Response of Barley varieties to Phosphorus and Sulphur levels

A field experiment was performed at Agronomy Research Farm, The University of Agriculture Peshawar during winter 2013-14 to evaluate the response of barley varieties to phosphorus and sulphur levels. Treatments were replicated three times in randomized complete block (RCB) design having split plot arrangement. Area of subplot was 3 m x 1.8 m with six rows. Phosphorus levels (20, 40 and 60 kg ha) and sulphur (15, 30 and 45 kg ha) levels were placed in main-plots while barley varieties (BAJAUR-2000 and AAJ) were kept in sub-plots. Main-plots treatments consist of one control (no P and S). Phosphorus and sulphur doses were applied at sowing time. Results from the experiment indicated that highest number of leaves tiller (5.19), leaf area tiller 1 (92.93 cm), leaf area index (2.56), grains spikes (31.33), thousand grains weight (39.33 g), biological yield (8397 kg ha), grain yield (1714 kg ha) and harvest index (20.47 %) was produced by variety AAJ as compared to BAJAUR-2000. Phosphorus rate of 60 kg ha produced maximum leaf area index (2.76), grains spikes (32.56), thousand grains weight (40.95 g), grain yield (1722 kg ha), biological yield (8444 kg ha) and harvest index (20.46%) of barley. Application of sulphur at 45 kg ha resulted in highest leaf area tiller (92.33 cm ), leaf area index (2.48), grains spikes (31.83) and biological yield (8202 kg ha) while 30 kg S ha produced maximum thousand grains weight (39.22 g), grain yield (1601 kg ha) and harvest index (19.66%). It is concluded that barley variety AAJ produced optimal grain yield when received 60 and 30 kg ha phosphorus and sulphur respectively.


Introduction
Barley (Hordeum vulgare L.) belongs to family poaceae is one of the most important annual cereal grain crop.It is the most salt and drought tolerant crop grown under adverse conditions than other cereals [1].In Pakistan barley is cultivated in rain fed areas for seed purpose, but on fertile lands having irrigation facilities and near the cities barley is cultivated for forage purpose.Barley grain is mainly used as feed for live stock and as food for human consumption.The principal industrial use of barley is for malting.In Pakistan barley crop occupied about 86 thousand hectares area, the production of which was 81.5 thousand tones and the average yield was 948 kg ha -1 .While in Khyber Pakhtunkhwa, it occupied 30.5 thousand hectares area, the production was 27.5 tones and the average yield was 902 kg ha -1 [2].Proper amount of fertilizer is important for the cultivation of any crop because without inorganic fertilization the desired production cannot be obtained.Phosphorus is a very essential element for plants as it helps the healthy development of root system and also hastens the maturity.It is necessary for seed formation and its deficiency resulted in reduce number of heads and grains [3].Phosphorus is not only necessary for proteins and enzymes synthesis, but also vital for photosynthesis and almost all features of plant growth.Though, the reality is that phosphorus contributes to the major limiting factors of the world in areas of wheat production [4].There is a deficiency of phosphorus due to alkaline nature of these soils, but importance should be given to complete soil analysis before carrying out any experiment in Pakistan.Sulphur ranks the fourth major nutrient of plants because it is important constituent of various compounds [5].Effects of sulphur on quality and yield of crops like oilseed rape and cereals have been observed globally [6].Ramos (2008) [7] found that grain yield of barley increases with sulphur application due to maximum number of ears plant 1 and plot -1 .Keeping in view the important role of sulphur and phosphorus fertilization for higher production of barley, this research study was planned to evaluate the effects of phosphorus and sulphur application on barley.

