Relationship of Percentage and Oil Yield with The Physicochemical Properties of Native Castor Genotypes from Iran

Results

Effects of genotypes on the physicochemical properties of castor

Leaf color

The native castor genotypes exhibited four different leaf colors. As such, they were classified into four genotypic groups. The first group with dark green leaves included eight genotypes, namely, Ricindozho, Kashan, Shahrood, Darab, Damghan, Ardebil, 14283, and Tabriz. The second group with green leaves comprised 14 genotypes, namely, Mobarakht, Arak, Semnan, Birjand, Zabol, Urmia, Karaj, 1574, 1083, 1084, Mashhad, Fasa, Yazd, and Ahwaz. The third group with pink leaves consisted three genotypes, namely, Dezful, Maragheh, and 1573. The fourth group with red leaves contained three genotypes, namely, Gachsaran, Jiroft, and Sirjan (Figure 1). Castor plant is characterized by various growth traits, such as leaf, size and number of leaf lobes, and polished mode of stems^10-11. However, the most evident variety was observed in the shape, color, and size of seeds, number of flowers in each cluster, pedicle length, and capsule opening. Leaf color was positively and significantly correlated with stem color (r = 0.54**) at 1% probability level (Table 4).

Figure 1: Result leaf color from cluster analysis of Iranian castor genotypes Click here to View Figure

Vein Color

The native castor genotypes manifested different vein colors. As such, they were classified into four genotypic groups. The first group with white vein included four genotypes, namely, Sirjan, Ahwaz, Dezful, and Kashan. The second group with green vein comprised eleven genotypes, namely, Arak, 1048, Mobarakeh, Maragheh, Zabol, Urmia, Tabriz, Jiroft, Yazd, Mashahd, and 14283). The third group with pink vein consisted of seven genotypes, namely, Karaj, 1274, Fasa, Damghan, Semnan, Birjand, and 1083). The fourth group with red vein contained six genotypes, namely, Ardebil, Gachsaran, 1573, RicinDonzho, Shahrood, and Darab (Figure 2). Leaf color positively and significantly correlated with grain length (r = 0.56 **) and grain width (r = 0.57**). Therefore, grain length and width increase as veins change their color from white to dark red. As a result, grain weight, yield, and oil yield increase (Table 4).

Figure 2: Result Vein color from cluster analysis of Iranian castor genotypes Click here to View Figure

Stem Color

The native castor genotypes display different stem colors (Table 3). As such, they were classified into five genotypic groups. The first group with dark green stem included three genotypes, namely, Kashan, RicinDonzho, and Ahwaz. The second group with green stem comprised six genotypes, namely, Urmia, Karaj, 1573, Jiroft, Farab, and Dezful. The third group with pink stem consisted of thirteen genotypes, namely, Gachsaran, Mashahd, 1083, Ardebil, Damghan, Tabriz, Zabol, Semnan, Yazd, Birjan, 1048, Arak, and Mobarakeh. The fourth group with red stem contained five genotypes, namely, Fasa, 14283, 1574, Shahrood, and Sirjan. The fifth group with dark red stem included one genotype, namely, Maragheh (Figure 3). A wide diversity was observed in growth traits, such as stem color of castor plant^{10, 11-27}. Stem color was positively and significantly correlated with grain length (r = 0.62 **) and grain width (r = 0.60 **) at the 1% level. This finding indicated that grain length and width increase as stem color changes from white to dark red. At high latitudes, seed weight, yield, and oil yield increase (Table 4).

Figure 3: Result Stem Color from cluster analysis of Iranian castor genotypes. Click here to View Figure

Seed Color

The native castor genotypes showed different Seed Colors (Table 3). As such, they were classified into five genotypic groups. The first group with white seed coat included three genotypes, namely, Kashan, Arak, and RicinDonzho. The second group with black seed coat included ten genotypes, namely, Mobarakeh, Semnan, Birjand, 1573, 1083, 1084, Fasa, Darab, Damghan, and Sirjan. The third group with pink seed coat consisted of 11 genotypes, namely, Ahwaz, Mashhad, 14283, Gachsaran, 1574, Karaj, Ardebil, Tabriz, Zabol, Jiroft, and Dezful. The fourth group with dark red seed coat comprised two genotypes, namely, Yazd and Shahrood. The fifth group with black seed coat included two genotypes, namely, Urmia and Maragheh (Figure 4). Differences in fertility rate, shape, color and seed size, number of flowers in a cluster, pedicle length, and capsule opening¹¹ .

