Effect of Potassium Application Methods on Some Wheat Varieties (Triticum aestivum L.) Production Under Middle Egypt Conditions

World population is envisaged to increase by 34% till 2050 reaching about 9.1 billion, thus necessitating 70% more food production (FAO, 2005). Wheat (Triticum aestivum, L.) is considered as the major cereal crop in world in respect of the cultivated area and total production. It provides an almost 20% of food calories for people in the world (Hamouda et al., 2015). In Egypt, wheat provides 37% of the total calories for the people and 40% of protein in Egyptian diet (Abd El-Ghany et al., 2013). Also, it is a major source of straw for animal feeding. However, the local production of wheat grain (about million tons) covers only about 60% of the local consumption demand which reflect the need to import about 40% of wheat grains from abroad. Therefore, improving the productivity of this crop consider the national goal.

Potassium is one of major nutrients considered essential for crop growth and yield development, although it is not an integral component of any cellular organic or structural part of the plant. It is the most abundant cation in plants and is associated or involved with many of the physiological processes supporting plant growth and development. Water relations, photosynthesis, assimilate transport and enzyme activation, all can be impact by potassium (Pettigrew, 2008). Furthermore, potassium plays a key role in the survival of plants under abiotic stress conditions, as stress negatively affects the physiological processes of plants such as root and shoot elongation, enzyme activity, water and assimilate transport, synthesis of protein, photosynthetic transport and chlorophyll content (Gerardeaux et al., 2010 and Kanai et al., 2011).

In recent years, foliar fertilization for satisfying a part of the major nutrient requirements has gained interest. Foliar spraying may be feasible in cases where plants reach a stage where the supply through roots cannot meet the demand of the crop (Arabia et al., 2002). Moreover, the beneficial effects of foliar nutrition of K in mineral form containing K as a supplemental or a partial substitution to soil application were reported by many authors such as Shaaban et al. (2009) and Abd El-Ghany et al. (2013) on wheat. The foliar application method is usually preferred because very small amounts of fertilizers are applied per unit area and decrease ground water application. In addition exogenous application through foliar application of essential elements like K was found promising to enhance the growth parameters (Mahmoud and Rafiq, 2011).  In this concern, Kettlewell et al. (2000), Nadin et al. (2012) and Hamouda et al. (2015) found that foliar application of nutrients on wheat plant had significant positive effects on plant growth and yields and its components.

Therefore, the aims of this investigation is to study the effect of potassium fertilization as soil application and/or foliar spraying for four wheat varities on growth, yield, yield components and nutrients content of grain and straw of wheat.

MATERIAL AND METHODS

Field experiments were conducted during the two growth seasons of 2014/2015 and 2015/2016 in the experimental Farm of Sids Agricultural Research Station, ARC, Beni-Suef Governorate, Egypt to study the response of two bread wheat varieties (Sids 12 and Sids 13) and two durum wheat (Beni-Suef 5 and Beni-Suef 6) to potassium fertilization as soil application and/or foliar spraying; i.e.: without potassium (K1), 24 kg K2O/feddan added before planting (K2), 12 kg K2O/feddan added before planting and 12 kg K2O/feddan added two month later (K3), Foliar spraying of 2% potassium sulphate one time (K4), Foliar spraying of 2% potassium sulphate twice (K5), 12 kg K2O/feddan added before planting + foliar spraying of 2% potassium sulphate one time (K6) and 12 kg K2O/feddan added before planting + foliar spraying of 2% potassium sulphate twice (K7), and its effects on growth, yield components, yields and content of nutrients grains and straw of wheat.

The experimental design was split plot in completely randomized blocks in four replications, where the wheat varieties were located in main plots and potassium treatments were set up in sub plots. The plot area was 2.0 m x 1.4 m (2.8 m² = 1/1500 feddan). Wheat varieties were sown in 15 and 16 November in both seasons, respectively. Some physical and chemical properties of surface soil samples collected from plough layer (0.0-30 cm) before planting was done according to the Klute (1986) and Page et al. (1982) and listed in Table (1). Foliar spraying on time treatments were performed at one month from sowing, while foliar spraying twice treatments were carried out at one month from sowing and at one month later. The other practices of growing wheat were properly used for the management of the experimental plots throughout the cropping season.

