ITEMS FROM PAKISTAN

AGRONOMIC RESEARCH STATION

Bahawalpur, Pakistan.

Muhammad Sarwar Cheema, Liaquat Ali, and Muhammad Akhtar.

Identifying sources of resistance to wheat leaf rust under induced and natural conditions. [p. 79-81]

Altaf Hussain Tariq, Saeed Ahmad, Muhammad Arshad Hussain, Muhammad Ziaullah,Lal Hussain Akhtar, and Sabir Zameer Siddiqi.

Background. Rust diseases pose a major threat to the productivity of wheat crop when epidemics develop. Leaf rust is world wide in distribution and a most dreaded disease that can spread rapidly and devastate the wheat crop (McIntosh et al. 1997). In Egypt, Abdel Haq et al. (1980) estimated yield losses up to 50 % in wheat. This disease has appeared in epidemic form several times in Pakistan. During 1978, a national loss of 86 x 106 USD was estimated (Hussain et al. 1980). Chemical control of rust diseases is not economical. Therefore, cultivation of resistant cultivars is of paramount importance. Breeders need to plan their hybridization program judiciously in order to produce cultivars with different genetic backgrounds for resistance to rusts so that any danger of a disease epidemic can be avoided. The present studies explored new sources for rust resistance in wheat, which will help the breeders in planning future wheat-breeding programs.

Materials and methods. Local Wheat Diseases Screening Nurseries (LWDSN) comprised of 293 and 346 advanced wheat lines were planted at Bahawalpur during 2001 and 2002, respectively. Ten commercial wheat cultivars also were included in the nurseries. The entries, which gave reactions from trace to MRMS at Bahawalpur, and 10 commercial cultivars also were sown at Kaghan. Each entry was planted in a single 2-m row, 30 cm apart, at both the locations. Two rows of susceptible checks (Morocco and Local White) were sown repeatedly after every fifth entry and around the block. The nurseries were inoculated artificially with a spore suspension of leaf rust by injecting, rubbing, and spraying from the first week of February until 10 March at Bahawalpur during both the years. Kaghan is a summer station about 7,000 ft ASL. Natural rust epidemics occur frequently in this area. The planting at Kaghan was made during the first week of June. Observations on rust infections were recorded at 10-15 day intervals throughout the growing period at Bahawalpur and during the end of August at Kaghan. Data were recorded according to the modified Cobb's scale at both locations (Peterson et al. 1948). The observations were compared among years and locations to establish the distribution of rust incidence.

Results and discussion. The observations of leaf rust on the 10 commercial wheats sown at Bahawalpur and Kaghan in 2001 and 2002 indicated that the intensity of rust infection during 2001 was comparatively higher than that in 2002 at both locations. Natural infection at Kaghan was less in 2002 because of less precipitation throughout the country during 2002 and the environmental influence on the host-pathogen interaction at Kaghan where the growing season is shorter (80­90 days) and cooler with a shorter daylength (Table 1). Six cultivars, FSD-85, Inqlab-91, Rohtas-90, MH-97, Uqab-2000, and Iqbal-2000, were resistant with < 5­30 % infection during both years at Bahawalpur. At Kaghan, these cultivars exhibited almost the same reaction but with less intensity during 2002. These cultivars have the Lr10 gene along with Lr27+Lr31 have been very effective in providing resistance to leaf rust. In field experiments conducted at Faisalabad in Pakistan, Khan et al. (1997) found Pavan, Faisalabad-85, and Inqlab-91 to be slow rusting. Chaudhry et al. (1996) evaluated 14 commercial wheat cultivars in the field and reported Inqlab-91, Parwaz-94, and Chakwal-86 resistant to leaf and yellow rust throughout Punjab and the North Western Frontier Province during 1994 and 1995. Kohinoor-83, Pasban-90, and Punjab-96 remained susceptible to leaf rust at both sites under induced and natural conditions, whereas Bahawalpur-97 maintained its MR-MS level during both the years.

The leaf rust observations at the different locations of new advanced lines during 2001 and 2002 are presented in Table 2. These observations indicate the number of test entries under different categories of rust-infection levels. During 2001, 95 of 293 entries were immune and 135 (46 % of the total) were trace to moderately resistant. Among 346 lines, 77 remained immune, 92 had trace infection, 103 were resistant, and 51 were moderately resistant during 2002. At Kaghan, the number of entries was less compared to Bahawalpur during both years, because they were selected on the basis of disease reactions (traces to resistant and moderately resistant) and yield traits. Generally, the entries that were moderately susceptible under induced conditions at Bahawalpur were mostly resistant to moderately resistant reactions at Kaghan during both years. The inheritance of leaf rust resistance was better in these lines. Rust inoculum is dynamic in nature and changes from year to year and place to place. Virulence in one environment may not necessarily appear in another (Khan et al. 2002). The virulence patterns observed at the two sites confirm this hypothesis.

