**3.2 Nitrogen, protein, fresh weight and dry weight analyses**

The highest nitrogen yield was obtained from seeds that had been soaked for 1 h and irrigated for 12 h (Treatment 5), while the lowest yield was obtained from Treatment 17 (**Figure 5**). Similarly, the protein content of the samples follows the same pattern, with the highest and lowest nitrogen yields recorded in Treatments 5 and 17, respectively (**Figure 6**). Furthermore, the freshly harvested *H. vulgare* sample

#### **Figure 5.**

*Effect of soaking time and irrigation interval on the nitrogen content of* H. vulgare. *Tukey pairwise comparisons was used to compare means of combined effects of soaking time and irrigation interval at P* ≤ *0.05. Means that do not share the same letters are significantly different.*

#### **Figure 6.**

*Effect of soaking time and irrigation interval on the protein content of* H. vulgare. *Means that do not share the same letters are significantly different.*

*Seed Soaking Times and Irrigation Frequencies Affected the Nutrient Quality and Growth… DOI: http://dx.doi.org/10.5772/intechopen.104503*

*Effect of soaking time and irrigation interval on fresh weight of* H. vulgare. *Means that do not share the same letters are significantly different.*

#### **Figure 8.**

*Effect of soaking time and irrigation interval on the dry weight of* H. vulgare. *Means that do not share the same letters are significantly different.*

weighed the most in Treatment 2 (1 h soak–4 h irrigation) and the least in Treatment 24 (**Figure 7**). The dry weight of *H. vulgare*, on the other hand, was highest in Treatments 4 and 14, and lowest in Treatment 1 (**Figure 8**).

Furthermore, the two-way ANOVA revealed that soaking time and irrigation interval had no independent effect on nitrogen and protein yield of *H. vulgare*, as well as the interaction of the two factors. Similarly, the fresh weight was not significantly affected by the two factors independently, but soaking time significantly affected the dry weight of the harvested plant samples. The interaction of the two factors had a significant effect on the dry weight of the sample, although the irrigation interval indicated otherwise.

## **4. Discussion**

Findings from this study suggest that the seeds of *H*. *vulgare* responded more favorably to a shorter soaking time for a longer period of irrigation. The average leaf height increases as the irrigation period lengthens, with mean average heights ranging from 8 to 12 cm. For example, Treatment 6 with a 3-h soaking time and a 2-h irrigation interval had the greatest effect on average leaf height. Treatments 1 and 3 (**Figures 3**–**5**) were of slightly less significance because they both had a 1-h soaking treatment but were subjected to 2 hourly and 8 hourly irrigation intervals. These treatments differed greatly from the soaking control of 16 h as reported in [33, 39] but in agreement with [24] with an irrigation control of 2 h. Although Treatment 20 had the highest mean length value of 14.33 cm, it appeared that the seedlings and their corresponding lengths responded more to the increased irrigation frequency of 2 h, confirming the irrigation control used in this study (**Figure 4**). This was consistent with the soak control of 16 h, but it differed significantly from the irrigation control of 2 h [33, 40]. Also, the average height of barley recorded in this experiment differed significantly from previous studies where heights of 14.0 cm and 6.2 cm were respectively recorded by [20, 41].

Treatment 12 (8-h soak with 4 hourly irrigation) had the highest mean root expansion (3.07 cm) after the 8-day growing cycle, which was significantly different from the control. Treatment 2 followed with a mean of 3.03 cm (1-h soak with a 4-hourly irrigation interval; **Figure 5**), which was less significant than Treatment 12 due to a marginal difference of 0.04 cm, which is significant. Treatment 2 would thus allow the cultivator to reduce soaking time again to achieve similar results, with both treatments having the greatest effect with an irrigation frequency of 4 h, though other researchers have reported that transient exposure of *H. vulgare* roots to heavy metals may also have an adverse effect on root mat expansion [35, 42]. It would be interesting to see if changing the irrigation type, from drip to spray, or the mineral/trace metals composition of the irrigation water, would improve seedling root expansion, and if adding liquid fertilizer would do the same.

