الفهرس 
Acknowledgement
Performance of selections and their basesOnly 14 pages are availabe for public view
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Abstract
The obtained results of evaluation some different genotypes of alfalfa in two seasons as well as study the effects of one cycle of mass selection to root characteristics on forage yield could be summarized as follows:
I– Evaluation of six alfalfa cultivars for forage yield and its components:
1- Highly significant differences were found over six cuts among studied genotypes of alfalfa for plant height, number of tillers/m2, leaf/plant ratio, seasonal fresh and dry forage yield/plot in both respective seasons. This result confirms the genetic make-up and differences among those studied genotypes of alfalfa. Moreover, the combined analysis showed highly significant differences between the two years, varieties and year x var. interaction for plant height, leaf/plant ratio and seasonal dry forage yield/plot, revealing differential genetic responses for the studied genotypes from year to other.
2- The second growing year gave higher values than the first one recorded general means of 70.9 cm, 578.6, 46.0%, 85.5 kg and 22.0 kg for plant height (cm), number of tillers/m2, leaf/ plant ratio (%), seasonal fresh and dry forage yield/plot, kg, respectively.
3- The great variation was recorded with the obtained values of P.C.V. and G.C.V. for studied traits except leaf/plant ratio and interpreted the significant differences and means possessed with studied genotypes. This variation will be benefit for new line selection through those genotypes of alfalfa.
4- The all values of correlation coefficient were highly significant, positive and recorded more than 95%. The highest strong and positive estimates were found between number of tillers/m2 and each of seasonal dry forage yield/plot (0.9975) and fresh forage yield/plot (0.9947).
5- Strongly positive direct and indirect effects were reported for number of tillers/m2 on seasonal fresh forage yield/plant. This direct effect was 0.9702 and the indirect effects through plant height and leaf/plant ratio were 0.9429 and 0.9446, respectively, confirming the powerful direct and indirect effects of number of tillers on seasonal fresh forage yield for alfalfa.
II- Mass selection effects of root characteristics on forage yield and its components in two alfalfa varieties.
1-Root traits in base population and selections:
1- Large variability estimates were recorded among the 1500 plants of the two base populations for root characteristics. The range were 6-25, 0.80-16.75 and 0.4-1.4 with mean of 12.5, 5.2 and 0.7 in Wady local and 4.5-26, 1.26-11.14 and 0.4-1.1 with mean of 15 cm, 3.8 g and 0.7 cm in exotic Melissa cultivar for root length, root weight and crown diameter, respectively.
2- The range were 12.8-25, 6.45-16.75 and 0.8-1.4 with mean of 15.4, 8.7 and 0.9 for selections of Wady local and 15.1-24.0, 4.7-11.14 and 0.8-1.1 with mean of 17.1 cm, 5.9 g and 0.8 cm for selections of exotic Melissa cultivar for root length, root weight and crown diameter, respectively. The coefficient of variation in selections recorded values lower than those of base population in both cultivars. The estimates in selections were 12.5, 21.7 and 10.6% in selections compare to 22.4, 42.3 and 14.3% in base population of Wady local; and 9.3, 17.5 and 7.5% in selections compare to 16.7, 34.2 and 14.3% in base population of exotic Melissa for root length, root weight and crown diameter, respectively. Consequently, selections had less genetic variation comparing their bases of both cultivars. It is obvious that the variability among plants of Wady local cultivar is higher than exotic Melissa cultivar.
3- The selection differential between means of selections and base population were 2.9, 3.5 and 0.2 in Wady local and 2.1, 2.1 and 0.1% in exotic Melissa for root length, root weight and crown diameter, respectively
4- The correlation coefficients between each pair of root length, root weight and crown diameter were significant and positive in base population and selections of both cultivars.
2-Performance of selections and their bases:
1- Significant differences were found for the fresh and dry forage yield between selected genotype and its base Wady local in first cut, leaf/plant ratio between each selected genotype and its base in both cultivars and plant height of exotic Melissa cultivar in third cut, number of tillers/plot, fresh and dry forage yield/plot of both cultivars, leaf/plant ratio between selected genotype and its base in Wady local cultivar and plant height in exotic Melissa cultivar in fourth cut, number of tillers/plot between the selected genotype and its base in both cultivars, fresh and dry forage yield/plot in Wady local cultivar and plant height in exotic Melissa cultivar fifth cut, and fresh and dry forage yield/plot between selected genotype and its base in both cultivars and number of tillers/plot in Wady local cultivar in sixth cut.