The evolution of new rust races is a permanent feature of the rust pathogen. Whenever new cultivars are deployed in the field, new races of the pathogen develop after several years and the existing cultivars become susceptible. This phenomenon has been reported by number of workers (Ezzahiri 1989; Meshkova 1990; Meena-Kumari et al. 1992). At present, more than 80 % of the area under wheat cultivation is occupied by the single cultivar Inqlab-91, which is fraught with the danger. Under these circumstances, steps to avoid monoculture need to be taken. A number of advanced lines are available from the present studies that were resistant to prevailing rust races to provide sufficient material for developing new, resistant wheat cultivars.

References.

• Abdel Hak ATM, El-Sherif NA, Bassiourny AA, Shafik II, and El-Dauadi Y. 1980. Control of wheat leaf rust by systemic fungicides. In: Proc Fifth Eur Mediterranean Cereal Rust Conf, Bari, Itlay. Pp. 255-266.
• Chaudhary MH, Hussain M, and Shah JA. 1996. Wheat rust scenario, 1994-1995. Pak J Phytopathology 8(1):96-100.
• Ezzahiri B and Rolelf AP. 1989. Inheritance and expression of adult plant resistance of leaf rust in Era Wheat. Plant Dis 73:549-551.
• Hussain M, Hassan SF, and Kirmani MAS. 1980. Virulence in Puccinia recondita Rob.Ex. Desm. of sp. tritici in Pakistan during 1978 and 1979. In: Proc Fifth Eur Mediterranean Cereal Rust Conf, Bari, Itlay. Pp. 179-184.
• Khan MA and Hussain M. 2002. Wheat leaf rust (Puccinia recondita) occurrence and shift in its virulence in Punjab and NWFP. Pak J Phytopathology 14(1):1-6.
• Khan MF, Ilyas MB, and Hussain M. 1997. Impact of leaf rust infection on grain yield of various wheat cultivars. Pak J Phytopathology 9(1):64-66.
• McIntosh RA, Wellings CR and Park RF. 1997. Wheat rusts. An Atlas of resistance genes. CSIRO Publications, P.O. Box-89, 314 Albert Street, East Melbourn, Victoria 3002, Australia.
• Meena-Kumari KVS, Singh DV and Srivastava KD. 1992. Estimation of yield losses in wheat cultivars due to leaf rust at different growth stages under artificial inoculation. Ind Phytopathology 45(2):266-268.
• Meshkova LV. 1990. Source of resistance to wheat brown rust in Western Siberia. Nauch noissledovatel, Skii Institut Sels Kogo Khozyatstva 6:10-16 and USSR Rev Plant Path 1992, 71(2):802.
• Peterson RF, Campbell AB, and Hannah AE. 1948. A diagrammatic scale for estimating rust intensity on leaves and stems of cereals. Can J Res Sec C 26:496-500.

Performance of advanced wheat genotypes to Helicoverpa armigera Hubner. [p. 81-82]

Abdul Rashid, Habib Ahmad Saeed, Lal Hussain Akhtar, Altaf Hussain Tariq, and Sabir Zameer Siddiqi.

Background. Wheat is the staple diet of the people of Pakistan, contributing 12.1 % to value added in agriculture and 2.9 % to the GDP. Wheat was grown on an area of 6.30 x 10^6^ ha with a production of 15.42 x 10^6^ tons in 2000-01 in Punjab (Anonymous 2001). The by-products of wheat are used in bakery products and confectionery. For the last few years, Pakistan has become self sufficient in wheat production. Surplus wheat is exported to various countries such as Vietnam, United Arab Emirates, Somalia, Egypt, Ethiopia, Kenya, and Afghanistan. Various rust and smut diseases, aphids, Helicoverpa armigera, and termites attack this crop. Ann (2002) observed that aphids can be controlled easily with predators such as Coccinelid beetles and chrysopa and syrphis flies, whereas the reverse is true for H. armigera, which is a devastating pest of many crop plants world wide (Patankar et al. 2001). Saleem and Rashid (2000) reported a loss of 13.98 % in grain yield in wheat caused by a single caterpillar of H. armigera per tiller. Being the staple diet, the use of chemicals is not feasible for the control of this pest because of residual effects that may be hazardous to human health. The ultimate solution to the problem is the screening of genotypes with built-in resistance to H. armigera. Keeping in view the significance of the pest, we screened for genotypes of wheat resistant or tolerant to H. armigera.

