**3. Results and Discussion**

### *3.1. Yield Per Hectare*

The total yield of petioles was estimated from data of six harvests per every tested cultivar grown at a density of 11,000 pl/ha. According to Table 5, the highest average values reached 'Red Champagne' (45.58 t/ha) and the lowest 'Canadian Red' (28.77 t/ha). As shown in Figure 1, the influence of the cultivar effect was significant (*p* < 0.001), as well as the year influence (*p* < 0.0025), when the average yield was higher in 2019. *Plants* **2021**, *10*, x FOR PEER REVIEW 6 of 16

**Figure 1.** Effect of the experimental year and cultivar on the mean juice yield of all rhubarb cultivars. Abbreviations: PON, ´Poncho´; CRE, ´Canadian Red´; VAL, ´Valentine´; RCH, ´Red Champagne´; VIC, ´Victoria´. LSD test with significance: significant at *p* ≤ 0.01 (\*\*), or *p* = 0.0000 (\*\*\*\*). **Figure 1.** Effect of the experimental year and cultivar on the mean juice yield of all rhubarb cultivars. Abbreviations: PON, 'Poncho'; CRE, 'Canadian Red'; VAL, 'Valentine'; RCH, 'Red Champagne'; VIC, 'Victoria'. LSD test with significance: significant at *p* ≤ 0.01 (\*\*), or *p* = 0.0000 (\*\*\*\*).

2911.40a

3933.40b

Champagne´

2633.00a

´Canadian Red´

**Figure 2.** Average petiole yield for tested rhubarb cultivars. Values with different letters are signif-

Cultivar

´Poncho´ ´Victoria´ ´Valentine´ ´Red

As shown in Table 6, the juice yield significantly (*p* < 0.05) differed among the tested rhubarb cultivars. The average juice yield of the rhubarb cultivars ranged from 75% ('Poncho', HTA) to 85% ('Red Champagne', HTB). Generally, ´Red Champagne´ was characterized by the highest juice yield potential for both harvests, as it significantly reached the highest values as compared with other tested cultivars. The statistical analysis of all tested results (Figure 3) showed significant differences (*p* < 0.001) in the case of morphological variability and influence of tested years on rhubarb juice yield. The term of harvests has not been shown to be significantly important to juice yield. The yield and composition of petioles are clearly influenced by the technology applied to a crop, especially the cultivar, the planting distance, and the nutritional regimen [14]. There were no data about juice yield of rhubarb found in the available literature. A comparison to similar celery petioles

2556.07a 2489.30a

icantly different at *p* < 0.05 by LSD test in ANOVA (Statgraphic XVII).

*3.2. Juice Yield* 

0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00

yields (g/plant)


**Table 5.** The yields of rhubarb petioles.

Values with different letters are significantly different at *p* < 0.05 by LSD test in ANOVA (Statgraphic XVII). Abbreviations: PON, 'Poncho'; CRE, 'Canadian Red'; VAL, 'Valentine'; RCH, 'Red Champagne'; VIC, 'Victoria'.

The yield of the rhubarb cultivars is influenced both by the cultivar and the density according to Cojocaru et al. [14], where the total yield varied between 27.20 t/ha in the case of the 'Glanskin's perpetual' cultivar, at a reduced density, up to 39.02 t/ ha in the case of the 'Moldova Local population' cultivar, at a high density. A study by Stoleru et al. [9] on the establishment of the rhubarb crop highlighted the fact that in the first year after a crop was established, there were obtained yields of 0.7 kg/pl. at a density of 8000 pl/ha. In the second and third year of a plantation, intensive plant growth was observed according to Salata and Kozak [22]. Our plants were harvested in the second and third years after the planting. The results correspond with the study by Stoleru et al. [9] who reported that, at a density of 13,300 pl/ha, the Victoria cultivar obtained an overall yield of 46.64 t/ha as compared with at a density of 8000 pl/ha, where the obtained yield was 21.72 t/ha. Lepse [23] observed no differences in total yield and yield quality in the second year of a plantation in an experimental study on rhubarb propagation by different methods. Very good commercial yields for rhubarb are approximately 1.5–3 kg of petioles per plant according to Welbaum [2], which corresponds with our results as shown in Figure 2. The average yields per plant varied between 2489.3 ('Victoria') and 3933.4 g/plant ('Red Champagne'). **Figure 1.** Effect of the experimental year and cultivar on the mean juice yield of all rhubarb cultivars. Abbreviations: PON, ´Poncho´; CRE, ´Canadian Red´; VAL, ´Valentine´; RCH, ´Red Champagne´; VIC, ´Victoria´. LSD test with significance: significant at *p* ≤ 0.01 (\*\*), or *p* = 0.0000 (\*\*\*\*).

**Figure 2.** Average petiole yield for tested rhubarb cultivars. Values with different letters are significantly different at *p* < 0.05 by LSD test in ANOVA (Statgraphic XVII). **Figure 2.** Average petiole yield for tested rhubarb cultivars. Values with different letters are significantly different at *p* < 0.05 by LSD test in ANOVA (Statgraphic XVII).

*3.2. Juice Yield* 

As shown in Table 6, the juice yield significantly (*p* < 0.05) differed among the tested rhubarb cultivars. The average juice yield of the rhubarb cultivars ranged from 75% ('Pon-

ized by the highest juice yield potential for both harvests, as it significantly reached the highest values as compared with other tested cultivars. The statistical analysis of all tested results (Figure 3) showed significant differences (*p* < 0.001) in the case of morphological variability and influence of tested years on rhubarb juice yield. The term of harvests has not been shown to be significantly important to juice yield. The yield and composition of petioles are clearly influenced by the technology applied to a crop, especially the cultivar, the planting distance, and the nutritional regimen [14]. There were no data about juice yield of rhubarb found in the available literature. A comparison to similar celery petioles
