Comparative studies of semi-dwarf wheat genotypes (Triticum aestivum L.) for yield and yield components
Karim Dino Jamali
Nuclear Institute of Agriculture (NIA), Tando Jam, Pakistan
Corresponding author: Karim Dino Jamali
Nuclear Institute of Agriculture (NIA), Tando Jam, Pakistan
E-mail: karimdino2001@yahoo.co.in
Abstract
In yield comparison line 04 had comparatively the highest grain yield. The subsequent lines 01, 02, 06, 07 had comparatively higher grain yields. The possible reasons for higher grain yield in line 04 could be due to early heading date, double dwarf plant height and higher number of grains per spikelet and the boldest grain size. Correlation analysis for pooled data was calculated for the genotypes. Plant height had positive and highly significant correlation for spike length, number of spikelets per spike, number of grains per main spike and grain yield of main spike. Grain yield of main spike is a very important character; it has positive and highly significant correlation with all the characters such as plant height, spike length, number of spikelets per spike, number of grains per spike and number of grains per spikelet.
Introduction
The control of plant height in cereals is known to be complex because of its polygenic nature and subject to environmental effects. Tall wheat cultivars and lines (Triticum aestivum L. 2n=6x=42) are more prone to lodging, particularly when in favourable environments whereas semi-dwarf cultivars are shorter less prone to lodging (Ahmad et al. 2002). The primary sources of semi-dwarfism in wheat are the Norin 10 reduced height genes, Rht1 and Rht2. These genes are located on the 4B and 4D chromosomes of wheat, (Gale et al. 1975; Gale and Marshall 1973). Sayre et al. (1997) suggested the strong relationship between grain yield and harvest index and grain yield and kernels per square meter. Jamali et al. (2003) reported that the important character plot grain yield was not correlated with days to heading, plant height, number of spikelets, number of grains per spike, main spike grain yield, grain weight, number of grains per spikelet, plot grain yield and harvest index. The aim of present study was to compare the genotypes for yield and yield components and their relationship with plant height.
Materials and methods
Sixteen advance entries were selected and evaluated for yield and yield components with two check varieties viz. Sarsabz and Kiran-95. The genotypes were planted into four rows each with row length of 03 meters. The experiment was laid out in a Randomized Complete Block Design with three replicates. Weekly mean temperature during the crop ranged from 12.2 oC (minimum) to 28.84 oC (maximum) and average humidity remained at 71.56. Five plants from each replicate were selected at random for recording the data. The statistical data analyzed according to Steel and Torrie (1981).
Results and discussion
Comparative performance
The results of yield and yield components are presented in Table 1. The yield comparison studies showed that line 04 had comparatively the highest grain yield. The subsequent lines which had higher grain yields were lines 01, 02, 06, 07. The possible reasons for higher grain yield in line 04 could be due to early heading date, double dwarf plant height and higher number of grains per spikelet and the boldest grain size. Villarreal et al. (1992) reported that double dwarf varieties yielded over 2.4% than the single dwarf gene (Rht2) varieties. However, the varieties with double dwarf (Rht1Rht2) were not significantly different than the varieties carrying Rht1Rht1. Higher grain yield in line 01 could be due to its early heading dates, higher number of grains per spikelet and also increased grain weight. Higher grain yield in line 02 may be due to its early heading dates; probably it escapes from the effect of high temperature during grain filling period. The high grain yield in line 06 could be due to early heading dates, the highest main spike grain yield and increased number of grains per spikelet. Waddington et al. (1986), who studied more recent semi-dwarf cultivars pointed out the importance of increased kernels per spike and indicated that the most recent progress (cultivars after 1975) appeared to raise from increased biomass and not increased harvest index. The higher grain yield of line 07 could be due to its bold grains. Shearman et al. (2005) suggested that recent genetic gains in grain yield have been accomplished due to increased number of grains per unit area in modern semi-dwarf wheat varieties.
Correlation studies
The correlation studies are presented in Table 2. Combined/ pooled correlation analysis was calculated for genotypes. Plant height has positive and highly significant correlation for spike length, number of spikelets per spike, number of grains and grain yield of main spike. These results suggest that an increase in plant height may increase the spike length, number of spikelets, number of grains per spike and main spike grain yield in semi-dwarf wheat. Li et al. (2006) reported that both the Rht-B1b (Rht1) and Rht-D1b (Rht2) semi-dwarfing genes had significantly positive effects on kernel number per spike and grain yield per spike. The semi-dwarf genes (Rht1 or Rht2) may increase grain yield, grains per spike, grain weight, grain volume weight, biomass, coleioptile length, stand establishment potential and protein content when compared to their non semi-dwarf alleles (Allan 1983; Gale and Youssefian 1985). Muhammad et al. (2006) reported that plant height had negative correlation with grain yield. However, plant height had non significant correlation with number of grains per spikelets. The results reveal that plant height do not affect the spike fertility. Belay et al. (1993) reported that plant height had a non significant correlation with number of grains per spike and spikelet. Spike length had highly significant positive correlation with number of spikelets per spike, number of grains per spike and grain yield of main spike. These results indicate that an increase in spike length may also increase the number of spikelets per spike, number of grains per spike and grain yield of main spike. However, spike length had negative but non significant correlation with number of grains per spikelet. Number of spikelets per spike had highly significant positive correlation with number of grains per main spike and grain yield of main spike. Jamali et al. (2003) reported that the number of grains per main spike had positive and significant correlation with grain yield of main spike. However, number of spikelets had highly significant negative correlation with number of grains per spikelet. These results suggest that an increase in number of spikelets may reduce the spike fertility. Number of grains per spike had highly significant positive correlation with grain yield of main spike and number of grains per spikelet. Main spike grain yield had highly significant positive correlation with number of grains per spikelet. Grain yield of main spike is a very important character; it has positive and highly significant correlation with all the characters such as plant height, spike length, number of spikelets per spike, number of grains per spike and spikelet. Selection based on grain yield of main spike could result in better genotypes.
Keeping in view these results, we may conclude that selection based on number of grains per main spike and grain yield of main spike could result in evolution of quality genotypes.
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