Materials and methods. To asses wheat losses caused by H. armigera, 20 advance strains of wheat including two checks were evaluated for spike and grain damage during the Rabi season 1998-99 at the Regional Agricultural Research Institute, Bahawalpur. The experiment setup was a RCB design with three replications and plot size of 12 m^2^. Similar agronomic practices were applied to all genotypes throughout the growing season. Observations of spike damage were recorded at the harvest by counting the total number of spikes and the number of spikes damaged by the pest from three randomly selected spots of 1 ft^2^ from each plot. Grain-damage data were recorded by counting the total number of grains and number of grains damaged by the pest from five randomly selected spikes from each plot after harvest. Thus, the percentage of damaged spikes/grains was calculated as follows:

No. of damaged spikes / grains
Spike/grain damage (%) = x 100
No. of total spikes/grains

Data were subjected to statistical analysis using a computer package MSTATC. Correlations were computed using the Correlation subprogram of MSTATC. Means were compared by Duncan's New Multiple Range Test (Steel and Torrie 1980).

Results and discussion. Statistical analysis of the data revealed the highly significant differences among the mean values of spike and grain damage (P < 0.01) of all the genotypes (Table 3). Spike and grain damage ranged from 19.95 to 80.47 and 3.90 to 22.16 % in the check genotypes, respectively (Table 4). The most susceptible genotypes in terms of spike damagewere D-94654 (80.47 %), PR-68 (76.00 %), WS-94194 (59.53 %), and V-94091 (58.28 %). The genotype 92T001 was found to be the most tolerant with the least spike damage (19.95 %). For grain damage, SD-4 had the maximum damage (22.16 %) and V-8120 had the least (3.89 %), a vast range of damage differences. The present results support the data of Saleem and Rashid (2000) who found that a single caterpillar of H. armigera per tiller caused 13.98 % loss in grain yield of wheat. Such information will encourage the wheat breeders to incorporate this character in their breeding program. Efforts are being made to develop the wheat genotypes tolerant to H. armigera at our institute.

References.

• Anonymous. 2001. Agriculture. Economic Bulletin, Economic & Business Research Wing, National Bank of Pakistan. 28(8):19-20.
• Anonymous. 2002. Agriculture. Economic Bulletin, Economic & Business Research Wing, National Bank of Pakistan. 29(7-8):19-20.
• Patankar AG, Giri AP, Harsulkar AM, Sainari MN, Deshpade VV, Ranjekar PK, and Gupta VS. 2001. Complexity in specificities and expression of Helicoverpa armigera gut proteinases explains polyphagous nature of insect pest. Insect Biochem Mol Biol 31:453-464.
• Saleem M and Rashid A. 2000. Helicoverpa armigera infestation on various wheat varieties. Ann Wheat Newslet 46:101-102.
• Steel RGD and Torrie JH. 1980. Principles and Procedures of Statistics. McGraw Hill Book Company, New York, NY. Pp. 187-188.

Manthar - a high-yielding cultivar of wheat released for general cultivation in southern Punjab. [p. 82-85]

Sabir Zameer Siddiqi, Mushtaq Ahmad, Manzoor Hussain, Lal Hussain Akhtar, Abdul Rashid, Ghulam Hussain, Muhammad Aslam, Muhammad Safdar, Muhammad Masood Akhtar, Muhammad Rafiq, and Muhammad Arshad.

Background. Wheat is the main staple food of the people of Pakistan and is grown on the largest area covering more than 15 x 10^6^ acres in the Punjab. Although Pakistan is a wheat exporter, this situation has been changing for the last 2 years. New steps now are needed to be adopted to progress forward. Agronomic advancement is the utmost need, including the development of genotypes possessing high-yield potential. Wheat breeders are trying to improve the potential at their research stations, resulting in wheat cultivars with acceptable and improved characteristics.

Manthar is selection from CIMMYT material and has been tested at Regional Agricultural Research Institute, Bahawalpur and outstations for 7 years. This strain has the famous CIMMYT line Kauz in its pedigree, which is a more adapted and a high yielder. Genetically, this strain differs from existing commercial cultivars of Punjab. Manthar rated a position among the top five strains in National Uniform Wheat Yield Trial the first year and the first position in late planting and second in 23 sites in Pakistan in its second year. Manthar has improved yield potential and better adaptability. Dry and unfavorable conditions in 2001­02 produced a successful wheat crop during a continuous drought. This genotype rated the second position in Pakistan based on drought and heat tolerance. The cultivar is resistant to leaf rust and yellow rust at CDRI, Islamabad. We hope that Manthar will help boost the average wheat yield because of its better economic characteristics while being a general-purpose cultivar.