An experiment was conducted at Agronomy
Research Farm, The University of Agriculture, Peshawar (Khyber Pakhtunkhwa, Pakistan) during the year 2013-14.The experiment was laid out in randomized complete block design with split plot arrangement having three replications.The crop was sown on 12th November.Phosphorus and sulphur levels were assigned to main plots while varieties to the sub plots.Sub plot size was 5.4 m 2 (3 x 1.8m -2 ) with row to row distance of 30 cm.Single Super Phosphate and Ammonium Sulphate was used as source of phosphorus and sulphur respectively.Two barley varieties i.e.BAJAUR and AAJ were taken from Cereal Crops Research Institute (CCRI).Uniform cultural practices were applied for all the sub plots.Treatments were included in the experiment are main plots include control having no Phosphorus and Sulphur while others are P1 (20 kg ha -1 ), P2 (40 kg ha -1 ), P3 (60 kg ha -1 ) and S1 (15 kg ha -1 ), S2 (30 kg ha -1 ), S3 (45 kg ha -1 ).Sub plots factor includes Barely Varieties V1 (BAJAUR-2000) and V2 (AAJ).Data were recorded on the observations which are Number of leaves tiller -1 , Leaf area tiller - 1 (cm 2 ), Leaf area index, Grains spike - 1 ,Thousand grain weight (g), Biological yield (kg ha -1 ), Grain yield (kg ha -1 ) and Harvest index (%).At heading stage ten tillers were randomly selected from three central rows in each sub plot.All the leaves were detached, counted and averaged to obtained leaf number tiller -1 .For calculating leaf area tiller -1 the following formula was used.Leaf area tiller -1 (cm 2 ) = Leaf area of all leaves Number of tillers Leaf area index (LAI) was estimated at heading stage in each subplot and the data was calculated by substituting the values in the given formula: LAI = (Leaf area tiller -1 ) x (Number of tiller m -2 ) 10,000 In each sub plot ten randomly selected spikes were threshed, grains were counted and averaged to calculate grains spike - 1 .Thousand grains weight was recorded by weighing thousand grains taken randomly from the grain lot of each sub plot with the electronic balance.Data concerning biological yield was taken by reaping three central rows of each sub plot, sun dried, weighed (above ground yield) and then changed to kg ha -1 .The harvested three central rows in each sub plot were threshed, cleaned, weighed and then converted to grain yield kg ha -1 .Harvest index was calculated by using the following formula.
Harvest index (%) = Grain yield x 100 Biological yield Method applicable to the randomized complete block design (split-plot arrangement) was used for statistical analysis of the recorded data.For mean comparison in case of significant difference least significant difference (LSD) test at 5% level of significance was used [8].

Number of leaves tiller -1
Data regarding number of leaves tiller -1 of barley varieties are presented in Table 1.Statistical analysis of the data indicated that different phosphorus levels significantly influenced the number of leaves tiller -1 of barley, whereas the effect of varieties, sulphur levels and all interactions showed no significant variation in number of leaves tiller -1 .Both varieties (BAJAUR-2000 and AAJ) produced same number of leaves tiller - 1 (5).Application of 60 kg P ha -1 resulted more number of leaves tiller -1 (5.39), while less number of leaves tiller -1 (4.33) was observed in control plots.[9] also carried out experiment in1996 and reported that phosphorus deficiency decreases leaf area due to less number of leaves.Sulphur rate of 15 kg ha -1 produced highest number of leaves tiller -1 (5) while minimum (4) were recorded in control plots.
Leaf area tiller -1 (cm 2 ) Data concerning leaf area tiller -1 (cm 2 ) are reported in Table 1.Statistically analyzed data showed that varieties, phosphorus and sulphur rates significantly influenced the leaf area tiller -1 .All interactions were found non-significant.Maximum leaf area tiller -1 (92.93 cm 2 ) was recorded in variety AAJ as compared to BAJAUR-2000 (86.67 cm 2 ).This might be attributed to the genetic variations between the varieties and some other environmental factors [10].Leaf area tiller -1 increased with each increment of phosphorus.Maximum leaf area tiller -1 (101.17cm 2 ) was recorded in plots received phosphorus at the rate of 60 kg ha -1 .The findings of [11] supported our results, who stated that leaf area tiller -1 and leaf area index increased with increasing of phosphorus rates.Sulphur rate of 45 kg ha -1 produced higher leaf area tiller -1 (92.33 cm 2 ) which is at par with 30 kg S ha -1 while lowest (64 cm 2 ) were measured in control plots.

Leaf area index
Effects of varieties, phosphorus, sulphur and P x S were significant on leaf area index (Table 1).Variety AAJ resulted higher leaf area index (2.56) and lower leaf area index (2.17) was recorded for BAJAUR-2000.In case of phosphorus application, 60 kg P ha  1 represents data regarding grains spike -1 of barley varieties in relation to different levels of phosphorus and sulphur.Statistical analysis of the data indicated that numbers of grains spike -1 significantly varied by various phosphorus and sulphur levels, while none of the interactions was found significant.In case of varieties, highest number of grain spike -1 (31.33) was recorded for variety AAJ and minimum grains spike -1 (27.44) were counted for BAJAUR-2000.Similarly more grains spike -1 (32.56) were counted in plots that received phosphorus at the rate of 60 kg ha -1 and less grains spike -1 (24.33) were recorded in control plots.Our results are supported by [14] who stated that phosphorus application significantly improved number of grains spike -1 .Sulphur level of 45 kg ha -1 produced maximum grain spike -1 (31.83) and minimum (24.33) were recorded in control plots.
[15] conducted field trials in 2004 who investigated that sulphur rate of 45 kg ha -1 produced highest number of grains spike 1 .

