Germination and Seedling Characters as Influenced by Sunflower Hybrids, Nitrogen Fertilizer Rates and Hill Spacing

In order to study the performance of some sunflower genotypes to nitrogen fertilizer rates and plant population density to germination and seedling parameters. A laboratory experiment conducted in the Agronomy Department seed lab, Faculty of Agriculture, Mansoura University, Egypt during March and April 2017.The goals of this study aimed to study the effect of sunflower hybrids, nitrogen fertilizer rates and hill spacing on germination and seedling characters.The results indicated that Nsovak genotype recorded the highest values of abnormal seedling percentage. Highest mean germination time was obtained from MS.sirena F1 genotype. The highest coefficient of velocityand value of the vigour was produced from Biest Brima genotype without significant differences with sown Nsovak genotype.The results indicated that increasing nitrogen fertilizer rates from 72, 120 and 168 kg N/ha significantly increased mean germination timeandvalue of the vigour. The highest coefficient of velocity percentage produced from addition nitrogen fertilizer at 120 Kg/ha.The results designated that increasing hill spacing from 15, 20 and 25 cm reduced germination percentage and mean germination time, however, significantly increased coefficient of velocity anddead seed percentages and value of the vigour.It could be concluded that sown Nsovak genotype at hill spacing of 15 cm and fertilizing with 120 kg N/ha enhanced seed germination and viability.

INTRODUCTION Sunflower (Helianthus annus L.) has higher seed and oil yieldsfrom the essential oilseed crop that gives a main share in edible oil production. It cultivated widely in the arid and semi-arid regions. In order to obtainseeds good in quality,so essential to getabetter plant stand. Sunflower Hybrids, nitrogen fertilizer levels and plant population density may affect germination parameters and seedling characters. In this respect, Sakha 53 exceeded Giza 102 in seed yield, its attributes and percentage of oil (Aml-El-Saiedy et al., 2011).The higher germination index, germination rate, number of days to 50% germination, germination index, root and shoot length and their dry weight produced from Urfloar cultivar as compared with Blazar cultivar (Moghanibashiet al., 2012). Line S 102 surpassed other studied cultivars in final germination percentage, germination rate and germination index, energy of germination and seedling vigor index(Kandil et al.,2016a).Sunflower differed from germination and seedling parameters, theLine S 102 outdone Sakha 53, Giza 102 and Line S 1 in the length of shoots, length of roots,weight of fresh and dry roots and weight of fresh and dry shoots (Kandil et al., 2016b). Germination percentage and seed vigor did not affect by increasing applications of nitrogen fertilizer rates of0, 66, 132 to 600 kg/ha (Osechas and Torres 2002). Nitrogen fertilization in wheat enhanced of seed vigor and percentages of final germination and decreasedmean germination time and the time that 50% of the seeds germinated (Warraich, 2002). Seed viability, seedling vigour and cool germination test performance of cottonseed were all found to increase due to the addition of nitrogen fertilizer rate of 142.8 kg N/ha (Zakaria, 2007). Environmental conditions affect seed quality of seed formation and affect seedling establishment of the next growing season (Zakaria, 2009). Fertilization of biological or artificial source as organic or inorganic material of nitrogen supplies nutrients essential to the soil and enhanced growth of plants (SSSA, 2011). The late in germination time was obtained from of Okapi cultivar by increasing nitrogen fertilizer levels. Planting cultivar of Zarfam and fertilizing with 100 kg/h enhanced the amount of coefficient of speed of germination whichnitrogen fertilizer was applied of topdressing, however, the lowest amount was produced from sown Okapi cultivar without top dress of nitrogen fertilizer(Oskouie and Divsalar, 2011). Increasing nitrogen fertilizer increased seed yield for producing vigorous seeds (Wambugu et al, 2012).Nitrogen fertilization at a rate of 165 kg/ha produced the highest percentages of seed germination and seedling vigor index. Maximum electrical conductivity related to seeds that received nitrogen fertilizer at a rate of 165 kg/ha. They concluded that uses of 165 kg/ha nitrogen fertilizerson mother plants will produce seeds with higher vigor, germination characteristics and seedling establishment (Farhidi et al., 2014).Increasing nitrogen fertilizer rates in the mother plant field, genotypes and interaction of genotypes among nitrogen fertilizer influenced seed viability, germination, vigor of aromatic rice seeds (Hossain, 2014). Urea application produced the highest germination rate and followed by organic manure. Inorganic nitrogen fertilizer at Urea depicted maximum rate of shoot and root length. They suggested that urea is best fertilizer for germination of seedlings of sunflower and second one is FYM fertilizer (Shahzaman et al., 2017). Therefore, the purpose of this investigation aimed to study the effect of nitrogen fertilizer rates application for mother plants of sunflower cultivars and hill spacing on germination and vigor characters of resulted seed.

