Sunflower (Helianthus annuusL.) is one of the most important and valuable oil crops in this world. It ranks the 4^th oil seed plants, preceded by soybean, oil palm and rapeseed plant 1,2. Botanically, it is a native plant of North America. The plant belongs to order Asterales, family Asteraceae and genus Helianthus3. It is classified as annual or perennial plant. Some species can grow to a height of 120 in. The stem is unbranched in domesticated cultivars, but branched in the upper part in wild plants. The plant has erect stem with broadleaf. Leaves are dentate, petiolated. The lower leaves are opposite and ovate. The plants bear one head with bright yellow ray florets at the outside and yellow disc florets inside. Some ornamental cultivars  have red-colored ray florets 4. During the growth, sunflowers tilt during the day to face the sun, but stop once they begin blooming. This phenomenon enables the plant to utilize more sunlight in the process of photosynthesis, and it called heliotropism5. 

The seeds contain of excellent quality and high oil content (40-50%), high unsaturated fatty acid concentration, low linolenic acid content, and 30% digestible protein6. They have several uses, among these, human use; like cocking oil, snack food, beside baking uses(granola bars, multigrain breads). Sunflower seedmeal is used asfeed for livestock (green fodder and silage). Other uses like paints, adhesives lubricants, soap manufacture, plastics and detergents, biofuel production etc. However, few species have other economic importance such as medical source and ornamentals7.

Sunflower has broad adaptation to different edaphoclimatic zones. It gained more importance because of its unique oil quality, photo-insensitivity, tolerant to both low and high temperatures, short duration of maturity, can be grown year around, and the possibility of incorporating the crop in different cropping patterns. Therefore it is grown over much broader geographic regions, in the arid and semi arid regions under optimum temperature ranging from 23 to 28 °C. 8 and it performs better under drought conditions compared to other field crops9.

To obtain high yield potential, the crop requires a good crop husbandry in terms of adequate water, nutrient supply; weed control and pest/diseases management throughout the growing period 10.

The crop has a big, branched and extensive root system which enables to utilize nutrients with high efficiency compared with other field crops like Maize and Sorghum 11.

Sunflower is considered one of the promising oil crops in Sudan. It is well suited to Sudan environmental conditions. It is grown as winter crop under irrigated conditions, and as summer crop under rain-fed 12.

To attain maximum yield, the crop requires fertilizers. Synthetic fertilizers are widely used, with less attention to organic fertilizers. However, today more attention is paid to organic fertilizers as a remedy to cure the ills of the chemical fertilizers in the face of dramatic and substantially increase prices of the chemical fertilizers. However, it is reported that application of organic fertilizer in Sunflower production has increased both sunflower oil quality and yield attributes 13, therefore; it became necessary to develop a workable, compatible package of nutrient management through organic sources for various crops, capable of providing all the essential minerals to promote crop growth and development 13.

In Sudan; most if not all Sunflower growers use synthetic fertilizers in crop production for a long time. For the above quoted reason farmers began to look for alternative sources of fertilizers; among which a herb plant called Argel which had been traditionally in use in different parts of Sudan since.

Argel (Solenostemmaargel) is a herb plant14; which is locally known as Hargal (Arabic). The plant has many uses; ranging from medicinal to fertilizer and pesticides. Nevertheless, tradition farmers in some parts of Sudan use Argel as pest replants, curing illness and sometimes as fertilizer. Despite the great importance; Argel is not given the necessary care as fertilizer except in the field of horticulture, specifically the palm date tree.

Sunflower yield differs according to cultivars, prevailed climate condition and adopted cultural practices. During the season 2015/2016 the world total production was about 39.19 million metric tons, with an average yield of 1.7 metric tons/ha obtained from an area of 23.06 million hectares 15, compared to the domestic productivity of 222 kg/Fed 16. It is clear that there is a gap between the local and world average yield, but, recently the yield improved due to the application of new technologies. However, the major producing countries are Ukraine, Russia, European Union, Argentina Turkey, United States, India and China, accounting for 70% of global production 14, while the major exporting countries are the Union of Soviet Socialist Republic (USSR), United States of America (USA), and Argentina are the biggest exporting countries 15.

According to Arab Organization for Agricultural Development, the other producing countries are Turkey, Pakistan, Egypt, Syria, Morocco and Iraq with the latest having the largest cultivated area of about 5,975,000 ha. producing 89,000 metric ton17.