Materials and methods. Manthar, selected from CIMMYT (Mexico) material, was tested at Regional Agricultural Research Institute, Bahawalpur, and outstations for 7 years (1996-2002) and given the number 97B2210. This line was evaluated for its yield potential in 81 trials at various locations Preliminary Yield and Advanced Yield Trials, the Micro Wheat Yield Trials (2000-01), and the National Uniform Wheat Yield Trial (2000-01). Sowing date and fertilizer trials also were conducted to evaluate its production technology during 2000-01 to 2001-02. The line 97B2210 also was tested for resistance to rusts, loose smut, and Karnal bunt at the Regional Agricultural Research Institute, Bahawalpur; the Wheat Research Institute, Faisalabad, and the Crop Disease Research Institute, NARC, Islamabad during 2000-02 and compared with standard cultivars. The Coordinator Wheat, NARC, Islamabad, also studied the quality characteristics of the line in 2000-01. The Federal Seed Certification and Registration Department, Islamabad, evaluated plant characteristics. The yield data were subjected to ANOVA using the MSTAT statistical program and means were compared using Duncan's Multiple Range Test (Steel and Torrie 1980).

Results and discussion.
Yield performance. Station Yield Trials. Manthar was tested in preliminary and advance yield trials at the Regional Agricultural Research Institute, Bahawalpur, between 1996-97 and 2001-02 in late planting and compared with the national checks, Uqab-2000 and Inqlab-91. The performance of Manthar is given in Table 5. Over a 3-year average, the cultivar had a 7.1 % higher yield than Inqlab-91 (Table 5) and also outyielded the check by a margin of 3.7 % in zonal trials conducted at three locations in 1999-2000 (Table 6).

Micro Wheat Yield Trial. The Director, Wheat Research Institute, Faisalabad, also evaluated the performance of Manthar under a coded number during 2000-01 at various locations in Punjab in replicated yield trials. The results show yields 2.0, 13, and 11 % higher for Manthar when compared to Inqlab-91, Uqab-2000, and Iqbal-2000, respectively, an average of 10 locations (Table 7).

National Uniform Wheat Yield Trial. The Coordinator Wheat, Islamabad, also evaluated Manthar in a replicated trial called the National Uniform Yield Trial under normal and short conditions throughout Pakistan during 2001-02. The performance of Manthar in this trial is given is Table 8. Manthar had a 7.1 % higher yield than the local check at the National level on the basis of 12 locations in 24 trials.

Varietal characteristics. Various varietal characteristics recorded by the Federal Seed Certification and Registration Department, Islamabad, in comparison with Inq-91 are given in Table 9.

Agronomic studies. Six trials were conducted at Regional Agricultural Research Institute, Bahawalpur, during 2000-02 to ascertain production technology. Sowing time is 10 November to 10 December at a seeding rate of 125 kg/ha. Fertilizer requirements include 125­100­50 NPK with 4-5 irrigations.

Pathology studies. The response of Manthar to various foliar diseases was studied at Crop Diseases Research Institute, NARC, Islamabad; the Wheat Research Institute, Faisalabad; and the Regional Agricultural Research Institute, Bahawalpur. The data are given in Table 10-11. The data indicates that Manthar is resistant/tolerant to the yellow rust, leaf rust, loose smut, Fusarium, and Karnal bunt pathogens.

Entomology studies. The response of Manthar to aphid and Helicoverpa armigera also was studied at Regional Agricultural Research Institute, Bahawalpur, in 2000-02. Data are given in Table 12 shows the performance of Manthar as compared to commercial checks.

Quality studies. The quality characters were recorded by the National Agricultural Research Centre, Islamabad, and are given in Table 13-14. The new cultivar is better than the existing checks.

Conclusion. The cultivar Manthar (97B2210) not only is a high-yielder and tolerant/resistant to all diseases but also best suited to a wheat-cotton-wheat rotation. Because of better adaptability, Manthar has the potential of replacing previously approved wheat cultivars, especially in the southern Punjab. This cultivar was approved and released by Variety Evaluation Committee, Islamabad, for general cultivation during 2002.

References.

• Anonymous. 2002. National Uniform Wheat Yield Trials Summary Results 2001-2002. National Agricultural Research Centre, Islamabad.
• Mustafa SZ, Yasmin S, and Kisana NS. 2001. Results of the National Uniform Wheat Yield Trials, 2000-2001. Coordinated Wheat-Barley and Triticale Programme, Pakistan Agricultural Research Council, P.O. Box 1031, Islamabad. P. 25.
• Steel RGD and Torrie JH. 1980. Principles and Procedures of Statistics. McGraw Hill Book Company, New York. Pp. 187-188.

Development of 012679, a new wheat strain with special characteristics. [p. 85-86]

Mushtaq Ahmad, Ghulam Hussain, Muhammad Rafiq, Manzoor Hussain, Lal Hussain Akhtar, and Sabir Zameer Siddiqi.

