Omoto G et al Proc S Afr Sug Technol Ass (2013) 86: 19-155 SHORT O-REFEREED PAPER EFFECT OF ROW SPACIG O SEEDCAE YIELD AD YIELD COMPOETS I WESTER KEYA OMOTO G 1, AUMA EO 2 AD MUASYA RM 2 1 Kenya Sugar Research Foundation, P.O Box -0100 Kisumu-Kenya 2 Eldoret University, P.O Box 53-3900 Eldoret-Kenya georgeomoto@ymail.com elmadaauma@yahoo.com muasya@africaonline.co.ke Abstract Sugarcane planted at wide row spacing grows slowly in the early stages, and this is detrimental to both the soil and the crop because the delayed closure of the crop canopy in wide rows hinders efficient use of light, water and nutrients. Two experiments were conducted at Kibos and asewa during 2002/03, with the objective of determining the effect of row spacing on seedcane yield and yield components of two varieties. The experiments were laid out as 2x factorials in randomised complete block designs, replicated three times each. Treatments were two cane varieties (KE82-27 and 1) and four row spacings (120, 60, 50 and 0 cm). Three-budded cane setts were planted in plots measuring 72 m 2. Each plot had a length of 10 m and width of 7.2 m. Data on yield and yield components at 12 months after planting were determined. Analysis of variance for yield, stalk weight (tch), stalk population/ha and setts/ha showed significant differences (P<0.05) between the row spacings. There were no significant interaction effects between variety and site for any of the yield components. The 120 cm spacing gave significantly lower yields (58 tch) than the other three spacings, which gave similar yields (103, 103 and 10 tch for the 60, 0 and 50 cm spacings, respectively). The results from the study show that any row spacing between 0 and 60 cm nearly doubled yields and can therefore be a better option for sugarcane growers to adopt for seedcane production. The 50 cm row specing cannot be managed with current machinery, and will require modifications to be made to existing equipment. Keywords: sugarcane, seedcane, row spacing, variety, effect, yield Introduction Sugarcane (Saccharum spp.) is an important economic crop in the tropics and sub-tropics due to its high sucrose content and bioenergy potential (FAO, 2010). It is one of the main cash crops grown in western Kenya and plays an important role in the agricultural and socioeconomic development of the country (KSB, 2011). The main varieties grown are Co95, Co21, 1, Co617, KE83-737 and EAK73-335. Annually, 20 130 hectares are developed for sugarcane production (KESREF, 2011). Seedcane is an important input in sugarcane production and high seedcane quality is a prerequisite for increasing productivity. Some of the factors influencing seedcane production are effectiveness of seed treatment plants in disease control, seed certification schemes and spacing production systems (wide and narrow row spacings). The first two factors have been addressed through hot water treatment of seed setts at 50 C for 2 hours. However, the issue 19
Omoto G et al Proc S Afr Sug Technol Ass (2013) 86: 19-155 of a narrow row spacing production system has not been adequately addressed in the sugar industry. The wide row spacing farming system (1.2 m on outgrower farms and 1.5 m on nucleus estates) has delivered small profits because of low cane yields obtained (KESREF, 2000). This is because the wide row spacing provides a poor geometry that does not intercept all the available light. The narrow row spacing is of particular interest because it describes a planting strategy that increases the number of setts planted above the rate used for standard row spacing (1.2-1.5 m). The narrow spacing production system provides an estimate of increase in yield that depends on variety and form of narrow row spacing. Plants in narrow row spacing intercept almost all the available light utilize all the available water, access the available nutrients and can deliver yield increases of up to 60% (Anon, 2000). The system also provides a more efficient way for cane growers to produce high yields (tch) from reduced areas because plants in smaller unit areas intercept most of the available sunlight (Anon, 1993). Bull and Bull (1996) reported 0.5 m row spacing to have increased yield by up to 60 t/ha. Chebosi (1982) reported spacing of 0.75 m to outyield spacings of 1.25 and 1.5 m. The aim of this study is therefore to determine the effect of row spacing on seedcane yield and yield components. Materials and Methods Experimental site The experiments were established at Busia Sugar Company (BSC) at asewa and at the Kenya Sugar Research Foundation (KESREF) at Kibos, between August and October 2002. asewa lies between latitude 0 25 and longitude 3 5 E. The mean monthly maximum temperature range is 30 C, while the mean monthly minimum temperature is 18 C. The mean annual rainfall is 1500 mm. The altitude varies from 1130 to 1375 m above sea level (Anon, 1997-2001). Kibos is situated 16 km north-east of Kisumu City, latitude 0 2 and longitude 3 8 E. The mean monthly maximum temperature is 31 C, and means monthly minimum temperature is 23 C. The mean annual rainfall is 187 mm. The altitude is 120 m above sea level (KESREF, 2001). The soils of the study areas are mainly vertisols and nitrosols (KESREF, 2001). Land preparation was done using a disc plough, and thereafter left to weather