PHENOLOGY, YIELDS AND THEIR CORRELLATIONS IN POPULAR LOCAL AND EXOTIC MAIZE HYBRIDS AT VARIOUS NITROGEN LEVELS

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1 Sarhad J. Agric. Vol.27, No.3, 2011 PHENOLOGY, YIELDS AND THEIR CORRELLATIONS IN POPULAR LOCAL AND EXOTIC MAIZE HYBRIDS AT VARIOUS NITROGEN LEVELS INAMULLAH*, NAZEER HUSSAIN SHAH**, NAVEEDUR REHMAN*, MUHAMMAD SIDDIQ*** and ZAFARULLAH KHAN**** * Department of Agronomy, Agricultural University, Peshawar Pakistan. ** Agricultural Research Station, Mingora Pakistan. *** National Agricultural Research Center, Islamabad Pakistan. **** Department of Agriculture Extension Education & Communication, Agricultural University Peshawar Pakistan inamullah72@yahoo.com ABSTRACT Three maize hybrids including Baber (Local), Pioneer 30P45 and Syngenta 6621 (both are exotic) were compared phonologically and yield-wise; and correlations were worked out among the phenological and yield parameters at various nitrogen levels in an experiment conducted at KPK Agricultural University, Peshawar (34 o 00 N, 71 o 30 E, 510 MASL) Pakistan during summer The experiment was laid out in randomized complete blocks with split plot arrangement having three replications. Nitrogen levels (i.e. 0, 180, 240 and 300 kg ha -1 ) were allotted to main-plots and hybrids to subplots. Result data showed that nitrogen levels affected various parameters significantly. The highest level of 300 and 240 kg N ha -1 recorded maximum and at par days to tasseling and maturity, plant height, stover and grain yields as well as harvest index. Among the hybrids, Pioneer 30P45 recorded significantly the highest number of days to emergence while Syngenta 6621 and Pioneer 30P45 recorded significantly higher and at par values for days to tasseling, silking, maturity as well as grain yield. Syngenta 6621 recorded significantly higher plant height and stover yield while Pioneer 30P45 and Baber recorded significantly higher and at par values for harvest index. The interaction of nitrogen and hybrids affected plant height, stover yield, grain yield and harvest index. When the nitrogen level was increased from 0 to 300 kg ha -1, plant height of Syngenta 6621, Pioneer 30P45 and Baber increased by 6%, 3% and 2.5%, stover yield by 33%, 25% and 19%, grain yield by 59%, 60% and 51%, while harvest index increased by 45.5%, 66.5% and 36.3%, respectively. Based upon the significance of correlations, days to maturity and plant height were found suitable markers for selecting a maize hybrid for higher grain yield. Key Words: Maize (Zea mays L.), hybrids, nitrogen, phenology, grain yield, stover yield Citation: Inamullah,. N.H. Shah, N. Rehman, M. Siddiq and Z. Khan Phenology yields and their correlations in popular local and exotic maize hybrids at various nitrogen levels. Sarhad J. Agric. 27 (3): INTRODUCTION Maize (Zea mays L.) is the second most important food crop after wheat in Khyber Pakhtunkhwa (KPK) (Asif et al., 2007) and ranks third after wheat and rice in Pakistan (Chaudhry, 1994). Average maize yield in KPK is low as compared with the average yield of Pakistan (MINFAL, 2008) although maize yield in Pakistan is itself lower than its potential yield. Hybrid maize production has increased maize yield manifolds in many maize growing areas of the world (Maidni, 2006). In Khyber Pakhtunkhwa, hybrid seed is still sown on very small area, which is one reason of lower maize yield in the province. Hybrid maize production requires an understanding of various management practices especially of its fertilizers requirement which is higher as compared to that of ordinary maize varieties. In KPK, land holdings are generally smaller and growers are interested in higher crop intensity for which they need maize varieties which mature early along with giving high yield so that they could raise another crop (sunflower etc.), before wheat sowing. Maize hybrids are generally late in maturity (Valentinuz and Tollenaar, 2004). Improvements in maize grain yield overtime have been associated with delayed leaf senescence in newer maize hybrids (Lee and Tollenaar, 2007). Longer time to maturity may, therefore, be one reason of hybrids higher productivity; however, clear results need to be reported regarding any correlation between yields and phenology in hybrids. When a crop plant stays green for longer time, there are more chances of larger photoassimilates movement from source (leaves) to sink (seed) and thus size of the sink increases. It has also been reported that higher doses of fertilizer nitrogen delay maturity (Gardner et al., 1985; Uhart and Andrade, 1995). Thus, keeping in view the findings of Valentinuz and Tollenaar, (2004), Uhart and Andrade (1995) and Gardner et al. (1985), the intrinsic late maturity of hybrids and the corresponding further delay in hybrids maturity due higher doses of nitrogen should theoretically increase maize