Thousand grains weight (g)
Statistical analysis of the data showed that phosphorus, sulphur and varieties had significant effect on thousand grains weight of barley crop, whereas the entire interactive responses on thousand grains weight showed non significant result (Table 2).Variety AAJ produced heavier grains (39.23 g) as compared to BAJAUR-2000 (37.03 g).The difference in thousand grains weight among barley varieties might be due to genotypic variations and other environmental factors.In case of phosphorus levels application of 60 kg P ha -1 resulted in highest thousand grains weight (40.95 g) as compared to control which gave lowest thousand grains weight (35.42 g).Our results are in accordance with [16] who performed experiments in 2007 and reported increase in thousand grains weight with increasing phosphorus rates.Application of sulphur at 30 kg ha -1 produced heaviest grains (39.22 g) which was statistically at par with 45 kg ha -1 and lower grain weight (35.42 g) was recorded in control treatments.Sulphur application significantly affected thousand grain weight of wheat [17].

Biological yield (kg ha -1 )
Data pertaining to biological yield (kg ha -1 ) of barley are shown in Table 2.It is evident form statistical analysis of the data that phosphorus and sulphur levels considerably altered biological yield of barley varieties.Among interactions only phosphorus x sulphur was also found significant.Between varieties maximum biological yield (8397 kg ha -1 ) was produced by variety AAJ as compared to BAJAUR-2000 which produced minimum biological yield (7734 kg ha -1 ).Similarly Six-row cultivar produced higher biological yield and number of grains spike -1 as compared to two-row cultivar [18].Phosphorus application also improved biological yield of barley.Highest biological yield (8444 kg ha - 1 ) was observed in 60 kg ha -1 phosphorus treated plots, while lowest biological yield (7254 kg ha -1 ) was maintained by control plots.With reference to sulphur levels maximum biological yield (8202 kg ha -1 ) was recorded at 45 kg S ha -1 which was at par with 30 kg S ha -1 .In control plots minimum biological yield (7254 kg ha -1 ) was observed.[19] carried out experiment in 2008 who stated that application of sulphur increase biological yield.In case of P x S highest biological yield (8805 kg ha 1 ) was observed in combination of 60 kg ha -1 and 30 kg ha -1 phosphorus and sulphur, respectively. .Table .2Thousand grains weight (g), Biological yield (kg ha -1 ), Grain yield (kg ha -1 ) and harvest index (%) of barley varieties as affected by Phosphorus and Sulphur levels

Varieties
Thousand grains weight (g) Grain yield (kg ha -1 ) Effect of phosphorus and sulphur levels on grain yield of barley varieties is presented in Table 2. Statistical analysis of the data revealed significant effect of phosphorus, sulphur and varieties on grain yield (kg ha - 1 ).In case of interactions only P x S was found significant.Highest grain yield (1714 kg ha -1 ) was obtained from variety AAJ as compared to BAJAUR-2000 which gave 1432 kg ha -1 grain yield.The difference in grain yield between varieties might be due to genotypic difference, heavier grains, highest number of grains spike -1 and other ecological factors [20].Application of 60 kg ha -1 produced highest grain yield (1722 kg ha -1 ) as compared with control.These results agree with those of [21] who reported that grain yield increases with increasing phosphorus application rate.In case of sulphur levels maximum grain yield (1601 kg ha -1 ) were observed in plots that received sulphur at the rate of 30 kg ha -1 which was at par with 45 kg S ha -1 while minimum grain yield (1080 kg ha -1 ) was obtained from control plots.Application of sulphur at 45 kg ha 1 produced highest grain yield of barley [22].Regarding P x S interaction, although no constant trend was noticed but higher grain yield (1817 kg ha -1 ) was observed with 60 kg ha -1 and 45 kg ha -1 P and S, respectively.