for 21 days before harrowing. Furrowing followed immediately by manual labour because of the different row spacings used. The land preparation conformed to the KESREF recommended standards. Experiment design and treatments The treatments consisted of two cane varieties, KE82-27 and 1, with four spacing arrangements as follows: (i) 120 cm between the rows, (ii) 0 cm between the rows, (iii) 60 cm between the rows, and (iv) 50 cm between the rows. The four spacing treatment combinations were arranged in varying inter-row spacing using 2x factorial in randomised complete block design (RCBD) replicated three times. Each plot was separated from the neighbouring plot by a path 150 cm wide. Variety KE82-27 is the result of crosses between Phil 60 and Co61 and 1; variety 7 is a polycrossed cane bred at the South African Sugarcane Research Institute. Planting The end-to-end method of planting is where cane setts are placed a few centimetres from one another in a furrow. Setts with three buds were dipped in Confidor SL 200 solution at the rate of 200 ml/ha to control insect attack on the setts, and thereafter buried in furrows 15 cm 150
Omoto G et al Proc S Afr Sug Technol Ass (2013) 86: 19-155 deep using the end-to-end method. In every furrow of 10 m, 25 setts from clean seedcane of 12 months old were planted. Phosphate as diammonium phosphate (DAP, 6% P 2 O 5 and 18% ) and nitrogen as urea (6% ) were applied to the plots at the rates of 80 kg P 2 O 5/ ha and 100 kg /ha at asewa, and 50 kg P 2 O 5/ ha and 100 kg /ha at Kibos. DAP was applied during planting and urea was top-dressed in splits, at the ages of 3 and 6 months. Crop management conformed to KESREF recommended standards. Data collection and analysis Data collected included stalk population/ha - the number of stalks were counted, extrapolated, then recorded; setts/ha - cuttings with three buds were recorded; stalk weight (tch) - weighed by electronic weigh balance; and setts/stalk - cuttings with three buds from each stalk of each treatment were counted. These were measured from the middle 10 m 2 in each plot taken at 12 months after planting. Five stalks were randomly taken from each plot and final stalk height (cm) measured at harvest. Both experiments were harvested at 12 months after planting. The data was analysed by standard analysis of variance (AOVA) using SPSS Version 12.0 General Linear Model. Microsoft Excel was used for graphic presentation. Means were separated using the least significant difference (LSD) at the 0.05 level of significance. Correlation between seedcane yield (tch) and various yield components were done by use of the scatter diagram. Results The main effects of various yield components of seedcane (Table 1) showed that the 120 cm spacing and the 60, 50 and 0 cm spacings were significantly different in yield (P 0.05). The 120 cm spacing had the lowest yield (tch); followed by 60 and 0 cm. Spacing of 50 cm out yielded all other spacings. The three narrow spacings (0, 50 and 60 cm) had higher stalk numbers than the 120 cm spacing that differed significantly (P 0.05). The setts/ha was significantly affected by the four varied inter-row spacings. o interactions in yields between the spacing and variety were detected. There were no significant differences in yield between the two varieties (Table 1). Trends shown in Table 1 indicate that 1 stalk populations/ha were heavier than those of KE82-27 by 3.3%. However, KE82-27 had more setts/ha than 1 that did not differ significantly. There were no significant differences in yield (tch), stalk population/ha and setts/stalk between Kibos and asewa (Table 1). The results showed that site location did not affect the seedcane yield components. The main effect of treatments on final plant height (Table 1) indicates that plant height of the three narrow spacings (0, 50 and 60 cm) did not differ significantly from the wide spacing (120 cm). Similarly, the final plant height between the two varieties and sites did not differ. Although it was expected that plant height would differ between the narrow and wide spacings, this was not observed. 151
Omoto G et al Proc S Afr Sug Technol Ass (2013) 86: 19-155 Treatments Table 1. Main effects of treatments on various yield components of seedcane. Stalk population/ha Yield (tch) Setts/ha Setts/stalk Plant height (cm) Spacing 0 cm 20 000 103 11 000.9 308.9 50 cm 230 000 10 101 500.9 309.1 60 cm 210 000 103 9 000.9 311.9 120 cm 100 000 58 5 000 5. 303. Mean 195000 92 90 900 5.0 308.3 LSD (0.05) S S S S S CV% 15.5 19.6 18.5 19 1.0 Variety KE82-27 200 000 91 9 000.8 303. 1 170 000 95 90 000.7 303.3 Mean 185 000 93 92 000.8 308. LSD (0.05) S S S S S CV% 8. 0.3 1.2 0. 1.2 Site Kibos 190 000 95 89 000.7 305.8 asewa 180 000 92 9 000 5. 310.9 Mean 185 000 9 91 500 5.1 308.9 LSD (0.05) S S S S S CV% 2.7 1.6 2.7 2. 0.8 S = Significant, S = ot significant, tch = tons cane per hectare Correlation relationship of various yield components of seedcane The relationship between seedcane (tch) and various yield components is shown in Table 2. The correlation between seedcane (tch) and various yield components is positive and significant (P0.05 and P0.01). These relationships could be represented by the equations: setts/ha = Y= 0.699 + 0.097x and stalk population/ha = Y=2.550+0.368x. There was a closer relationship between seedcane yield and stalk number than seedcane yield and setts. The relationship between seedcane yield and stalk number was higher than for setts. 152
