EFFECT OF FORAGE CLIPPING ON GRAIN YIELD AND ASSOCIATED TRAITS OF WINTER WHEAT IN NORTHERN PAKISTAN

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1 Sarhad J. Agric. Vol.24, No.3, 2008 EFFECT OF FORAGE CLIPPING ON GRAIN YIELD AND ASSOCIATED TRAITS OF WINTER WHEAT IN NORTHERN PAKISTAN Iftikhar Hussain Khalil, Sultan Akbar Jadoon and Ghulam Hassan ABSTRACT Winter wheat (Triticum aestivum L.) has the potential to be used as a dual purpose crop for forage-plus-grain production in the Northern regions of the North West Frontier Province (NWFP) of Pakistan. A set of 28 elite lines obtained from the winter wheat breeding program at Oklahoma State University (USA) were evaluated in a randomized complete block design with factorial treatment (unclipped and clipped) arrangements at Abbottabad, NWFP during crop season. Analysis of variance revealed significant genetic variation (P<0.01) among genotypes for plant height, spike length, spikelets spike -1, spike weight, biological yield and grain yield, while non-significant for green forage production and days to maturity. Moreover, highly significant differences (P<0.01) were observed among the unclipped and clipped treatments for all plant traits of winter wheat genotypes. Genotype clipping interaction was highly significant (P<0.01) for plant height, spike length and grain yield, significant (P<0.05) for spikelets spike -1 and non-significant (P>0.05) for days to maturity, spike weight and biological yield. Means of 28 winter wheat lines for days to maturity, plant height, spike length, spikelets spike -1, spike weight, biological yield and grain yield under the unclipped and clipped treatments averaged vs days, vs 89.5 cm, 11.2 vs 9.8 cm, 19.5 vs 18.2, 2.4 vs 1.5 g, 9056 vs 4386 kg ha -1 and 2725 vs 1393 kg ha -1, respectively. Maximum grain yield producing genotypes under the unclipped treatment were 05F 5 04 (3750 kg ha -1 ) and 05F 5 87 (3292 kg ha -1 ), while under clipped treatment genotypes 05F 5 87 (2500 kg ha -1 ) and 05F 5 15 (2229 kg ha -1 ), respectively. The apparent reduction in yield and yield contributing traits can be reduced to an acceptable level by using better crop management and input practices. Key words: Winter wheat, Dual-purpose wheat, Forage clipping, Genotype clipping interaction INTRODUCTION Winter wheat (Triticum aestivum L.) is usually used for three major purposes; grain-only, forage-only and dual-purpose of forage-plus-grain, in the Southern states of USA and other winter wheat growing regions of the world (Krenzer, 1994). In grain-only production system, winter wheat is planted only to harvest grains upon maturity, while in forage only system, livestock graze the crop through out the crop growing season and no grain is harvested at all. In the dual-purpose production system, winter wheat is grazed by livestock from November until development of first hollow stem in late-february or early-march (Redmon et al., 1996) and then grain is harvested from the same crop. About 65% of the total winter wheat acreage in the Southern states is managed for the dual-purpose (Pinchak et al., 1996; Hossain et al., 2004). Wheat producers choosing a dual-purpose management system have greater flexibility and additional economic advantages compared with those choosing to grow wheat as forage-only or grain-only crop (Redman et al., 1995). To produce plenty green forage for livestock, dualpurpose wheat is generally planted earlier (Hossain et al., 2003), more densely (Epplin et al., 2000), and is applied with additional fertilizer to account for N removal in form of green forage by cattle (Krenzer, 1991 and Zhang et al., 1998). Farmers in the Northern regions of NWFP face sever shortage of green forage for livestock from November to February due to prevalent harsh winter season. Wheat forage is reported to be of high nutritive value and daily weight gain of grazing livestock is excellent (Horn, 1984). Genetic variations do exist among winter wheat cultivars for green forage and grain yield production (Krenzer et al., 1992). But selecting a winter wheat genotype merely on the basis of forage or grain yield alone seldom results in the greatest economic return because higher grain yielding genotypes are not always among the highest forage producing ones and vice versa (Krenzer et al., 1996). The potential of winter wheat as a dual-purpose crop has not yet