Figure 4: Result Seed Color from cluster analysis of Iranian castor genotypes Click here to View Figure

Grain yield

The native castor genotypes resulted in different grain yields (Table 3). Therefore, they were classified into six genotypic groups. The first group with very low yield included three genotypes, namely, Damghan, Birjand, and Mobarakeh.  The second group with low yield comprised seven genotypes, namely, Karaj, Kashan, Arak, Zabol, RicinDonzho, Maragheh, and Dezful. The third group with moderate yield consisted of eight genotypes, namely, Gachsaran, Darab, Jiroft, 1084, Urmia, Semnan, Ardebil, and 1573. The fourth group with high yield contained six genotypes, namely, Shahrood, 1083, Ahwaz, Mashahd, Yazd, and Sirjan. The fifth group with very high yield included two genotypes, namely, 14283 and 1754 (Figure 5).

Figure 5: Result grain yield from cluster analysis  of Iranian castor genotypes Click here to View Figure

The highest seed yield was observed in the native genotype of 14283 with 2134.6 kg per hectare, and the lowest seed yield was detected in the native genotype of Mobarakeh with 1183.02 kg per hectare. Although other genotypes were classified among the highest or lowest grain yield groups, the lowest and highest yields were recorded in the two aforementioned genotypes (Table 5). The least and most productive native genotypes were compared by considering various traits, such as weight of 1,000 seeds, seed length, and seed width. Thus, differences were observed in the seed yield of the genotypes investigated in this experiment. These results were consistent with the findings of^{11, 19-21}. Genotype 14283 exhibited a higher seed yield and weight of 1,000 seeds⁸. The seed yield of the castor plant depended on environmental conditions. Seed yield was positively and significantly correlated with oil yield (r = 0.85^**) at 1% probability level. This result indicated that oil yield increased as the seed yield increased (Table 4). Nevertheless, the weight of 1,000 seeds was not significantly related to seed yield, consistent with another study¹⁸. Sarwar and Chaudhry investigated the effects of various traits, such as ripping time, plant height, number of clusters, length of main cluster, number of capsules in the main cluster, capsule weight, and weight of 100 seeds, on the yield of 16 castor genotype mutants with gamma radiation to determine the proper criterion for ideal types with high yield²¹. A significant, positive correlation was seen between number of clusters, capsule weight, weight of 100 seeds and grain yield.

Weight of 1,000 seeds

The native castor genotypes yielded different weights of 1,000 seeds (Table 3). The highest and lowest weights of 1,000 seeds were 411.48 and 146.44 g for Karaj and Birjand genotypes, respectively. Therefore, the weight of 1,000 seeds differed. Karaj exhibited a higher weight of 1,000 seeds than the other genotypes in the same group. This finding can be a useful reference to achieve future breeding objectives (Table 5). Several researchers have related the differences in the weight of 1,000 seeds to genotype and environmental conditions^22-24. Other researchers related this difference only to genotype^18-19.

Width and length of seeds

The native castor genotypes manifested different widths and lengths of seeds (Table 3). The maximum seed length was 14.52 mm recorded in Yazd, and the maximum width was 9.52 mm documented in Karaj. The minimum seed length was 8.71 mm and the minimum width was 6.55 mm observed in Birjand (Table 5). The weight of 1,000 seeds was positively and significantly correlated with the seed length (r = 0.83**) and seed width (r = 0.86**) at 1% probability level. This finding revealed that the weight of 1,000 seeds increased as these two traits increased. As a result, seed yield improved (Table 4).

Oil percentage

The native castor genotypes exhibited different seed oil percentages (Table 3). Thus, they were classified into four genotypic groups. The first group with low seed percentage included 17 genotypes, namely, Ardebil, Mobarakeh, Urmia, Tabriz, Yazd, 14283, 1084, Arak, Sirjan, Darab, Shahrood, RicinDonzho, 1573, 1083, Semnan, Damghan, Fasa, and Karaj. The second group with medium percentage consisted of eight genotypes, namely, Dezful, Ahwaz, Mashhad, Zabol, Kashan, 1574, Jiroft, and Maragheh. The third group with high percentage comprised two genotypes, namely, Gachsaran and Birjand. The fourth group with very high percentage included one genotype, namely, 1084 (Figure 6).