Furthermore, the highest nitrogen and protein concentrations were obtained in Treatment 5 with a 1-h soaking treatment and a 12-h irrigation interval (**Figures 6** and **7**). These results did not agree with the controls of 16 h of soaking and 2 hourly irrigation intervals. This indicated that the seed requires a shorter soaking treatment (1 h) as well as a longer (12 h) irrigation interval to achieve the highest level of nutrients in the seedling at harvest time. However, as discovered during the growth experiment, a 12-h irrigation interval is not beneficial to seedling growth. It was interesting to note that the next highest statistical mean belonged to treatment 1 (1-h soak with a 2-h irrigation interval), which was only marginally less than the highest mean achieved in treatment 5, which also had a 1-h soak time but a 12-h irrigation interval. This was consistent with the control and resulted in seedlings that were stronger and healthier. The shorter soaking time benefits the grower by reducing the time spent pre-soaking the seed, but it does not help with water conservation because it is

*Seed Soaking Times and Irrigation Frequencies Affected the Nutrient Quality and Growth… DOI: http://dx.doi.org/10.5772/intechopen.104503*

irrigated every 2 h. However, as the salinity of the hydroponic medium changes, this may change. However, this might change as the salinity of the hydroponic medium changes [43, 44]. Only crude nitrogen and protein were tested in this experiment, and further research into trace element levels would be required to determine the seedlings' full nutrient spectrum post-harvest. Other studies found that shortening the growing period from 8 to 4 days resulted in higher nutrient levels, which could be investigated further.

Furthermore, all of the highest dry weight means were obtained using a 10-h irrigation interval. The most significant results were obtained with soaking treatments lasting 1 and 3 h, as shown in Treatments 4 and 9, respectively. Although less significant, Treatment 14 with an 8-h soaking time was only 0.24 g lighter than treatments 4 and 9. This indicated that the seed pre-soaking time before germination could be reduced to 1 h. Under a 10 hourly irrigation interval, all three treatments (Treatments 4, 9, and 13) produced the highest dry weight. The highest fresh weight recorded came from that of Treatment 12, with a soaking time of 8 h and an irrigation interval of 4 h. It can be deduced that the seedlings benefitted from longer pre-soaking treatment. They still required moderate watering as the irrigation interval was every 4 h. Neither of the treatments agreed with the controls for soaking nor irrigation. The second highest mean value was achieved with Treatment 2 with a 1-h soak and 4 hourly irrigations. This proved that the pre-soaking time could be reduced without it affecting the total weight of the seedling post-harvest, however, the water consumption required to enable growth remained relatively high. Therefore, the disparity recorded in the weight of fresh samples compared to dry samples agrees with the results of the previous study as reported by Emam [20]. An investigation into the use of a nutrient solution to the irrigation water would be required to establish if this would improve overall fresh weight, post-harvest and if the introduction of a nutrient solution would allow the irrigation interval to be decreased thereby saving water.

#### **5. Conclusion**

This study reveals that a 1-h pre-soaked treatment, under 4 or 12 hourly irrigation intervals (T2 and T5) was the best treatment for cultivating barley hydroponically to achieve better yield for optimal fresh fodder production. For dry fodder weight, the highest yields were obtained with irrigation intervals of 10–12 h. Even though other growth parameters investigated such as length and root map expansion deviated from this trend, shorter soaking time at increased irrigation frequencies, proved to be beneficial to the farmer in terms of weight, nutrient yield, and height of *H. vulgare*. In the future, it would be helpful to ascertain if a change in irrigation type, from drip to spray, or increasing the mineral/trace metals composition of irrigation water would improve the root expansion of the seedling or bring about a marked decrease in irrigation water, thereby saving water.

#### **Authors' contributions**

*Ryan Anthony Smith*: Designed and performed the experiments; collated and analyzed data; wrote the original paper.

*Muhali Olaide Jimoh*: Analyzed and interpreted collated data; revised the manuscript with technical inputs.

*Charles Petrus Laubscher*: Conceived and designed the experiments; sourced for funding; supervised the experiments; edited the manuscript.