2 Inamullah et al. Phenology, yields and their correlations in popular local and exotic 364 yields. Study of the association among yield traits and phenology is thus of significant importance. The objective of the present research is to compare phenology and yields of local and exotic maize hybrids and to find out whether there is any correlation among yields and phenology in these hybrids. MATERIALS AND METHODS To study the correlation among phenology, yields and harvest index of maize hybrids at various nitrogen levels, an experiment was conducted at KPK Agricultural University, Peshawar (34 o 00 N, 71 o 30 E, 510 MASL) Pakistan during summer The experiment was laid out in randomized complete block (RCB) design with split plot arrangement having three replications. Previous crop in the field was spring wheat. Nitrogen was applied to the main-plots while hybrid to the subplots. Area of each subplot was 4.5 x 5 m having six rows, 75 cm apart and 5 m long. All the recommended agronomic practices were followed. Three levels of Nitrogen (180, 240 and 300 kg ha -1 ) and control, and three hybrids i.e. Baber (a double-cross produced by Cereal Crops Research Institute, Pirsabak KPK), Pioneer 30P45 (Pioneer Hi-Bred International) and Syngenta 6621 (Syngenta International) were used. Data were recorded on days to emergence, emergence m -2, days to tasseling, silking and maturity, plant height, stover yield, grain yield and harvest index. Days to emergence were recorded by counting number of days from sowing to the date on which at least 50% seedlings emerged. Emergence m -1 was recorded by counting the number of plants in one meter row at five various places in each subplot and then averaged. Days to tasseling were recorded by counting number of days from sowing to the date on which 50% plants produced tassels. Days to silking were counted from the date of sowing to the date on which 50% plants produced silk. Days to maturity were counted from the date of sowing till harvest maturity. Plant height was recorded by selecting ten plants randomly in each sob plot, their heights were measured from base to tip of tassel and averaged. Stover yield, which is the non-grain part of a plant, of each subplot was recorded using the formula: [Stover Yield = (Grain Yield/Harvest Index) Grain Yield] (Tollenaar, 1989). Grain yield was recorded by weighted the grain yield obtained from the each plot and convert it into kg ha -1. Harvest index was calculated using the formula: [Harvest Index (%) = (Grain yield/biological yield) x 100] (Reddy, 2004). For calculating the coefficients of correlation, data of the mentioned parameters were averaged across the hybrids at various nitrogen levels and then coefficients of correlation were worked out among the mentioned parameters using excel worksheet (Gomez and Gomez, 1984; Iqbal et al., 2009). Data were analyzed using the statistical package MSTAT-C (Russel and Eisensmith, 1983) and the significant differences between treatments were determined using least significant difference (LSD) test. RESULTS AND DISCUSSION Days to Emergence and Emergence m -2 The hybrids differed significantly from each other at (P 0.01) in days to emergence and emergence m -2 (Table I). Pioneer 30P45 took significantly larger number of 10.6 days to emerge while Syngenta 6621 and Baber took at par (7.3 days) each to emerge. Similarly, Baber produced the largest number of 7.6 seedlings m -2 which was statistically at par with 7.3 seedlings m -2 produced by Syngenta Pioneer 30P45 produced the lowest number of 7 seedlings m -2 also statistically at par with seedlings produced by Syngenta Nitrogen levels and the interaction of nitrogen and hybrid did not show significant effect on days to emergence and emergence m -2 of the hybrids. Slafer and Whitechurch (2001) reported that soil moisture, sowing depth