SINHAS-1 Maize Seed Production Through Male-Female Ratio and Pruning Technique

The research was aimed to obtain male and female rows ratio and best pruning technique towards SINHAS 1 maize production. This research was conducted in Experimental Farm Faculty of Agriculture, Hasanuddin University, Tamalanrea District, Makassar, South Sulawesi with elevation of 22,4 meters above the sea level throughout May – August 2020. The experiment was carried out in the form of Split Plot Design with male-female row ratio as main plot, which consisted of three levels: 1:2 ratio, 1:3 ratio, and 1:4 ratio. Sub plot was pruning techniques: no pruning, male parent pruning and leaf pruning under the cob of female parent. The result showed that the favorable male-female row ratio towards SINHAS 1 maize production was 1:4 ratio. Male parent pruning was the best pruning technique for SINHAS 1 maize production. The interaction between male-female ratio and best pruning technique was 1:3 male-female ratio with male parent pruning technique. Characters that showed positively direct significance towards productivity were cob diameter, cob length, and number of seed rows per cob

A. Introduction potential of the leaves on 1/3 part of the plant is twice as more than 1/3 of leaves in the middle part of the plant and five times as much than 1/3 part of the leaves on the bottom of the plant (Permanasari & Kastono, 2012). Therefore, leaf pruning after pollination was expected to increase maize seed production. This research was aimed to determine the male-female row ratio settings and the application of suitable pruning technique in maize crops.

B. Methodology
This research was conducted in Experimental Farm, Faculty of Agriculture, Hasanuddin University, Tamalanrea District, Makassar, South Sulawesi on the elevation of 22,4 m above sea level throughout May-August 2020.
This research was designed under Split Plot Design with male-female row ratio as main plot and pruning techniques as sub plot. Male-female row ratio consisted of three levels: 1:2 ratio (R1), 1:3 (R2), and 1:4 (R3). Sub plot also consisted of three levels: no pruning (P0), male parent pruning (P1) and leaf pruning under the cob of female parent (P3). Overall treatment combination was replicated three times, thus resulting 27 experimental units. Plot width of each experimental unit depended on male-female ratio, yet each ratio was replicated twice in every unit. The plot width of 1 : 2, 1 : 3 and 1 : 4 male-female ratio was 3,5 m x 12,6 m, 3,5 m x 16,8 m and 3,5 m x 21 m respectively.
Path analysis was calculated according to stimultan equation with formula as follows:

Rx C Ry
Based on this equation, C value (direct effect) can be calculated with following formula C = Rx -1 x Ry Note : Rx = Corelation matrix between free variable; Rx -1 = Rx Inverse matrix C = Path coefficient vector which indicated direct effect from each standarized free variable towards dependent variable. Ry = Corelation coefficient vector towards Xi variable with dependent variable. Parameters observed in this research was weight of cob without corn husk (g), cob diameter (cm), cob length (cm), number of kernel rows per cob, seed rendement (%), 1000 seed weight (g) and productivity (ton ha-1).

Weight of cob without corn husk
Least significance difference test shown in table 1 indicates that male parent pruning (P1) gave the best weight of cob without corn husk with male-female ratio 1:2 (R1) with average of 220.85 g and was not significantly different with no pruning treatment (P0) and pruning of leaf below cob (P2). 1:3 male-female ratio (R2) and male parent pruning (P1) presented a better weight averaging in 235.76 g, which was not significantly different with no pruning treatment (P0) and pruning of leaf below cob (P2). 1:4 male-female ratio (R3) and pruning of leaf below cob (P2) gave better weight of cob without corn husk, averaging 263.24 g and significantly different with no pruning treatment (P0) and male parent pruning (P1).

Cob Diameter
Least significance difference test shown in table 2 indicates that male parent pruning (P1) gave the best cob diameter with male-female ratio 1:2 (R1) with average of 46.55 mm and was significantly different with no pruning treatment (P0) and pruning of leaf below cob (P2). 1:3 male-female ratio (R2) and male parent pruning (P1) presented a better diameter averaging in 47.69 mm, which was not significantly different with pruning of leaf below cob (P2) and significantly different with no pruning treatment (P0). 1:4 male-female ratio (R3) and pruning of leaf below cob (P2) gave better diameter, averaging 48.50 mm and not significantly different with no pruning treatment (P0) and male parent pruning (P1).

