Lines IN-06-92 and IN-14-92 had the highest grain yields. Line IN-14-92 was comparatively late in days to heading with having higher number of spikelets per spike, higher above-ground biomass production and also increased number of grains per main spike than the check varieties. The same line (IN-14-92) had the lowest grain weight. Subsequent high yielding lines were IN-04-92, IN-08-92, IN-07-92, IN-05-92 and IN-03-92. Line IN-04-92 was not significantly different than the lines IN-06-92 and IN-14-92 for their plot grain yield. However, line IN-04-92 was also not significantly different than the check varieties Sarsabz and Soghat-90. Line IN-08-92 had a short plant height with a high harvest index value. Line IN-08-92 had a comparatively higher number of tillers/meter2(Jamali and Ahmad 1998). Line IN-07-92 had the highest above-ground biomass production than the lines and varieties.
Correlation studies of individual genotypes were conducted for main spike yield with other characteristics (Table 2). In this environmental condition only the number of grains per spike and spikelet showed positive and significant correlation in all the varieties and lines. While studying the adaptation of advanced CIMMYT wheat lines to water stress environments in Australia Cooper et al. (1994) have reported that grain number per fertile tiller/spike was positively associated with grain yield. Sayre et al. (1997) also reported the strong relationships between grain yield and kernels per square meter. It suggests that number of grains per spike is a very important character and the selection should be based on this character for developing new high yielding wheat varieties. Plant height showed positive and significant correlation with main spike yield in lines IN-17-92, IN-54-92, Sarsabz, Anmol and Mehran. These results agree with the findings of Law et al. (1978) in which yield was positively related to height within major dwarfing gene group. However, Busch and Rauch (1993) reported the lack. of a positive association between plant height and grain yield.Villareal et al. (1992) reported negative correlation for plant height and grain yield within the groups of single gene dwarfs. The results contradict the earlier findings presented by Law et al. (1978) wherein yield was positively related to height. It suggests that the genetic background or environment may be playing a significant role for either positive or negative impact of plant height on grain yield. However, line IN-45-92 showed negative but significant correlation of plant height with main spike yield. Lines /varieties showed positive and significant correlation for number of spikelets per spike are IN-07-92, IN-45-92, IN-59-92 and Anmol. Line IN- 05-92 showed negative and significant correlation for number of spikelets with main spike grain yield. Grain weight is an important character for improving wheat yields. In this study the lines which showed positive and significant correlation for grain weight with grain yield are IN-04-92, IN-08-92, IN-15-92, IN-42-92, IN-59-92, Soghat-90 and Anmol.
Combined correlation analysis studies are presented in Table 3. These studies show that days to heading was positively correlated (r = 0.627) with number of spikelets per spike, negatively associated (r = -0.439) with grain weight (mg), grains per spikelet (r = -0.297) and harvest index (r = -0.364). Flood Halloran (1986) have reported that days to heading is positively correlated with number of spikelets. Negative correlation of days to heading with grain weight, grains per spikelet and harvest index suggests that high temperature affect negatively for grain development. Plant height is positively associated (r = 0.378) with grain weight and negatively correlated (r = -0.355) with harvest index. The main characteristic of semi-dwarf wheats is to transmit assimilate towards the developing grain. Number of spikelets are positively associated (r = 0.554) with number of grains per spike and main spike yield (r = 0.311), however, it is negatively correlated (r = -0.382) with grain weight and harvest index (r = -0.244). It is a physiological process that higher number of grains will increase competition for assimilate requirement and hence the grain weight may be reduced. Main spike yield is positively associated (r = 0.689) with grains per spikelet. It suggests that higher fertility may increase the main spike yield. Grain weight is negatively correlated (r = -0.256) with number of grains per spikelet. It is already stated that higher number of grains may reduce the grain weight. Number of grains per spikelet is positively correlated with harvest index. The higher harvest index may increase the spike fertility. Above-ground biomass was positively and significantly correlated with days to heading (r = 0.284) and plant height (r = 0.287).Flood and Halloran (1986) reported that longer growing period habit is positively associated with higher dry matter accumulation at anthesis (Villareal et al. 1992). Biomass production was positively and highly significantly correlated with number of spikelets (r = 0.374) and plot grain yield (r 0.729). A number of workers observed positive correlation between dry matter at anthesis and grain yield (Flood and Halloran 1986; Villareal et al. 1992). However, biomass production was negatively correlated with number of grains/spikelet (r = -0.254) and harvest index (r = -0.523). These results are in agreement with those reported by Villareal et al. (1992) that above-ground biomass production was -negatively correlated with harvest index. The negative correlation between biomass production and number of grains/spikelet suggests that increased number of spikelets creates competition for assimilate supply to the developing grain during grain filling period. The very important character plot grain yield is non-significantly correlated with all the characters except above-ground biomass production. It is not known that some of the positive associations why do not affect final yield at this environment.