ITEMS FROM PAKISTAN

AGRONOMIC RESEARCH STATION

Bahawalpur, Pakistan.

Prospects for resistance to loose smut of wheat in southern Punjab. [p. 89-92]

Hafiz Muhammad Ziaullah, Altaf Hussain Tariq, Saeed Ahmad, Muhammad Arshad Hussain, and Lal Hussain Akhtar.

Summary. One hundred forty-four advance strains and 18 commercial cultivarss of wheat were screened for resistance to loose smut of wheat by artificial inoculation in southern Punjab during three consecutive years (2001-03). Of the 144 advanced wheat genotypes, 55 were highly resistant, 56 resistant, 11 moderately resistant, 9 moderately susceptible, 19 susceptible, and 12 highly susceptible. The commercial cultivars Inqlab-91, CRS-1, Punjab-96, Faisal-85, Bwp-95, Derawar-97, and MH-97 had a susceptible reaction, whereas Iqbal-2000, Uqab-2000, and Bwp-2000 were resistant. The resistant genotypes could be used in future breeding programs for the development of disease-resistant cultivars.

Introduction. Wheat is attacked by large number of pathogens and pests. However, rusts and smut fungi are highly destructive and cause enormous damage. Looking at the long list of diseases and pests (Bajaj and Gosal 1986) to which wheat is prone, the tremendous job of breeding for disease resistnce is of high priority to escape crop losses. Loose smut of wheat occurs commonly throughout the country and is characterized by the appearance of black, sooty ears containing fungal spores in place of normal grain. On average, loose smut causes 1 % damage, but in humid parts of the country and the foot-hill districts, damage can be as high as 10-20 % depending upon the wheat cultivar under cultivation. Epidemiological studies have indicated that if loose smut is not controlled, the disease will increase every year in some localities but remain constant in others (Hafiz 1986). The peculiar behavior of these fluctuations is becuse of the variation in humidity at the time of flowering in various localities. Based on surveys conducted in northwestern India, a 2-4 % yield reduction of wheat from loose smut is estimated every year (Joshi et al. 1985; Srivastava et al. 1992).

Artificial inoculation of anthers to test genotypes with U. segetum causes a wide range of embryonic infection (up to 84 %) in seed, depending upon the resistance against the disease. When these test seeds are sown, a direct correlation is observed between the level of embryo infection and the field expression of the pathogen. Evaluating germ plasm for resistance to loose smut of wheat through a screening process is the best and effective control measure. The present studies were conducted under stress conditions to identify the sources of resistance among different wheat cultivars and advanced lines by artificial inoculation.

Material and Methods. Studies were conducted at Regional Agricultural Research Institute, Bahawalpur, for 3 years (2001-03). One hundred forty-four advanced wheat strains and 18 commercial cultivars were screened for resistance to loose smut. Two lines of each entry were sown in 2-m rows with a 4-cm plant-to-plant distance in the field on 20 November of each year. Entries were inoculated with the fresh inoculum collected from the naturally occurring loose smut affected heads in the field (Mishra et al. 1990) by preparing a spore suspension. Undehisced anthers were selected for artificial inoculation of loose smut. The experiment was repeated for 2 years to test the stable response of the strains or cultivars. Observations were recorded on the following scale:

Grade	Disease intensity	Reaction
1	No dymptoms on any plant or < 1 % infection	Highly resistant (HR)
2	1-5 % of the plants with smutted heads	Resistant ( R)
3	6-10 % of the plants with smutted heads	Moderately resistant (MR)
4	11-20 % of the plants with smutted heads	Moderately susceptible (MS)
	21-50 % of the plants with smutted heads	Susceptible (S)
	> 51 % of the plants with smutted heads	Highly susceptible (HS)

Data recording and observations on infection percent began in 2001 at the appearance of black sooty ears containing spores of the fungus instead of normal grains.

Results and Discussion. Out of 144 advanced wheat cultivars and 18 commercial cultivars tested for resistance to loose smut, 55 were immune or had less than 1 % infection, an HR reaction, 56 were R , 11 MR, 9 MS, 19 S, and 12 HS (Table 1). These results show that the resistance in the 144 advanced wheat lines are indicative of the entire 3-year consecutive study could be compared with the yearly resistance response (Table 3). The comparative data reflects the gradual trend towards a stable resistance pattern with a distinctive increase in response between the first and second years for preinoculated advanced wheat cultivars, followed by the minor edges during third year due to maintenance of resistance. Beniwal et al. (1998) reported similar findings regarding stable source of resistance during evaluation of some 2,190 wheat cultivars in India from 1981-82 to 1996-97. The results obtained in the third year (Table 3) showed a gradual increase in reaction (resistant to susceptible) that remained consistently higher than that of the preceding years, which represents the potential of the test cultivars.

Our experiment also tested 18 commercial cultivars that have been sown in the Bahawalpur region for many years (Table 2). The data showed that two cultivars, Bwp-97 and Iqbal-2000, were free of infection in 2001 and over the next 2 years exhibited responses ranging from HR to R. Two other cultivars, Uqab-2000 and Bwp-2000, also maintained their resistance to loose smut during the 3 years (Table 3).

