Germination Characters as Affected by Salinity Stress and Soaking Grain Sorghum Genotypesin Humic acid

In order to investigate salinity stress on sorghum germination indices, an experiment conducted in the Faculty of Agriculture, Mansoura University from June and July 2017 in Agronomy Department, Seed Science Laboratory. The goals of the investigation aimed to screening for five (Sorghum bicolor L.(Moench) cultivarsviz. Dorado, hybrid 306, Giza 15, Mecca hybrid and H-305 under salinity stress, sodium chloride (Na Cl) at the levels of 0 (as control), 3, 6, 9, 12 and 15 dS/m-1 and soaking in humic acid. The results showed that soaking seed in humic acid exceeded percentage of germination, germination rate, germination index, energy of germination and chlorophyll content by 5.2, 7.7, 17.1, 65.8 and 17.8 %, respectively. The highest germination percentage (91.9 %), germination rate (3.08), germination energy (59.7), seedling vigor index (1483.7) and chlorophyll content (2.88) were obtained from sown Mecca hybrid. The maximum germination index (117.22) was obtainedfrom sown Giza 15 cultivar.The results point out that cumulative salinity level from 3 to 15 dSm-1condensedall studied germination characters. Accumulative salinity levels to 15 dSm-1condensedpercentage of germination, germination rate, index of germination, germination energy and seedling vigor index by 15.9, 15.0, 30.0, 35.9 and 37.6 %, respectively compared without salinity application. It could recommended that soaking sorghum seed of Meeca hybrid with humic acid for 12 h under salinity of concentration of 6 dSm-1 enhanced germination characters compared with other cultivars and salinity concentrations, it mean cultivated it under reclaimed saline soil in Egypt.

The lessening connected to the salinity rate of 12 dS/m -1 betweensorghum genotypes, the greatest in terms of germination parameters were Kimia, Sepideh, and Payam genotypes. Salinity stress significantly influencedmost germination traits and reduced the germination related the same characters (Sawamery and Mojaddam, 2014). The highest percentage of germination produced from the control, but the lowest onesobtained from 1.5% salinity level. The sensitive cultivar to salinity produced from Barbarei cultivars compared to Tabat and Wad-Ahmed cultivars, Tab at cultivar was recorded themost-salt tolerant cultivars (Siddig and Idris, 2015).Therefore, the goals of this exploration intended to study the performance of seed viability of studied sorghum cultivars under salinity stresses.

Treatments and Experimental Design:
A laboratory experiment carried out in the Faculty of Agriculture, Mansoura University from June 2017 to July 2017 in Agronomy Department, Seed Science Laboratory. The aimed of the investigation conducted to screening forfive (Sorghum bicolor L.(Moench) cultivars i.e. Dorado, hybrid 306, Giza 15, Mecca hybrid and H-305 under salinity stress, Na Cl at the levels of 3, 6,9, 12 and 15 dS/m -1 beside the control, soaked or non-soaked in humic acid.The conducted experimentwas assignedto factorial experiment in RCBDin four replication. The first factorcontain two treatments with and without soaking in humic acid. The second factor includesthe five-grain sorghum cultivars i.e. Dorado, hybrid 306, Giza 15, Mecca hybrid and H-305 obtained from ARC Ministry of Agriculture. The third factor contained withinfive different levels of NaCl include 0, 3, 7, 11 and 15 dS/m -1 . The experiment comprised 240Petri dishes assigned in factorial experiment of Randomized Complete Block Design (RCBD). Then, the Petri dishes placed in a growth chamber for 14 days at 28 ± C º for germination according to ISTA, 2013 roles.

Studied characters:
The studied of germination parameters as follows:

Statistical Analysis:
According to the technique of variance (ANOVA) for the factorial in RCBD as published by Gomez and Gomez (1991)of the subjected data was statistically analyzed.LSDmethod was used as defined by Snedecor and Cochran (1980) the.The data analyzed statisticallyin RCBD design by MSTAT-C computer package as described by Russel (1986).