and thermal conditions at the sowing depth are the factors that affect the length of the phenophase termed as days to emergence. While the emergence m -2 in addition to the mentioned factors, depends on the viability and germinability of the seed also (Singh, 2004). Major (1980) is, however, of the view that if all the above factors are satisfied, there is third factor, the genetic factor, which affects the plant growth and development. Like final grain yield, there must be G x E interaction which may affect the days to emergence and germination m -2. Babar showed high emergence m -2 with the same soil moisture level and temperature while Pioneer 30P45 and Syngenta 6621 which are foreign hybrids showed comparatively low emergence m -2. Before sowing the seed, all the hybrids showed 100% germination in a laboratory test (data not shown in table). Days to Tasseling, Silking and Maturity Nitrogen affected days to tasseling, silking and maturity (Table I) significantly at (P 0.01). Significantly higher 61.8 and 62 days to tasseling were recorded when 240 or 300 kg ha -1 nitrogen was used, respectively. Significantly lower 60.7 days to tasseling were recorded in plots where no nitrogen was applied. Similarly, significantly higher 68.3 days to silking and 99.4 days to maturity were recorded when 300 kg ha -1 nitrogen was used and significantly lower 66.1 days to silking and 98 days to maturity were recorded in plots where nitrogen was not applied. Delay in tasseling, silking and maturity due to higher doses of nitrogen was according to the results as

3 Sarhad J. Agric. Vol.27, No.3, reported by Chaudhry and Jamil (1998) and Gardner et al., (1985). Muchow (1988) and Uhart and Andrade (1995) also reported that optimum N increased plant growth rate and delayed maturity. Table I Days to emergence, emergence m -2, days to flowering, silking and maturity of maize hybrids as affected by nitrogen levels Nitrogen Hybrids Mean (kg ha -1 ) Baber Pioneer 30P45 Syngenta 6621 Days to Emergence Mean 7.3 b 10.6 a 7.3 b Emergence m Mean 7.6 A 7.0 B 7.3 AB Days to Tasseling c bc ab a Mean 53.5 b 65.7 a 64.9 a Days to Silking c b b a Mean 63.5 b 68.6 a 69.7 a Days to Maturity b b a a Mean 90.8 b a a Means in the same category followed by different capital or small letters are significantly different at P 0.05 or P 0.01 level, respectively. The hybrids were also significantly different from each other in days to tasseling, silking and days to maturity at (P 0.01). Significantly higher 64.9 days to tasseling, 69.7 days to silking and days to maturity were recorded by Syngenta 6621, followed by Pioneer 30P45 with 65.7, 68.6 and days, respectively. Babar on the other hand took the lowest number of 53.5 days to tasseling, 63.5 days to silking and 90.8 days to maturity, respectively. The interaction effects of nitrogen and hybrids on days to tasseling, silking and maturity of hybrids were non significant. Maize hybrids generally differ in reaching various phenophases. It has been observed that two environmental signals i.e. photoperiod and temperature affect maize growth and development the most. Wiebold (2002) reported that modern corn hybrids respond little to photoperiod, but are affected more by temperature. When hybrids are said to differ in calendar days to maturity ; they actually differ in the growing degree days or the thermal units they consume. On the basis of growing degree days, some hybrids have short and others have long duration or maturity periods (Capristo et al., 2007). The higher number of days to tasseling, silking and maturity in Pioneer 30P45 and Syngenta 6621 showed that these hybrids higher heat units requirements as compared with the Baber. Among the three hybrids, the phenology of Sygenta 6621 was found different from others. It was one of the early emerging hybrids but in tasseling, silking and maturity, it recorded longer durations. On the average, its maturity was 12 days late as compared with the locally produced Baber hybrid. It showed that the soil moisture, sowing depth and thermal conditions at the sowing depth (Slafer and Whitechurch, 2001) While after emergence, probably because of the high growing degree days requirements, it showed late maturity. It should be noted that most of the scientists and seed companies start calculation of growing degree days after the seedling emergence (Wiebold, 2002).