Nine cultivars, Blue Silver, Pak-81, Faisal-85, Faisal-83, Derawar-97, Bwp-97, Pasban-90, Rohtas, and Kohinoor-83, did not resist the inoculum pressure and were susceptible to loose smut of wheat with 11-20 % infection. Sutluj-86 had the highest susceptibility (76.32 %). This cultivar, however, could be used in further screening investigation as a source of inoculum. Inqlab-91, the most popular cultivar of the Punjab province, was rated R, MR, and MS in the years 2001, 2002, and 2003, respectively, which reflects its meagre potential against the disease. Due to susceptibility of this cultivar, smutted heads from Inqlab-91 were easily available for preparation of inoculum suspensions.

Beniwal et al. (1999) evaluated resistance in 19 wheat cultivars commercially grown in the North-Western Plain zone of India during the 1995-96 and 1996-97 crop seasons. Popular cultivars such as WH-147 and HD-2329 were highly susceptible to loose smut of wheat. Sharma et al. (1998) screened 17 bread wheat and three durum wheat genotypes plus 19 Canadian loose smut differential lines for resistance to U. segetum in 1994-95. Few genotypes were resistant to disease.

Different methods af artificial inoculation were used for studying the degree of resistance in the test cultivars. Mishra et al. (1990) screened 92 cultivars against U. segetum by needle inoculation in 1980-82. Fifteen lines were R and three were rated MR. Sherif et al. (1991) graded Giza 155, Giza 160, and Giza 162 as R, Sakha 61 and Sakha 92 as S out of 10 Egyptian cultivars. The resistant source found during these studies will be the best for future breeding programs wanting to minimize the effect of loose smut in the new wheat cultivars.

References.

• Bajaj YPS and Gosal SS. 1986. Biotechnology of wheat improvement. In: Biotechnology in agriculture and forestry, Vol 2 (Bajaj YPS ed). Springer-Verlag, Berlin. Pp. 3-38.
• Beniwal MS, Karwasra SS, Anil-Gupta, Chhabra ML, Singh R, Gupta A, and Singh R. 1998. Stable source of resistance to loose smut of wheat. Ann Biol, Ludhiana 14(2):231-232.
• Beniwal MS, Virk KS, Singh R, and Singh R. 1999. Relative resistance of commercially grown wheat varieties of North-Western plain zone of India against important diseases. Crop Res Hisar 18(2):296-298.
• Hafiz H. 1986. Wheat and barley. In: Plant Diseases (Hafiz A ed.). Pak Agric Res Coun, Islamabad. Pp. 20-66.
• Joshi LM, Singh DV, and Srivastava KD. 1985. Monitoring of wheat disease during 1984-1985. In: Proc 24th All India Wheat Res Workers' Workshop, GBPUAT, Puntnagar.
• Mishra RP, Tiwari SP, and Khare MN. 1990. Studies on loose smut of wheat. X. Testing of resistance and susceptibility for wheat varieties to Ustilago tritici (pers) Rostr under artificial inoculation. Ind J Mycol Plant Path 20(2):171.
• Sharma DL, Basandrai AK, Guleria SK, and Pandey DP. 1998. Genetic diversity for loose smut resistance in wheat (Triticum aestivum). Ind J Agric Sci 68(12):796-797.
• Sherif S, Ghanem EH, Shafik I, Mustafa EE, and Abdel-Aleem MM. 1991. Integrated control of wheat loose smut in Egypt. Assiut J Agric Sci 22(1):153-163.
• Srivastava KD, Singh DV, Aggarwall R, Bahadar P, and Nagarajan S. 1992. Occurrence of loose smut and its sources of resistance in wheat. Ind Phytopath 45:111-112.

Effect of high moisture stress on wheat genotypes under late-sowing conditions. [p. 92-94]

Manzoor Hussain, Altaf Hussain Tariq, Ghulam Hussain, Lal Hussain Akhtar, Muhammad Zubair Khan, and Abdul Majeed Iqbal.

Abstract. Four approved wheat cultivars and six newly developed wheat strains were compared for yield and yield components under acute drought conditions during 1999-2000 and 2000-01 at the Regional Agricultural Research Institute, Bahawalpur. Significant differences were observed in grain yield, plant height, number of kernels/spike, and 1,000-kernel weight. The maximum grain yield was produced by 962098; the minimum by 972317. Maximum plant height was in Bahawalpur 2000 and the minimum in 972317. Higher kernel numbers were in Inqlab-91 and 962098 and the minimum in 972317. Bahawalpur-2000 and 962098 produced the maximum 1,000-kernel weight, whereas 972317 and 962552 were very low.