III. RESULTS AND DISCUSSIONS 3.1. Humic acid soaking effect:
The results presented in Table (1) clearly showed that soaking in humic acid significantly affected studied germination parameters and chlorophyll content, except seedling vigor index insignificantly affected. Soaking seed in humic acid exceeded germination %, germination rate, germination index, energy of germination and chlorophyll content by 5.2, 7.7, 17.1, 65.8 and 17.8 %, respectively. Extra of 90% from seeds germinated after five days with soaking of 100-ppm potassium humate, for 24 hours (Ali and Elbordiny, 2009).Priming of wheat seed with humic produced higher percent seed germination as compared to priming seeds in alone water (Ali et al., 2014).

Cultivars performance:
The outcomes of statistical analysis was presented in Table (1) clearly revealed that studied sorghum cultivars significantly affected studied germination parameters and chlorophyll content. The highest germination percentage (91.9 %), germination rate (3.08), energy of germination (59.7), seedling vigor index (1483.7) and chlorophyll content (2.88) were obtained from sown Mecca hybrid.  et al., 2012). The more tolerant of salinity stress produced from Hoars cultivar followed by Mabrouk cultivar, which will cultivate under new reclaimed saline soils (Kandil, et al.,  2012). Germination percentage was clearly demonstrated varietal differences (Khan et al., 2014).

Salinity level effects:
The outcomes of statistical analysis was presented in Table (1) clearly revealed that salinity concentration significantly affected studied germination parameters, except chlorophyll content insignificantly affected. The results indicated that increasing salinity concentration from 3 to 15 dSm -1 significantly condensed the percentage of germination, and germination rate, germination index, energy of germination and seedling vigor index. The highest germination percentage (73.7 %), germination rate (2.46), germination index (122.5), energy of germination (52.0) and seedling vigor index (1166.8) were produced from the control treatment. However, the lowest percentage of germination (62.0 %), germination rate (2.09), germination index (85.26), energy of germination (33.3) and seedling vigor index (727.9) were produced from the highest salinity concentration of 15 dSm -1 . Increasing salinity concentration to 15 dSm -1 significantly decreased germination (%), germination rate, germination index, energy of germination and seedling vigor index by 15.9, 15.0, 30.0, 35.9 and 37.6 %, respectively compared with the control treatment. It exercises an adverse effect of osmotic inhibition and ionic toxicity (Munns et al.,  2006).

Interaction between humic acid soaking and cultivars effects:
Regarding to the interaction between humic acid soaking and studied sorghum cultivars, the results clearly revealed that this interaction significantly affected the moststudied germination parameters and chlorophyll content, however, germination index, insignificantly affected. The results graphically illustrated in Figs. 1, 2 and 4 indicated that highest germination percentage (96.33 %) and germination rate (3.20), seedling vigor index (1646.7) were produced from sownMecca hybrid when soaked with humic acid. In addition, energy of germination (92.83) and chlorophyll content (3.81) were obtainedfrom sown Giza 15 cultivar when soaked with humic acid as shown in Fig. 3 and 5. Whereas, the lowest germination percentage (31.33 %), energy of germination (5.50), seedling vigor index (375.46) were produced from sown Giza 15 cultivar without soaking in humic acid as shown

Interaction between humic acid and salinity levels effects:
Concerning to the interaction between humic acid soaking and salinity levels, the results clearly revealed that this interaction significantly affected the most studied germination parameters and chlorophyll content, however, insignificantly affected germination rate.The

Interaction between studied sorghum and salinity levels effects:
Concerning to the interaction between studied sorghum and salinity levels, the results clearly revealed that this interaction significantly affected the most studied germination parameters and chlorophyll content insignificantly affected.  (Nazi et al., 2014).The inhibiting effect of salt on the seed germination improved in variable degrees by pretreatment of humic acid (Çavuşoğlu and Ergin, 2015). Fig.11: Average of germination percentage as influenced by studied sorghum cultivars and salinity levels. Fig.12: Average of germination rate as affected by studied sorghum cultivars and salinity levels.

Interaction between humic acid soaking x cultivars x salinity levels effects:
The outcomes of statistical analysis was presented indicated that the interaction between humic acid soaking x cultivars x salinity levels insignificantly influencedall studied germination parameters and chlorophyll content. IV. CONCLUSION It could recommended that soaking sorghum seed of Meeca hybrid with humic acid for 12 h under salinity of concentration of 6 dSm -1 enhanced germination characters compared with other cultivars and salinity concentrations, it mean cultivated it under reclaimed saline soil in Egypt.