2- The highest values of plant height were 97.3 and 94.3 in fourth cut for Sel.1 and its base Wady local cultivar, respectively. Also, the highest values of 84.0 in fourth cut and 76.3 cm in fifth cut recorded for Sel.2 and its base exotic Melissa cultivar, respectively. It is obvious from these results that the plant height was increased from the first cut until the maximum value in fourth cut (sometime in fifth cut) and decreased again in next cuts. This may be due to regrowth with subsequent cuts in optimum environment conditions and adaptation, especially for Sel.1 and its base Wady local cultivar.
3- The values of G.C.V. and P.C.V. were decreased gradually from 5.50 and 5.78 in first cut to 0.15 and 0.30 in sixth cut between Sel.1 and its base Wady local cultivar and from 18.66 and 19.57 in second cut to 7.43 and 7.80 in sixth cut between Sel.2 and its exotic Melissa cultivar, respectively. The values of G.C.V. and P.C.V. were less between Sel.1 and its base Wady local when comparing the values between Sel.2 and its base exotic Melissa. This may be due to the expressing genes of adaptation with local ones.
4- The highest value of selection response for plant height was 8.5% in first cut and gradually decreased in next cuts until 0.5% in sixth cut for selected genotype Sel.1. The highest value of selection response in Sel.2 was 32.2% in second cut and also decreased gradually to 9.2% in fifth cut.
5- In general, there is remark observation that the highest values of selection response for plant height were correlated with the highest values of G.C.V. and PCV and vice versa in both cultivars. For example, the highest selection response of 8.5% correlated with highest G.C.V. of 5.50% and P.C.V. of 5.78% in first cut and lowest selection response of 0.5% correlated with lowest G.C.V. of 0.15% and P.C.V. of 0.30% in sixth cut for Sel.1 and its base. Also, the highest selection response of 32.2% correlated with highest G.C.V. of 18.66% and P.C.V. of 19.57% in second cut and lowest selection response of 9.2% correlated with lowest G.C.V. of 6.01% and P.C.V. of 6.20% in fifth cut of Sel.2 and its base. This result may be due to the greater amount of genetic variation could express in more response to selection.
6- The third cut possessed the highest values of number of tillers for Sel.2 (365.3) and its base exotic Melissa cultivar (304.0) as well as the Wady local cultivar (450.7). But, it was late to fourth cut for Sel.1 (522.7). It was clear that the regrowth in third and fourth cuts expressed in highest values of number of tillers/m2 for both selected genotypes and their bases. The selected genotypes Sel.1 and Sel.2 surpassed significantly their bases in fourth and fifth cuts and in addition to Sel.1 in sixth cut for number of tillers/m2.
7- The values of G.C.V. and P.C.V. for number of tillers/m2 varied from 6.95 and 7.15 (third cut) to 12.49 and 12.52 (fifth cut) for Sel.1 and its base Wady local cultivar, respectively. Also, it ranged from 8.23 and 9.64 (first cut) and 20.44 and 20.56 (fourth cut) between Sel.2 and its base exotic Melissa cultivar, respectively. It is obvious that the high values of G.C.V. and P.C.V. were correlated with the significant differences in analysis of variance between selected genotypes and their bases of both cultivar in late cuts and expressed the differences in regrowth among those selections and bases of alfalfa.
8- The estimated values of direct selection response for number of tillers/m2 ranged from 10.7 (third cut) to 19.4 % (fifth cut) for Sel.1 over its base Wady local cultivar. The values varied from 14.6 (first cut) to 34.0% (fourth cut) for Sel.2 over its base exotic Melissa cultivar.
The highest estimates of selection response for number of tillers/m2 were correlated with the highest values of G.C.V. and P.C.V. and vice-versa for both selected genotypes and their bases. For example, the highest selection response of 19.4 was correlated with highest G.C.V. of 12.49 and P.C.V. of 12.52% (fifth cut), and lowest selection response of 10.7 expressed with lowest G.C.V. of 6.95 and P.C.V. of 7.15% (third cut) for Sel.1 and its base Wady local cultivar. Same trend could be found with Sel.2.
