Effect of Seed Priming on Growth and Yield of Wheat (Triticum aestivum L.) Under Non-Saline Conditions

MATERIALS AND METHODS

The present investigation was carried out at the field of Agricultural Chemistry Section, Agricultural Research Institute Tando Jam, Pakistan, during, winter, 2003-2004. Prior to sowing the land was prepared thoroughly by plowing (4-5 times), clod crushing and leveling. After preparation, the land was soaked with two heavy irrigations. The experiment was laid out in split-plot design with four replications and four seed priming treatments. Plot size was 33 H 22 m (726 m²) with 80 sub-plots of 3.8H1.7 m (6.46 m²) size. Composite soil samples before sowing were collected from two (0-15 and 16-30 cm) soil depths. Soil texture was analyzed using the Bouyoucos hydrometer method. Electrical conductivity (EC_e) and pH were determined following the method of Rowell (1994).

The seed of five wheat cultivars (Mehran-89, V-7001, T.J-83, Anmol and Abadgar) was primed for 10 hours by placing them into the fresh water (T₂), 0.2% gypsum (T₃) and 0.4% gypsum (T₄). Prior to sowing, the primed seed was air-dried back to its original moisture content. Sowing was done by hand drilling method. The recommended rate of nitrogen (150 kg N haG¹) was applied in the form of Urea and diammonium phosphate (DAP). Urea was applied in three splits (at sowing, at 1st irrigation and at 2nd irrigation). Phosphorus at the rate of 75 kg P₂O₅ haG¹ was applied in the form of DAP at the time of sowing only.

At maturity three plants from each treatment of all replications were harvested at random. Ears were separated from straw, placed in separate paper bags and oven-dried at 78°C for 48 h. Grains were separated from ears by threshing with hands. Straw and grain yields were recorded. Grain samples were prepared by ash digestion and concentrations of phosphorus and potassium were determined by spectrophotometer and flame photometer respectively. All plant data were subjected to analysis of variance and the significant differences between means were tested by calculating Least Significant Difference (LSD) values at 5% probability level.

RESULTS AND DISCUSSION

The results indicated no marked variation in topsoil and subsoil properties (Table 1). At both (0-15 and 15-30 cm) depths the soil was clay in texture, moderately alkaline in reaction, calcareous in nature, non-saline and non-sodic.

Table 1:	Some physico- chemical properties of experimental soil (before sowing)

Table 2:	Effect of seed priming with fresh water, 0.2% gypsum and 0.4% gypsum on days to emergence of five wheat cultivars

Table 3:	Effect of seed priming with fresh water, 0.2% gypsum and 0.4% gypsum on days to maturity taken by five wheat cultivars

Although, soil had chlorides and bicarbonates at both depths, the values observed were still in the range of non-saline soils (USSL, 1954). The calcium and magnesium contents in soil at both depths were adequate enough for wheat growth (Rajpar and Wright, 2000).

The effect of seed priming treatments on days to emergence (Table 3) and maturity (Table 4) was significant (p<0.05). Compared to the control, seedlings in priming treatments took significantly fewer days to emerge and reached maturity earlier (Table 2). The increase in the rate of emergence and early maturity in seed priming treatments was possibly due to advancement in metabolic state (Oluoch and Welbaum, 1996; Harris et al., 1999). This advancement in maturity is desirable in semi-arid and tropical countries, where wheat is grown as winter crop and hot and dry climate during grain filling in April often result in premature ripening, leading to substantial yield losses (Rajpar and Wright, 2000). It is also evident from the reports of other workers including, Ashraf and Foolad (2005) that during seed germination, the soil environment does not often remain conducive to rapid germination and seedling growth, possibly due to several biotic and a-biotic stresses.

The plants established from primed seed were significantly taller in height (Table 5) and produced significantly higher grain yield per hectare (Table 6). It is well documented (Harris et al., 1999) that seed priming markedly improves stand, establishment and early vigor in several crop species, which results in faster development, earlier flowering and maturity and higher yields.

Table 4:	Effect of seed priming with fresh water, 0.2% gypsum and 0.4% gypsum on plant height (cm) at maturity of five wheat cultivars

Table 5:	Effect of seed priming with fresh water, 0.2% gypsum and 0.4% gypsum on straw yield of five wheat cultivars

Table 6:	Effect of seed priming with fresh water, 0.2% gypsum and 0.4% gypsum on grain yield of five wheat cultivars

The effects were more promising when seeds were primed with fresh water than with 0.2 and 0.4% gypsum. Among, the 2 gypsum treatments, seed primed with 0.2% gypsum tended to be more effective than with 0.4% gypsum. This was possibly due to the hydration process, which can cause marked biochemical changes in seed such as breakdown and transport of reserve materials, especially transport from endosperm to the growing parts of the embryo and synthesis of new materials (Mayer and Polijakoff-Mayber, 1989 ). According to Mayer and Polijakoff-Mayber, (1989) that the desiccated seed is well-equipped functional unit that can undergo many biochemical reactions if the initial hydration of proteins in particular enzyme proteins has taken place

Averaged overall seed priming treatments, the difference between cultivars was significant (p<0.05) for days from sowing to emergence, plant height and ion contents. Cultivar Abadgar was earlier and Mehran-89 was later in emergence than other test cultivars. The effect of interaction of seed priming treatments*cultivars for most of the parameters remained non-significant.

Table 7:	Effect of seed priming with fresh water, 0.2% gypsum and 0.4% gypsum on P content of grains of five wheat cultivars

Table 8:	Effect of seed priming with fresh water, 0.2% gypsum and 0.4% gypsum on K+ contents in grains of different wheat cultivars under non-saline conditions

The effect of seed priming treatments and the interaction of seed priming *cultivars for P and K⁺ contents (Table 7) in grains was not significant. However, the difference between cultivars for P and K⁺ contents of grain was significant (p<0.05). Cultivars TJ-83 and Mehran-89 accumulated significantly lower P and K⁺ in grains than other three cultivars (Table 8). That was possibly due to genetic variability amongst the cultivars.

CONCLUSIONS

This study demonstrated that prior to sowing, seed priming with fresh water can improve wheat yield under non-saline conditions.

ACKNOWLEDGEMENT

The authors would like to thank Islamic Development Bank that funded the postdoctoral tenure awarded to the main author of the article. In addition, authors wish to thank the Sindh Agriculture University Tandojam, Pakistan for providing the financial support to carry out this work. Thanks are also due to the Department of Land Management, Faculty of Agriculture, University Putra Malaysia for providing computer facilities.