52 Plant Knowledge Journal Southern Cross Publishing Group ISSN: 2200-5390 AUSTRALIA EISSN: 2200-5404 1(2): 52-56 (2012) Influence of capsule position on seed traits and oil content of linseed (Linum usitatissimum L.) Sidra Mukhtar 1 , Muhammad Arshad 1 , Saikat Basu 2*, Fayyaz-ul-Hassan 1 , Mukhtar Ahmed 1 and Muhammad Asif 3 1 PMAS-Arid Agriculture University, Rawalpindi, Punjab, Pakistan 2 University of Lethbridge, Lethbridge, AB Canada T1K 3M4, Canada 3 Agricultural Food and Nutritional Science, University of Alberta, Canada *Corresponding author: saikat.basu@uleth.ca Abstract Seed traits (Seeds per capsule, thousand seed weight and Seeds-husk ratio) and oil content were influenced by prevailing environmental conditions during maturity and post flowering period. A study was executed to document the influence of capsule position on seed traits and oil contents of linseed. The seeds of linseed (Linum usitatissimum L.) cultivar L-6 were sown during month of October, 2009. Prior to appearance of flowers at terminal node, 300 plants were selected (100 plants in each replication) in three replications. On the appearance of first capsule on terminal node labeling to take capsule samples from different positions of plant was done on the day of emergence. The treatments were twelve (Label-1 to Label-12) and it was based on the appearance of capsules on different dates. Capsules labelled on each position were harvested and thrashed separately. Seed traits like seed per capsule, thousand seed weight, seed-husk ratio and oil content were recorded from harvested capsules separately. The maximum seed per capsule (9.05) was recorded for the first label and it decreased significantly for the last label (6.01).This might be due to strong relationship between first sink with source compared to last where plant might requires more ATP to build source-sink relationship. Similar results were obtained for thousand seed weight, seed-husk ratio and oil accumulation. Therefore, it can be concluded that capsule position has significant effect on seed traits and oil contents of linseed that could be due to differential partitioning of photoassimilate at different points of capsule. In addition consistent decrease in values of above parameters may have been caused due to weaker source-sink link and competition for assimilates. Keywords: capsule position, linseed, photosynthates, physiochemical characteristics. Abbreviations: ATP- Adenosine Triphosphate; AOAC- Association of Official Analytical Chemists; PMAS- Pir Mehr Ali Shah; TSW-Thousand seed weight. Introduction Linseed or Oilseed flax (Linum usitatissimum L.) belongs to family Linaceae comprising of nine genera and ~150 species (Tadesse et al., 2009). According to a new classification it consists of 22 genera with ~300 species (Vromans, 2006). It is the only economic species under Linaceae that is agronomically important. It is the sixth largest oilseed crop in the world and is one of the oldest known cultivated plant species (Bhatty and Rowland, 1990). Linseed is a cool temperate annual herb with erect, cylindrical stems, 20-100 cm tall. Being a cool season crop, fall air temperatures under 10 °C possibly inhibit growth rate subsequently delaying the flowering process (Gusta et al., 1997). Linseed as an oilseed is crop grown many parts of world and has wide adaptability (FAOSTAT, 2012). It is an important source of fatty acids for human diet and health (Millis, 2002). Linseed also has the potential to be used as food, fuel and fiber. However, the limiting factor which affects its adaptability is the great variability of seed yield (Weiss, 2000). Thus, understanding of the factors that can affect seed traits and oil contents is of prime importance. The principal stem axis and the corresponding lateral branches exhibit narrow multi-branched floral arrangement (Millam et al., 2005). The inflorescence was reported as corymbose raceme type bearing blue/white flowers at the tip of the branches (Gill, 1987; Millam et al., 2005). Flowers are mostly self-pollinated. A considerable rate of cross pollination was reported in certain cultivars (Gill, 1987). The fruit is a capsule, containing ~10 shiny, flat seeds of different colors. Flowering starts following 60-75 days of sowing. Flowers bloom in clusters, petals open up at down and are usually shed by early afternoon time period. Hence floral blooms occur only for a few hours. In its natural environment linseed is pollinated during morning hours. The petals dropped off after 4-5 h of blossoming (Cullis, 2007). The mature fruit of the linseed is a capsule (dry boll). The bolls are reported to start maturing within 20-25 days following flowering. Individual capsule has five distinct chambers segmented by a wall/septum. The capsules were reported to produce around 10 seed in case of complete maturity, but in most cases lower number of seeds/capsule was observed under field conditions (Cullis, 2007). During the development of capsule dry weight increases consistently and touches the peak at maturity. Seed weight was influenced by prevailing environmental conditions during post flowering period (Berti et al., 2007). The most active period of oil