Introduction Wheat (Triticum aestivum L.) is one of the most important staple food crops of the world Wheat ranks first in area and production and contributes more calories and proteins to the world’s human diet than any other cereals Wheat is grown on about 217 million hectares with total production of about 653 million metric tons (FAO,2010). The highest average yields are obtained in Western Europe, with more than 8 t ha-1, in contrast to less than 1 t ha-1 in several countries in Africa and Asia.
Nigeria production currently stands at about 37,200 tonnes from about 51,000 hectares according to estimate by FAO (FAO, 2010). Wheat is used in various local dishes in Nigeria as well as in bread making, Spaghetti, Semolina, Macaroni and Biscuits. The consumption of wheat in Nigeria has increased significantly in the last due largely to urbanization. Bread is very popular as breakfast food. Nigeria’s requirement for wheat is about 3.7 million tons and the country expends annually about $650 million to import wheat.
Introduction (Cont.) Water and Temperature stress are the critical abiotic stresses that affect wheat production in Nigeria Wheat production environment is characterized by terminal heat stress accompanied by low humidity (Fischer, 1985, Pfeiffer et. al., 1989). The effects of water and Temperature on growth, development and yield of wheat have been documented by previous workers (Kuroyanagi and Paulsen, 1988; Blum, 1988; Harding et al.,1990; Slafer and Rawson, 1995; Slafer et al.,1996; Ouda et al., 2005). Hot, dry and short season coupled with inadequate irrigation water are the major factors responsible for the low wheat yield in Nigeria Climate change has aggravated the effects of water and temperature through various scenarios of drought, extreme temperatures, desertification and flooding.
Introduction Cont. Wheat in Nigeria is grown entirely under irrigation during the cool hamattan period of the dry season between the months of November and March. As water is not unlimited, the need to use it efficiently to produce high yield becomes paramount. There is also the management need to irrigate the crop as frequently as possible in order to mitigate the effects of high temperature particularly during critical yield determining stages of crop growth. The need also for high yielding variety that tolerates the high temperature conditions and produce high yield to compensate the cost of irrigation cannot be over emphasized. Management practices that ensure the optimum utilization of the cool period through appropriate time of sowing, use of heat tolerant variety and determination critical period of water stress is important.
Objectives To evaluate the response of two wheat genotypes to water stress and sowing date To evaluate the interaction between sowing date and water stress on yield of wheat
Materials and Methods Location The trials were conducted during 2009/10 and 2010/11 dry seasons at the Fadama Teaching and Research Farm, Usmanu Danfodio University, Sokoto (latitude 13001’N; longitude 5015’E, altitude of 350 m above sea level). Relative humidity ranges from 26-39 % in the dry season Maximum temperature ranges from 32 to 43 0C and Minimum temperature of 18 to 29 0C during the period of experiment The area was previously used for the cultivation of vegetables and cereals crops
