Response of wheat cultivars toward successive delayed sowing under rainfed condition in Lower Dir

Meeting the food requirements of increasing population, production of more wheat is one of the key areas for researchers. Selection of cultivar with respect to sowing time for a particular agro-ecological zone plays a vital role in the improvement of wheat productivity. Therefore, an experiment was conducted to work out the suitable sowing time for the cultivars’ high yield at the Herbarium of Malakand University, Dir (Lower), Khyber Pakhtunkhwa (KP), Pakistan during 2014-15. The experiment was laid out in RCB design with split plot arrangement, replicated three times. The plot size was 4x1.75 m accommodating six rows, 25 cm apart. Five sowing dates (November 11, 21, December 2, 12 and 22) were applied to main plot, while ten wheat cultivars (Pak-2013, Dharabi-2011, Tatara, Lalma, Chakwal-50, Shahkar2013, Pirsabak-2005, Hashim-2008, KT-2000 and Siran-2010) were allotted to sub plot. More productive tillers m, taller plants, longer spikes, more spikelets spike, grains spike maximum biological and grain yield were recorded for the plots sown on 11 November and linear decrease was recorded with delay in sowing. Among different cultivars higher number of productive tillers m and taller plants were observed in Hashim-2008, while more spikelets spike, grains spike and biological and grain yield were higher for Pakistan-2013. With respect to sowing time and cultivars interaction, greater yields (3708 kg ha and 3553 kg ha) were recorded for Pakistan-2013 sown on November 11 and 21, followed by PS-2005 on 21 November (3553 kg ha) and 2 December (3525 kg ha), respectively. It was concluded that early sowing in the season improved the yield and yield component of wheat crop. Wheat cultivar Pakistan2013 was found the best in all aspects. Hence, wheat cultivar Pakistan-2013 is recommended for early sowing, while wheat cultivars Shahkar-2013 and Chakwal-50 are recommended for late sowing in the rainfed areas of Malakand division particularly Dir valley.


Introduction
Wheat (Triticum aestivum L.) is a long day self pollinated crop.In many countries of the Asia, it is cultivated for grain production where it mainly contributes to staple food for human consumption.Wheat crop ranked first in cultivation and production than the other crops in countries like Morocco, Uruguay, Syria, Australia and Argentina [1].The total cultivated area covered by wheat in Pakistan is 9.2 million hectares.This produced 25.26 million tones grains with average yield of about 2824 kg ha -1 .In Khyber Pakhtunkhwa (KP) province, wheat is grown on 0.78 million hectares area by producing 1.4 million tons of grains.The average yield of KP is reported as 1755 kg ha -1 [2].Due to global climatic change, water scarcity is the main proposed emerging big threats to agriculture crops in Pakistan.Water shortage resulted in drought effect that led to dearth and famine inhumanities.Therefore, accessibility of water is openly linked through foodstuff safety of the nation.Crop like wheat yield in rainfed climate of Pakistan is very low that needs enormous struggle for ensuring the potential food stuff safety in the deprived masses of the country.Agronomist are trying their best to address numerous matter associated to all crops in common and wheat crop in particular by developing varieties resistant to disease, for improvement wheat yield, and also re-validating the performance of existing cultivars in the area and in multiple locations of the region.Wheat as one of the most essential food commodity of Pakistan, is cultivated on an area of about 0.153 million hectare under rainfed conditions of Malakand division (57% of total area).The average yield in rainfed area is far below than the yield achieved in the other rainfed area of this country [3].Besides, many other factors including the predominated drought, nonavailability of variety, variety identified for the area as a reserve of hope and substandard organizations are the main reasons of sinking yield.Keeping in view the topographic-cum-ecological conditions of the area, the cultivable land in this country has been classified into different ecological zones.
Consequently, numerous organizations have been established in different ecological zones addressing the explicit problems of those particular areas, but as a result of inadequate budget for research they lacked to show potential performance.Similarly, the responses of crop plants vary with respect to the time of sowing in the season [4, 5].The scientists are actively involved in development of drought and disease resistance cultivars that produced higher grain yield per hectare.A number of wheat cultivars are released by various researchers/institutions but their comparative study is still missing in the literature.The released and/or approved high yielding varieties are conceivably tested in the local climate of the area but their collective performance with climate change effect of the local weather and time of sowing is still an issue to be tackled properly.
The proper moisture at the start of sowing season ensures the better emergence and crop stand.Hence, the unavailability of irrigation water and change in rainfall pattern in the target locality are considered as the main issues behind the staggered wheat sowing.Moreover, the growing of short season vegetables like tomato, cucumber and peas etc in the northern areas of Pakistan including Lower Dir valley also delays the sowing of wheat because the land is occupied by the aforementioned crops.Therefore, the present study was aimed to figure out a reliable wheat cultivar on the basis of its performance under the rainfed condition for the area.

