Evaluation of different exotic sugarcane genotypes

A research experiment was conducted at research area of Sugarcane Research Institute, Faisalabad, Pakistan to evaluate the best sugarcane clones amongst twenty eight clones against two standard varietiesHSF-240 and CPF-249 for different agronomic traits and yield characters during the crop season 2016-17 at third selection stage of variety development. In the experiment, three clones (S2014-SL-1322, S2014-SL-1359, S2014-SL-1372) out of twenty eight (11 %) were selected on the basis of good performance and did not show splits, lodging tendency, pithiness, aerials roots, disease infestation and these showed good crop stand and thick canes. These three clones were promoted to next stage of variety development cycle. In set-1, Clone S2014-SL-347 gave higher cane yield (58.37 tha)with sugar yield of 7.18 tha. But it showed some bad characters of high aerial roots and pithiness and so rejected. In set-II, the clone S2014-SL-1224 gave higher cane yield of 71.51t ha with 8.73t ha sugar yield and showed high disease infestation of red rot and smut and so rejected. But S2014-SL-1322, S2014-SL-1359, S2014-SL-1372 produced cane yield of 71.37 t ha 68.56 t ha 67.33 t ha with 8.71 t ha 8.34 t ha 8.31 t ha sugar yield respectively. These three clones performed well with no bad characters. The remaining twenty five clones (89 %) out of twenty eightwere rejected due to diseases susceptibility, lodging, pithiness, poor crop stand, aerial roots and high splits.


Introduction
Global interest in sugarcane has increased significantly in recent years due to its economic impact on sustainable energy production. Sugarcane breeding and better agronomic practices have contributed to a huge increase in sugarcane yield in the last 30 years. Sugarcane is the main sugar-producing crop (Junejo et al., 2010) [8] . This crop plays a pivotal role in economy of Pakistan in order to drive the large sugar industry. It has 0.7% share to Gross Domestic Product. In the Punjab, during 2016-17, sugarcane was grown on an area of 791.94 thousand hectares as compared to 705.35 thousand hectares planted previous year. This shows an increase of 12.30% over the last year. The production was 47.96 million tonnesas compared to 41.97 million tonnes of the previous year. The production thus shows an increase of 14.30% over the previous year (Anonymous, 2017) [1] . Sugarcane is cultivated in many of the world countries with Brazil as a major producer followed by India, China, Pakistan, Thailand and Mexico (FAO., 2010) [5] . It provides employment and by products for industrial sector. The sugar industry is second to textile in Pakistan which is primarily based on the mercy of sugarcane cultivation (Bahadar et al., 2002) [3] . It is also an important cash crop of Pakistan (Ahmad et al., 1991) [2] , which plays an important role in economic uplift of farmers. In Pakistan about 99% of the sugar is extracted from sugarcane to meet the demand at domestic level (Azam and Mukarram, 2010) [1] . The average per hectare yield in Pakistan is less than other cane growing countries of the world (Sohu, et al., 2008) [16] . One and major reason for that, is our farmers do not have option regarding high yielding varieties (Majeedano, et al., 2003) [15] . The cane and sugar yield of sugarcane crop can be improved with high yielding varieties and better agronomic practices (Heinz, 1987) [6,13] . Sugarcane crop improvement in many countrieslies on conventional breeding, mutation breeding, somaclonal variation and genetic engineering (Dalvi et al., 2012) [4] . Sugarcane improvement through conventional methods is dependent on the nature of flowering, viability of pollen and seed (Moore and Nuss, 1987;Khan et al., 2008) [11] and thegenomic complexity of sugarcane crop (Ingelbrecht et al., 1999) [7] . Sugarcane having complex genome, low fertility and large genotype x environment interactions make traditional varietal improvement and genetic studies difficult and laborious (Mendoza, 2000) [14] . In Pakistan, the flowering and seed set under natural conditions is a very serious problem in sugarcane that hampers varietal improvement. The basic facilities for hybrid seed production and variety development are lacking in the country. Though the coastal belt in Sindh, is blessed with specific climatic conditions where sugarcane plants flower. But at local spots where plants flower, non-synchronization in genotypes for cane flowering reduces the possibility of hybridization (Tiawari et al., 2009) [18] . Therefore, sugarcane variety development in Pakistan is mainly based on import of germplasm from the cane breeding stations abroad and also through exotic or locally collected fuzz (Kaloi et al., 2007) [10] . Most of breeding material was imported from USA, Sri Lanka and Mauritius.
In cane breeding program in Pakistan, large numbers of seedlings are grown from fuzz (true seed), selections are made in subsequent generations to obtain superior clones/genotypes for release as new varieties. The development of new sugarcane varieties is not possible in Pakistan because of intricate flowering of the plant and non-availability of sugarcane breeding facility and acclimatization (Javid et al., 2001) [9] . Thus the selection is the base line to cane agronomist in Pakistan to develop new varieties. Potential of new genotypes needs to be tested in local environment before deciding to release as a new cultivar in a particular region (Khan et al., 2000) [12] . All the selection phases are important varietal development cycle but establishment of a good nursery is of prime importance. Keeping in view the importance of nursery, the present study was conducted to evaluate the best sugarcane genotype in agro climatic condition of Faisalabad, Pakistan.

