Data on the average percentage of parents indicated parental performance as shown in (Table 3). On average, parents took more days (115.43) to reach 75% maturity, whereas the F₁ hybrids took significantly fewer days (109.12) to 75% maturity. The results revealed that parent Prodip took maximum days to 75% full development (119.50), whereas parent Sonalika took minimum days to reach 75% maturity (108.90). Regarding plant height, the parents on average, attained 78.41 cm plant height against 58.20 cm of F₁ hybrids, thus F₁ hybrids were shorter as compared to parents and were more desirable and can be regarded as resistant to lodging. From parents, Balaka produced taller plants measuring 85.55 cm; however, the shorter plants were noted by the parent Agrahani (64.20 cm).

For the spike length, the parents on an average produced shorter spikes (11.46 cm) as compared to longer spikes of F₁ hybrids (12.10 cm). Among the parents, Agrahani produced the longest spikes (12.40 cm), and the minimum spike

* = Significant at 5% level, ** = Highly Significant at 1% level.

length (10.60 cm) was noted for parent Kanchan. While the parents produced 15.91 spikelets on average as compared to 18.83 spikelets produced by F₁ hybrids. Among the parents, Sonalika produced the highest numbers of spikelets spike⁻¹ (17.10), while Kanchan produced the lowest (14.00) number of spikelets spike⁻¹. For grains spike⁻¹, the parents averagely recorded 42.25 grains spike⁻¹ against a huge increase in grains per spike of F₁ hybrids (74.04). The maximum grains spike⁻¹ (49.65) were recorded in parent Prodip while minimum grains spike⁻¹ (35.35) was noted in parent Kanchan.

On an average basis, the seed index of parents was 39.40 g, whereas the F₁ hybrids gave less seed index weighing 34.94 g. This large difference in parents and hybrids may be due to a greater number of grains in hybrids which ended up in less seed index. Among the parents, the highest seed index (45.21 g) was observed in Sonalika and lowest seed index (35.97 g) in Prodip. Regarding grain yield plant⁻¹, the parents on an average produced 17.69 g as compared to 31.47g of F₁ hybrids. Thus, F₁ hybrids showed a big increase in grain yield due to their heterotic effects. From parents, the maximum yield per plant was recorded in Kanchan (19.30 g) and minimum in Sonalika (15.75 g). Harvest index in parents, on an average, was recorded as 42.78% as compared to 46.34% of F₁ hybrids. The highest yield index among parents was given by Kanchan (45.97%) and the lowest harvest index was recorded in Protiva (42.63%). On average, total dry matter recorded for parents was 14.00 g, whereas F₁ hybrids produced considerably higher biomass (67.91 g) against the average of parents. These results suggested that due to heterotic effects the hybrids accumulated more total dry matter as compared to their parents. Among the parents, Agrahani weighed maximum total dry matter per plant (44.00 g), while less biomass was weighed by Sonalika (38.20 g).

The average percentage of F₁ hybrids is given in (Table 3). The data revealed that cross Protiva × Prodip took maximum days (111.35) to reach 75% maturity, while cross Prodip × Agrahani took minimum days for 75% maturity (107.8) as compared to rest of the hybrids. For plant height, Prodip × Kanchan cross produced taller plants measuring 64.15 cm, and the shorter plants of 54.20 cm were observed in Protiva × Prodip cross. However, for the spike length, the maximum value was noted in Agrahani × Kanchan cross (13.15), while cross Protiva × Prodip showed minimum value (10.90) against the other crosses. For spikelets spike⁻¹, Prodip × Agrahani developed a greater amount (20.90), whereas Balaka × Agrahani produced the lowest amount (15.10) for this trait. For grains/spike, the cross Prodip × Kanchan developed a greater number of grains spike⁻¹ (84.20) against other crosses, yet minimum (63.45) amount of grains spike⁻¹ were achieved from cross Balaka × Agrahani. The cross Prodip × Protiva gave a higher seed index (44.19 g); however, the lower seed index (21.41g) was recorded in Prodip × Kanchan cross. The Prodip × Kanchan cross-produced maximum grains yield plant⁻¹ (36.45 g), whereas the cross Balaka × Agrahani gave the lowest yield plant⁻¹ (26.00 g). The maximum harvest index (%) was noted for Prodip × Agrahani cross (51.66) while minimum value was observed in Protiva × Prodip cross (43.23). In the case of total dry matter, hybrid Prodip × Kanchan produced plants, which weighed more biomass plant⁻¹ (83.15 g), while less biomass plant⁻¹ (52.20 g) was recorded for Balaka × Agrahani.