been exploited in the Northern areas of NWFP, Pakistan. We hypothesized that introduction of winter wheat would serve as a source of forage for livestock in winters and then grain from the same crop. MATERIALS AND METHODS This research was carried out at Hazara Research Station, Abbottabad during crop season of The experimental material comprised of 28 winter wheat lines planted in randomized complete block design having two replications under unclipped and clipped treatments. These winter wheat lines were obtained from the Winter Wheat Germplasm Enhancement Project at the Oklahoma State University, USA. Experiment was planted in 1 st week of October 2005, about 4-5 weeks earlier than the recommended planted date for wheat in the area. A standard seed rate of 110 kg ha -1 was used for all Department of Plant Breeding & Genetics, NWFP Agricultural University, Peshawar Pakistan

2 Iftikhar Hussain Khalil et al. Effect of forage clipping on grain yield and associated traits 424 wheat lines. Each winter wheat line was assigned to a four row plot with row length of four meters and row to row space of 25 cm. Two of the four rows were sickle harvested in mid- March, 2006 to determine the effect of forage clipping on grain yield and other related traits. Data were taken on green forage production (from clipped treatment only), plant height, days to maturity, spike length, spikelets spike -1, spike weight, biological and grain yield. Ten plants in each replication were randomly selected to record data on yield traits and then averages were used for statistical analysis. Data on green forage production was determined by harvesting two of the fours rows in each replication. Plant height was measured from base of the plant to the tip of last spikelet excluding awns. Similarly, spike length was measured from base of first spikelet to the tip of last spikelet excluding awns. Days to maturity were counted from date of sowing till date of harvesting. The harvested material was sun dried for seven days and was weighed before threshing to determine biological yield. The grains obtained after threshing were weighed to determine grain yield. Data were statistically analyzed using SAS standard procedures for a factorial treatment arrangement in randomized complete block design and means were separated by least significant difference (LSD) test. RESULTS AND DISCUSSION Green forage production The analysis of variance for green forage indicated non-significant (P=0.16) differences among the 28 winter wheat lines evaluated (Table I). However, green forage yield ranged from kg ha -1 for winter wheat line 05F to kg ha -1 for line 05F 5 83 (Table II). Other close competitors in green forage production were 05F 5 78 (9792 kg ha -1 ), 05F 5 15 (9167 kg ha -1 ) and 05F (9167 kg ha -1 ). Twenty one of the total 28 winter wheat lines produced >6000 kg ha -1 green forage indicating potential of selecting superior forage producing lines from the current set of germplasm. This appears to be ample quantity of green forage for the small ruminants being raised by the farmers of the region. Plant height The analysis of variance indicated highly significant genetic differences (P<0.01) among winter wheat lines as well as the unclipped and clipped treatments for plant height (Table I). The genotype clipping interaction was also highly significant (P<0.01) indicating differential response of winter wheat lines to the unclipped and clipped treatments. All winter wheat lines experienced a consistent reduction in plant height due to forage clipping (Table II). Similar results about reduction in plant height due to forage removal during early seedling stage have been reported by Welton and Morris (1931) and Clippedler et al. (1949). Plant height of lines ranged from 83.1 cm for 05F to cm for line 05F under clipped treatment vs 93.4 cm for line 05F 5 04 to cm for line 05F 5 64 under unclipped treatment. Like green forage, 21 of the total 28 winter wheat lines had plant height of >100 cm under unclipped treatment. Averaged across 28 winter wheat lines, plant height was cm under unclipped vs 89.5 cm under clipped treatment indicating a net reduction of 14.4 cm or 13.9% in height due to forage clipping in early spring. Shorter wheat genotypes are generally most tolerant to lodging and are more responsive to increased fertilizer as compared to the traditional tall