4 Inamullah et al. Phenology, yields and their correlations in popular local and exotic 366 Plant Height (cm) Nitrogen showed a significant differential effect on plant height in interaction with hybrids (P 0.05) (Table II). Significantly higher plant height of cm was recorded by Syngenta 6621 when it was applied with 300 kg ha -1 nitrogen, 12 cm greater than it produced in plots which received no or 180 kg ha -1 nitrogen. On the other hand, Baber produced plant height of cm in plots which received 300 kg ha -1 nitrogen, only 4 cm greater than it produced in plots which received no or 180 kg ha -1 nitrogen. Pioneer 30P45 produced plant height of cm with 240 kg ha -1 nitrogen, 6 cm greater than it produced in plots which received no nitrogen. This differential and active response of Syngenta 6621 to higher nitrogen levels shows its superiority over other hybrids in producing more plant height with higher dose of nitrogen. Abbas et al. (2003) reported that different height of the varieties is genetic but N being primary yield constituent when increased resulted in tallest plants. Our study shows that some genotypes (e.g. Syngenta 6621) are more responsive to N as compared with others in plant height. Similar results have been reported by Akmal et al. (2010). Nitrogen, in its main effect, increased plant height significantly (P 0.01), producing cm height with 300 kg ha -1 nitrogen and cm plant height in plots where no nitrogen was applied. These findings are in accordance with Haque and Jakhro (1996) who reported that nitrogen enhances vegetative growth and plant height. Uhart & Andrade (1995) have also reported similar results with the same viewpoint. The hybrids were also significantly different from each other (P 0.01) in plant height. Syngenta 6621 recorded significantly higher plants of cm height while Baber recorded the lowest plant height of cm. Different heights seems to be the genetic characteristic of the hybrids. Stover Yield (kg ha -1 ) Like the plant height, nitrogen showed a significant differential effect in interaction with hybrids on stover yield also (P 0.01) (Table II). Higher stover yield of kg ha -1 was recorded by Syngenta 6621 with 300 kg ha -1 nitrogen. It was 6855 kg ha -1, 33% lower in plots which received no nitrogen. Baber and Pioneer 30P445 produced stover yield of 6778 and 7383 kg ha -1 with 300 kg ha -1 nitrogen, which were 25% and 19% greater than they produced in plots which received no nitrogen. Again this differential and active response of Syngenta 6621 to higher nitrogen levels shows its superiority over other hybrids in producing more stover yield with higher doses of nitrogen. Akmal et al. (2010) has also reported differential response of maize varieties in producing biological yield at various nitrogen levels. Nitrogen, in its main effect, increased stover yield significantly (P 0.01) producing higher stover yield of 8133 kg ha -1 with 300 kg ha -1 nitrogen and significantly lower yield of 5959 kg ha -1 with no nitrogen. These findings are in accordance with Haque and Jakhro (1996), Muchow (1988) and Uhart and Andrade (1995) who reported that nitrogen enhances vegetative growth. Similar results have been reported by Muhammad et al. (2002) Chaudhry and Jamil (1998), and Jokela and Randall (1989). Among the hybrids Syngenta 6621 recorded significantly higher stover yield of 8522 kg ha -1, while Baber the lowest stover yield of 5930 kg ha -1, which can be attributed to the genetic characteristic of the hybrids. Grain Yield (kg ha -1 ) Nitrogen showed significant effect in interaction with hybrids on grain yield (P 0.05) (Table II). Syngenta 6621 produced 1700 kg ha -1 grain yield with no nitrogen, which increased to 4135 kg ha -1 with 300 kg ha -1 nitrogen. This increase was 59%. Baber produced grain yield of 1489 kg ha -1 without nitrogen which increased to 3022 kg ha -1 with 300 kg ha -1 nitrogen, recording a 51% increase. Pioneer 30P45, on the other hand, produced grain yield of 3933 kg ha -1 with 300 kg ha -1 nitrogen, and 