The hybrid vigor of various traits was calculated, and the potential of F₁ hybrids to improve various yields and their related traits were determined by using the hybrid vigor. The results of the hybrid heterotic effect of days to 75% in the F₁ hybrid are shown in (Table 4). Results showed that all F₁ hybrids showed negative comparative heterosis and hetero-beltiosis. The destructive comparative heterosis is between −2.65% and −9.11%, while the heterosis is between −6.21% and −9.97%. The highest negative relative heterosis was recorded in the cross Prodip × Sonalika (−9.11%) as compared to Prodip × Agrahani (−9.02%). The cross Prodip × Agrahani showed a greater hetero-beltiosis (−9.79%), followed by Prodip × Sonalika (−9.49%). All hybrids showing negative effects were considered to take 7 days to reach 75% maturity, as such hybrids produce premature hybrids.

The heterotic effects of F₁ crosses on the height of the plant are shown in (Table 5). The results showed that the relative mid-parent heterosis and hetero-beltiosis of all hybrids are expressed as negative values. Negative relative mid-parent heterosis ranges from −16.19 to 36.64, and hetero-beltiosis ranges from −22.19 to −43.35. The maximum relative value for heterosis was calculated in cross Protiva × Agrahani (−36.64) followed by Prodip × Sonalika (−32.94). The maximum hetero-beltiosis value was recorded by Protiva × Prodip (−43.35%) followed by Balaka × Agrahani (−41.30%). The negative hetero-beltiosis is considered desirable for plant height.

The spike length has a direct impact on grains plant⁻¹ because elongated spikes have extra spikelets, so there are more grains spike⁻¹ and therefore, improved grain yield. The wheat flower is an important for efficient production of hybrid seed. Wheat flowers are composed of spikelets; it is a complex procedure (Figure 1). The relative heterosis and hetero-belitiosis of F₁ hybrids present are shown in (Table 6). The relative heterosis of spike length ranged from 16.52% to 8.35%, while hetero-beltiosis ranged from 12.50% to −9.27%. However, the maximum value of relative heterosis was noted in the cross Prodip × Agrahani (16.52%), while the minimum value was recorded in Sonalika × Agrahani (8.35%). For the hetero-belitiosis, the maximum and minimum values recorded in Prodip × Sonalika and Sonalika × Agrahani had a hybrid effect of 12.50% to −9.27%, respectively. The heterotic effects of spikelets for spike⁻¹ are shown in (Table 7). Eight out of nine hybrids and two out of nine hybrids exhibited a positive relative effect of heterosis and hetero-beltiotics, ranging from 33.11% to −5.91% and 25.15% to −11.17%, respectively. It was observed that the crosse Agrahani × Kanchan showed greater relative heterosis of 34.19%, while the minimum value (5.91%) was recorded in Balaka × Agrahani. For hetero-beltiosis,

the highest value was recorded for cross Prodip × Kanchan (25.15%), while the minimum value was noted for cross Balaka × Agrahani (−11.17%). The results showed that two hybrids, Prodip × Agrahani, and Prodip × Kanchan showed the highest heterotic effect and were the most ideal hybrids among the remaining crosses. The hybrid effects of average hybrids of F₁ hybrids and improved parents on number of grains spike⁻¹ in hexaploid wheat are shown in (Table 8). Interestingly, all nine hybrids showed positive relative and hetero-biotic effects which are different from 43.58 to 113.52 and 29.70% to 95.98%, respectively. Many hybrids showed excellent heterosis effects, but the Agrahani × Kanchan

showed greater relative heterosis (113.52%), and for hetero-beltiosis cross, Agrahani × Kanchan showed the greatest heterosis (95.98%).

The effect of heterosis of F₁ hybrids in hexaploid wheat on the seed index of middle and superior parents is given in (Table 9). Among nine hybrids, five showed positive relative heterosis and hetero-beltiosis. Hybrids showing the greatest relative heterosis accordingly exhibited higher hetero-beltiosis. Prodip × Sonalika and Prodip × Kanchan indicated that the relative heterosis of the seed index was between 16.32% and −41.84%. For hetero-beltiosis, the ranges recorded for Agrahani × Kanchan and Prodip × Kanchan were between 14.60% and −43.15%, respectively. The two highest-ranked hybrids were: Prodip × Sonalika and Prodip × Kanchan, which showed higher relative heterosis and hetero-beltiosis effects, and may, therefore, be the first choice to increase wheat seed index. The effect of heterosis for F₁ hybrids in hexaploid over their mid and better parents of yield plant⁻¹ is given in (Table 10). The results showed that all nine hybrids showed considerable positive relative heterosis and hetero-beltiosis. However, the relative heterosis ranged from 38.82 to 108.22, while the influence of hetero-beltiosis ranged from 35.23% to 93.71%. Six hybrids showed that the maximum value for relative heterosis (108.22) was shown by cross Sonalika × Prodip, while minimum heterosis (38.82) was recorded for Kanchan × Sonalika. While, for hetero-beltiosis, cross Sonalika × Agrahani and Kanchan × Sonalika showed greater and minimum values of 93.71 and 35.23, respectively. At least six hybrids exhibited above 65% hetero-beltiotic effects.