wheat types. Spike length Genetic differences among winter wheat genotypes and clipping treatments were highly significant (P<0.01) for spike length (Table I). Genotype clipping interaction was also significant indicating inconsistent performance of winter wheat lines for spike length under the unclipped and clipped treatments. There was a general reduction in spike length due to forage clipping in all winter wheat genotypes except 05F and 05F wherein longer spikes were observed under clipped treatment (Table II). Spike length ranged from 9.8 to 15.8 cm in unclipped vs 8.3 to 13.3 cm in clipped treatment. Maximum spike length of 15.8 cm was recorded in wheat line 05F 5 64 followed by wheat genotype 05F 5 63 with a spike length of 14.2 cm under the unclipped treatment. Under the clipped treatment, maximum spike length of 13.3 cm was observed in wheat line 05F Averaged across the 28 wheat lines, spike length was 11.2 cm under unclipped vs 9.8 cm under clipped treatment showing a net significant decrease of 1.4 cm or 12.3% in spike length due to forage clipping. Spikelets spike -1 Differences among winter wheat lines as well as clipping treatment were highly significant (P=0.01) for number of spikelets spike -1 (Table I). Similarly, genotype clipping interaction effects for spikelets spike -1 were also significant (P<0.05) indicating differential response of winter wheat lines in spikelets production under unclipped and clipped treatments. Number of spikelets spike -1 among wheat genotypes ranged from 16.4 to 24.6 under the unclipped vs 16.2 to 20.0 under clipped treatment (Table III). Two wheat lines (05F 5 21 and 05F 5 134) produced similar spikelets spike -1 under the two clipped treatments. Similarly six winter wheat lines

3 Sarhad J. Agric. Vol.24, No.3, produced numerically more number of spikelets spike -1, while remaining 20 lines produced fewer spikelets spike -1 under the clipped treatment. Winter wheat line 05F 5 63 consistently produced more number of spikelets spike -1 under the clipped (22.8) as well as un-clipped (24.6) than other lines evaluated in the current trial at Abbottabad. Averaged over the 28 winter wheat lines, the number of spikelets spike -1 were 19.5 in unclipped vs 18.2 in clipped treatment. This is equivalent to net reduction of 1.3 spikelets spike -1 or 7% due to forage removal during vegetative growth stage in early spring. Days to maturity The analysis of variance indicated non-significant differences (P=0.09) among winter wheat lines for days to maturity (Table I). Differences among the unclipped and clipped treatments were highly significant (P<0.01) for days to maturity but the resultant genotype clipping interaction was nonsignificant indicating similar response of wheat lines to maturity under the unclipped and clipped treatments. Forage clipping generally delayed maturity of all lines by 2 to 6 days. Our results confirmed the earlier findings of Clippedler et al. (1949) who have also reported delay in flowering as well as maturity due to forage removal. Maturity of wheat lines ranged from to days under the unclipped vs to days under clipped treatment (Table III). Minimum days to maturity of were observed each for wheat lines 05F 5 04 and 05F 5 05, while maximum days to maturity of were recorded for wheat genotype 05F 5 09 and 05F 5 64 under clipped treatment. In contrast 12 of the total 28 wheat lines took the minimum days of to maturity under the unclipped treatment. Averaged over 28 wheat lines, days to maturity were in unclipped vs in clipped treatment. This indicates a delay of 3.4 days in maturity due to forage clipping. Spike weight Highly significant differences (P<0.01) were observed among the winter wheat lines as well as clipping treatments regarding single spike weight at maturity (Table I). However, the genotype clipping interaction for spike weight was non-significant (P=0.32) indicating similar trend among winter wheat genotypes for this important yield related trait under the two clipping treatments. Mean single spike weight of wheat genotypes ranged from 1.5 to 3.5 g and 1.0 to 3.5 g under unclipped and clipped treatments, respectively (Table III). Thus, there was a general reduction in single spike weight of all winter wheat lines due to forage clipping. Winter wheat line 05F 5 63 produced heavy spikes both under unclipped (3.5 g) and clipped (3.5 g) treatments. The