During the period from 1980's to 199's Sudan has witnessed a leap in Sunflower production, when Sunflower hybrid cultivars; the Hysun-33 and PAN-7351 were introduced from Australia and South Africa 18,19, beside the release of two open pollinated varieties namely; Bolero and Rodio under the names Damazin-1 and Damazin-2, respectively20. The crop gained ground, and was grown in the central clay plain under large scale ran-fed farming, and limited areas in irrigated schemes. But its expansion was confronted with several production constraints21.

It is reported that Sunflower was introduced to Gezira Research Station-Wad Medani -Sudan in 1932, then the research was extended to other research stations in 1960s. The commercial production of Sunflower began in late 1980’s and the early 1990’s following the introduction of hybridscultivars 18,19. It began in Blue Nile State El Damazin area, which considered as the highest potential for growing sunflower under mechanized rain-fed farming due the good amount of rainfall, and vast arable fertile cultivable land. This experience was pioneered by EL Sheik Mustafa El Amin Company. Then it expanded from Blue Nile to other rain-fed areas like Gedarif and El Renk 14. The crop also grown under irrigation sector in ALRahad, Al Gezeria, Sennar and El Gash, Blue Nile and White Nile Pumps Irrigation Schemes. The highest yield (621 Kg/fed.) was obtained during 2011/2012. Unfortunately, due to financial and political reasons, the productivity deteriorated and the area declined to 57000 fed14.

Moreover, in Sudan, the hybrid varieties such as Hysun 33 and Pioneer were reported to perform better than the open pollinated as far as yield concern. Therefore, hybrid cultivars were widely grown in Sudan due to seed availability in the market; representing 90% of the cultivating area by Sunflower22. It is reported that, there are many cultivars in the world; but they differ in their seed characteristics, oil content, plant height, and maturity date23.

A trial was conducted during 2017/2018; at Agricultural Farm of the College of Agriculture-University of Bahri –AlKadaro- Sudan, in a heavy clay soil with pH ranges between 7.5 - 8 described as saline soil. Where the two Sunflower cultivars, the Serena and Opera (H-16-096\0306) were studied in split-split-plot experiment based on Randomized Complete Block Design (RCBD) with four replications. The two cultivars were considered as the main-plot treatments, whilethe four levels of Nitrogen (N0, N1, N2 and N3)as subplot treatments, and the four levels of Argel (A0, A1, A2, and A3) as sub-subplot treatments.

The rates of application of Argel were 0, 140, 240 and 340 Kg/fed., while the treatments of Nitrogen were 0, 25, 50 and 75 kg/fed. All cultural practices such as sowing date; frequent irrigation, thinning, and application of herbicide were timely carried out as recommended by the Research Centre in Sudan. Data pertaining agronomic traitslike Leaf Area (LA), Plant Height (m), Leaf Number (LN), Leaf Area Index (LAI) and Mean Seed Weight were randomly collected. The said data were analyzed by Statistic 8 Software. The results were presented in the form of tables and figures. (Plate 1 and Plate 2)

All results of data analysis presented in tables and figures followed by discussion. Moreover, the results of statistic 8 software are found in the appendix.

The results of the data analysis demonstrated that the overall leaf Area of Serena and Opera cultivars (Table 1 and Figure 1) has significantly increased when treated with Argel and Nitrogen (F=7.22, P<0.001). Both treatments N1 and A1 for Serena produced bigger Leaf Area (134.29 and 137.95) respectively compared with other treatments. For Opera, both N2, and A1 produced the biggest Leaf Area (136.27, 118.53) respectively compared with the control. Moreover, the result showed there is no significant difference in the leaf area of Serena and Opera cultivars due to application of either Argel or Nitrogen. Furthermore, the two cultivars “Serena and Opera” responded similarly (F=2.68, P<0.2001) to Argel and Nitrogen treatments. (Table 2, Figure 2)

Considering Table 2, and Figure 2, the results showed that the Plant Height of Serena and Opera cultivars was significantly influenced by application of Argel or Nitrogen as fertilizers (F= 4.28, P <0.0012). Moreover, the Nitrogen level N2 and Argel level A1 gave the highest Plant Height (53.88, 53.97 cm) for Serena compared to other treatments, while N1 and A2 gave the highest Plant Height (52.97, 54.19 cm) respectively for Opera compared with the other treatments. Furthermore, the result exhibited there is no significant difference in the plant height of Serena and Opera cultivars as a result of application of either Argel or Nitrogen. In addition, the plant height of the two the cultivars responded equally to Argel and Nitrogen applications (F=0.03, P < 0.877).

