Effect of Growing Media and Fertigation on Asparagus (Asparagus officinalis L.) Seedlings

Asparagus (Asparagus officinalis L.) is an export product and one of the most lucrative products compared to other vegetables; and it is a valuable economic, pharmaceutical, food and industrial crop. The most important agriculture aspect of asparagus is the quality of the seedlings; they depend on the percentage of rooting after planting and are very important for future crop quality. This study was conducted to determine the best level of municipal waste compost and fertigation on asparagus seedling growth with thick buds and large and dense crown, strong roots, and a high number of summer branches.

The experiment was conducted in a completely randomized design with three replications and with two factors of substrate composition (at four levels) and fertigation (at two levels) with three replications and at least 20 seedlings per replication. Asparagus seeds were planted in four different litter compositions that of 50% by volume of garden soil and sand used as a base bed and mixed with different amounts of municipal waste compost (0, 10, 20, 30% by volume). After germination, half of the seedlings in each bed were fed with fertigation containing nitrogen, potassium, and pure phosphorus at the rate of 150, 100, 50 grams per cubic meter of irrigation water. Finally, after a three-month feeding period, the important traits of seedlings including root length, number of buds, number of summer shoots, summer stem height, SPAD index, number of roots, root volume, root diameter, percentage of ash, percentage of dry matter, fresh weight, potassium, phosphorus, phenol, flavonoids and antioxidants were measured.

The results of data analysis of variance showed that the effect of fertigation and the effect of compost levels of composition on plant height, number of top summer branch, fresh weight of the plant, plant dry weight, crown thickness, number of buds, root length, number of roots, root volume, chlorophyll index (SPAD), total phenol, total flavonoids, and potassium were significant. The results showed that the highest average of these traits was related to fertigation treatment and the lowest average of these traits was obtained without fertigation treatment. The results of comparing the average simple effects of compost levels, the highest average of these traits from culture medium containing 30% municipal waste compost and the lowest average of these traits was obtained from culture medium containing no municipal waste compost. Also, the interaction effect of compost levels in fertigation on plant dry weight and canopy thickness was significant. The highest average of these traits was related to treatment with fertigation and culture medium containing 30% municipal waste compost.

It seems that due to the long production period of asparagus seedlings, paying attention to feeding the seedlings through fertigation and enriching the culture medium can help improve the quality of seedlings. As the results of our experiment showed, the use of municipal solid waste compost has an effect on germination, growth and number of summer shoots, number of buds, increase in volume, length, diameter and number of roots, crown thickness and chlorophyll index, fresh weight and plant dryness, percentage of dry matter, amount of phenol and absorption of potassium could have a great effect on the growth and quality of the seedlings of this plant. On the other hand, with the increase in plant growth and as a result, more yield, the plant needs irrigation to expand the roots and increase the number of summer stems because it needs a lot of nutrients. Therefore, it is better to use mineral fertilizer in growing asparagus. In this condition, the plant produces more roots, and the underground stems that lead to produce more and stronger seedlings. Stronger asparagus seedling growth faster than the weeds and overcomes and reaches economic performance sooner. Therefore, carefulness in the use of municipal solid waste compost and the amount of animal and mineral fertilizers, by affecting the yield and as a result the profitability of this plant, will encourage farmers to cultivate this crop. On the other hand, it is possible to use municipal solid waste compost in other ways. There is no need to use a large number of chemical fertilizers and the safe product is healthier than other plant products that use a large number of chemical fertilizers for their production.