During the growing seasons, days to heading and days to maturity were determined. At harvest time, wheat plants were collected and the following parameters were determined: plant height (cm), number of spikes/m², number of grains/spike and 1000-grain weight (g) as well as grain yield (ardab/feddan) and straw yield (ton/feddan). Also, NPK concentration in grains and straw were determined according to the method described by A.O.A.C (1985), and then calculated to NPK uptake (kg/feddan).

The results were submitted to analysis of variance according to Snedecor and Cochran (1980). The means of treatments were compared by L.S.D. at 5% probability level.

Table (1). Some physical and chemical properties of the experimental soil

RESULTS AND DISCUSSIONS

1- Growth traits

The data presented in Table 2 show the effect of potassium application as soil and/or foliar application on some growth parameters of four wheat variaties. The results exhibited that Sids 12 variety recorded the shortest period for heading and maturity stages, while Beni-Suef 6 varieties exerted the highest number of days from planting to heading and maturity in both growing seasons. It is obvious to notice that the differences between the effects of Sids 13 and Beni-Suef 5 are not greal enough to reach the 5% level of significant in both growing seasons. These results might be explained according to the fact that crop varieties differed remarkably on the genitical attributs and subsequently on growth characters. These results are in line with those obtained by Mahmoud (1987) and Abd El-Majeed (1990). As for plant height, the data obtained revealed that Beni-Suef 5 variety gaves the tallest plant (112.0 and 111.8 cm during the two growing seasons, respectively), while Sids 13 variety recorded the shortest one (102.9 and 102.0 cm during both growing seasons, respectively). It is obvious to notice that the difference between plant height of Beni-Suef 5 and Sids 12 not reached the significance value. The variation in plant height among the studied varieties may be due to its gentic make up and the mode of utilization of metabolic products (Abd El-Ghany et al., 2013). These results are in harmony with those obtained by Ahmed et al. (2011) and Abd El-Ghany et al. (2012).

Regarding the effect of potassium fertilization, the obtained data revealed that days from planting to heading or maturity stages were significantly affected by methods of potassium fertilization during both growing seasons. The treatments of 12 kg K2O/feddan added before planting + 12 kg K2O/feddan added after one month later (K3) and 12 kg K2O/feddan added before planting + foliar sprying of 2% potassium sulphate twice (K7) recorded the latest heading or maturity stages, while the treatment without potassium application (K1) produced the earliest heading or maturity stages. This may be explained by the fact that plants needs to be supplied with sufficient amount of potassium for plant development, especially in the eritical stage, therefore plants with low potassium fertilization tried to terminate their life cycle earlier and grew more rapidly than those of sufficient potassium (Gul et al., 2011). Similar results were obtained by Pettigrew (2003) who mentioned that potassium difficieny in cotton depress yield by decreasing late season growth and its reportedly more harmful to early maturity cotton genotypes. Concerning the effect of potassium treatments on plant height, the results showed that K3 and K7 treatments produced the tallest wheat plants, while plants without potassium fertilization (control treatment) yielded the shortest plants during both growing seasons. The promoting effect of K3 and K7 treatments than other treatments on wheat plant height may be attributed to the direct effect of potassium on plant growth and development, since those treatments contain higher potassium than others (Jabbar et al., 2009). These results are in line with those obtained by Hamouda et al. (2015).

Table (2). Effect of potassium fertilization on some growth parameters of  four wheat varieties

Considering the interaction effects, the data revealed that the number of days from planting to heading or maturity stages as well as plant height did not respond to the interaction between treatments. This means that, in general, Sids 12 variety in absence of potassium recorded the earliest heading and maturity stages, while Sids 13 variety under K3 or K7 treatments exerted the latest ones. Moreover, Beni-Suef 6 variety under K3 or K7 treatments showed the tallest plants, while Sids 12 variety with non potassium application produced the shortest plants in both growing seasons.