Figure 6: Result oil percentage from cluster analysis of Iranian castor genotypes Click here to View Figure

Table 4: Correlation Coefficients among traits 17 of Iranian Castor Genotypes

^ns,* and**: Non Significant, Significant at 5% and 1% Levels Respectively.

Table 5: Means of traits of Iranian Castor genotypes (Duncan Multiple Range Test at The Level of 5%).

Mean Followed By Similar Letters In Each Column are not Significantly Different.

Fluorescence parameters

The native castor genotypes exhibited different maximum fluorescence rates and F_V/F_M. By contrast, F_V and F_O did not differ (Table 3). The following parameters were positively and significantly correlated at 1% probability level: F_M and F_V (r = 0. 92**); F_V/F_M(r = 0. 99**); and F_M and F_V/F_M (r = 0. 96**). This finding indicated that other fluorescence variables (F_O, F_V, F_M, and F_V/F_M) are altered as each of the fluorescence variables changes. The following parameters also exhibited a positive and significant correlation: leaf color and F_V (r = 0.56**); leaf color and F_M (r = 0. 48**); stem color and F_V (r = 0.63**); and stem color and F_M/F_V (r = 0.54**). This finding revealed that the fluorescence rate increased as leaf and stem colors changed (Table 4).

Oil yield

The results of analysis of variance showed that oil yield had significant difference among castor Genotype at 1% probability level. Table comparing means showed that the maximum oil yield were obtained by   the Ahwaz Genotype with 906.22 kg per hectare and lowest oil yield achieved by Mobarakeh Genotype with 528.86 kg per hectare (Table 5). Ahwaz genotype by maximum seed yield and oil content were; therefor, these traits can significantly effect on oil yield. Although Ahwaz genotype had characterized by lowest levels for the traits, such as grain weight, grain length and width but shall proposed Ahwaz genotype as a superior genotype in breeding programs because of its high oil percentage.

This study was conducted to identify genotypes with high oil yield. The results showed that genotype Ahvaz has high oil content than other genotypes. Castor oil a genetic trait that is depends has  to  genotype, environmental conditions and cultivation practices and harvesting time. In this study, seed yield was positively correlated with oil yield, and a significant risk was observed (r = 0. 85 **; Table 4). Cluster analysis revealed that the traits of castor native genotypes could be divided into two main groups. The first group includes 1084, Damghan, Ricindozho, Tabrizu, Mobarakht, Gachsaran, Yazd, Darab, Dezful, Sirjan, Zabol, Jiroft, Ardebil, Karaj, Maraghehe, Birjand, and Urmia. The other group comprises Arak, Kashan, 1573, Mashhad, Fasa, Semnan, 1083, Shahrood, Ahwaz, 1574, and 14283. The subgroups in each group were treated with the greatest similarity (Figure 7).

Figure 7: Result Studied Characters of Iranian Castor Genotypes from cluster analysis. Click here to View Figure

 