Wheat not only is the main staple food of Pakistan, but more than 33 % population of world also depend upon it for nourishment. Hybridization efforts are not bearing significant yield improvements. Improvement in grain yield is the ultimate objective of all agronomic and breeding investigations. Genetic yield potential can be improved by increasing the number of grains/unit area and grain weight. Efforts at the Regional Agricultural Research Institute, Bahawalpur, seek to improve grain weight and grain number/unit area and combine them in the same plant with required protein and gluten levels. A new wheat strain was bulked during 2000-01 with number 012679. Strain 012679 is a local cross (Debaria/WL-711) attempted during 1994-95. The F1 to F6 were grown from 1995-96 to 2000-01 at RAI, Bahawalpur. The cultivar was evaluated for yield in yield trials during 2001-02 with under the number 012679.

Strain 012679 produced 41.12 % and 61 % more yield than the commercial checks Inqbal-91 and PND-I, respectively (Tables 15 and 16). Further studies are in progress in yield trials during 2002-03 to confirm these results. Strain 012679 differs from the existing cultivars in following characteristics: a thick stem is resistant to lodging; increasing the seeding rate compensates for a lower number of tillers/seed; early maturity fits in a wheat-based cropping pattern; a thick, dense head with 100 % maturity gives more grains/spike; and more grains than commercial standards results in a higher grain yield.

Effect of irrigation and various nitrogen and phosphorus levels on wheat yield. [p. 86-87]

Muhammad Aslam, Manzoor Hussain, Lal Hussain Akhtar, Mushtaq Ahmad, Ghulam Hussain, Abdul Rashid, Muhammad Safdar, Muhammad Masood Akhtar, Muhammad Arshad, and Sabir Zameer Siddiqi.

Background. Wheat, a major food grain of Pakistan, is being adversely affected by shortage of water. During 2001-02, a decline of 2.4 % in cultivated area and yield was found due mainly to dry weather, a shortage of irrigation water, low application of NP fertilizer, and a delayed sowing of the 2001-02 season crop (Sabir et al. 2000; Anonymous 2002). Under these circumstances, the positive role of irrigation and NP levels need to be demonstrated. Similarly, the high use of irrigation water also is being restricted due to shortage of canal water and high prices of subsoil water. The NP fertilizer and irrigation factors play an important role in getting the highest grain yield from the wheat crop. Ibrahim (1999) obtained a high grain yield of 4.6 and 4.8 t/ha using three and four irrigations. Kalita et al. (2000) achieved a high grain yield from three irrigations. Laxminarayana and Thakur (1999) found that grain yield increased with an increase in applied phosphorus up to 90 kg/ha. Sabir et al. (2000) obtained their highest yields with the application of 150:100 kg/ha N:P. Pandey et al. (1999) reported that grain yield increased up to 150:75 N:P levels. Naser et al. (1999) and Maliwal et al. (2000) found that irrigation treatments increase the yield. Therefore, this project was to determine the best NP level with three and five irrigations for obtaining best wheat yield.

Materials and methods. The study was conducted at Regional Agricultural Research Institute, Bahawalpur, during the years, 2000-02. The wheat cultivar Punjnad-1 was sown during both the years on well prepared seed bed with a single-row drill in rows 30 cm apart. Ten treatments involving two irrigation levels (three (at crown root, boot, and milk stages) and five (at crown root, tillering, boot, milk, and grain-formation stages)) with five levels of NP 0-0, 50-50, 100-75, 150-100, and 200-125 kg/ha, were studied. K was kept constant (60 kg/ha) in all treatments. A split-plot design with four replications was used with net plot size of '6 m x 1.8 m'. All phosphorus and potassium was applied as a basal dose at sowing. All nitrogen fertilizer was applied with the first irrigation. Other agronomic practices were kept uniform for all the treatments. Grain yield (kg/ha) was recorded at harvest. The data were analyzed statistically by using Fisher's analysis of variance and differences among the treatments means were compared by Duncan's Multiple Range Test (Steel and Torrie 1980). Table 17 lists the treatments given.

Results and discussion. Grain yield significantly increases with interactive effects of irrigation and NP (Table 18). T4 gave the highest grain yield of 3,678 kg/ha, which was more economical than T5 because addition of 50-25 kg/ha more NP in T5 compared to T4 resulted in only 144 kg/ha additional yield which is uneconomical. T7 gave four times more yield (2,360 kg/ha) than T6 (558 kg/ha). Similarly T8 and T9 gave maximum yield of 3,983 and 4,178 kg/ha, respectively. T10 was at par with T9. The present results support the findings of E1-Far and Teama (1999) who reported that grain yield was the highest when crop was irrigated after every 31 days and lowest when irrigation was applied after every 60 days. Ibrahim (1999) obtained grain yield of 4.6 t/ha and 4.8 t/ha using three and four irrigations, respectively. Kalita et al. (1999) obtained the highest grain yield from three irrigations. Pandey et al. (1999) reported that grain yield increased up to 150:75 kg/ha NP. Sabir et al. (2000) obtained the highest yield with the application of 150-100 NP. Laxminarayana and Thakur (1999) reported that grain yield increased with increase of phosphorus upto 90 kg/ha. Five irrigations were applied at crown root, tillering, boot, milk, and grain-formation stages.