The results of analysis (Table 3, and Figure 3) revealed that the Leaf Number of both Serena and Opera cultivars was significantly increased when treated with Argel and Nitrogen (F =3.90, P <0.0024). Moreover, the results displayed that N1 and A0 produced more number of leaf (29, 27) respectively for Serena, while N3 and A1, A2 produced more similar Leaf Number (23) for opera compared to the other treatments.

Furthermore, the result presented that there is no significant difference in the leaf number of Serena and Opera cultivars as a result of application of either Argel or Nitrogen. Additionally, the leaf number of Serena and Opera cultivars responded similarly to Argel and Nitrogen (F=7.02, P < 0.0770)

The results in Table 4 and Figure 4, present the Leaf Area Index of Serena and Opera cultivars was significantly enlarged due to application of Argel or Nitrogen as stimulants (F= 3.83, P< 0.0026). Moreover, the results displayed that N2 and A1 gave the highest Leaf Area Index (574.12, 591.85) respectively for Serena compared to the other treatments, while N3 and A1 produced the highest Leaf Area Index (544.06, 494.19) for Opera respectively compared with other treatments (Table 4, Figure 4). Furthermore,the result showed no significant difference in the leaf area index of Serena and Opera cultivars as a result of application of either Argel or Nitrogen. Furthermore, the leaf area index of the two cultivars responded in the same way to Argel and Nitrogen applications (F=0.88, P < 0.4166).

However, all results obtained in this study coincide with the results obtained by experiment conducted at Quoz Hindi area, Elgureir, Merawi Locality, Northern State, Sudan during 2004/2005 and 2005/2006, when Argel was applied to Palm date tress as dry fertilizer., this treatment has enhanced flowering and yield parameters of date palms and improved the physical characteristics of the fruits 23Tagelsir I. M. Idris,1 Asma M. A. Ibrahim,1 Elfatih M. Mahdi2 and AwadK.Taha (2011): Influence of argel (Solenostemma argel Del. Hayne) soil applications on flowering and yield of date palm (Phoenix dactylifera L.). Agriculture and Biology Journal of North America ISSN Print: 2151-7517, ISSN Online: 2151-7525, doi:10.5251/abjna.2011.2.3.538.542 © 2011, ScienceHuβ, http://www.scihub.org/ABJNA ^{(30) 27}

Table 5 reviled that N2 (47.713) and A3 (56.847) produced highest Mean Seed Weight for Serena, while N3 (43.232) and A1 (57.474) produces the highest Mean Seed Weight for Opera.

It worth mentioning that, in Sudan, despite the technological advancement in the area of Sunflower crop production, yet there a big gap between the yields obtained by farmer 99 to 374 kg/fed. under rain-fed and 09 to 813 kg/fed under irrigation compared to Research plots 513 to 1062 kg/fed and 410 to 874 kg/fed under irrigation and rain-fed farming respectively. This low productivity is attributed to many factors; including organization set up, crop management, finance, marketing, pests/diseases, policy, environmental factors like erratic and fluctuating rainfall, Poor extension services, strategies and production plans15.

Mamoun I. Dawelbeit (2012): Sunflower Production in the Sudan. Opportunities and Challenges. The First International Conference on Seeds Oil –Corinthia Hotel, Khartoum –Sudan, Nov. 2012. (31)²⁸.

This study aimed at investigating the possible potentiality of Argel as an economic organic fertilizer that can play an important role to improve crop yield and save hard currency, in a word characterized by low crop yield, dynamic population expansion, increasing demand for food in the face of substantially; dramatic increases of prices of the synthetic fertilizer.

In the light of the above discussion, it is time to look for alternative sources for fertilizers, particularly the organic fertilizers. Therefore, this study was directed towards looking for easy, accessible, socially acceptable, economic sound and environmentally friend. In this regard, Argel, was studied. The results displayed that Argel is similar to nitrogen fertilizer has significantly increased all studied parameters of the two Sunflower cultivars,.

The study recommends for further study; to include all agronomic traits, yield, yield components, and oil content of different sunflower cultivars as well as other field crops.

Appendix