Introduction. Wheat is often sown in month of December in the cotton-growing districts of Pakistan. The wheat crop faces moisture stress due to shortage of water in rivers and the cleaning of canals. Millions of acres of wheat in southern Punjab produce low grain yields because of moisture stress resulting in a loss of billions of rupees. The Bahawalpur Region is hot and dry. During 1999, the lowest rainfall (155 mm) in Punjab was received in Bahawalpur (Agriculture Statistics of Pakistan 2000). The crop season often passes with very low rainfall. Drought is a problem in only Pakistan but is worldwide, which is why many countries are breeding for drought tolerance in wheat. ICARDA (Syria) is one very important institute in world that is working on drought tolerance. The wheat Cham 6 was released by ICARDA in 1991 as commercial cultivar for areas of Syria with less than 350 mm rainfall (Anonymous 1992). Low rainfall areas are those that receive an annual rainfall of 250-350 mm; moderate rainfall areas have 350-600 mm annually (Anonymous 1999). Siakia et al. (1999) studied the different responses of wheat cultivars related to yield under rainfed conditions. Singh and Uttam (1995) observed a considerable effect of rainfed conditions on grain yield, straw yield, number of spikes/m2, number of seeds/spike, water use efficiency, and maximum root development when they were studying the behavior of wheat cultivars under rainfed conditions. Tanveer et al. (2002) observed significant differences among wheat cultivars in plant height, spike length, and harvest index. The objective of our study was to compare wheat genotypes for yield and yield components under acute drought conditions following late planting.

Materials and Methods. The experiment was conducted at Regional Agricultural Research Institute, Bahawalpur, during 1999-2000 and 2000-01. Ten wheat cultivars and lines, 962098, 972236, Bahawalpur-2000, 962552, Chakwal-86, 972563, 972561, Kohistan-97, Inqlab-91, and 972517, were planted in a randomized complete block design with three replications. Plot size was 5 x 1.8 m^2^. The experiment was late sown, i.e., sowing was on 10 December after harvest of a cotton crop. N and P2O5 fertilizers were applied at 90 and 60 kg/ha, respectively, at the time of soil preparation. For germination, a soaking dose (Rowni) was applied. No supplemental irrigation was applied. The size of the harvested plot size was 5 x 1.2 m^2^. Data for some quantitative characteristics like plant height (cm), average number of kernels/spike, 1,000-kernel weight (g), and grain yield (kg/ha) and some qualitative characters like plant color, waxiness, and spike sterility were recorded. Rainfall and temperature (maximum and minimum) also were recorded at the Cotton Research Station, Bahawalpur. Analysis of variance was done by the method as described by Steel and Torrie (1980) and observations were compared by using the Duncan's Multiple Range Test (Duncan 1955).

Results and Discussion.
Environment-rainfall. During 1999-2000, only 12 mm of rainfall was received during January of the growing season, only a trace in 2000-01, and 21 mm was received in April after crop maturity (Table 4). Total Precipitation (soaking rains and other rainfall) during 1999-2000 was 112 mm. The 100 mm received in 2000-01 was only as a soaking dose, showing acute drought conditions.

Environment-maximum temperature. During the 1999-2000 season, the maximum temperature was 22 C to 39.8 C; in 2000-01 it was 22.1 C to 39.5 C. During both years, high temperature were observed in April and low temperatures in January (Table 5).

Environment-minimum temperature. During the 1999-2000 crop season, minimum temperatures ranged from 6 C to 21.4 C. The highest minimum temperature was recorded in April 2000 and the lowest minimum temperature in January 2000 (Table 6).

During 1999-2000, 12 mm of rainfall was received in January, which increased the tillering capacity by delaying a moisture shortage and resulted in better yields. During 2000-01, only a soaking dose was received, which was one of the causes of low yields. Temperatures in February and March play an important role in yield. Maximum and minimum temperatures in February and March 2000-01 were less than those in 1999-2000. Lower maximum and minimum temperatures help to prolong the growing period, which results in higher yields.

Grain yield and yield components-grain yield. Differences in grain yield among the strains and cultivars were significant during both years; the values for individual cultivars and lines are given in Table 7. During 1999-2000, strain 962098 (3,750 kg/ha) out yielded all the wheat genotypes. Strain 972236 was similar to Bahawalpur 2000 and 962552 but was different from all other wheat genotypes. Bahawalpur 2000 was significantly different from 962098, 972561, Koh-97, Inqlab-91, and 972517. The strain 962552, with a yield of 2,833 kg/ha was different from 962098, 972561, Koh-97, Inqlab-91, and 972517 but not different from the remaining genotypes. Ch-86, with a grain yield of 2,792 kg/ha, was different from all genotype except Bahawalpur-2000, 962552, 972563, and 972561. Line 972563 (2,708 kg/ha) was different from all except Bahawalpur 2000, 962552, Ch-86, and 972561. Inqlab-91, Koh-97, and 972517 had similar low yields in 2000-01. In 2000-01, 962098 again was the best performer at 2,677 kg/ha). 972236 was different from all genotypes except 962098, and Ch-86 (2,300 kg/ha) was different from 962098 and 972563. Inqlab-91 was significantly different from 972517, 962552, Ch-86, 972236, and 962098. The strain 972317 (1,111 kg/ha) was lowest significantly. Seven wheat genotypes performed better than check during moisture stress, KOH-97 during both the years. Similar studies were conducted by S.K.Tanveer and coworkers in 1999-2000 and 2000-01 at the NARC, Islamabad, Pakistan. They found that Inqlab-91 gave 3,836 kg/ha when 242 mm precipitation was received during the 1999-2000 growing season, whereas in 2000-01, Inqlab-91 produced 3,817 kg/ha with 96 mm precipitation during the wheat cropping season.