Seed Weight
Least significance difference test shown in table 3 indicates that male parent pruning (P1) gave the best 1000 seed weight with male-female ratio 1:2 (R1) with average of 411.97 g and was significantly different with no pruning treatment (P0) and pruning of leaf below cob (P2). 1:3 male-female ratio (R2) and male parent pruning (P1) presented a better weight averaging in 421.95 g, which was significantly different with pruning treatment (P0) and pruning of leaf below cob (P2). 1:4 male-female ratio (R3) and pruning of leaf below cob (P2) gave better weight of 1000 seeds, averaging 426.50 g and not significantly different with no pruning treatment (P0) and male parent pruning (P1).

Cob Length
Least significance difference test shown in table 5 indicates that male parent pruning (P1) gave the best cob length with male-female ratio 1:2 (R1) with average 17.82 cm and was significantly different with no pruning treatment (P0) and pruning of leaf below cob (P2). 1:3 male-female ratio (R2) and male parent pruning (P1) presented a better length averaging in 19.53 cm, which was significantly different with pruning treatment (P0) and pruning of leaf below cob (P2). 1:4 male-female ratio (R3) and pruning of leaf below cob (P2) gave better length of cob, averaging 20.38 cm and not significantly different with no pruning treatment (P0) and male parent pruning (P1).

Number of Seed Rows Per Cob
Least significance difference test shown in table 4 indicates that male-female ratio 1:4 (R3) gave the best number of seed rows per cob with average 15.51 and was not significantly different with 1:3 male-female ratio (R2) and significantly different with male-female ratio 1:2 (R1). The best pruning technique was pruning of leaf below cob (P2) averaging in 15.01, which was not significantly different with pruning of leaf below cob (P2) and significantly different with no pruning treatment (P0).

Seed Rendement
Least significance difference test shown in table 6 indicates that male parent pruning (P1) gave the best seed rendement with male-female ratio 1:2 (R1) with average 75.06 % which was not significantly different with pruning of leaf below cob (P2) and significantly different with no pruning treatment (P0). 1:3 male-female ratio (R2) and male parent pruning (P1) presented a better rendement averaging in 76.96%, which was not significantly different with pruning treatment (P0) and significantly different with pruning of leaf below cob (P2). 1:4 male-female ratio (R3) and pruning of leaf below cob (P2) gave better seed rendement, averaging 83.48% and not significantly different with no pruning treatment (P0) and male parent pruning (P1).

Productivity
Least significance difference test shown in table 7 indicates that male parent pruning (P1) gave the best productivity with male-female ratio 1:2 (R1) with average 3.78 t ha-1 which was significantly different with no pruning treatment (P0) and pruning of leaf below cob (P2). 1:3 male-female ratio (R2) and male parent pruning (P1) presented a better productivity averaging in 4.37 t ha -1 which was significantly different with pruning treatment (P0) and pruning of leaf below cob (P2). 1:4 male-female ratio (R3) and pruning of leaf below cob (P2) gave better production, averaging 4.39 t ha-1 and significantly different with no pruning treatment (P0) and male parent pruning (P1).  Table 8 indicates that the characters showing direct positive effect towards productivity were cob length without corn husk (CW) (0.21), cob diameter (CD)(0.29), cob length (CL) (0.66) and number of seed rows per cob (NR) (0.29), whilst the negatively direct influenced characters were seed rendement (R) (-0.17) and 1000 seed weight (1000 W) (-0.23). Character that exhibited highest direct influence value was cob length (0.66) meanwhile the lowest was derived from 1000 seed weight (-0.23). Indirectly influenced characters which showed highest value was cob length (2.83) and the lowest from 1000 seed weight (-0.92).