Treatment and Experimental Design The treatments consist of factorial combination of Water stress which was imposed by withholding water at (Tillering, Flowering, Grain filling) and Control (No stress), Two genotypes (STAR//TR771773/SLM and Kauz/ Weaver) and Four planting dates (21st Nov., 5th Dec., 19th Dec. and 2nd Jan.). The experiment was laid out in a split plot design with three replications Water stress and Date of planting occupied the main plot while Variety was assigned to the sub plots
Cultural PracticesExperimental materials Two varieties (STAR//TR771773/SLM and Kauz/ Weaver) Seeds of the wheat from Lake Chard Research InstitutesLand preparations The land was cleared, ploughed, harrowed and leveled. Basins and water channels were constructed Gross plot size was 3m x 3m (9m2) while the net plot was (4.5m2). One meter (1m) lee-way was left between blocks and 0.5m between plotsSowing The seeds was treated with Apron star (20% w/w thiamethoxam, 20% w/w metalaxyl-M and 2 % w/w difenoconazole) at the rate of 10 g/ 4 kg of seed before sowing to prevent seedling diseases and sown by drilling at 20 cm inter row spacing at 2-3 cm depth at the rate of 120 kg/ha, while the date of sowing was as per the treatments
Cultural Practices Cont.Irrigation Four irrigations were given before imposing irrigation treatment. The first was given immediately after sowing while the remaining 3 were given at 5 days interval for the crop to get established.The method of irrigation used was check basin irrigationWeeding Weeding was done manually with a hoe. Two hoe weeding at 3 and 6 WAS were employed to ensure weed free plotsFertilizer application 120, 60 and 60 kg N, P2O5 and K2O ha-1 Half of N and all of P and K was applied at sowing Other half applied prior to tillering
Cultural Practices Cont.Pest and disease control Birds were controlled by scaring while Rodents were controlled by using baits and traps No incidence of diseases was recordedHarvesting, threshing and winnowing Manually harvested from the net plot area at physiological maturity using sickles when 50% of the peduncles have turned brown The plants was cut at ground level. The spikes was beaten out with sticks to expose the grains, which was winnowed in open air with the help of wind current
Data CollectionData were collected on length of spike, Number of spikelets per spike, Number of grains per spike and Grain yield t ha-1 Data analysis The data collected were subjected to analysis of variance (ANOVA) using SAS (2003) computer package Least significant difference (LSD) (Gomez and Gomez, 1984) and New Duncan’s Multiple Range Test (DNMRT) were used for mean separation
ResultsTable 1: Effects of water stress, sowing date and variety on length of spike of bread wheat in 2009/10, 2010/11 dry seasons and combined at SokotoTreatment Length of spike (cm) 2009/10 2010/11 CombinedWater stress Tillering 11.44b 14.20b 12.82b Flowering 12.02a 15.03a 13.52a Grain filling 12.12a 15.12a 13.62a Control 12.17a 15.10a 13.67a SE± 0.049 0.149 0.094Sowing date 21st November 12.57a 15.47a 14.02a 5th December 12.50a 15.46a 13.98a 19th December 11.47b 14.41b 12.94b 2nd January 11.21b 14.18b 12.70b SE± 0.106 0.097 0.101Variety Star II TR77173/SLM 11.97 14.92 13.45 Kauz/ Weaver 11.90 14.84 13.37 SE± 0.096 0.098 0.051Interaction SXD Ns * * SXV Ns Ns Ns DXV Ns * * SXDXV Ns Ns Ns
Table 2: Effects of water stress, sowing date and variety on number of spikelets per spike of bread wheat in 2009/10, 2010/11 dry seasons and combined at SokotoTreatment Number of spikelets per spike 2009/10 2010/11 CombinedWater stress Tillering 12.11b 13.51b 12.81b Flowering 13.36b 15.65b 14.50b Grain filling 17.76a 19.91a 18.84a Control 20.59a 18.75a 19.67a Significance * * * SE± 1.004 1.175 1.077Sowing date 21st November 22.34a 22.50a 23.42a 5th December 21.36a 22.54a 23.45a 19th December 8.73b 10.57b 9.65b 2nd January 5.38b 7.22b 6.30b Significance * * * SE± 3.092 3.229 3.160Variety STAR//TR771773/SLM 16.36 18.35 17.35a Kauz/ Weaver 15.55 17.56 16.55b Significance Ns Ns * SE± 0.476 0.477 0.244Interaction SXD Ns * * SXV Ns * * DXV Ns * * SXDXV Ns Ns Ns