1566 kg ha -1 with no nitrogen. The increase in grain yield with 300 kg ha -1 nitrogen was 60%. It shows that Pioneer 30P45 and Syngenta 6621 responded more actively to higher nitrogen levels. Similar findings have been reported by Chaudhry and Jamil (1998) and Akmal et al. (2010), who documented that various maize genotypes responded differently to different nitrogen doses. We used the highest dose of 300 kg ha -1 nitrogen, at which the yield response of Baber and Syngenta 6621was not significantly higher than at 240 kg ha -1, however, Pioneer 30P45 showed significantly higher yield at 300 kg ha -1 than at 240 kg ha -1. It shows that Pioneer 30P45 may give more yield with nitrogen doses higher than 300 kg ha -1, however, more experiments should be conducted in this regard. Nitrogen, in its main effect, increased grain yield significantly (P 0.01), producing higher grain yield of kg ha -1 with 300 kg ha -1 nitrogen and significantly lower yield of 1585 kg ha -1 with no nitrogen. Many authors have reported similar results. To name a few are Abayomi et al. (2006), Mahdi and David (2005), Dobby et al. (2000), Muchow (1988) and (Uhart and Andrade, 1995). Among the hybrids Syngenta 6621 produced the highest

5 Sarhad J. Agric. Vol.27, No.3, yield of kg ha -1, Pioneer 30P45, kg ha -1 while Baber gave the lowest grain yield of kg ha -1. Ragheb and Rassy (1989) reported that hybrids generally differ from each other in grain yield which is mostly due to genetic factors and the different physiological performance. Harvest Index The interaction of nitrogen and hybrids showed significant effect on harvest index (HI) (P 0.05) (Table II). Syngenta 6621 exhibited an HI of 19.8% with no nitrogen while its HI increased to 29.5% with 240 kg ha -1 N not significantly different from HI produced at 300 kg ha -1 nitrogen. Baber produced an HI of 22.6% without nitrogen which increased to 30.8% with 300 kg ha -1 nitrogen. Pioneer 30P45, on the other hand, produced an HI of 34.8% with 300 kg ha -1 nitrogen, and 20.9% with no nitrogen. Table II Plant height, stover yield, grain yield and harvest index of maize hybrids as affected by nitrogen levels Nitrogen (kg ha -1 ) Hybrids Mean Baber Pioneer 30P45 Syngenta 6621 Plant height (cm) b b a a Mean c b a Stover yield (kg ha -1 ) b b a a Mean 5930 c 6797 b 8522 a Grain yield (kg ha -1 ) b b a a Mean b ab a Harvest Index (%) c b a a Mean 27.5 a 27.8 a 25.5 b Means in the same category followed by different letters are significantly different at P 0.01 level. Nitrogen increased HI significantly (P 0.01) producing higher HI of 31.4% with 300 kg ha -1 nitrogen, which was not significantly different from the HI of 30.1% recorded at 240 kg ha -1 nitrogen. The lowest HI of 21.1% was recorded in plots where nitrogen was not applied. Muhammad et al. (2002) reported an increase in HI in maize while Ali et al. (2002) reported that HI is not affected by change in nitrogen dose in maize. Among the hybrids, significantly higher HI of 27.8% was recorded by Pioneer 30P45 which was at par with the HI recorded by Baber. Syngenta 6621 recorded the lowest HI of 25.5%. Correlations among Phenology, Yields and Harvest Index of Maize Hybrids It was observed that days to maturity (r = 0.96) and plant height (r = 0.95) showed positive and significant correlation with the grain yield (Table III). Saleem et al. (2007), after studying ten S1 families of maize reported a positive and significant correlation between plant height and biomass and grain yield. They termed plant height as one of the selection criteria for high yield. Similarly, the plant height (r = 0.95) and grain yield (r = 0.97) showed significant and positive correlation with stover yield while only the grain yield (r = 0.99) showed highly significant and positive correlation with harvest index which is clear from the harvest index calculation formula. Phenological parameters like days to emergence, days to tasseling, silking and maturity exhibited positive correlations with plant height, grain yield, stover yield and harvest index but statistically these correlations were non significant except the correlation of days to maturity with grain yield as discussed earlier. Sujiprihati et al. (2003) has reported a significant and negative correlation between days to silking and plant height. Similarly, Iqbal et al. (2009) has also reported a negative non-significant in all the four maize crosses and negative significant correlation in only two