same line also had the maximum spike length and number of spikelet spike -1 under unclipped and clipped treatment too. Averaged over 28 winter wheat lines, single spike weight was 2.4 vs 1.5 g under the unclipped and clipped treatments showing a significant net reduction of 0.9 g spike -1 or 35.4 % due to green forage removal. Biological yield Analysis of variance for biological weight showed highly significant differences among winter wheat genotypes as well as clipping treatments (Table I). However, non-significant difference was observed for genotype clipping interaction indicating similar response of wheat genotypes to unclipped and clipped treatments. Biological yield of wheat genotypes ranged from 5458 to and 2791 to 8125 kg ha -1 under the unclipped and clipped treatments, respectively (Table IV). Maximum biological yield of kg ha -1 by genotype 05F 5 04 was produced under the unclipped, while 8125 kg ha - 1 by 05F 5 69 under the clipped treatment. Minimum biological yield of 2791 and 5458 kg ha -1 were recorded in 05F and 05F under clipped and unclipped treatments, respectively. When averaged over all 28 winter wheat genotypes, a net reduction of 4670 kg ha -1 (48.4%) was observed among unclipped and clipped treatments for biological yield. Grain yield Differences among wheat genotypes, clipping treatments and genotype clipping interaction were significant for grain yield (Table I). Maximum and minimum grain yield under unclipped treatment were produced by genotypes 05F 5 04 (3750 kg ha -1 ) and 05F (2067 kg ha -1 ), respectively (Table IV). Wheat line 05F 5 04 also produced maximum biological yield both under unclipped and clipped treatments showing potential to be selected for further testing at different locations in the Northern NWFP. Maximum grain yield (2500 kg ha -1 ) was produced by genotype 05F 5 87 under clipped treatment while the minimum yield of 833 kg ha -1 each by genotypes 05F and 05F Average over 28 winter wheat genotypes, grain yield was 2725 kg ha -1 under unclipped and 1393 kg ha -1 under clipped treatment. Thus, net reduction in grain yield among the two clipping treatments was 1332 kg ha -1 or 48.9% due forage clipping in early spring. Dunphy et al. (1982) and Winter and Thompson (1987) have also reported reduction in grain yield of winter wheat due to forage clipping and/or cattle grazing. A reduction of about 23% in grain yield due to forage removal through cattle grazing in winter wheat has been previously reported by Khalil et al. (2002).

4 Iftikhar Hussain Khalil et al. Effect of forage clipping on grain yield and associated traits 426 However, the apparent losses in yield and yield contributing traits can be minimized to acceptable level by better management practices like optimum planting date, appropriate stage and interval of clipping, better irrigation and additional nitrogen application after forage clipping (Carver et al., 2001) CONCLUSION All winter wheat genotypes experienced reduction in grain yield and associated traits due to forage clipping in early spring. However, winter wheat offers a unique additional advantage of green forage during scarcity season from November to February. The differential response of winter wheat genotypes to forage clipping necessitates further research involving actual grazing practices at several locations and years to draw valid conclusions. ACKNOWLEDGEMENT This research was conducted under the Pakistan Agricultural Research Council (PARC) sponsored project titled Developing Forage-plus-Grain Winter Wheat Production System for Northern Areas under the Agricultural Linkages Program (ALP) Batch-II for years Table I. Mean squares for green forage, plant height, spike length, spikelets spike -1, maturity, spike weight, biological and grain yield of 28 winter wheat lines evaluated under unclipped and clipped treatments at Hazara Research Station, Abbottabad during Parameter Replication Genotype Clipping Genotype Clipping Error CV (%) d.f (27) - Green forage NS NS Plant height * ** ** 44.0 ** Spike length 0.2 NS 3.8 ** 53.2 ** 1.3 ** Spikelets spike NS 6.4 ** 43.4 ** 2.3 * Maturity 37.7 ** 3.7 NS ** 0.8 NS Spike weight 1.1 * 0.6 ** 19.8 ** 0.2 NS Biological yield NS ** ** NS Grain yield NS ** ** ** NS = Non-significant. * ** = Significant at 5 and 1% probability level, respectively. = df in parenthesis pertains to green forage only.