Table 18. Grain yield in Punjand-1 wheat under various treatment regimes varying in level of nitrogen and phosphorus fertilizer and number of irrigations.

References.

• Anonymous. 2002. Agriculture: wheat production below target. Economic Bulletin, National Bank of Pakistan. 29(11-12):16.
• Ibrahim SM. 1999. Wheat cultivation under limited irrigation and high water table conditions. Egypt J Soil Sci 39(3):361-372.
• Kalita MC, Sarmah NN, and Barkakoty PK. 1999. Irrigation regimes on growth and yield of wheat under different land situations. J Agric Sci Soc North East India. 12(1):18-23.
• Laxminarayana KI and Thakur NSA. 1999. Effect of phosphorus on yield performance of wheat in acidic soils of Mizoram. J Hill Res 12(2):138-140.
• Maliwal GL, Patel JK, Kaswala RR, Patel ML, Bhatnagar R, and Patel JC. 2000. Scheduling of irrigation for wheat (Triticum aestivum) under restricted water supply in Normada region. Ind J Agric Sci 70(2):90-92.
• Naser HM, Islam MT, Begum HH, and Idris M. 1999. Effects of time and frequency of irrigation on yield of wheat. Thai J Agric Sci 32(2):205-209.
• Pandey AK, Chauhan VS, Prakash V, and Singh RD. 1999. Seed and fertilizer management under non-availability of irrigation at crown root initiation stage in wheat. Crop Res (Hisar) 17(3):286-291.
• Sabir MI, Ahmad I, Shah SAH, and Shahzad MA. 2000. Effect of different rates and NP levels on growth and yield of wheat (Triticum aestivum). J Agric Res 38(4):311-317.
• Steel RGD and Torrie JH. 1980. Principles and Procedures of Statistics. 2nd Ed. McGraw Hill Book Co. Inc. Singapore. Pp. 172-177.

Effect of irrigation at different growth stages on the grain yield of wheat. [p. 87-89]

Muhammad Aslam, Manzoor Hussain, Lal Hussain Akhtar, Abdul Rashid, Ghulam Hussain, Muhammad Safdar, Muhammad Arshad, and Sabir Zameer Siddiqi.

Background. Wheat is the most important Rabi cereal crop of Pakistan. Because of deficits in irrigation water in the rivers, the country is facing long-lasting moisture stress. A plan that utilizes our limited sources of irrigation water in such a way that country does not suffer food shortage is needed. Ibrahim (1999) obtained grain yields of 4.3, 4.6, and 4.8 t/ha by applying 2, 3, and 4 irrigations, respectively. Naser et al. (1999) obtained the highest yield with two irrigations applied 30 and 50 days after sowing. Kalita et al. (1999) obtained high grain yields from three irrigations. Similar results have been reported by Lidder et al. (1999), Tripathi et al. (2000), and El-far and Teama (1999). The present study was planned to define the critical stages of the wheat crop using limited number of irrigation water to obtain an optimum yield.

Materials and methods. The study involved 15 treatments laid out in a RCBD with three replications (Table 19). Net plot size was '6 m x 1.8 m'. The wheat cultivar Punjnad-I was sown during the first week of December 2000-02.

The recommended fertilizer dose was applied to all the treatments. Punjnad-I was sown during both years on a well-prepared seed bed with a single-row hand drill in rows 30 cm apart. All other agronomic practices were kept uniform for all treatments. Grain yield/ha was recorded at harvest. The data were analyzed statistically using Fisher's ANOVA and differences among the treatment means were compared by LSD (Steel and Torrie 1980).

Results and discussion. One irrigation. One irrigation was applied at different four growth stages of wheat crop. Irrigation applied at boot stage gave the maximum yield compared to other stages (Table 20). Similar results were reported by Ibrahim (1999).

Two irrigations. Two irrigations were applied in six of the combinations. Treatment T10 (boot + milk; 2,676 kg/ha) gave the highest yield of these treatments. Ibrahim (1999), Naser et al. (1999), and Lidder et al. (1999) also achieved best results when irrigation was applied at similar stages.