Grain yield and yield components-height. Differences in plant height were significant in 1999-2000; similar to those of S.K. Tanveer and coworkers. Bahawalpur 2000 achieved maximum height in both years under moisture stress. In 1999-2000, BWP-2000 did not differ from 992236, Chachwal-86, or 972563 but was different from 962552, KOH-97, Inqlab-91, 972561, and 972517. In 2000-01, Bahawalpur 2000 was significantly different from 972317, 972561, KOH-97, Inqlab-91, and 972563 but did not differ from 972236, Ch-86, or 962552.

Grain yield and yield components-average number of kernels/spike. Response within the cultivars and strains to high moisture stress was significant during both the years of the study. In 1999-2000, Inq-91 had the greatest average number of grains/spike; significantly different from 972517, KOH-97, 972561, 962552, and BWP-2000. No significant differences were found among 962098, 972236, Ch-86, 962552, BWP-2000, Inqlab-91, and 972563. The strain 962098 and Inq-91 were significantly different from 972317, 972561, and KOH-97.

Grain yield and yield components-1,000-kernel weight. Under high moisture stress, the wheat strains and cultivars also showed significant differences. BHP-2000 had a high 1,000-kernel weight during both the years. BHP-2000 was different from 972517, 962552, KOH-97, and CH-86. In 1999-2000, 972517 and 962552 were badly affected by moisture stress. In 2000-01, BHP-2000 was different from 972317, 972561, Koh-97, 972563, and 962552 but did not differ from 962098, 972236, CH-86, Inqlab-91, 972317, and 962552, which were affected greatly by the moisture stress.

Qualitative characteristics. The following characteristics were recorded in all the genotypes under an acute moisture stress conditions:

- plant color changed to dark green in all entries,
- waxiness increased in all the genotypes,
- leaf curling was observed in all genotypes, and
- genotypes with long spikes like Inqlab-91 showed tip sterility.

Conclusion. High moisture stress affects grain yield and yield components. Wheat genotypic response to high moisture stress was found to be significant. The strains 962098 and 972236 gave the maximum grain yield during both cropping years, whereas 972317 was affected badly. Bahawalpur 2000 and Chakwal-86 were found to be better than Inq-91 and KOH-97 under conditions of high moisture stress. Inqlab-91 should not be cultivated under high moisture stress. Moisture levels in the soil of the cotton zone is sufficient to produce yields of 2,000 kg/ha or more.

References.

• Agriculture Statistics of Pakistan. (1999-00). Government of Pakistan, Ministry of Food, Agriculture and Livestock Division (Economic wing). Pp. 158.
• Anonymous. 1999. Germplasm Programme, Annual Report. Pp. 161.
• Anonymous. 1992. Cereal Programme, Annual Report, Syria. Pp. 115.
• Duncan DB. 1955. Multiple range and multiple F-tests. Biometrics II:1.
• Siakia TP, Serma A, Medhi BK, and Sarma A. 1999. Performance of wheat varieties under rainfed conditions of North East India. 12:239-240.
• Singh PN and Uttam SK. 1995. Effect of wheat (Triticum aestivum L.) varieties on yield components, yield and moisture use patterns under rainfed conditions of central U.P. Adv Agric Res India. 4:161-166.
• Steel RGD and Torrie JH. 1980. Principles and procedures of statistics, 2nd Ed. McGraw Hill Book Co Inc, New York, USA. 633 pp.
• Tanveer SK, Khan B, Kisan NS, Mujahid MY, and Hussain L. 2002. Comparison of wheat varieties based on yield and yield components under rainfed conditions. Science, Technology and Development, Pakistan Council for Science and Technology, Islamabad. Pp. 35.
  

Comparative genotypic resistance to Russian wheat aphid in the wheat crop in the southern Punjab, Pakistan. [p. 95-97]

Manzoor Hussain, Asghar Ali Malik, Muhammad Aslam, Muhammad Masood Akhtar, and Lal Hussain Akhtar.

Summary. To identify resistance to RWA in different wheat genotypes, 10 wheat cultivars or strains were sown in a randomized complete block design with three replications at the at Regional Agricultural Research Institute Bahawalpur. The wheat cultivar Uqab-2000 was found to be the most resistant, giving a maximum grain yield (3,062 kg/ha) with 50 aphids/tiller. The strain V-2333 was second best with 43 aphids/tiller and a grain yield of 2,964 kg/ha. V-2278 was found to be less attractive to the aphids (34 aphids/tiller). Wheat strains V-2237 and V-4012, with 46 and 44 aphids/tiller, respectively, had better grain yield (2,816 kg/haI for V-2237 and 2,865 kg/ha for V-4012). Two commercial wheats, Inqlab-91 and Iqbal-2000, had low grain yields (2,371 kg/ha) with a comparatively low number of aphids/tiller (35 each). This situation is alarming because Inqlab-91 covers maximum area in the province and Pakistan. A new wheat cultivar, Manthar-3, was resistant to aphids when compared to Inqlab-91. The wheat strain V-2460 was affected badly.

