Since micropropagation is performed in sterile conditions, it seems that an additional step should be considered to achieve a high germination rate.When a viable seed is not able to germinate under appropriate conditions, the seed is considered to be dormant.While cannabis seed is generally not thought to exhibit dormancy, it would appear that under these unusual circumstances, it demonstrates some physical dormancy. Following water uptake by the quiescent, dry, mature seed, germination occurs once the embryo can prevail over the constraints imposed by the testa and associated tissues.As shown in Figure 4, the main constraints exerted by the covering seed structures include the mechanical prevention of radicle protrusion, water uptake interference, interference with gas exchange, especially carbon dioxide and oxygen light filtration, and inhibitor leakage restraint from the embryo.
The removal of the seed coat had an important role in breaking seed dormancy, which ultimately resulted in higher germination speed and frequency. Our results showed that seed scarification by removing the seed tips significantly increased the speed and frequency of seed germination. In line with our results, Pérez-Jiménez et al. reported that seed scarification significantly increased the in vitro seed germination of Prunus persica L. Batsch. For the first time, we have demonstrated this method with respect to the micropropagation of cannabis.To assess the effect of seed scarification, the micropyle and its surrounding tissue were removed by scalpel, without injury to the embryo . This experiment was performed based on a completely randomized design with two treatments with three replications. Each replication contained four seeds.White lupin is considered one of the most important domesticated lupin species, when regarding the nutritional value of seeds .
Characterized by its protein-rich composition,a high-quality fatty-acids’ profile, and a plethora of health-promoting bioactive molecules, white lupin denotes a nutritional treasure worthy to be harnessed . However, antinutritional compounds like quinolizidine alkaloids present in high contents in wild white lupin populations and bitter cultivars, reduce its nutritional value and prevent the use of unprocessed seeds for human and animal consumption. From an agronomic perspective, white lupin promotesboth N- and P- soil enrichment, through the formation of nodules and proteoid roots , and can be cultivated under rainfed intercropping systems, encouraging low-input farming systems . Therefore, it suggests a promising choice for promoting global food security and environmental protection, through sustainable agriculture . White lupin originates in the southern Balkans, and “graecus-type” natural populations disperse throughout the Eastern Mediterranean basin, where landraces are used for human consumption and fodder, dating back to 2000BC . However, because of its adaptability to marginal regions, and the requirement of a post-harvest debittering process , white lupin’s cultivation was restricted mainly to local communities on barren lands.
Currently, lupins account for only 1% of the main grain legumes cultivated worldwide. Lupin production and cultivated area worldwide for 2019 was estimated at about 1,006,842 tonnes and 887,111 ha, respectively. Australia is the largest producer, with 47.1% of the global production, while Europe is second according to FAOSTAT . In Europe L. angustifolius L. and L. luteus L. are the predominant cultivated species in the north and countries with more than 10,000 ha of lupins are Poland, the Russian Federation, Germany, Belarus, and Ukraine. In the south, where L. albus L. is predominant, Italy , France , and Spain are the main lupin-producing countries.Thus, there is still significant variability even among commercial germplasm for the most essential breeding targets, namely, the seed’s nutritional value and the toxic, bitter secondary metabolites QAs.The total alkaloid content in white lupin varies from 0.02 to 12.73% of the seed’s dry weight. Cultivars possessing the pauper gene contain 0.02–0.05% alkaloids of the seed dry weight.The recently published white lupin pangenome study demonstrated that pauper locus has a key role in the species domestication and breeding.Other important agronomic characters of white lupin, which attracted the breeders’ attention, are vernalization insensitivity,anthracnose resistance,yield stability,and abiotic-stress acclimation.