Heterotic effects of F₁ hybrids on improved and better parents for harvest index in hexaploid wheat are shown in (Table 11). Eight out of nine hybrids exhibited positive relative heterosis while only six hybrids showed positive hetero-beltiotic effects. In the case of relative heterosis, the value varied from 0.03%

to 17.39% and positive hetero-beltiosis varied from 14.35% to −3.37%. It was also observed that the greatest value for the trait of grain yield plant⁻¹ (17.39) was obtained in cross Prodip × Agrahani of and the lowest was recorded in cross Protiva × Prodip (−1.52).

The results regarding relative heterosis and hetero-beltiosis are presented in (Table 12). The results showed that the relative heterosis in F₁ hybrids ranged from 21.53% to 100.24%. However, the maximum value of relative heterosis was recorded in cross Prodip × Kanchan (100.24%) followed by the cross Sonalika × Agrahani (92.21%). The minimum value for the relative heterosis was recorded in cross Balaka × Agrahani (21.53%) for total dry matter. As far as hetero-beltiosis is concerned, the maximum value was recorded for the cross Prodip × Kanchan (91.58%) and the minimum value was shown by the cross Balaka × Agrahani (18.63%).

Correlations

The correlation coefficients were worked-out among the grain yield and its mechanisms, so as to determine one or several traits highly correlated with yield and can be improved through indirect selection. The outcomes are presented in (Table 13).

Days to 75% maturity

Number of days to 75% maturity was significant but negative correlation with grains spike⁻¹ (r = −0.747**), harvest-index (r = −0.600**), spike length (r = 0.444**), spikelets spike⁻¹ (r = −0.504**) grains production plant⁻¹ (r = −0.682**) and total dry matter (r = −0.617**). Nevertheless, by 75% of maturity days and the seed index (r = 0.362**) revealed significant-positive correlation through height of plant (r = 0.720**).

* = Significant at 5% level, ** = Highly Significant at 1% level.

Grains spike⁻¹

Grain spike⁻¹ was significant and positively correlated with harvest-index (r = 0.388**) and yield plant⁻¹ (r = 0.362**), spikelet spike⁻¹ (r = 0.779**), grains yield plant⁻¹ (r = 0.930**), total dry matter (r = 0.895**), but this characteristic did not prove ideally correlated with plant height (r = −0.738**) and seed index (r = −0.642**).

Harvest index

There was a positive and significant correlation between the harvest index and spike length (r = 0.340**) and grain yield plant⁻¹ (r = 0.323**), while this parameter was only negatively related to plant height (r = −0.257*).

Plant height

Plant height was positively correlated with seed index (r = 0.580**), total dry matter (r = 0.716**) and grains yield plant⁻¹ (r = 0.747**). While a negative but significant interrelationship was observed through characters such as spike length (r = −0.339**) and spike⁻¹ (r = −0.54**).

Seed index

The seed index was negatively but significantly correlated with spikelets spike⁻¹ (r = −0.418**), total dry matter (r = −0.717**) and grain yield plant⁻¹ (r = −0.63**).

Length of spike

The length of the spike was only positively correlated with spikelets spike⁻¹ (r = 0.527**). It was positively correlated but non-significant with total dry matter (r = 0.140) and grain yield plant⁻¹ (r = 0.206).

Spikelets spike⁻¹

This trait confirmed a positive and significant correlation with total dry matter (r = 0.765**) and grain production plant⁻¹ (r = 0.786**).

Total dry matter

Total dry matter showed a positive correlation in grain yield plant⁻¹ (r = 0.97**).