Experimental site
A field trail was conducted at the Herbarium of Malakand University, Lower Dir, Khyber Pakhtunkhwa, Pakistan during 2014-15.Malakand is situated at 34.57° North latitude, 71.93°East longitude and 844 meters elevation above the sea level.

Experimental design and procedure
The experiment was performed in randomized complete block design with split plot arrangements replicated three times.Five sowing dates (November 11 th , 21 th , December 2 nd , 12 th and 22 nd ) were applied to main plot, while ten wheat cultivars Wheat cultivars, collected from various research stations were planted at the rate of 130 kg ha -1 on the aforementioned dates.Nitrogen (N) and phosphorus (P) were applied at the rate of 120 and 60 kg ha -1 .Half of N and full P were applied at sowing, while remaining half N at tillering stage.Field was irrigated for the respective sowing date only.Planting was done manually using hand hoe.Rain fall data was recorded during the crop growth period (Figure 1).Data recording procedure Using the prescribed procedures data were recorded on productive tillers, nonproductive tillers, plant height, flag leaf area, spike length, spikelets per spikes, biological and grain yield.For recording data on the number of productive tillers m -2 , fertile spikes in one meter length at three randomly selected places in each experimental unit were counted and were converted by the given formula The difference between total tillers m -2 and productive tillers m -2 were recorded as nonproductive tillers m -2 .Data on plant height was recorded by measuring the heights of randomly selected ten tillers in each plot from the basal node to tip of spike without awns at physiological maturity stage.The length and width of ten randomly selected flag leaves in each plot was measured with the help of measuring tape and flag leaf area was calculated with the formula suggested by [6].
Flag leaf area (cm 2 ) = Leaf length (cm) × Leaf width (cm) × CF (0.75) Data on spike length was recorded by taking the lengths of ten randomly selected spikes and was averaged for each plot.Data regarding spikelets spike -1 were recorded by counting the number of spikelets in randomly selected ten spikes in a plot and was averaged accordingly.Biological yield (BY) data was recorded by harvesting four central rows (R) in each plot followed by sun drying for about seven days, weighing and converting to kg ha -1 using the formula Grain yield (GY) data was recorded on four central rows after manual harvesting in each plot followed by sun drying for about a week time.The grains were threshed separately for recording each plot grain yield.Data was converted to kg ha -1 as per formula:

Statistical analysis
The recorded data was statistically analyzed by using analysis of variance techniques for randomized complete block design with split plot arrangement.Significant difference among different treatments was worked out by using least significant difference (LSD) test for main and interactive effects [7].

Results and discussions Productive tillers m -2
Sowing dates (SD), cultivars (V) and their interaction significantly affected productive tillers m -2 of wheat ( Non-productive tiller m -2 SD and V significantly influenced nonproductive tiller m -2 of wheat, whereas their interaction was non-significant (   Flag leaf area (cm 2 ) SD and V significantly influenced flag leaf area (cm 2 ) of wheat, whereas their interaction was non-significant (Table 4).Early sowing (11 th November) resulted in maximum flag leaf area (35.2 cm 2 ) which was at par with 21 st November sowing (33.1 cm 2 ) followed by 2 nd December sowing (32.3 cm 2 ), while lower flag leaf area (30.0 cm 2 ) was recorded for sowing on 22 nd December.Wheat cultivar PS-2005 had higher flag leaf area (37.6 cm 2 ) followed by Pak-2013 and Tatara (34.5 and 34.3 cm 2 ), statistically at par with one another, while lower flag leaf area (28.