D. Discussion
From overall variance analysis, male-female ratio and pruning techniques gave significant and highly significant influence upon weight cob without corn husk, cob diameter, 1000 seed weight, cob length, number of seed rows per cob and seed rendement. The found result was supported by similar research by. Pratama & Purnamaningsih (2019), where male-female ratio gave significant influence towards productivity-supporting characters such as early cob weight, fresh treshed weight, dry treshed weight, number of kernels per cob and comparison percentage of seed and cob. Pruning treatment gave significant effect towards cob length, cob circumference, cob weight, number of seed rows per cob and number of seed per row and gave higher values compared to those without pruning. Thus, it is necessary to conduct further analysis of the male-female ratio and pruning tecniques.
1:4 male-female ratio (R3) was deemed to have more effective pollinating space than of other ratios. Seed production are mainly done with detasseling in order to avoid self pollination in maize. The moderate width of detasseling on 1:4 male-female ratio resulted more effective pollination due to precision of pollen dispersing angle not limited by the close proximity of male and female flower. Detasseling also increasing assimilation towards the cob in female parents. Therefore, productivity from 1:4 female ratio was preffered than 1:2 or 1:3 ratio. This was supported by Chamecki, Gleicher, Dufault, & Isard (2011), arguing that one of the factors affecting pollen dispersal patterns was the presence of barrier plants where the height, width and compactness of the plant can influence the wind speed as the primary factor of pollen dispersal.
Male parent pruning (P1) resulted an empty row between female rows group, causing the planting pattern appeared to be similar with jajar legowo planting pattern and for the instance, sun radiation absorption and water storage became more optimal. This was aligned with Rahmansyah, Bayu, & Sudiarso (2018), stating that productivity can be increased through jajar legowo planting pattern due to the effects of side plants which are expected to give high production and better grain quality. Furthermore, it can also increase cob width in maize and population per hectare in rice, empty space for water management, increasing sun radiation absorbtion which is beneficial in maize production.
Male pruning technique (P1) in the likings of jajar legowo planting system is able to maximize sun radiation intake by plants used for photosynthesis and for increasing cob weight and diameter, where increased number and weight of kernels will be resulting in increased cob weight and diameter. This was supported by Rahimi, Zuhry & Nurbaiti (2013), stating that seed weight is influenced by dry materials in the seeds. Thus, male pruning (P1) became the recommended pruning technique in SINHAS 1 seed production.
Interaction between male-female ratio and pruning techniques with best productivity value was found in 1:4 male-female ratio and pruning of leaf below female row cob (R3P2) with 4.39 t ha-1. Interaction between 1:4 male-female ratio and pruning of leaf below female row cob (R3P2) significantly influenced other characters: weight of cob wihtout husk (263.24 g), cob diameter (48.50 mm), 1000 seed weight (426.50 g), cob length (20.38 cm), and seed rendement (83.48%).
Pruning of leaf below female parent cob (P2) was the preffered pruning technique followed by male pruning (P1). Pruning of leaf below female parent cob was carried out in order to increasing seed filling assimilate due to the photosyntetically inactive aging leaves below the cob. This condition was supported by Sugito (2009), stating that the position of aged leaves in the bottom part of the canopy causes reduced sun radiation intensity and photosynthesis and for supporting them, carbohydrate supply from other leaves was taken, therefore disadvantaging the respective plant. Photosynthetically inactive pruning resulted in larger transferred assimilate to the cob and with pruning such will leave more active leaves for photosynthesis purposes and increasing cob weight more than those without pruning (Zuchri, 2010). Pruning of leaf below cob also gives higher dry cob weight, dry threshing weight and 100 treshed seeds weight compared to without pruning (Surtinah, 2005).
Male-female ratio and pruning technique treatment towards productivity correlated significantly upon other characters. However, it is necessary for the correlations to be detected in order to determine the main character from secondary analysis that highly influencing productivity. Therefore, another test was needed, which was path analysis towards characters which were corelated with productivity.
The goal of path analysis is to determine the direct and indirect effect between growth characters and seed production (Nasution, 2010). Path analysis can calculate crucially contributing characters in maize production (Abdulkhaleq & Tawfiq, 2014). The highest direct effect on productivity was cob length with highest path coefficient, 0.95, while the character that showed highest indirect effect was stem diameter, 0.95. Moderate value of indirect effect usually has moderate correlation value (Rachmawati, Kuswanto, Purnamaningsih, 2014).