2- Yield components traits

The effect of different potassium treatments on yield components of four wheat varieties are presented in Table 3. The results revealed that the number of spikes/m², the number of grains/spike and 1000-grain weight were significantly affected. Sids 12 variety gave the greatest number of spikes/m² and number of grains/spike during both growing seasons (415 and 65.4 during the first growing season and 419 and 66.8 during the second one, respectively). On the other hand, Beni-Suef 6 variety gave the lowest ones (402 and 58.6 during the first growing season and 412 and 60.1 during the second growing season, respectively). Moreover, Beni-Suef 5 variety produced the highest values of 1000-grain weight (55.7 and 56.0 g during both growing seasons, respectively), while Sids 13 gave the lowest 1000-grain weight (48.2 and 48.7 g during both growing seasons, respectively). The differences between varieties may be due to its gentical make up. These results are in harmony with those obtained by Ahmed et al. (2006) and El-Habbasha et al. (2008).

As for potassium treatments, the obtained data revealed that the yield components of wheat plants were significantly responded to potassium treatments. Added 24 kg K2O/feddan at two equal doses, before planting and two month later (K3) or combined 12 kg K2O/feddan as soil application with foliar spraying of potassium sulphate twice (K7) gave the highest values of number of spikes/m², number of grains/spike and 1000-grain weight (416, 416; 66.5, 66.5 and 54.7 and 54.7 g for K3 and K7 in the first growing season, respectively). Whereas, the lowest yield components were recorded under without potassium treatment in both growing seasons (345, 55.8 and 48.0 g in the first growing season and 399, 57.1 and 48.5 g during the second one, respectively).

The promoting effect of K3 and K7 treatments may be support the benifical effect of application of potassium at two equal doses, during land preparation and two month later or combined soil application with foliar spraying on wheat growth as already pointed out above. Similar results were obtained by Thalooth et al. (2006) and Zafar et al. (2016). Regarding the interaction between wheat varieties and potassium treatments, the results clearly showed that there was no significant effect between wheat varieties and potassium fertilization on yield components of wheat. This means that the Sids 12 variety when fertilized with K3 or K7 treatments yielded the greatest number of spikes/m² and number of grains/spike, while Beni-Suef 5 variety under K3 or K7 treatments produced the heaviest grains.

Table (3). Effect of potassium fertilization for four wheat varieties on yield components

3- Yield traits

Data given in Table 4 showed the effect of potassium fertilization as soil and/or foliar spraying on grain and straw yields of four wheat varieties. The results indicated that wheat varieties were significantly varied in its grain and straw yields during both growing seasons. It could be arrange the grain yield of the four varieties of wheat as the following descending order: Beni-Suef 5 > Sids 12 > Beni-Suef 6 > Sids 13 in both growing seasons. The relative increasing of grain yield produced by Beni-Suef 5 comparing by other three wheat varieties were 10.5, 14.9 and 20.3% over Sids 12, Beni-Suef 6 and Sids 13 varieties in the first season, respectively. The same trend was obtained in the second growing season. On the othe hand, Beni-Suef 5 gave the highest straw yield followed by Sids 12 and Beni-Suef 6 varieties, while Sids 13 variety produced the lowest one in both growth seasons. These variations in grain or straw yields to for varieties of wheat may be due to its gentic structure and its tolerance variation to the environmental conditions, which in turn effect the yield components (Table 3) as discussed earlier (Abo-Ward, 2002 and Abd El-Ghany, 2003). These results are in harmony with those obtained by Hassanein (2001) and Mekky et al. (2007). With regard to potassium fertilization, the obtained data revealed that both grain and straw yields are significantly affected to potassium fertilization. K3 and K7 treatments gave maximum values in terms of grain and straw yields (23.3 and 23.2 ardab/feddan and 4.2 and 4.2 ton/feddan for grain and straw yields in the first growing season, respectively (Table 4). The promotive effect of K3 and K7 treatments is mainly due to its effect on number of spikes/m², number of grains/spike and 1000-grain weight as the above mentioned disucussion. Similar results were obtained by Mousavi (2011) and Zafar et al. (2016). Also, there was no significant effect between wheat varieties and potassium fertilization on grain and straw yield of wheat (Table 4). This means that the highest grain and straw yield were obtained for Beni-Suef 5 variety when fertilized with K3 or K7 potassium treatments. On the other hand, Beni-Suef 6 and Sids 13 without potassium fertilization yielded the lowest grain and straw yield, respectively.