6 Inamullah et al. Phenology, yields and their correlations in popular local and exotic 368 crosses in days to silking and plant height. However, Sumathi et al. (2005) and Abdelmula and Sabiel (2007) obtained non-significant and positive correlations between days to silking and plant height. Positive correlation of non significant nature was obtained between plant height and days to maturity in our experiment as reported by Sujiprihati et al. (2003). Beyene (2005) reported a positive and significant correlation between the two traits. Iqbal et al. (2009), however, has reported contrasting results, of negative and significant nature in some crosses while negative and non significant in some other crosses. Positive correlation of non-significant nature in days to silking and maturity were obtained as reported by Iqbal et al. (2009) in two maize crosses. However, in another two crosses, Iqbal et al. (2009) reported positive and significant correlation between days to silking and maturity. Table III Coefficients of Correlation (r) among days to emergence (DEM), emergence m -2 (EPM), days to tasseling (DT), days to silking (DS), days to maturity (DM), plant height (PH), grain yield (GY), stover yield (SY) and harvest index (HI) of three maize hybrids grown at four nitrogen levels during summer 2009 EPM DT DS DM PH GY SY HI DEM EPM DT DS DM * PH * 0.95* 0.90 GY * 0.99* SY * = Significant (P 0.05) CONCLUSION AND RECOMMENDATIONS It was concluded that increasing nitrogen levels delayed tasseling, silking and maturity, and increased plant height, stover yield, grain yield and harvest index. Syngenta 6621 was found late in maturity among the tested hybrids while it excelled in stover and grain yields. Based upon the significance of correlations, days to maturity and plant height may be used as suitable markers for selecting a maize hybrid for higher grain yield. REFERENCES Abayomi, Y., A. George-Arijenja and I.A. Kolawole Comparative leaf growth and grain yield responses of hybrid and open-pollinated maize genotypes to nitrogen fertilizer application. Agro Search. 8(1-2): Abbas, M., M.Z. Rizwan., A.M. Maqsood and M. Rafiq Maize response to split application of Nitrogen. J. Agric. Biol. 5: Abdelmula, A.A. and S.A.I. Sabiel Genotypic and differential responses of growth and yield of some maize (Zea mays L.) genotypes to drought stress. Conf. Int l. Agric. Res. Dev. Univ. Gottingen, Khartoum, Sudan. pp.1-6. Akmal, M., H. Rehman, Farhatullah, M. Asim and H. Akbar Response of maize varieties to nitrogen application for leaf area profile, crop growth, yield and yield components. Pak. J. Bot. 42(3): Ali, J., J. Bakht, M. Shafi, S. Khan and W. Ali Uptake of nitrogen as affected by various combinations of Nitrogen and Phosphorus. Asian J. Plant Sci. 1(4): Asif, M., Amanullah and M. Anwar Phenology, Leaf Area and Yield of Spring Maize (cv. Azam) as affected by levels and timings of potassium application. World Appld. Sci. J. 2 (4): Beyene, Y.A Phenotypic diversity of morphological and agronomical traits in traditional Ethiopian highland maize accessions. S. Afric. J. Plant & Soil. 22: Capristo, P.R., R.H. Rizalli and F.H. Andrade Ecophysiological yield components of maize hybrids with contrasting maturity. Agron. J. 99: Chaudhry, A.U. and M. Jamil Determination of optimum level of nitrogen and its effect on maize (Zea mays L.). Pakistan J. Biol. Sci. 1(4): Chaudhry, F.M Kharif Cereal Crops. In Crop Production. Bashir, E. and R. Bantel (Eds). National Book Foundation, Islamabad, Pakistan. pp

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