Introduction. Wheat is an important food crop in Pakistan, being sown on an area of 8.057 x 10^6^ ha (Agriculture Statistics of Pakistan 2001-2002). The wheat crop passes through a series of stresses from sowing to harvesting, including heat, moisture shortage, disease, and insects. In Pakistan, attacks by aphids are increasing on the wheat crop, especially in cotton zones of Multan, D.G. Khan, and Bahawalpur. Aphids hinder photosynthesis but infestations during the last few years on leaves, stems, and spikes have been severe, causing necrosis and blackening of these parts. Necrosis and blackening affect grain yield. During 2002-03, aphid attacks on wheat fields in southern Punjab was at the maximum and the aphid population increased to a dangerous level. A good wheat crop had been expected in Pakistan in 2003, similar to that of 1999-2000, which was a record 21.078 x 10^6^ tons (Agricultural Statistics of Pakistan 1999-2000). In 2002-03, the average yield per unit area also was less than the expectations due to aphid attack on wheat. In the present study, the behavior of wheat genotypes against aphid attack was investigated.

Bahawalpur is characterized by low humidity with drought stress. Russian wheat aphid is most often found in low humidity areas with moderate drought stress (Anonymous 1992). The RWA injects a toxin into the plant tissue that destroys the chloroplast membrane, causing longitudinal chlorotic streaks to develop (Anonymous 1999). At the ICARDA research field, 10 RWA nymphs/plant were found at tillering stage (Anonymous 1999). The RWA is a harmful pest damaging grain yield worldwide. The importance of the RWA to the U.S. wheat industry is substantiated by the reported economic damage of over $130 x 106 USD in 1987-88 (Peairs et al. 1989).

Materials and Methods. The experiment was sown at the research area of the Regional Agricultural Research Institute, Bahawalpur, in 2002-03. The trial was consisted of five approved cultivars (Manthar-3, Uqab-2000, Punjnad-1, Inqlab-91, and Iqbal-2000) and five advanced wheat lines (V-2237, V-2460, V-2278, V-4012, and V-2333). The experiment was conducted by using an randomized complete block design with three replications. Plot size was 6 m^2^. N and P2O5 fertilizers were applied at the rate of 160 and 110 kg/ha, respectively. The experiment was sown on two dates, S1 (30 November, 2002) and S2 (20 December, 2002) to ensure maximum chance of RWA infestation. Four irrigations were applied to each sowing. Weeds were controlled chemically with Bromoxynil. Yield (kg/plot) and RWA population were recorded from 10 tillers selected at random from each plot. Harvesting was complete by 25-26 April, 2003. Analysis of variance was performed following the method described by Steel and Torrie (1980), and the treatments were compared using a Duncan's Multiple Range test (1955).

Results and Discussion.
Aphid infestation. Aphid attack always is found at the reproductive stage of the crop in the reported area. Aphids were found on each tiller, present on heads, leaves, and stems (Table 8). At the early sowing date (S1), a significant difference in RWA populations was observed. Maximum aphid populations were found on Punjnad-I (78 ahpids/tiller) and Uqab-2000 (65 aphids/tiller), which is significantly different from all other cultivars or strains but there was no difference between these two wheat cultivars. The wheat Manthar-3 was significantly different from Inqlab- 91, V-2460, V-2278, Iqbal-2000, Punjnad-I, and Uqab-2000, but was not significantly different from V-2237, V-2233, and V-4012. The line V-2237 with 55 aphids/tiller was similar to Inqlab-91, V-2460, V-4012, Iqbal-2000, and V-2333, but different from Punjnad-I, Uqab-2000, Manthar-3, and V-2278. The lines V-2460 and V-4012, both with 49 aphids/tiller, were significantly different from cultivars Punjnad-I and Uqab-2000 but was similar to all the other cultivars and lines.

At the second planting date, S2, significant differences in aphid population were observed. Line V-2460, with 61 aphids/tiller, was more attractive than all other wheat cultivars or lines, whereas Punjnad-I at this sowing date was less attractive to the RWA. Manthar-3 (46 aphids/tiller) was similar to Uqab-2000, V-2237, V-2333, and V-4012, but different from V-2460, Inqlab-91, V-2278, Uqab-2000, and Punjnad-I. Lines V-4012 and V-2333 were found to be statistically different from V-2460 and Punjnad-I but similar to the other six lines. The wheat Punjnad-I was statistically different from V-2460, Manthar-3, V-2333, and V-4012.