3- Total nutrients uptake

The effect of potassium fertilization for four wheat varieties on total N, P and K uptake are given in Table 5. The data revealed that Beni-Suef 5 uptake more N, P and K (60.59, 58.41 and 81.98 kg/feddan in the first growth season, respectively) followed by Sids 12 (56.19, 56.65 and 78.85 kg/feddan). On the other hand, Beni-Suef 6 and Sids 13 gave the lowest values of total NPK uptake.

 The variation in NPK uptake among the wheat varieties is mainly explained by the effect of varieties on NPK concentration in grains and straw as well as its effect on grain and straw yields (as shown in bresviously Table 4). Similar results of varietal differences on nutrients uptake were reported by many investigators such as Hassanein (2001) and El-Abady et al. (2009).

Table (4). Effect of potassium fertilization for four wheat varieties on grain yield (ardab/ feddan) and straw yield (ton/feddan)

Also, (Table, 5) showed that potassium fertilization had significant effect on N, P and K uptake in both growing seasons. (K3) and (K7) gave the highest values of total N, P and K uptake in both growing seasons (67.24, 63.73; 61.33, 61.25 and 98.33, 96.17 kg/feddan in the first growing season, respectively).

The same trends were obtained for the second growing season. On the other hands, wheat plants without potassium fertilization (K1) uptake less N, P and K in both growing seasons (37.13, 44.43 and 52.14 kg/feddan in the first growing season and 38.24, 46.22 and 57.78 kg/feddan in the second one, respectively).

 It is obvious to observe that the effect of  potassium treatments were parallel to its effect on both grain and straw yields, since nutrients uptake calculated as multiplying grain or straw yield by nutrients content in grains or straw yield. Similar results were obtained by Bahrananyar and Ranjbar (2008) and Mitra et al. (2009).

As for interaction effect, the data revealed that N, P and K uptake were not affected by the interaction between treatments.

 In general, Beni-Suef 5 variety under K3 or K7 treatments uptake the highest amount of NPK. Whearas, Beni-Suef 6 or Sids 13 varieties without of potassium fertilization K1 recorded the lowest NPK uptake.The previous results exhibited that the interaction between varities and potassium fertilization was not significant for all studied traits. This indicated that the behaviours of these varieties were similar under these conditions.

Thus, the behavious were controlled by gentic affect. These results are in harmony with those obtained by El-Abady et al. (2009), Ahmed et al. (2011) and Abd El-Ghany et al. (2013) who reported that the interaction effect between wheat varity and foliar application of K on wheat productivity were no significant.

CONCLUSION

From the obtained results it can be concluded that, to obtain the best quantity and quality of wheat under these conditions it could be recommended to planting Beni-Suef 5 or Sids 12 variety under the application of 24 kg K₂O/feddan at two equal doses or 12 kg K₂O/feddan + foliar spraying of 2% potassium sulphate twice.

Table (5). Effect of potassium fertilization for four wheat varieties on total N, P and K uptake (kg/feddan)

APPENDIX

Appendix (1). Effect of potassium fertilization for four wheat varieties on N, P and K concentration (%)

Appendix (2). Effect of potassium fertilization for four wheat varieties on N, P and K uptake (kg/ feddan)