Conclusion

Evaluation of plants’ genetic diversity is vital for modification and preservation of inheritance reserves. Knowledge of plants’ genetic diversity is very important for selection of suitable parents for hybridization and obtaining suitable results. Phenotype evaluation may help collection management, species identity validation, error diagnosis in identification and determination of phenotype relations in hybrid species and their parents, rather than usage for plants classification²⁶. Diversity of leaf color, vein colors, stem color, and seed color were observed in this research. There were four color types (dark green, red, pink, green) in leaf genotypes; four color types (red, pink, green, white) in vein genotypes; 5 color types (red, pink, green, dark green, dark red) in stem genotypes; and 5 color types (black, white, bright black, pink, hepatic red) in seed genotypes. A wide diversity was observed especially in the growth traits such as stem color of the castor plant^{10, 11-18}. Popova and Moshkin (1986) reported variety in the fertility rate, shape, color, seed size, number of flowers in a cluster, pedicle length, and capsule opening¹⁰.  Popova and Moshkin (1986) and Savy-Filho (2005) reported varieties in the growth traits of the castor plant, such as leaf, size and number of leaf lobes, and polished mode of the stems^10-11. However, the most evident variety was observed in the seed shape, color, and size; number of flowers in each cluster; pedicle length; and capsule opening. Since these are genetic changes due to the environmental conditions, it is recommended to do new studies due to the importance of anthocyanin. Other scholars also have reported diversity in leaves, stems, etc. ^14-15. Furthermore, the highest and lowest oil percentages were 52% and 38% recorded in Darab and 14283, respectively. Seed weight is positively related to oil percentage^22-24. However, this finding was contrary to our results. Seed weight is negatively related to oil percentage (r = –0.65**), but this finding was in consistent with our results¹⁸. The oil percentage in castor seed is a genetic trait influenced by various factors, including genotype, environmental conditions, agricultural operations, and harvest time and so on²³.The amount and ingredients of castor oil are related to climate, cultivar, and cultivation and processing methods⁷. The oil percentage in trade varieties normally differs between 40% and 60%. Oil yield is a combination of seed yield and oil content⁶. Therefore, a reduction in the seed yield decreases oil yield¹⁷. In this study, the positive correlation between seed yield and oil yield significant risk was observed (r = 0. 85 **). 1000-seeds weight had a positive and significant relation with seed width, Length seed, Grain volume and stem color (r=0.82**, 0.86**, 0.87**, 0.41*), but it had a negative and significant relation with number of seeds (r=-0.68**).Number of seeds per plant had a positive and significant relation with seed yield, oil yield, and Oil percentage (0.55**, 0.53**, 0.63*). This was due to the positive role of seeds per plant with seed yield, and oil yield, which is compatible with the results of SayadiDizaj et al. (2010), who studied 12 native masses to achieve productive masses¹⁸. Kittock et al. (1967) and Koutroubas et al. (2000) reported a positive relationship between the seed weight and the oil percentage, which was contrary to the findings in accordance with the findings of the present study^22-24. However, SayadiDizaj et al. (2010) reported a negative relationship between the seed weight and the oil percentage (r= –0.65**) which was contrary to the findings the present study. According to Laureti and Marras (1995), the oil percentage in the castor seed is a genetic trait that is influenced by the genotype, environmental conditions, agricultural operations, harvest time, and so on . Weiss (2000) reported that the amount and ingredients of castor oil are related to the climate, cultivar, and cultivation and processing methods⁷. The oil yield is a combination of seed yield and amount of oil. Therefore, a reduction in the seed yield reduces the oil yield¹⁷. However, number of seeds per plant had a negative and significant relation with 1000-seeds weight, seed length, seed width, Grain volume and Vein (r=-0.68**, -0.59**, -0.63**, -0.62*, -0.32*). This indicates that seeds per plant is decreased by 1000-seeds weight. Since, number of seeds per plant is more effective on seed and oil yield than 1000-seeds weight, it can be used as an important attribute in this research. The highest seed yield was in the native genotype of 14283 with 2,2134.59 kg per hectare and the lowest seed yield was in the native genotype of Mobarakeh with 1183.03 kg per hectare. Although other genotypes were classified among the highest or lowest seed yield groups, the lowest and highest yields were observed in the two aforementioned genotypes  These results were in accordance with the findings of Koutroubas et al. (1999) ¹⁸, RezvaniMoghadam et al. (2008)¹⁹, and SayadiDiza et al. (2010) ²² .

Sarwar and Chaudhry (2008) investigated traits, such as the ripping time, plant height, number of clusters, length of main cluster, number of capsules in the main cluster, capsule weight, and weight of 100 seeds, in the yield of 16 castor genotype mutants with gamma radiation to find the proper criterion for the ideal types with high yield²¹ .

They found a significant positive relationship between the capsule weight and yield and the number of clusters, capsule weight, and weight of 100 seeds, which has a strong and positive effect on the seed yield. the cluster analysis showed The similar genotypes are placed in one group by categorizing them and valuable attributes of each group were identified for probable hybridization. Also, the genotypes of groups with some attributes with higher than average values can be used for ethnical improvement programs.

Acknowledgements

The authors are grateful to the Science and Research Branch, Islamic Azad University, Tehran for providing facilities to conduct and complete this study. The authors declare that there is no conflict of interest.