NUCLEAR INSTITUTE OF AGRICULTURE (NIA)
Tando Jam, Pakistan.
Karim Dino Jamali, Saima Arain, and M.A. Arain.
The production of wheat has always been the main occupation of the farmers in the diversified agroclimatic conditions of Sindh, because wheat is an important source of human nutrition and deserves special attention. The evolution of cultivars with high yield potential and a desirable combination of traits has always been the major objective of our wheat-breeding programs. In 2005-06, an overall production of 21.7 x 106 tons was achieved from an area of 8.307 x 106 hectares, which is an improvement of 0.4% in production over last year's harvest of 21.6 106 tons (Table 1).
| Province | Area (x 106 ha) |
Production (x 106 ha) |
Yield (kg/ha) |
|---|---|---|---|
| Punjab | 6.322 | 16.811 | 2,660 |
| Sindh |
0.933 | 2.897 | 3,104 |
| NWFP | 0.743 | 1.294 | 1,742 |
| Balochistan | 0.309 | 0.706 | 2,284 |
| Pakistan | 8.307 | 21.708 | 2,615 |
Wheat breeding at NIA is being pursued with the objective of developing high-yielding, good-quality cultivars with tolerance to biotic and abiotic stresses. The institute has released nine cultivars of wheat for the province of Sindh, Pakistan, which have contributed significantly to the national economy. Currently, our breeding material is at different stages of evaluation and is summarized below.
Work done during the year 2004-05. National Trials. The candidate line 7-03 completed 2 years of evaluation in National Uniform Wheat Yield Trials (NUWYT). This line produced comparatively higher yields than other lines, especially that in the Sindh province, and also is resistant to yellow rust with an RRI value of 6.
Advance Station Trials. Advanced lines developed at NIA were evaluated in different yield trials and the results are summarized here.
Sowing Date Trials. Wheat sowing in the Sindh province begins the 1st week of November and continues until the end of December; however, the ideal sowing period is during the first 3 weeks of November. We evaluated 15 lines at three different sowing dates (11 November, 25 November, and 22 December) with three replicates in a 9-m2 plot for each genotype.
Sowing date 1 (11-11-2005). In this comparison, line 7-03 had the highest grain yield (1,358g)/plot. Other lines that had high grain yield/plot were 15-10 (1,258 g), 54-03 (1,250 g), 6-12 (1,233 g), 51-02 (1,200 g), 17-11 (1,200 g), 3-02 (1,183g), 14-06 (1,175 g), and 8-14 (1,175 g). The higher grain yield in line 7-03 could be due to its medium number of days-to-heading and bolder grains and line 15-10 due to its maximum number of spikelets/spike and highest main spike grain yield. Similarly, line 54-03, with a dwarf plant height, long spike (12.97 cm), and greater number of grains/spikelet, and line 6-12, due to a medium heading date and higher number of spikelets/spike, also gave good yields.
Sowing date 2 (25-11-2004). In this yield comparison, line 7-03 again had the highest grain yield (1,217 g/plot). Other lines that had high grain yields were 15-10 (1,192 g/plot) and 54-03 (1,175 g/plot). The higher grain yield in line 7-03 could be due to its higher grain weight (33.42 g); line 15-10 has a longer vegetative period resulting in delayed heading, longer spikes, a greater number of spikelets/spike, grains/spike, a higher main spike grain yield, and an increased 1,000-kernel weight (32.90 g); and line 54-03 has a tall plant height, long spikes, increased number of grains/spike and grains/spikelet, and an increased main spike grain yield.
Sowing Date-3 (22-12-2004). In this yield comparison, the highest grain yield was in line 15-10. Other lines having high grain yields were 54-03, 7-03, 6-12, and 4-03.
Mean performance over the sowing dates. In this comparison, line 7-03 (1150 g/plot) a candidate cultivar had the highest grain yield. However, line 7-03 was not significantly different from 15-10 (1,128 g/plot) and 54-03 (1,108 g/plot). Other lines with high grain yields were 6-12 (1,064 g/plot) and 14-06 (1,000 g/plot). These results show that line 7-03 has stability to perform better in different agro-ecological environments. A significant difference between the sowing dates was observed. The early sowing date had a 1,162 g/plot, the middle sowing date 1,049 g, and the late sowing date 756 g grain yield. Lines 7-03 and 15-10 had the highest mean grain yields over the three sowing dates.
Breeding material. Five F7 trials were conducted. Each trial consisted 13 genotypes including two check cultivars. Each trial had six 3-m rows with three replicates. Agronomic and yield data were recorded for these trials.
Line 05 (817 g/plot) had the highest grain yield, followed by lines 06 (800 g/plot), 03 (767 g/plot), and 04 (758 g/plot). The high grain yield in line 05 could be due to an early heading date and increased number of spikelets/spike; in line 06 to early heading date, a high grain yield of main spike, and an increased 1,000-kernel weight; and in line 03 to the 'tall dwarf' plant height and increased number of grains/spike.
Isoline studies. Thirty isogenic lines varying for plant height (47.53 to 111.5) were selected from four different cross combinations. Line, 07 had the highest grain yield (371.7 g) followed by lines 23 (356.7 g) and 20 (338.3 g). The high grain yield in lines 07 and 23 could be due to their early heading date and semidwarf plant height. Line 20 also was high yielding, early in heading, and had a double dwarf plant height. Of the 30 lines, eight (03 semidwarf and 05 double dwarf) yielded comparatively higher than the best check cultivar Sarsabz. These studies will be continued for further selection.
Introduction of Rht8. Mara, which has Rht8, a new semidwarfing gene, was introduced into existing candidate lines for further studies in combination with Rht1 and Rht2. Rht8 is GA3-sensitive, less temperature sensitive, and may not reduce coleoptile length unlike the Norin-10 genes, which tend to restrict coleoptile elongation that results in poor stand establishment.
The following wheat cultivars were released for general cultivation in Sindh province of Pakistan during the year 2006:
Khirman. This cultivar was released in 2006. Khirman is a medium-duration cultivar with a high grain yield that is particularly suitable for areas where water availability is a limiting factor. The average yield of Khirman is 4,619 kg/ha with a potential yield of 7,667 kg/ha.
Sassui. The cultivar was introduced in 2006 and has a high grain yield, bold amber grain, is drought tolerant, of good quality, and resistant to leaf and yellow rust. Sassui's average yield is 4,700 kg/ha with a potential yield of 7,800 kg/ha.
A wheat 'Field Day' and a 'Farmers' Day' are the regular activities of the institute that provide opportunities for sharing knowledge with progressive growers. Wheat 'Field Day' was held on 17 February and 'Farmers' Day' on 9 March, 2006. In these events, eminent growers from the Sindh province visited the wheat fields and shared their views. These events provide a means for farmer-participatory research and technological transfer.