Yield related characters, as well as other complex traits, are regulated by various genetics factors. Due to the genetic complexity of traits and interaction among genotypes and the environment, the selection of parents becomes difficult, which provides hybrids with a higher yield [32]. ANOVA analysis showed that the genotypes change significantly with all production characteristics analyzed in this study (p ≤ 0.01), for example, days to 75% maturity to, height of plant, spike length, spikelets spike⁻¹, grains spike⁻¹, seed index, grains yield plant⁻¹, harvest-index and total dry matter (Table 2). The average percentages obtained by the analysis of parameter suggested significant changes in parents and hybrids of all traits except grains yield plant⁻¹, which is not significant only in the parents. On average, however, parents took many days to reach 75% maturity, whereas the F₁ hybrids took significantly fewer days to 75% maturity. Similarly [33] described that parents took more days to 75% maturity compared to F₁ wheat hybrids. Regarding plant height, the parents attained 78.41 cm plant height against 58.20 cm by F₁ hybrids, thus F₁ hybrids were shorter as compared to parents and were more desirable and resistant to lodging. With respect to the length of the spike, the parents produced shorter spikes (11.46 cm) as compared to longer spikes by F₁ hybrids (12.10 cm). For the number of spikelets spike⁻¹, the parents produced 15.91 as compared to 18.83 spikelets spike⁻¹ in F₁ hybrids. As far as grains spike⁻¹ is concerned, the parents recorded 42.25 grains/spike against a huge proliferation in grains/spike of F₁ hybrids (74.04) (Table 2). Similarly, [20] revealed that parents comparatively showed higher plant length, shorter spikes, lesser spikelets spike⁻¹ as well as grains spike⁻¹ than F₁ hybrids.

On an average basis, the seed index of parents was 39.40 g, whereas the F₁ hybrids revealed less seed index weighing 34.94 g. This large difference in parents and hybrids may be attributable to the higher number of grains in hybrids which ended up in less seed index. Regarding grain yield plant⁻¹, the parents on an average gave 17.69 g as compared to 31.47 g of F₁ hybrids. Thus, F₁ hybrids showed a big increase in grain yield due to their heterotic effects. [34] reported higher grain yield plant⁻¹ for maize hybrids LM-13 × IC-32809. Harvest index in parents was recorded as 42.78% as compared to 46.34% of F₁ hybrids. Similarly, the harvest index in F₁ wheat hybrids (Prodip × Kanchan) was higher as compared to parents [33]. The total dry matter of parents stood at 14.00 g, whereas F₁ hybrids produced considerably higher biomass (67.91 g) against the average of parents. These results suggest that due to heterotic effects, the hybrids accumulated more total dry matter as compared to their parents (Table 3).

The heterotic effects in F₁ hybrids and parents for 75% days to maturity are presented in (Table 5), which showed that all the hybrids indicated a positive association for heterosis and hetero-beltiosis. The negative heterosis varied from −2.65% to −9.11%, and hetero-beltiosis ranged from −6.21% to −9.79%. The highest but desirable negative relative heterosis (−9.11%) was observed for the cross of Prodip × Agrahani, followed by Prodip × Sonalika (−9.02). While the cross Prodip × Agrahani showed greater hetero-beltiosis (−9.79%), followed by Prodip × Sonalika (−9.49%).The results of heterotic effects in F₁ hybrids for plant height are in (Table 4). The negative heterosis is desirable because plants with shorter heights are considered as resistant to lodging. Results showed negative effects for both relative heterosis and hetero-beltiosis. The negative relative heterosis varied from −16.1992 to −36.6426, while hetero-beltiosis ranged from −22.19 to −43.35. The maximum value of relative heterosis was calculated for cross Protiva × Agrahani followed by Prodip × Sonalika. For hetero-beltiosis, the maximum value was observed in Protiva × Agrahani followed by Balaka × Agrahani. Similar to present findings [35] [36] [37] observed negative heterosis for plant height. Spike length had a direct effect on individual plants for seed yield because longer spikes had more spikelets. The relative heterosis ranged from 16.52 to −8.35, and the hetero-beltiosis ranged from 12.50 to −9.27. The largest heterosis of the spike length was observed in cross Prodip × Agrahani and the smallest heterosis was observed in cross Sonalika × Agrahani. For hetero-beltiosis, the maximum (12.50) and minimum (−9.27) peak lengths were recorded in Prodip × Sonalika and Sonalika × Agrahani, respectively. Our results are consistent with those of [38] [39] [40] who reported highly significant and maximum heterosis of the spike length.

