Mass selection for enhancement fruit yield in Edkawy cultivar of tomato under different irrigation intervals in southern of Egypt

Field experiments were carried out during the period from 2013 to 2017 in the winter season at the experimental farm, Faculty of Agriculture, South Valley University, Qena, Egypt. Improvement yield and its attributes in Edkawy local cultivar via mass selection were done for three cycles. The unselected base population (C0) and selected populations (C1, C2, and C3) evaluated under two different water availability, favorable normal condition, and drought. The combined analysis of variance showed that significant differences between unselected and selected populations as well as highly significant among three cycles populations were detected all studied traits. Average fruit weight, number of flowers per plant, fruit yield per plant, number of cluster per plant, number of fruit per plant, number of branches per plant, fruit set percentage, and plant height have significantly increased a response to mass selection under unfavorable conditions. These increasing values for average fruit weight were 3.24, 6.90, and 12.09% in C1, C2, and C3, respectively. Furthermore, there was a significant increase in the number of fruits per plant in the first (2.45%), second (9.48%) and the third (13.72%) cycles under drought conditions. Fruits yield per plant was increased by 4.70, 12.44 and 21.40% for unselected and selected population, respectively. There was positive and highly significant correlation among all studied traits. In the respect to base populations under water stress treatments, results revealed that the use of mass selection for improvement yield and its components of tomato cv. Edkawy appeared to be increasing significantly for all studied traits.

(introduction, mass selection, pure-line selection, hybridization), and evaluated germplasm under different abiotic stress, viz., heat, drought, and salinity.Egypt is the fifth largest producer of tomato in the world after China, USA, India and Turkey.Tomato is also the second largest vegetable crop in the world after potatoes.
The information of genotypic and phenotypic coefficient of variety is being helpful in outlining choice criteria from variable populace.When all is said in done, it was noticed that the estimation of phenotypic coefficient of variety is higher than the genotypic coefficient of variation (Tiwari et al., 2013).Mass selection utilized for cultivar improvement in plants included tomato for quite a long while back and it was valuable in developing cultivars.The proficiency of mass selection relies on upon quality impacts of the chose attributes, their heritability, population size and G×E interaction.Mass selection is compelling for characters controlled by additive genes.
In Egypt, tomato is grown over an area of 214016 ha annually, which produces 8288043 tons/ha with 38.37 tons/ha (FAO, 2014).Qena is one of the leading tomato production governorate in Egypt, it is occupies the third rank in tomato production after Sharkia and Noubaria.On the other hand, Qena ranked third after Sohag and Ismailia in terms of productivity by 22.3 ton per acre.Lessening the measure of water which is subjected or decreasing the quantity of water irrigation times is assuming an incredible part through upgrading plant capacities for water utilizes effectiveness (Kirda, 2002).
Water is typically the most restricting component for plant development.If plants do not get satisfactory precipitation or water system, the subsequent drought stress can lessen development more than all other environmental stresses.A plant reacts to absence of water by ending development and diminishing photosynthesis and other plant forms with a specific end goal to decrease water utilize (Khan et al., 2015).Drought and salinity are now far reaching in numerous locales and are relied upon to bring about genuine salinization of more than 50% of every single arable land by the year 2050 (Ashraf, 1994).
Tomato (Solanum lycopersicon L.) is a standout amongst the most vital vegetable products and is a standout amongst the most requesting as far as water utilize (Peet, 2005).The extent of change in tomato is for the most part in view of the degree of genotypic and phenotypic variation display in the material more is the hereditary potential and there will be more prominent odds of delivering a coveted sort.Information in regard of the nature and size of relationship of yield with different segment characters is an essential to acquire change the coveted bearing.A harvest rearing project went for expanding the plant efficiency requires thought of yield as well as of its segments that have an immediate or circuitous bearing on yield.Bodunde (2002), Metwally et al. (2003Metwally et al. ( , 2004)), Zakher (2005), Salib (2006), Bhnan (2008), Hidaytullah and Ghafoor (2008), Jitendra and Devendra (2011) and Rashwan (2015), the pervious researchers used different selection strategies for enhancing yield and its components of S. lycopersicon L, while Damarany (1994a) on cowpea and lettuce, Bakheit and Ali (2013) on Egyptian clover, and Gehan (2016) on sunflower.The review was done to improve the fruit weight and yield characters and to assess the performance of three cycles of mass selection in the drought stress of tomato cv.Edkawy.