Spike length (cm)
SD and V significantly influenced spike length of wheat, while their interaction was non-significant (Table 5).Lengthy spikes (10.8 cm) were recorded in early sowing (11 th November) followed by 21 st November (10.1) and 2 nd December (9.6 cm), while smaller spikes (8.9 cm) were recorded in 22 nd December sowing.In case of wheat cultivars, Dharabi-2011 had longer spikes (10.4 cm) which were at par with Pak-2013, Siran-2010, Shahkar-2013 and Lalma-2014.Lower spike length (8.9 cm) was recorded for Chawkal-50.Spike length significantly decreased with late sowing.More assimilation of photosynthates due to prolonged growth period contributed to longer spikes [10].Among cultivars, longer spikes were observed for Dharabi-2011, while shorter were for Chakwal-50.Cultivars have significant effect on spike length due to genetic variations [16, 17]..9d LSD (p≤ 0.05) for SD = 0.56 LSD (p≤ 0.05) for V = 0.62, V x SD = ns, ns = non-significant Spikelets spike -1 SD and V significantly differed for number of spikelets spike -1 , whereas their interaction was non-significant (Table 6).More spikelets (17.2) were recorded for 11 th November sowing, while 22 nd December sowing gave fewer spikelets spike -1 (15.8).Comparing wheat cultivars, Pak-013 had more spikelets, (17.1) and Chakwal-50 had less spikelet spike -1 (15.5).Spikelets spike -1 gradually decreased with delayed sowing.The reduction in spikelets may be due to shorter growing period prevailed during late season [12].Pakistan-2013 was dominated over the rest cultivars which resulted higher number of spikelets.Spikelets number is a genetic future of the plant and variation in the spikelet number of different cultivars might be due to the difference in their genetic makeup [18].Biological yield (kg ha -1 ) SD, V and their interaction significantly influenced biological yield of wheat (Table 7).Higher biological yield (8433) was recorded for early sowing (11 th November), followed by 21 st November and 2 nd December (7907 and 7851 respectively), while delayed sowing both 22 nd and 12 th December resulted in lower biological yield (7063 and 7106) respectively, which were similar in statistical approach.In case of wheat cultivars, Pak-2013 produced greater biological yield (8325), however it was similar to PS-5 and Shahkar-13.Hashim-2008 produced less biological yield (7120).SD and V interaction showed that biological yield decreased for all cultivars with delay in sowing, except KT-2000   Grain yield (kg ha -1 ) SD, V and their interaction significantly influenced grain yield of wheat (Table 8).Higher grain yield (3235) was produced in early sowing (11 th November), followed by both 21 st and 2 nd December (3002 and 2948) which was statistically at par with each other respectively, while lower grain yield (2506) was recorded for late sowing (22 nd December).Higher grain yield (3346) was obtained by Pak-013, followed by PS-2005 (3063) and Shahkar-2013 (2884), while lower yield (2700) was recorded for Hashim-2008 that was statistically similar to KT-2000, Chakwal-50 and Tatara cultivars.In case of SD and V interaction, grain yield of all cultivars was higher when sown early (11 th November) except PS-2005 and Shahkar-2013 cultivars that had produced higher grain yield when sown on 21 st November.Wheat cultivars Pakistan-13 and Shahkar-13 had relatively higher grain yield under late sowing as compared to other cultivars.More grain yield with early sowing might be the outcome of more spikes m-2 , more grains spike -1 and more thousand grains weight in early sown plots compared to late sown plots.Grain yield is reduced with delaying the sowing due to the decrease in proper growth duration, which resulted in lower growth and reduced yield [14, 22].Early sowing (1 st to 15 th November) produced greater grain yield (4134 kg ha -1 ) as compared to late sowing [20].Cultivars Pak-2013 was found better in terms of grain yield over the other cultivars.Similar trend among cultivars were also reported by [23,24].

Conclusion
It was concluded that early sowing on 11 th November improved the yield and yield component of wheat crop.Wheat cultivar Pakistan-2013 was found the best in all aspects.For late sowing, wheat cultivars Shahkar-2013 and Chakwal-50 performed better than the others.Hence, based on the performance wheat cultivar Pakistan-2103 is recommended for early sowing, while wheat cultivars Shahkar-2013 and Chakwal-50 are recommended for late sowing for the rainfed areas of Malakand division particularly Dir valley.

Figure 1 .
Figure 1.Average rainfall at Chakdara, Lower Dir (Farm Services Center, Chakdara, Lower Dir) 4 cm 2 ) was noted for Hashim-2008.Delay in sowing steadily decreased the flag leaf area.Early sowing resulted in greater flag leaf area than plants sown late.Difference in flag leaf area might be the outcome of different crop growth rates due to variation in growth period [14].Regarding wheat cultivars, PS-2005 produced highest leaf area than other cultivars probably due to genetic variability among cultivars [15].

Table 1 . Productive tiller m -2 of wheat varieties as affected by sowing dates under rainfed condition Sowing Dates (SD) Varieties (V) 11 th Nov 21 st Nov 2 nd Dec 12 th Dec 22 nd Dec Mean
Table 2).