9- The highest estimates of leaf/plant ratio were found in sixth cut and recorded 50.4 and 49.6 for Sel.1 and its base Wady local and 48.6 and 47.5% for Sel.2 and its base exotic Melissa, respectively. It is very clear results that the estimates of leaf/ plant ratio were increasing gradually from first cut to sixth cut for both selected genotypes (Sel.1 & Sel.2) and their bases, reflecting the good regrowth in late cuts comparing to early cuts in those genotypes of alfalfa.
10- Narrow values of differences for leaf/plant ratio were found between each selected genotype and its base, which expressed in less estimates for G.C.V. and P.C.V. It is clear results that the high values of G.C.V. and P.C.V. were correlated with presence of significant differences presented in analysis of variance for Sel.1, Sel.2 and their bases.
11- After one cycle of mass selection, the highest selection responses for leaf/ plant ratio were 4.3 (second cut) and 3.6% (third cut) for Sel.1 and Sel.2, respectively. It is obvious that the high values of selection responses were associated with high genetic differences between selected genotype and its base which expressed in G.C.V. and P.C.V. estimates and vice-versa. It is remark result that when the selection response was increased to the highest value decreased again in next subsequent cuts. That result may be due to the decrease in stem growth rate.
12- The highest values of fresh forage yield/plot were yielded in fourth cut for Sel.1 (21.0) and its base Wady local cultivar (19.2).
Also, the highest estimates for Sel.2 (13.0) and its base (10.2) were recorded in fourth and third cuts, respectively. It is remark observation that the fresh forage yield was increased gradually from first cut to the highest value in mid-cut and decreased again in late cuts. Concerning the adaptation issue, this result may be associated with the rate of regrowth with subsequent cuts.
13- It is clear that the lowest values of G.C.V. (0.60) and P.C.V. (0.70%) of third cut reflect the very less differential value (0.20) of fresh forage yield mean between Sel.1 (16.7) and its base Wady local cultivar (16.5 kg). Otherwise, the largest values of G.C.V. (9.66) and P.C.V. (9.85%) of sixth cut reflect the increasing of differential value (2.2) between mean for Sel.1 (14.0) and its Wady local (12.2 kg). The highest values of G.C.V. and P.C.V. between Sel.2 and its base exotic Melissa cultivar were 21.47 and 22.01% in fourth cut. This may be due to the largest differential value (3.5 kg/plot) between the mean of Sel.2 and its base exotic Melissa cultivar yielded with fourth cut. In general, the high estimates of G.C.V. and P.C.V. reflect the significant differences obtained with analysis of variance for fresh forage yield/plot among selected genotypes and their bases. It is remark measures that the G.C.V. and P.C.V. between Sel.1 and its base Wady local cultivar were less compare to those of Sel.2 and its base exotic Melissa cultivar, in spite of the mean of fresh forage yield/plot is larger for Sel.1 and its base than Sel.2 and its base for all cuts.
14- The estimates of selection response were 13.6, 10.8, 1.2, 9.4, 9.6 and 14.8 for Sel.1 and 15.0, 14.3, 25.5, 36.8, 24.4 and 21.3 for Sel.2 estimated over their bases for first, second, third, fourth, fifth and sixth cut, respectively. The highest selection response (14.8%) correlated with the highest G.C.V. (9.66%) and P.C.V (9.85%) in sixth cut for Sel.1. Also, the highest response (36.8%) associated with the highest G.C.V. (21.47%) and P.C.V. (22.01%) in fourth cut for Sel.2. It is concluded that the one cycle of mass selection for root characteristics has effectiveness to increase fresh forage yield/plot by 9.9 and 22.9% in local and exotic populations over all cuts, respectively. So, it is promising way for developing variety in alfalfa.
15- The highest estimates for dry forage yield/plot were 4.0 and 3.6 kg yielded in fourth cut for Sel.1 and its base Wady local, respectively. Also, the highest values for Sel.2 (2.5) and its base (1.9) were measured in fourth and third cuts, respectively.
It is general remark observation that the dry forage yield/plot was increased gradually from first cut to the highest values in mid-cuts (fourth or third) and decreased again in late cuts for Sel.1, Sel.2 and their bases. This result of dry forage yield/plot associated strongly with the trend of fresh forage yield/plot. Also, both traits were corresponding with regrowth in different cuts.