Three irrigations. Three irrigations were applied in three combinations. Irrigations applied at crown root + boot + milk stages (T12) gave a maximum yield of 3,200 kg/ha. These results are in line with those of Ibrahim (1999), Maliwal et al. (2000), Naser et al. (1999), and Lidder et al. (1999) who studied similar growth stages for irrigation and found that three irrigation applied at above-mentioned stages gave the best yield.

Four and five irrigations. Four and five irrigations were applied according to the tradition in the southern Punjab. Yields of 3,987 and 4,139 kg/ha were recorded for four and five irrigations, respectively. Grain yield declines of 55.6­69.6, 35.4­51.2, 22.7­33.0, and 3.7 % were observed using 1, 2, 3, or 4 irrigations, respectively, compared to five irrigations. The results are supported by the findings of Naser et al. (1999) and Lidder et al. (1999) who studied various numbers of irrigations at various growth stages and found that all irrigation treatments increased yield.

Conclusion. Depending on the amount of irrigation water available, the best growth stage for application of available irrigation water include:

1 irrigation Boot
2 irrigations Boot + milk
3 irrigations Crown root + boot + milk
4 irrigations Crown root + tillering + boot + milk
5 irrigations Crown root + tillering + boot + milk + grain formation

References.

• El-Far IA and Teama EA. 1999. Effect of irrigation intervals on productivity and quality of some bread and durum wheat. Assiut J Agric Sci 30(2):27-41.
• Ibrahim SM. 1999. Wheat cultivation under limited irrigation and high water table conditions. Egypt J Soil Sci 39(3):361-372.
• Kalita MC, Sarmah NN, and Barkakoty PK. 1999. Irrigation regimes on growth and yield of wheat under different land situations. J Agric Sci Soc North East India 12(1):18-23.
• Lidder RS, Jain MP, and Khan RA. 1999. Effect of irrigation and fertility levels on wheat (Triticum aestivum) cultivars in deep vertisol. Internat J Trop Agric 17(1/4):131-134.
• Maliwal GL, Patel JK, Kaswala RR, Patel ML, Bhatnagar R, and Patel JC. 2000. Scheduling of irrigation for wheat (Triticum aestivum) under restricted water supply in Normada region. Ind J Agric Sci 70(2):90-92.
• Naser HM, Islam MT, Begum HH, and Idris M. 1999. Effects of time and frequency of irrigation on yield of wheat. Thai J Agric Sci 32(2):205-209.
• Steel RGD and Torrie JH. 1980. Principles and Procedures of Statistics. 2nd Ed. McGraw Hill Book Co. Inc. Singapore. Pp. 172-177.
• Tripathi P, Tomar SK, and Adhar S. 2000. Effect of moisture regimes and genotypes on biomass accumulation, radiation interception and its use in wheat (Triticum aestivum). Ind J Agric Sci 70(2):97-101.

Wheat yield potential-current status and future research strategies in Pakistan. [p. 89-91]

Muhammad Sarwar Cheema, Muhammad Akhtar, and Liaquat Ali.

Wheat is the staple food for most of the people of Pakistan, and wheat straw is an integral part of the daily rations for livestock. The cultivation of wheat has spread throughout the four provinces of Pakistan. The wheat-growing area and production for the year 1999-2000 were 73 % and 78 %, respectively for the province of Punjab, with smaller amounts in the Sindh (13.5 % and 14.5 %), Northwest Frontier (9.5 % and 5 %), and Baluchistan (4 % and 2.5 %) provinces.

Yield potential. A substantial yield gap has been observed at the experimental stations, progressive growers, and on farmer's fields in each province. Six, high-yielding wheat cultivars were sown at three different locations in D.I. Khan, (Northwest Frontier Province), Pakistan, to explore their yield potential under prevailing climatic conditions. Daman 98 ranked first among all the tested cultivars by producing a grain yield of 12.5 t/ha (Khan et al. 2000). Choudhary and Mehmood (1998) obtained a maximum grain yield of 7 t/ha with Inqlab-91. Sadiq and Khan (1994) also reported 7 t/ha yield from Pak 81 in a study on the effects of intercropping and planting pattern on yield and yield components of wheat. Bajwa et al. (1993) reported the influence of different irrigation regimes on the yield and yield components of the wheat Pak 81, obtained maximum yield of 6.5 t/ha after the application of four irrigations.

Current status. Pakistan's average grain yield ranged between 2,053 to 2,490 kg/ha over the last 5 years, 1996-97 to 2000-01 (Table 21). A huge yield gap lies between the experimental yield and the average yield of the country, so there is great hope for double and even triple the wheat grain yield.