Omoto G et al Proc S Afr Sug Technol Ass (2013) 86: 19-155 Component Seedcane yield (tch) Final stalk height/m Stalks pop/ha Setts/ha Table 2. Relationships between various components of seedcane. Seedcane yield (tch) 930 070 837** 032 95* 06 Final stalk height/m 2 930 070 810 190 779 221 *Significant at P0.05 **Significant at P0.01 Stalk population/ha 837** 032 810 190 998** 002 Setts/ha 785** 06 779 221 998** 002 Discussion Cane yield and yield components of seedcane Yield is a complex parameter, which not only depends on stalk weight, stalk number and sett number, but also on soils, varieties and overall management. These factors when combined exert greater influence on cane yield than yield components. The high yields obtained were attributed to the production of high tillers/m 2 (stalk population) and increased light interception that increased photosynthetic activity of the cane. The results agreed with previous findings by Jaaffar and Gardner (1980) where sugarcane yields increased with decreasing row spacing. Results indicated that yield production was related to light interception and the efficiency of conversion of intercepted light to photosynthesis products. Gifford et al. (198) came to the same conclusion. Therefore the photosynthesis bases increasing yield are maximising the amount of light intercepted and the conversion efficiency of intercepted radiation to net dry matter production (Gifford et al., 198). arrow row spacing usually implies that the crop covers the ground quickly so that high canopy is efficient in converting intercepted radiation to biomass, and a high percentage of light is intercepted. Water energy is utilised faster to produce biomass efficiently, thereby increasing the crop yields. This was true with Salisbury and Ross (1980). Stalk population per unit area is directly affected by inter-row and intra-row spacings and changes rapidly with close spacing. A large decrease in area per plant and increase in population per unit area occurred at closer spacings. Stalk population is the most important component of cane yield, because it controls the interception of photosynthetically active radiation (PAR) that in turn determines the amount of biomass produced by the sugarcane canopy. This supports the leaf canopy that generates the potential source of photosynthate. 153
Omoto G et al Proc S Afr Sug Technol Ass (2013) 86: 19-155 The correlation between seedcane yield and various yield components The correlation between seedcane yield (tch) and various yield components (Table 2) showed that there were close positive relationships between seedcane yields (tch), setts/ha and stalk population/ha, and these relationships could be represented by the equations Y=0.699+0.097x (R 2 =79%) and Y=2.550+0.368x (R 2 =8%), respectively. The cane yield seems to be a function of setts/ha and stalk population/ha. Any differences in one or more of these yield components could therefore cause a variation in the final seedcane yield. It is apparent that the main determinants of seedcane yield were setts/ha and stalk population/ha. This is in agreement with the available evidence, which indicates there was strong a correlation between the seedcane yield and stalks numbers because of the canopy structure that rendered it to be in a better position to utilise the high energy. Conclusions The production of seedcane yield grown at row spacing of 0, 50 and 60 cm greatly exceeded that grown at the standard 120 cm row spacing. The 120 cm spaced seedcane produced the lowest yield (tch), followed by 60 cm, then 0 cm. The 50 cm spaced seedcane out yielded all other spacings. This is seen to have increased seedcane yield significantly by 76%. Seedcane is an expensive production input that consumes 25% of the total cost of producing one hectare of sugarcane. It is thus possible for farmers to reduce production costs and increase their yields by planting cane at narrow row spacing on small unit areas. The narrow row spacing needs modified equipment for furrowing, and will require the involvement of engineers before the system can be fully implemented by large-scale farmers. Recommendations Seedcane grown at the row spacing of 50 to 60 cm is of more value to farmers than that grown at row spacing of 120 cm. The farming system appears to be a viable option for farmers to attempt to reduce costs while increasing yields on small unit areas, although there is a challenge for engineers to design machinery for use in narrow row spacing. Both KE82-27 and 1 are suitable for seedcane production at Kibos and asewa at narrow row spacing of 50 to 60 cm. Acknowledgements The authors express sincere gratitude to the Director of Kenya Sugar Research Foundation for financial support. The KESREF staff, especially Messrs D Omoka and S Mutai is greatfully acknowledged for assisting in carrying out field experiments, as are colleagues for offering technical and logistical support. Mr A Varle, General Manager, Busia Sugar Company and Mr M Esese, Agriculture Manager, are deeply thanked for providing land and security for the project. 15
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