Table 3: Effects of water stress, sowing date and variety on number of grains per spike of bread wheat in 2009/10, 2010/11 dry seasons and combined at Sokoto Treatment Number of grains per spike 2009/10 2010/11 Combined Water stress Tillering 32.06 39.89a 35.98ab Flowering 32.22 32.37b 32.29b Grain filling 34.79 41.40a 38.10a Control 35.76 39.65a 37.70a SE± 1.729 0.970 1.298 Sowing date 21st November 37.51 39.50a 38.51a 5th December 36.63 39.78a 38.21ab 19th December 31.22 35.50b 33.36b 2nd January 29.47 35.51b 32.49b SE± 2.310 1.008 1.430 Variety Star II TR77173/SLM 34.27 38.83 36.55 Kauz/ Weaver 33.15 37.83 35.49 SE± 0.734 0.595 0.535 Interaction SXD Ns * * SXV Ns * * DXV Ns * * SXDXV Ns Ns Ns
Table 4: Effects of water stress, sowing date and variety on grain yield of bread wheat in 2009/10, 2010/11 dry seasons and combined at Sokoto. Treatment Grain yield (t ha-1) 2009/10 2010/11 Combined Water stress Tillering 2.27b 3.80a 3.03a Flowering 1.73c 3.06b 2.40b Grain filling 2.26b 3.20b 2.73b Control 2.97a 4.30a 3.63a SE± 0.095 0.268 0.243 Sowing date 21st November 3.38a 4.62a 4.00a 5th December 2.75a 3.71b 3.23b 19th December 1.48b 3.31b 2.39c 2nd January 1.52b 3.16b 2.34c SE± 0.188 0.180 0.144 Variety Star II TR77173/SLM 2.60a 4.10a 3.35a Kauz/ Weaver 1.96b 3.30b 2.63b SE± 0.074 0.145 0.098 Interaction SXD * * * SXV Ns * * DXV * * * SXDXV Ns Ns Ns
Table 5: Interaction between water stress and sowing date on grain yield t ha-1 in 2009/10, 2010/11 dry seasons at Sokoto.Water stress Grain yield (t ha-1) 21st November 5th December 19 December 2nd January 2009/10Tillering 3.14b 2.78bcd 1.55efg 1.21fgFlowering 2.95bc 2.23cde 0.89g 0.85gGrain filling 2.40b-e 2.97bc 1.70efg 1.99defControl 5.03a 3.03bc 1.78ef 2.04def SE ± 8.154 2010/11Tillering 4.76a-c 3.85ab 3.40c-f 3.91b-eFlowering 3.79b-f 2.27f 2.66d-f 3.53c-fGrain filling 4.18b-d 3.53cf 3.16b-d 2.55efControl 5.74a 5.18ab 4.03b-d 2.65d-f SE ± 0.537
Table 6: Interaction between water stress and variety on grain yield t ha-1 in 2010/11 dry seasonand combined at Sokoto.Water stress Grain yield t ha-1 STAR//TR771773/SLM Kauz/ Weaver 2010/11Tillering 4.63a 3.35bFlowering 3.26b 2.87bGrain filling 3.34b 3.26bControl 4.78a 3.70abSE ± 0.291 CombinedTillering 3.47ab 2.86bcFlowering 2.65bc 2.14cGrain filling 3.14b 2.62bcControl 4.15a 2.89bc SE ± 0.196
Table 7: Interaction between sowing date and variety on grain yield t ha -1 in 2009/10,2010/11 dry seasons and combined at Sokoto.Sowing date Variety STAR//TR771773/SLM Kauz/ Weaver 2009/1021st November 4.02a 2.74bc5th December 3.17b 2.33cd19th December 1.47e 1.48e2nd January 1.76e 1.28e SE ± 0.243 2010/1121st November 5.08a 4.15abc5th December 4.22ab 3.20bcd19th December 3.78bcd 2.84d2nd January 3.33bcd 2.99cdSE ± 0.243
Conclusions Water stress at flowering and grain filling was the most critical growth stage in yield determination of wheat. Delay in sowing resulted in reduction in yield. STAR//TR771773/SLM was superior to Kauz/Weaver when sown on 21st November and 5th December. Therefore the best time/optimum of planting of this cultivars in Sokoto is November or at least first week of December. STAR//TR771773/SLM is the recommended variety for the area.