Heterotic effects showed that the cross Agrahani × Kanchan exhibited the highest relative heterosis (34.19%) while minimum value was recorded in Balaka × Agrahani (−5.91%). For hetero-beltiosis, the cross Prodip × Kanchan expressed higher value (25.15%), nevertheless, minimum hetero-beltiosis was recorded in cross Balaka × Agrahani (−11.17) respectively. [16] [41] [42] also reported positive heterosis for spikelets spike⁻¹. Heterotic effects of F₁ hybrids over their mid and better parents for grains spike⁻¹ in hexaploid wheat indicated that the cross Agrahani × Kanchan indicated a higher amount for relative heterosis (113.52%) while minimum relative heterosis was expressed by Protiva × Prodip of 43.58. Regarding hetero-beltiosis, the higher hetero-beltiotic effects were observed in cross Agrahani × Kanchan (95.98) and minimum effects in cross Protiva × Prodip (29.70%). Our findings are in conformity with those of [12] and [16] who also observed significant positive heterosis for grains per spike. Heterotic effects of F₁ hybrids over their mid and better parents for seed index in bread wheat indicated that relative heterosis ranged from 16.32 to −41.84 in hybrids Prodip × Sonalika and Prodip × Kanchan respectively. While for hetero-beltiosis it ranges from 14.60 to −43.15 of Agrahani × Kanchan and Prodip × Kanchan, respectively. Like our findings, [35] found a significant and fair amount of mid parent as well as better parent heterosis for seed index. The heterotic effects of F₁ hybrids over their mid and better parents for grains yield plant⁻¹ indicated that the maximum relative heterosis was shown by cross Sonalika × Agrahani (108.22%) while minimum heterosis was recorded by Kanchan × Sonalika of (38.82%). As far as hetero-beltiosis is concerned, the hybrids Sonalika × Agrahani and Kanchan × Sonalika showed maximum and minimum heterotic effects (93.71% and 35.23% respectively). [12] [40] [41] also reported significantly high relative heterosis and better parent heterosis for grain yield plant⁻¹.

However, the maximum relative heterosis was recorded in cross Prodip × Agrahani and minimum in cross Protiva × Prodip of −1.52. In the case of heterobeltiosis, the values varied from 14.35% to −3.37% in Prodip × Agrahani and Agrahani × Kanchan respectively. The results regarding relative heterosis and hetero-beltiosis for total dry matter are presented in (Table 12). The relative heterosis in F₁ hybrids ranged from 21.53% to 100.24%. Nonetheless, the maximum relative heterosis was recorded in hybrid Prodip × Kanchan (100.24) followed by Sonalika × Agrahani (92.21%). The minimum relative heterosis was recorded in cross Prodip × Agrahani (21.53%) for the trait total dry matter. As far as hetero-beltiosis is concerned, the maximum value was recorded for cross Prodip × Kanchan (91.58%) and minimum value in cross Balaka × Agrahani (18.63%) for total dry matter plant⁻¹.

Correlation coefficients played a role among the nine yields and their related characteristics. Days to 75% maturity were significant and positively correlated with grains yield plant⁻¹. Plant height showed a positive correlation with grains yield plant⁻¹. Spikelets spike⁻¹ was positively associated with grains yield plant⁻¹. The results of the current study were confirmed by [3] and [43] who described that the grains yield plant⁻¹ is critical, and the yield is divided by the tillers plant⁻¹, spikelets spike⁻¹ and grain spike⁻¹. [37] also showed a significant positive correlation between grains yield plant⁻¹ and its mechanisms (such as the production of tillers plant⁻¹, spike length, spikelets spike⁻¹, grain spike⁻¹ and 1000 grains weight g). [44] observed genotype and phenotypic correlations between grain yield and other yield components, such as tillers plant⁻¹, number of spike per square meter, number of grains spike⁻¹, total biomass plant⁻¹, and harvest index and 1000 grains weight (g). [45] pointed out that plant height has a significant positive correlation with the spike length, spikelets spike⁻¹, grain spike⁻¹ and grains yield spike⁻¹.

Generally, the correlation coefficient revealed that days to 75% maturity had negative associations with the majority of yield traits suggesting that the genotypes that mature earlier could be low yielding. Grains spike⁻¹ increased by increasing the spike length, and harvest index; consequently, grains yield will increase, thus grains spike⁻¹ presented the positive association with all of these yield characters. On the contrary, the increase in grains number will cause a reduction in speed index because of the negative association between these traits. As with 75% maturity and plant height present negative association to grains yield plant⁻¹ and its components. Similar to our findings [27] demonstrated that grains yield plant⁻¹ is positively correlated with grains number spike⁻¹, but is different from current results. They observed a positive correlation between grains yield and 75% of maturity days. Our results showed a negative correlation between grain yield and plant height, spike length, and 1000 grains weight (g). Grain yield was significantly and positively correlated with all characteristics (plant height, spike length, spikelets spike⁻¹, grains spike⁻¹, and grains spikelets⁻¹), which suggested that other positive correlations could be obtained through traits that increased grains yield and good selection criteria for wheat improvement.