Grain yield. At the early sowing date, significant differences in grain were observed (Table 9). Uqab-2000 and V-2333 produced higher yield than all the other cultivars or strains except Manthar-3. Uqab-2000, V-2333, and Manthar-3 had better resistance than all other genotypes. Strain V-2278 showed comparatively better resistance than V-2237, Punjnad-1, Iqbal-2000, Inqlab-91, and V-2460, but was similar in resistance to V-4012 and Uqab-2000. Strain V-4012 had a similar level of resistance with that of V-2278, Uqab-200,0 and V-2237 but had better resistance than Inqlab-91, V-2460, and Punjnad-1. Three wheats, Inqlab-91, V-2460, and Punjnad-1, were less resistant to RWA.

At the second sowing date, no significant differences in the wheats were found. Wheat strains V-2237 produced the highest grain yield (2,668 kg/ha); Manthar-3 the lowest (1,581 kg/ha).

Conclusions. Average data for the differenct cultivars and strains is given in Table 10. The wheat cultivar Uqab-2000 was found to be the most resistant to RWA, producing the highest grain yield (3,062 kg/ha) with 50 aphids/tiller. The wheat strain V-2333 with 43 aphids/tiller had the second highest yield at 2,964 kg/ha. Line V-2278 was less attractive to the RWA (34 aphids/tiller). Wheat strains V- 2237 and V- 4012 with 46 and 44 aphids/tiller yielded 2,816 kg/ha and 2,865 kg/ha respectively. Two commercial wheat cultivars, Inqlab-91 and Iqbal 2000, had low grain yields (2,371 kg/ha) with a comparatively low number of aphids/tiller (35). Because Inqlab-91 covers maximum area under wheat in the province and the country, this situation is alarming. The new wheat cultivar Manthar-3 exhibited better resistant to RWA compared to Inqlab-91. Wheat strain V-2460 was infected badly. Study on RWA occurrence in the area and identification of resistant cultivars should be encouraged. Area sown to cultivars with low levels of resistance should be decreased.

References.

• Agricultural Statistics of Pakistan. 1999-2000. Government of Pakistan, Ministry of Food, Agriculture and Livestock Division (Economic Wing). P. 7.
• Agricultural Statistics of Pakistan. 2001-2002. Government of Pakistan, Ministry of Food, Agriculture and Livestock Division (Economic Wing). P. 9.
• Anonymous. 1992. Cereal Programme, Annual Report, ICARDA, Syria. 139 pp.
• Anonymous. 1999. Germplasm Programme, Annual Report. P. 187.
• Duncan DB. 1955. Multiple range and multiple F tests. Biometrics II:1.
• Peairs F, Brooks L, Hein G, Johnson G, Massey B, McBride D, Morrison WP, Schultz JT, and Spackman E. 1989. Economic impact of RWA in Western U.S.A. 1987-1988. Great Plains Agric Council Pub 129.
• Steel RGD and Torrie JH. 1980. Principles and procedures of statistics, 2nd Ed. McGraw Hill Book Co, Inc, New York, USA. 633 pp.

The role of exotic sources in the evolution of wheat cultivars in Pakistan. [p. 97-98]

Muhammad Rafiq, Manzoor Hussain, L. H. Akhtar, Muhammad Safdar, Altaf Hussain Tariq, and Asghar Ali Malik.

Introduction. After the introduction of semidwarf wheat, wheat yields in the world increased. CIMMYT is working in many different aspects of wheat research. Every year, new wheat lines are tested and selected for different climatic zones in the world. Selected wheat entries are included in different wheat nurseries and trials and are distributed worldwide and relevant data collected. This new, circulated material is tested at local wheat research stations in the world and also is selected for local planting. The best performing entries are put into national testing programs and are released as cultivars in different countries. For example, the Veery line, which is cross between spring and winter wheat lines has the pedigree 'KavKaz/Buho's//Kal/BB (CM-33027)'. From this cross, 53 cultivars were released in different countries of the world. In Pakistan, Veey #5 was approved as the cultivar Pak-81, and it performed very well in the wheat fields of Pakistan. Different research stations and institutes in Pakistan also receive exotic material for testing under local conditions for a few years. The best performing lines are approved as cultivars.

Some researchers feel that wheat lines crossed locally and studied under local conditions can give better performance. For example, Inqlab-91, pedigree 'WL-711/CROW S' is a local cross made at Faisalabad. Generation studies were completed at Faisalabad (Proposal of a wheat cultivar 85060-1 (Approved) 1991). Inqlab-91 is the first wheat cultivar to be grown on 60-70 % of the country for many years. The cultivar still is present in the farmers' fields and will probably be around for about 5 more years. The success of Inqlab-91 supports the opinion of those experts who favor local hybridization. This study will help decide the dependency of agriculture research of wheat on exotic sources in Pakistan. At different research stations in Pakistan, valuable material resulting from local crosses is available and the best results can be achieved by interchanging material in Pakistan. Genetic variability in Pakistan can be achieved by crossing present material with the old species.

Materials and Methods. The National Uniform Wheat Yield Trial is comprised of 20 wheat entires from all research stations and institutes in Pakistan and is controlled by the Coordinator for Wheat, NARC, Islamabad. The nurseries were planted in a randomized complete block design with four replications. Plot size was '5 x 1.2 m' or 6 m^2^. Results are complied and published by the Coordinator for Wheat, NARC, Islamabad. In this study, 10 years of data have been collected from the results of National Uniform Wheat Yield Trials. Entries are divided in two groups, local crosses and selection from exotic sources. The number of wheat cultivars and strains have been compared by a percentage.