5 Iftikhar Hussain Khalil et al. Effect of forage clipping on grain yield and associated 427 Table II. Means for green forage, plant height and spike length of 28 winter wheat lines evaluated under unclipped and clipped treatments at Hazara Research Station, Abbottabad during Green forage (kg ha -1 ) Plant height (cm) Spike length (cm) Genotypes Unclipped Clipped Unclipped Clipped Unclipped Clipped 05F F F F F F F F F F F F F F F F F F F F F F F F F F F F Average LSD (0.05) LSD value for comparing genotype means under unclipped and clipped treatments for a trait.

6 Sarhad J. Agric. Vol.24, No.3, Table III. Means for spikelets spike -1, maturity and spike weight of 28 winter wheat lines evaluated under unclipped and clipped treatments at Hazara Research Station, Abbottabad during Spikelets spike -1 Maturity (d) Spike weight (g) Genotype Unclipped Clipped Unclipped Clipped Unclipped Clipped 05F F F F F F F F F F F F F F F F F F F F F F F F F F F F Average LSD (0.05) LSD value for comparing genotype means under unclipped and clipped treatments for a trait.

7 Iftikhar Hussain Khalil et al. Effect of forage clipping on grain yield and associated 429 Table IV. Means for biological and grain yield of 28 winter wheat lines evaluated under unclipped and clipped treatments at Hazara Research Station, Abbottabad during Genotype Biological yield (kg ha -1 ) Grain yield (kg ha -1 ) Unclipped Clipped Unclipped Clipped 05F F F F F F F F F F F F F F F F F F F F F F F F F F F F Average LSD (0.05) LSD value for comparing genotype means under unclipped and clipped treatments for a trait. REFERENCES Carver, B.F., I. Khalil, E.G. Krenzer, Jr., and C.T. MacKown Breeding winter wheat for a dual-purpose management system. Euphytica 119: Clippedler, G.H., D.S. Pavvez, and R.R. Mulvey The effect of clipping to simulate pasturing winter wheat on the growth, yield, and quality of the crop. Agron. J. 41: Dunphy, D.J., M.E. McDaniel, and E.C. Holt Effect of forage utilization on wheat grain yield. Crop Sci. 22: Epplin, F.M., I. Hossain, and E.G. Krenzer, Jr Winter wheat fall-winter forage yield and grain yield response to planting date in a dual-purpose system. Agric. Syst. 63: Horn, F.P Chemical composition of wheat pasture. P In G.W. Horn (ed.) Proc. Natl. Wheat Pasture Symp. Okla. Agric. Exp. Stn. MP-115. Hossain, I., F. M. Epplin, and E.G. Krenzer, Jr Planting date influence on dual purpose winter wheat forage yield, grain yield and test weight. Agron. J. 95: Hossain, I., F. M. Epplin, G.W. Horn, and E.G. Krenzer, Jr wheat production practices used by Oklahoma grain and livestock producers [online]. Oklahoma Agric. Exp. Stn. Publ.B-818. Available at pdf) (verified 6 July 2004). Oklahoma Stat. Univ., Stillwater. Khalil, I.H., B.F. Carver, E.G. Krenzer, C.T. Mackown, and G.W. Horn Genetic trends in winter wheat grain yield and test weight under dualpurpose and grain-only management systems. Crop Sci. 42:

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