Research time and location:
An experiment was conducted in the laboratory of seed science, Agronomy Department, Faculty of Agriculture Mansoura University Egypt during March and April 2017. The goals of this study was aimed to investigate the response of some sunflower cultivars (Giza102, Sakha 53, ) under three nitrogen rates (72, 120 and 168 Kg N/ha) and three hills spacing (15,20 and 25 cm apart) to germination and seedling parameters.Afactorial experiment in Randomized Complete Block Design in four replication was used. The experiment includes three factors, the first sunflower genotypes (Nsovak, MS.Sirena F1, BiestBrima).The second factor included three nitrogen rates (72, 120 and 168 Kg N/ha) and the third cultivar includesthree hills spacing (15,20 and 25 cm apart).Fifty seeds of uniform size in each treatment for each cultivar allowgerminating on Petri dishes in 9 cm diameter Petri dishes. Seeds were germinate in a germination chamber in 20 -25 о C (ISTA Rules, 2016).The experiment included 108 Petri dishes that moistened with a distilled water. The N mean the number of germinated seeds on day i and T is mean that the number of days from sowing. 5-Percentage of dead seed = Number of dead seed /total number of seeds 6-The value of the vigour (V) was calculated as following formula according to Bradbeer 1988:

Studied Characters
Where a, b, c . . . respectively represent the number of seeds which germinated after 1, 2, 3 . . . days of imbibition, x is the number of seed for day n and S the total number of seeds sown. The range of the V values is from 0 to 100 (maximum rate). The rates were categorized as five numbers categories: 0= Null; 1= Slow; 2=Medium; 3= Fast; and 4= Very fast was divided according to Mayer and Poljakoff, 1989.

Experimental analysis:
The analysis of data collected done, statistically by the analysis of variance technique using the MSTAT-C statistical package programmed as described by a procedure of Gomez and Gomez (1991). For comparisons between treatment means, least significant differences test (LSD) at 0.05level of probability was used according to Snedecor and Cochran (1980).

III.
RESULTS AND DISCUSSIONS 3.1. Performance of sunflower cultivar on seed germination and seedling characters: Averages of abnormal seedling percentages, mean germination time, coefficient of velocity,dead seed percentages and value of the vigour significantly affected by sunflower cultivars as shown in Tables 1 and 2, except germination and dead seed percentages insignificantly differed. The results indicated that Nsovak genotype recorded the highest values of abnormal seedling percentage (6.67 %). Highest mean germination time (2.53) was obtained from MS.sirena F1 genotype.The highest coefficient of velocity (41.29 %) and value of the vigour (42.19) were produced from Biest Brima genotype without significant differences with sown Nsovak genotype.The differences in final percentage of germination of seed may due to the amount of saved matters in endosperm and different seed size of genotypes. The processes that inhibit germination probably involve cell division and no transfer of nutrients (Bittman, 1989).Zarfam and Licord cultivars recorded the highest seed vigor (98%) of both cultivars and Talaieh cultivar produced the lowest was(92%)(Oskouie and Divsalar, 2011).

Effect of nitrogen fertilizer rates on seed germination and seedling characters:
Averages of mean germination time,coefficient of velocity andvalue of the vigoursignificantly affected by different nitrogen fertilizer rates, however insignificantly influencedgermination and abnormal seedling anddead seed percentages as shown in Tables 1 and 2. The results indicated that increasing nitrogen fertilizer rates from 72, 120 and 168 kg N/ha significantly increased mean germination time (2.55) andvalue of the vigour (42.24). The highest coefficient of velocity percentage (41.56 %) produced from addition nitrogen fertilizer at 120 Kg/ha. Seed lots with high vigor have lower mean germination time (Ellis and Robert, 1981). The lowest germination and vigour of seeds produced under conditions of lowsoil fertility (Songa et al., 1994). A fast and uniform field emergence is essential to do high yield with good quality and quantity of annual crops

Interaction between cultivars and hill spacing:
Averages of germination and abnormal seedling percentage, mean germination time, coefficient of velocitypercentage and value of the vigour significantly influenced by the interaction amonggenotypes and hill spacing, however, dead seed percentages insignificantly affected as shown in Tables 1 and 2

Interaction between nitrogen fertilizer rates and hill spacing:
Averages of germination, abnormal seedling, dead seed percentages and value of the vigour significantly affected by the interaction between nitrogen fertilizer rates and hill spacing, however, mean germination time and coefficient of velocity percentage insignificantly affected as shown in Tables 1 and 2 Tables 1 and 2. IV. CONCLUSION Accordingly, it could be summarized that sown Nsovak genotype at hill spacing of 15 cm and fertilizing with 120 kg N/ha enhanced seed germination and viability.