Results and Discussion. During 10 years of study, 167 entries were tested. The results are discussed here on province basis (see also Table 11).

The Punjab. The Punjab province consisted of six research stations/institutes and contributes a large number of entries. The Wheat Research Institute, Faisalabad, is the major wheat research institute of Pakistan. From Punjab, 97 entries were tested in national wheat program. Seventy-four entries were result of local crosses and 23 were selections from exotic nurseries and trials.

The Sindh and Baluchistan. Five research stations are in the Sindh and Baluchistan provinces of Pakistan. During the 10 years under study, 23 entries were tested in the National Uniform Wheat Yield Trials. Ninteen entries were selections from exotic crosses and four were local crosses.

The North-West Frontier Province. Five research stations/institutes are working on wheat in this province. During the 10 years under study, 37 entries were contributed by the province; 36 strains were selections from exotic sources and one was a local cross.

National Agricultural Research Centre, Islamabad. During the 10-year study, 10 entries were tested at this Institute. One strain was a selection from a local cross and nine were from exotic sources.

Total for Pakistan. The percentage of the entries from Pakistan tested in the National Uniform Wheat Yield Trials for 10 years is given in Table 11.

Wheat cultivars approved. During the 10-years period, 32 of 167 entires in the National Uniform Wheat Yield Trials were approved as cultivars. The percentages from local crosses or selected from exotic sources are given in Table 11.

During the 10-year period, 32 wheats were released for general cultivation. Of these lines, 34 % were selections from local crosses and 66 % were selections from exotic sources. The greatest number of cultivars were developed from exotic sources during the 10 years (1990-91 to 2000-01). However, cultivars grown over the greatest area in Pakistan were from local crosses. These wheats were approved for different purposes, such as for irrigated areas, rainfed areas, hilly areas, or late-sowing. Some important cultivars from this source are Inqlab-91, Punjab-96, Uqab-2000, Iqbal-2000, MH-97, Kirran, Anmol-91, Soughat, Marvi-2000, Bahawalpur-2000, Punjnad-1, Bakkar-2002, Noshera, Suleman, Daman-98, Sariab-92, and Zarlashta-99. The research institutes and stations in Punjab have produced 16 cultivars of which nine (56 %) were selected from local crosses and seven (44 %) were selected from exotic sources. During the 10 years, the main wheat cultivars planted to the greatest area in Pakistan were Inqlab-91, TJ-83, Parwaz-94, Punjab-96, and MH-97. Inqlab-91, Parwaz-94, and Punjab-96 resulted from local crosses and covered 60 to 70 % of wheat-growing area of Pakistan. TJ-83 and MH-97 are selections from exotic sources, but cover a smaller area of the country.

Conclusion. During the 10 year study from 1990-91 to 2000-01, 167 entries were tested in the National Uniform Wheat Yield Trials in Pakistan. Out of 167 entries, 48 % were selected from local crosses and 52 % were selections from exotic sources. For the Punjab province, 76 % were from local crosses and 24 % were from exotic sources. During this period, 32 varieties were released for general cultivation out of which 34 % were selections from local crosses and 66 % were selections from exotic sources. Wheat cultivars developed from local crosses covered the greatest area of the wheat fields in Pakistan during these 10 years. Local hybridization programs are very important and should be strengthened in future with increased facilities. Farmers in Pakistan have accepted these wheat cultivars.

Effect of irrigation and various nitrogen and phosphorus levels on wheat yield. [p. 99-101]

Manzoor Hussain, M. Zubair Khan, Abdul Rashid, Muhammad Rafiq, M. Zahid Aslam, Lal Hussain Akhtar, and Altaf Hussain Tariq.

Introduction. During 2002-03, the wheat crop in the Punjab province of Pakistan looked very good. With the expectation of a 15.36 x 10^6^ ton grain yield (Anonymous 2003), the average yield in the province of Punjab was only 2.52 t/ha. What happened to the grain yield? The main problems for low grain yield in the southern Punjab are late planting, shortage of irrigation water, weeds, and disease and insect pests. In 2002-03, the aphid population was at its maximum limit in the southern districts of Punjab; up to 78 aphids/tiller, which can cause high damage. In many countries, aphids damage the wheat crop at leafy stage but in southern parts of Punjab it attacks in the latter stages during the month of March. In the U.S. in 1987-88, an economic loss of 130 x 106 USD was reported (Peairs et al. 1988). Aphids may become a serious problem on wheat in the future. Heliothis also may attack the wheat crop in the southern Punjab, which is a special cotton growing area of Pakistan. Heliothis attacks leaves, awns, and especially the grain. Heliothis on wheat crop also has been reported in India. In the southern Punjab, the wheat crop is sown mostly in December and matures in mid April. Seasonal changes in this area also affect the average grain yield. The average number of days to maturity here ranges from 110-125, whereas under normal sowing it takes about 130-145 days. The technically called forced maturity occurs when wheat genotypes can not take proper time to mature. In this study, we have tried to elucidate situations preventing high grain yield in the southern district of Punjab during 2003. Temperatures during grain filling in this area play an important role in grain yield. We will discuss the possible causes of low grain yield and the expectations.