Materials and Methods
The research project was conducted at the farm area of Sugarcane Research Institute, Faisalabad, Pakistan during crop season 2016-17. Two sets of preliminary varietal yield trial consisting of 28Sugarcane clones and two check varieties HSF-240 and CPF-249 were laid out in randomized complete block design with three replications. Experiment was sown on 10-10-2016 with net plot size of 4 m x3.6 m by keeping interrow spacing of 120 cm. All the agronomic and cultural practices were applied as and when considered necessary during the course of study. The seed rate of 75,000 double budded setts per hectare was used and crop was planted in 120 cm apart double row strips. Trenches were made with the help of tractor drawn ridger. Fertilizer was applied at the rate of 168, 112 and 112 kg NPK per hectare. Twenty irrigations (80 acre inches) were applied at different intervals according to the crop need and climate.

Data Recording
Emergence and tillers per plot was counted at 45 days and 90 days after planting respectively. Number of canes was counted from the two strips in each plot at final harvest and was converted to canes per hectare. Crop was harvested at maturity by taking an area of two strips from each plot and cane yield per hectare was estimated. During selection, different crop parameters was also observed. It includes pithiness, lodging, aerial roots, splits disease infestation (smut, rust) and growth performance / crop stand of clones. These parameters were observed visually and noted. The observation of these parameters are of great concern for promotion and rejection of clones to next stage of variety development.

Statistical Analysis
The data collected were subjected to Fisher's analysis of variance technique and LSD test at 0.05% was used to compare the differences among treatment means (Steel & Torrie, 1984) [17] .

Results and Discussion
The results are summarized in Table 1 and Table 2. In set-I, 14 clones along with two standard varieties HSF-240 and CPF-249 were studied out of which Clone S2014-SL-347 gave higher cane yield (58.37 tha -1 ) with sugar yield of 7.18 tha -1 . But it showed some bad characters of high aerial roots and pithiness and so rejected. Similarly in this set remaining 13 others were also rejected due to smut, red rot, pithiness, aerial roots, high splits and poor growth performance. In set-II, fourteen clones were studied out of which the clone S2014-SL-1224 gave higher cane yield of 71.51 t ha -1 with 8.73 t ha -1 sugar yield and showed high disease infestation of red rot and smut and so rejected. But S2014-SL-1322, S2014-SL-1359, S2014-SL-1372 produced cane yield of 71.37 t ha -1, 68.56 t ha -1, 67.33 t ha -1 with 8.71 t ha -1, 8.34 t ha -1, 8.31 t ha -1 sugar yield respectively. These three clones performed well with no bad characters. The remaining twenty five clones (89 %) out of twenty eight were rejected due to diseases susceptibility, lodging, pithiness, poor crop stand, aerial roots and high splits. These results are in line with the findings of Khan et al., 2008 [11] . The parameters studied in the experiment are as under:

Growth Performance
In agronomic practices, the growth performance is related to cane thickness and crop stand. This is character that affects the yield of cane crop. Growth habits, erectness, internodal length, girth of cane, length of cane and stooling depends upon genetic makeup which may be detected by overall performance of clone. In set 1, S2013-US-876 and S2014-SL-365 showed poor crop stand with thick canes. In set 2, all the fourteen clones showed better growth performance as copared with stand varieties HSF-240 and CPF-249. These results are in line with the findings of Kaloi et al., 2007 [10] .

Pithiness
Hollow stem with fiber of cane is negative character, leads to lodging, disease infestation and lowers the cane quality. In set 1, four clones S2013-US-876, S2013-US-969, S2014-SL-347 and S2014-JG-525 showed presence of pith and so rejected but in set 2, pithiness was seen in any clone. These results are in line with the findings of Khan et al., 2008 [11] .

Aerial Roots
These are secondary roots which spoil the quality of cane as well as lowers the growth speed and deteriorate crop stand. In set 1, only one clone S2014-SL-347 showed the presence of aerial roots and so rejected. In set 2, aerial roots was not observed in the clones. These results are in accordance with the findings of Kaloi et al., 2007 [10] .  [11] .

Splits
The splits on the stem of cane deteriorate cane quality as well as tissues due to increase in transpiration rate. In set 1, three clones S2014-SL-353, S2014-SL-360 and S2014-SL-396 showed deep splits and cracks in canes. In set 2, splits were not observed in the clones under study. In set 1, the clones showing deep splits / cracks and were rejected. Because the splits reduces cane yield and recovery and also results in the attack of pests and diseases. These results are in line with the findings of Khan et al., 2008 [11] and Kaloi et al., 2007 [10] .

Conclusion
In the trial forty seven clones of sugarcane were studied. Fifteen clones were selected and promoted for further study in semi-final trial. The remaining thirty two clones were rejected due to disease susceptibility, pith, lodging and poor growth habits.