Population and wheat requirements. For 2001, the projected population for Pakistan is estimated to be 140.47 x 106 and wheat production is 19.02 x 106 tons. Domestic consumption requirements have been estimated at 20 x 106 tons. Pakistan became self-sufficient in wheat by producing 21.08 x 106 tons during the year 1999­2000, which was primarily due to 25 % increase in support price of wheat. Wheat growers produced about one million tons of surplus wheat grain, a marginal self sufficiency that can be changed at any time by natural hazards. Therefore, concerted efforts are needed to maintain increased production that meets future requirements.

Yield gap. A substantial yield gap has been observed between yield at the experimental stations and in farmers' fields in each province. This gap is primarily because of the lack of finances on the part of the majority of farmers for implementing modern technology for wheat production. Thus, we hope for improving wheat production and yield in the country.

Constraints to production. Like many developing countries, wheat production is confronted with both biophysical constraints (disease, fertilizer, water, seed, cultivars, cultural practices, and salinity/sodicity) and socioeconomic constraints (credit, knowledge, experience, tradition, and institutions.).

Disease. Although several diseases attack wheat, stripe and leaf rusts, loose and flag smuts, Karnal bunt, powdery mildew, Helminthosporium leaf spots, and foot and root rots are the most important in Pakistan. Other diseases, such as those caused by Septoria spp., downy mildew, black point, and black chaff, are of minor importance. Breeding programs try to develop wheat cultivars that are resistant or tolerant to these principal diseases. Measures to minimize their adverse effects on production also are being investigated.

Insect pests. Fortunately, wheat in not attacked by any serious pests, however, infestations of army worm, Hilothus, and green aphids have occurred in localized areas.

Drought. About 21 % of total wheat area in Pakistan is rainfed. The screening of plant material and the testing of new cultivars for drought tolerance are made in rainfed areas or under simulated moisture stress. Some cultivars (Inqlab 91, Punjnad1, and Iqbal 2000) that were developed for irrigated areas also have proven to be very successful under rainfed conditions. The testing of new cultivars under both irrigated and rainfed conditions is encouraged.

Salinity/sodicity. At present, 2.4 x 10^6^ ha of land in Pakistan have been rendered saline-sodic. With the continuous use of low-quality water, this menace increases every year. Wheat yield was found to be reduced by 19 % under moderately saline-sodic soils.

Lack of nutrients. Experiments on yield constraints in irrigated and rainfed areas indicate that the proper application of fertilizer is of utmost importance. Yield reductions ranging from 50 to 75 % have been observed without proper fertilizer use and clearly demonstrate that wheat yields can be substantially increased if fertilizer use is properly regulated in the country.

Planting date. More than 50 % of the wheat in Pakistan is planted late, i.e., during the month of December. Planting date experiments have shown that yield is progressively reduced with delayed planting. Yield was found to be reduced by 28.8 and 75.8 % when sowing was delayed from November to December and from November to January, respectively,

Weeds. With the introduction of high-yielding and fertilizer-responsive Mexican wheat cultivars during mid 1960s, weed populations have increased tremendously causing considerable losses in crop yield. No data regarding yield losses due to weeds is available, however, depending upon the degree of infestation, losses yield are estimated to be between 13-42 %. A number of weed species infest the wheat fields; both grasses and broadleaf weeds. Wild oat (Avena fatua), canary grass (Phalaris minor), Chenopodium spp., and Convolvulis arvensis has been found to be the major weeds. When weeds were controlled by the herbicides Dicuran M.A., Tribunil, Graminon, and Arelon, yield increases of 41, 22, 22, and 25 %, respectively, over the weedy controls were found (Ahmed et al. 1987).

Future research strategies. Future strategies for the improvement of wheat will involve more emphasis on breeding cultivars that possess wider adaptation and can withstand various types of stress (disease, high temperature, cold and frost, drought, salinity/sodicity, and water logging). Efforts also will be made to develop wheat cultivars with low input requirements. Improving grain characteristics and milling and baking quality of wheat also will receive greater attention.

References.

• Ahmad S, Cheema ZA, Bashir S, and Iqbal M. 1987. Weed management in wheat. Progressive Farming 7(1):33-36.
• Anonymous. 2002. Pakistan Statistical Year Book. Agricultural Statistics of Pakistan, Government of Pakistan, Islamabad. Pp. 114.
• Bajwa MA, Chaudhary MH, and Sattar A. 1993. Influence of different irrigation regimes on yield and yield components of wheat. Pak J Agric Res 14:360-365.
• Chaudhary AU and Mehmood R. 1998. Determination of optimum level of fertilizer nitrogen for varieties of wheat. Pak J Biol Sci 4:351-353.
• Khan MA, Hussain I, and Baloch MS. 2000. Wheat yield potential - current status and future strategies. Pak J Biol Sci 3(1):82-86.
• Sadiq M and Khan HKA. 1994. Effect of intercropping and planting patterns on yield and yield components of wheat. Sarhad J Agric 10:351-354.