Materials and Methods. The experiment was conducted at Regional Agriculture Research Institute, Bahawalpur. Ten wheat genotypes were sown using RCBD design. Each wheat variety in the experiment was sown in three replications with plot size of 6 m^2^ (5 m x 1.2 m). The N and P2O5 were applied at the rate of 160 and 110 kg ha-1. Weeds were controlled chemically. No. of aphids per tiller and number of predators per plot were recorded. Climatic data was recorded at CRS, Bahawalpur.

Results and Discussion.
Insect pests-aphids and predators. This year, aphids occurred on a large scale and three predators, Chrysopa, lady bird beetles, and syrphid flies, were found on the wheat crop in the farmers' fields and at the experimental area of the Regional Agricultural Research Institute, Bahawalpur (Table 12).

The average aphid population recorded on 18 March was high, 53 aphids/tiller, and decreased by 26 March to 36 aphids/tiller. On 18 March, wheat crop was lush green; by 26 March, the leaves were rather hard. Tender leaves attracted aphids and drying leaves were less preferred. The highest aphid populations were observed on 18 March on Punjnad-1 (78 aphids/tiller). The lowest populations were observed on V-2278 (38 aphids/tiller). V-2278 is light green, whereas Punjnad-1 has a dark green leaf.

Crysopa, ladybird beetles, and syphrid flies were found in farmers' wheat fields and at the experiment fields of the Regional Agricultural Research Institute, Bahawalpur. Crysopa was the dominant aphid predator averaging 24/plot, the highest number recorded, on 18 March and decreased to 10/plot by 26 March (Table 12). The predator population/plot was the highest (30/plot) on Punjnad-1 and V-2278 on 18 March; the highest number on 26 March was 16/plot on Iqbal-2000.

For the growing season 2003, the highest average number of aphids/tiller was 44 on V-2460; the lowest average was on V-2278 (34-55). The greatest number of predators were on V-4012 and Punjnad-1, whereas the minimum aphid population/tiller was found on V-2210 (13/plot, mean population range 13-20). The average predator population for the entire season was 17/plot.

Insect pests-Heliothis (Helicoverpa armigera). Heliothis has damaged the wheat crop for many years in Punjab. During 2003, no Heliothis was observed in wheat crop, possibly because of the high population of Crysopha.

Wheat cultivar response to aphids. Aphid infestations were reported on all wheat cultivars. Inqulab-91 covered the greatest area, followed by Punjab-96, Uqab-2000, MH-97, and Punjnad-1 (Table 12).

Climatic factors-maximum and minimum temperatures, rainfall, and humidity. Data on climatic factors for a few years is in Table 13. Data for 2002 show that the warmest temperature was low (24 C) compared to that of 2001. No difference in the maximum temperature during last 2 weeks of March from 2001 to 2003 was observed. Temperatures during the first and second weeks were favorable to the wheat crop. The warmest temperature during last 15 days was 32 C, which was similar to 2001 but less than that of 2002.

The weekly data in Table 14 show that in 2003, the first and second weeks of March were cooler than in the other years. The thrid week of March was hotter than 2000, which was a record year for grain yield. In the last week of March 2003, temperatures were higher than for 2001 or 2002. The first week of April 2003 was hotter than the similar period in 2000-01. Night temperatures during the last 15 days of March was higher than in 2002. From 25 March to 28 March, the minimum temperature was double that of 2002.

No rain fell during the month of March in 2000-03 (Table 15). No significant difference in rainfall was noted during the 2000 and 2002 crop seasos. No considerable diference in humidity for 2000-03 was noted (Table 15).

Conclusions. Maximum temperature and minimum temperature during growing season (2002-03) favored the wheat crop. However, higher minimum temperature during last 15 days of March 2003 disturbed the wheat crop. Hot nights in the last 15 days of March 2003 during grain filling decreased grain weight of wheat crop in the cotton region. No considerable changes in rainfall and relative humidity were noted. Aphids were at their maximum population during March 2003 in the southern Punjab. Increases in aphid populations caused an increase in the predators present, Crysopa, lady bird beetles, and syrphid flies. Crysopa was able to attack aphids better than the other predators. Heliothis was not present during the year, which may be because of Crysopa. We estimate that damage due to aphid and temperature may range from 57 % in the southern Punjab.

References.

• Anonymous. 2003. Final estimate of wheat crop for the year, 2002-03 in the Punjab. Crop Rep Serv, Punjab, Lahore, Pakistan. Pp. 1-6.
• Peairs F, Brookes L, Hein G, Johnson G, Massey B, McBride D, Morrison WP, Schultz JT, and Spackman E. 1989. Economic impact of RWA in western U.S.A 1987-1988. Great Plains Agric Council Pub. Pub 129.