Experimental site
A field experiment was carried out at the Experimental Farm of Faculty of Agriculture, South Valley University, Qena, Egypt (26° 11 N and 32°44 E) during 2013 to 2017 winter season.

Seeds material
Seeds of Edkawy tomato local cultivar were obtained from Agricultural Research Centre, ARC, Giza, Egypt.

Mass selection procedure
In the first season, base population (C0) seeds were sown in nursery at August, 1st 2013, without replication area, (50 rows 5.0 m long, 1 m apart and 30 cm between transplants).Agricultural practices were done and 50 plants with high yielding under drought stress (irrigation every 12 days) were selected according to 5% selection intensity.Seeds of selected plants were bulked together (C1) and sown in nursery at August 4th, 5th 2014 and 2015, respectively.The same procedure of mass selection was done to produce C2, and C3.Mass selection populations (C1, C2, and C3) and base population (C0) were sown on August 1 st 2016 and 2017 to evaluate selected plants to drought tolerance.All populations (C0, C1, C2, and C3) were assess under two irrigation intervals system which were: a. irrigation every 6 days (favorable), b. irrigation every 12 days (drought conditions).All agricultural practice was applied as recommend.

Data
Plant height cm (PH), number of branches per plant (NBP), number of cluster per plant (NCP), number of flowers per plant (NFP), number of fruits per plant (NFSP), average fruit weight (AFW), and fruit yield per plant g (FYP).

Statistical analysis
Data were statistically analyzed using analysis of variance for Randomized Complete Block Design (RCBD) for separate analysis.Combined analysis for the two years was analyzed using split plot analysis.Comparison among means was done using least significant differences (LSD) at 0.05% and simple correlation coefficient between traits were done according to Gomez and Gomez (1984).Realized gain% was estimated from combined means according to Gowda and Seetharam (2008) as follow: Realized gain% for C1 = C1 -C0 / C0 × 100, C2 = C2 -C0 / C0 × 100,

Population's performance
The separate and combined analysis for all studied traits in unselected (base population C 0 ) and selected population (C 1 , C 2 and C 3 mass selection) are presented in Table 1.The mean square for all studied populations under investigation as well as the variance among populations were significant for all studied characters, except fruit set in both seasons, and number of branches per plant in the second season indicating the wide diversity among all population and selected populations and the presence of true differences among the populations.Interaction among populations and years were insignificant for all studied traits.Means values of all studied traits in three cycles of selection increased gradually from C 1 to C 2 in both evaluations seasons as well as the combined analysis.The data are shown in Table 2.For plant height (cm), the means value ranged from 47.8 to 52.5 cm for C 1 and C 3 , respectively, and 9.5 to 11.2 for number of branches per plant, 18.8 to 21.3, number of cluster per plant, 55.5 to 58.8 number of flower per plant, 33.5 to 37.2 fruit per plant, 60.4 to 63.2% fruit set, 79.7 to 86.5 g average weight of fruit and 856.7 to 993.3 g for fruit yield per plant.These findings indicating that fruit yield of tomato could be improved via mass selection cycles because, its efficiency by improving such trait through increasing the frequencies of desirable genes which result to specific irregular mating which could have helped in breaking closely linkage group, sequence complexes of genes or eliminates the recessive alleles (Gowda and Seetharam, 2008).These results are in agreement with the findings of Damarany (1994a, b), Ghosh et al. (2010), Bakheit et al. (2011), Bakheit and Ali (2013), Hassan and Abdel-Haleem (2014), Rashwan (2015) and Gehan (2016).In the present study, mass selection cycles had a significant role in enhancing the mean values of most studied traits; this may be due to the presence of genetics factors that have more effect on such traits (Gehan, 2016;Rashwan, 2015) indicating that the mass selection cycles could be more effective after three cycles in improving fruit yield of tomato cv.Super strain B, and observed a positive and highly significant correlation among the fruit yield per plant and the other studied traits, and this indicate that mass selection can be used as a tool to improve the fruit yield per plant.
Data are presented in Table 2 indicating that the realized gain % was gradually raised from the first cycle of mass selection to the third cycle in all the studied traits.For plant height, it was 10.65, 16.90 and 21.53 for C 1 , C 2, and C 3 , respectively; 7.95, 15.91 and 27.27 number of branches per plant; 8. 67, 18.50 and 23.21 number of cluster per plant; 2.21, 4.97 and 8.29 number of flower per plant; 2.45, 9.48, 13.76 for fruit number per plant; 0.66, 4.33 and 5.33 for fruit set; 3.24, 6.87 and 12.05 for average weight of fruit, and 4.70, 12.44 and 21.90 for fruit yield per plant for C 1 , C 2 , and C 3 , respectively, as compared to base population C 0 .These results showed that significant increase was observed after application of mass selection cycles from the first cycle C 1 to the third C 3 .Many researchers (Kansouh, 2002;Zanata, 2002;Bhnan, 2008;Ara et al., 2009;Zakher, 2010;Singh and Cheema, 2011;Meseret et al., 2012;Kashif et al., 2013;  Rashwan, 2015) haave studied the effect of selection on tomato yield and yield attributes traits as number of fruit, number of cluster, number of flowers per plant and fruit yield per plant.They observed that the selection improved tomato yield and yield components and suggested that the presences heritability and genetic advance for yield characters.