16- The highest values for G.C.V. and P.C.V. were 11.29 and 11.20% recorded in sixth cut between Sel.1 and its base Wady local, respectively. Also, the highest values expressed 22.14 and 22.47% between Sel.2 and its base exotic Melissa cultivar in fourth cut, respectively.
It is clear that the estimated values of G.C.V. and P.C.V. for Sel.1 and its base Wady local cultivar were lower than those of Sel.2 and its base exotic Melissa cultivar. Otherwise, the means of dry forage yield/plot were large for Sel.1 and its base compare to Sel.2 and its base. This may be due to the good adaptation with strong growth for local ones. The high estimates of G.C.V. and P.C.V. reflect the significant differences resulted in mean square analysis for dry forage yield for both local and exotic populations.
17- The estimated values of selection response for dry forage yield/plot were 16.7, 10.7, 6.5, 11.1, 11.5 and 15.4 % for Sel.1 and 14.3, 11.1, 26.3, 38.9, 23.5 and 23.5 % for Sel.2 for first, second, third, fourth, fifth and sixth cut, respectively. It is clear result that value of selection response for dry forage yield/plot was higher for Sel.2 than Sel.1. The high selection response of 16.7 and 15.4% were correlated with the high G.C.V. and P.C.V. of 9.13 and 9.36; 11.20 and 11.29% for Sel.1 in first and sixth cut, respectively. Also, the highest response of 38.9% was associated with the highest G.C.V. and P.C.V. of 22.14 and 22.47% in fourth cut for Sel.2.
In general, the obtained results revealed that the one cycle of mass selection for root characteristics was effective to increase dry forage yield/plot by 11.9 and 22.9% (overall cuts) in selections of local and exotic populations, respectively. Consequently, it is powerful method to develop superior genotypes in alfalfa. The low response in local population comparing the exotic one may be due to the high adaptation for local population.
18- The correlation coefficients after one cycle of mass selection for root characteristics revealed that the positive highly significant values (more than 95%) were recorded between fresh and dry forage yield for all cuts in both local and exotic populations, reflecting the strong association among the expressed genes for both traits.
Number of tillers/m2 had highly positive and significant correlation coefficients (r= 0.863 ~ 0.984) with fresh and dry forage yield/plot in first and fifth cuts for both local and exotic populations, except in first cut for exotic one, reflecting the effectiveness of number of tillers on fresh and dry forage yield. Moreover, the high positive and significant correlation coefficients (r= 0.843 ~ 0.861) were recorded between number of tillers/m2 and each of plant height in fourth and sixth cuts and leaf/plant ratio in first, third, fourth and sixth cuts in exotic population only, reflecting the strong association among those traits in exotic comparing the local population. The same result conducted between plant height and each of leaf/plant ratio, fresh and dry forage yield, where recorded values of correlation coefficients ranged from 0.858 to 0.890 only in exotic one.
Likewise, strong positive and significant correlation coefficients were found between leaf/plant ratio and each of fresh and dry forage yield with values ranged from 0.799 to 0.894 in first, third, fifth and sixth cuts for exotic and from 0.814 to 0.825 in fourth cut for local populations. This last result express the gene associating among leaf/plant ratio, fresh and dry forage yield in respective cuts for the studied genotypes.
19- The path coefficient analysis overall cuts for selections and their base populations revealed that the direct and indirect effects of number of tillers/m2 exhibited superiority on fresh forage yield for selections comparing their bases. That direct effect of number of tillers/m2 on fresh forage yield was 0.2806 in base population increased to 0.8722 in selections. Likewise, its indirect effects on fresh forage yield were 0.2779 and 0.2802 in base population increased to 0.8350 and 0.8474 in selections with plant height and leaf/plant ratio, respectively. Otherwise, the direct and indirect effects of plant height exerted to be powerful in base population comparing the selections. The obtained direct effect of plant height on fresh forage yield was 1.4141 in base population and decreased to 0.3967 in selections. Moreover, its indirect effects on fresh forage yield were 1.4005 and 1.4044 in base population decreased to 0.3798 and 0.3843 in selections with number of tillers/m2 and leaf/plant ratio, respectively.
The results indicated that parameter like number of tillers of alfalfa should be given weight before preparing selection program for the alfalfa.