arrangement (varieties x propagules) of 4 treatments and 3 repetitions. The variables evaluated were: survival (SP) and plant height (AP) at 30 days, number of tubers per plant (NT), tuber diameter (DT), tuber weight (PT), tuber size (TT), tuber skin color (CP) and yield in kg per 14.05 m2 (R). Tubers produced from the microtubers stood out from the cuttings in yield for basic seed, presenting an R=26.89 ± 0,483 kg.14.05 m-2, PT= 0,12 ±0,0036 kg and a TD= 22.59 ±0,451 mm; being the variety "Peruanita" the most optimal in number and weight of tubers per plant for basic seed. The basic seed coming from microtubers was obtained in 5 months, being an alternative to guarantee a constant production, allowing to take care of the demand of farmers and to lower the costs of production.

Yield potential of sandponically produced sweetpotato (Ipomoea batatas (L.) Lam) pre-basic seed for selected genotypes

Sufficient sweetpotato (Ipomoea batatas (L.) Lam) pre-basic seed at the start of the “seed” value chain is critical and often a bottleneck in the production of sweetpotato in Sub-Saharan Africa. Predominantly, pre-basic seed is multiplied in screenhouse using the conventional soil substrate method which is costly, is untenable, and achieves sub-optimal yields. The sandponics system is a better alternative for sweetpotato pre-basic seed multiplication in the screenhouse attributed to increased yields and cost-effectiveness. This experiment compared sweetpotato yield- and growth-related traits of planting materials sourced from the sandponics system with conventional soil substrate planting materials for four genotypes when grown in the field. A randomized complete block design was used with three replicates. Results showed a significant difference (p ≤ 0.05) between sources of planting materials and among genotypes for the measured traits. The interaction of source of planting materials and genotype was significant (p ≤ 0.05) for harvest index. Vine survival, storage root yield, number of storage roots per plant, and vine yield were higher by 4.1%, 24%, 27%, and 24%, respectively, in favor of planting materials sourced from the sandponics system. Sandponically multiplied planting materials showed superior performance for yield and most of the measured growth-related traits to planting materials multiplied by the conventional soil substrate method.