Correlation coefficient
Table 3 shows the correlation between fruit yield per plant and the other studied traits in the   ).Improvement of crops depends on multiple factors; one of these, is in understanding the magnitude of the correlations among different yield characters components and it is considered the primary interest for enhancing yield through yield components.These results are in line with findings by Bakheit and Ali (2013), Meseret et al. (2012), Kashif et al. (2013), Rashwan (2015) and Gehan (2016).

Performance of tomato cv. Edkawy under drought stress conditions:
Water stress could have the vital effect on vegetative growth, flowering, fruit set, and yield of plants.The main effect of drought on plants is wilt.As a result of water shortage and this led to reducing growth and yield of plants (Khan et al., 2015).It is observed from the mean values of Figures 1 to 8 that there is a decrease in plant height cm, number of branches, number of cluster per plant, number of flowers per plant, number of fruits per plant, fruit set %, average weight of fruit, and fruit yield per plant by 21.4 and 22.8% in both seasons, respectively for plant height, 38.1 and 39.6 for number of branches, 26.5 and 26.9% for number of cluster, as for number of flower the decrease was 19.1 and 18.8%, in both seasons, respectively.While, it was 14.1 and13.3%for number of fruit per plant, on the other hand, the reduction in average weight of fruit per plant after application of drought was 33.3 and 33.6% and the huge reduction was observed in fruit yield per plant for 69.3 and 49.0% in both seasons, respectively.These results indicate that water stress reduced the growth parameters due to their harmful effect on photosynthesis, which led to decrease in growth and development of plants, as a result of lake energy production in plant cell.Similar results were detected by Pervez et al. (2009), Celebi (2014) (2017), Hussein and Abd El-Hady (2015), Hussein et al. (2014), andFarouk et al. (2011) on cowpea; Al Ameen (2012), Kheiralla et al. (1997) and Kheiralla and Ismail (1995) on wheat.

Conclusion
Data presented in this study indicated that mass selection for the three cycles has more effect for improving fruit yield per plant of tomato cv.Edkawy.In addition, the growth and yield parameters were reduced after exposure to water stress conditions.
combined analysis for both evaluation seasons 2016 and 2017of the 3 cycles of mass selection (C 1 , C 2 , and C 3 ) and base population (C 0 ).Fruit yield per plant g showed highly significant and positive association with plant height (r = 0.932 ** ), number of branches per plant (r = 0.970 ** ), number of cluster per plant (r = 0.939 ** ), number

Figure 1 .
Figure 1.Effect of water stress on tomato cv.Edkawy on plant height (cm) in 2016 and 2017.

Table 1 .
Mean square of separate and combined analysis of variance for all studied traits in selected and unselected populations after three cycle

Table 2 .
Mean performance of separate and combined for PH, NBP, NCP of the two seasons.