Drough tolerance estimation of several rainfed rice (Oryza sativa L.) of lokal veriety using polyethilene glycol (PEG)

The yield of rice crop was highly affected by water availability and drought condition . The effort was done to seek local varieties of rainfed rice which tend to be tolerance to drought condition. This research objective was to seek some local varieties of rainfed rice that tolerance to several drought conditions. This research was conducted at Farm Exprimentation Site of Agrotechnology Study Program, Baturaja University from November 2015 to April 2016. Exprimental design used in this research was Split Plot Design with three replications. The main plot was variety treatments (varieties of Henik, Henik Pisang, Serenik, Remaja, Semester, Selanggar, Duku, Serendah Putih, Agai and Tinta), whereas the subplot was Polyethilene glycol (PEG) treatments (concentrations of 0%, 20%, 25% dan 30%). The results showed that varieties of Henik, Henik Pisang, Serenik, Semester, Duku, Serendah Putih and Tinta had produced high yield at drought condition. Rainfed rice could produced high yield at treatments of 20% and 25% PEG, respectively. Treatment combination of Duku variety and 30% PEG had produced the highest weight of unhulled rice/clump and fully unhulled rice/clump, respectively. The highest weight of unhulled rice per 1000 grains was found on treatment combination of Duku variety and 25% PEG.


Introduction
Food increment need to be done in accord to the increase of population numbers.The effort to increase food production was done through dry land empowerment.According to Pusdatin (2013), dry land area in Indonesia that was not yet utilized was 14,262,383 ha.This dry land resource has potential to support food self sufficiency.Rainfed rice cultivation can be applied at dry land area.Ogan Komering Ulu District of South Sumatra Province had extensive dry land area and local varieties of rainfed rice that have potential to be developed in order to increase food self sufficiency.Danial and Nurbani (2015) had stated that rainfed rice development had received less attention from the government than that of paddy field rice.Productivity of rainfed rice is lower than that of paddy field rice.Yuniarti (2015) had stated that one factor which cause low productivity of rainfed rice is drought condition.According to Rahayu and Harjono (2010), rainfed rice crop that tolerance to drought would have high prolin content in its leaves.The crop height and tiller numbers of rainfed rice will decrease at drought condition.
The growth and yield of rice crop are highly affected by water availability.Unfavourable climate condition due to climatic change has high impact on crop yield or production.Short wet season period coupled with long dry season will results in crop management difficulty due to water availability which solely available from rainfall water.The impact of El Nino phenomenon in 2015 was extreme drought condition and long dry season.
Drought causes accmulation of absisate acid, decrease in transpiration and decrease of CO 2 assimilation (Razak et al., 2013).Drought condition will decrease rice yield level (Quampah et al., 2011).Drought tolerance characteristics of a rice genotype is always related to the changes of morphology and physiology as adaptation way toward drought condition so that a rice genotype can be classified as drought tolerance.Crop characteristics either morphology or physiology can be used as assessment base of tolerance properties toward drought condition.One of substance that can be used to select drought tolerance rice crop is PEG (Polyethylene Glycol).PEG concentration of 18.1% or equivalent to -6.24 bar of water potential can be used to determine the tolerance of variety to drought stress (Halimursyadah et al., 2013).PEG 6000 solution at 25% concentration is relatively effective concentration level to produce drought stress on rice crop.The used of PEG 6000 solution at 25% concentration at seedling phase can detect hybrid rice genotype which tolerance to drough condition (Afa et al., 2012).
This research was conducted to analyze the growth and yield of local varieties of rainfed rice originated from Ogan Komering Ulu District, South Sumatra Province, Indonesia at drought condition in order to determine the adaptive local varieties of rainfed rice at drought condition.
The first activity was planting media preparation in which yellowish red podsolic soil (PMK) was refined and sieved followed by putting it into polybag with size of 5 kg.Soil was then sprinkled with water until field capacity condition and subsequently was left over for one week.The seeds were soaked in beaker glass according to teatments for 12 hours and then were germinated within germination box.The next step was that seeds having 14 days old were transplanted into the previously prepared polybags in which each polybag was contained three stalks of seed.Crop maintenance was consisted of weeds cultivating, watering was done once per day and rice bug pest control was conducted by using demolish spraying.The observed parameters were crop height, crown dry weight, root dry weight, tiller emerging time, maximum tiller numbers, productive tiller numbers, flowering time, unhulled rice weight/clump, fully unhulled rice weight/clump and weight of 1000 grains unhulled rice.Data analysis was done by using Analysis of Variance with statistical package of SAS 6.12.If analysis results were significantly different, then it was followed by Duncan test using 5% level.

Results
Results of F-test (Table 1) showed that variety treatments had significant effect on parameters of crop height, crown dry weight, root dry weight, maximum tiller numbers, productive tiller numbers, flowering time, unhulled rice weight/clump, fully unhulled rice weight/clump and weight of 1000 grains unhulled rice.Variety treatments had no significant effect on tiller emerging time.The PEG treatments had significant effect on parameters of crown dry weight, productive tiller numbers and weight of 1000 grains unhulled rice, but had no siginificant effect on other parameters.Treatments interaction had significant effect on parameters of root dry weight, productive tiller numbers and weight of 1000 grains unhulled rice, but PEG treatments had no significant effect on other parameters.

Growth Parameter
The results of Duncan test showed that crop height of Henik variety (V 1 ) was not significantly different than that of V 2 , V 4 , V 7 and V 8 .Crown dry weight of V 1 was not significantly different than that of V 3 , V 7 and V 10 .Root dry weight of V 1 was not significantly different than that of V 4 and V 8 .Faster emerging time of tillers were found on treatments of V 1 , V 3 , V 4 , V 6 and V 9 .Maximum tiller numbers and productive tiller numbers were found on treatments of V 6 .Tiller emerging time for V 3 treatment was faster than that of other varieties (Table 2).The comparison of PEG treatments and without PEG treatment (G 0 ) showed that G 3 treatment had taller crop height, tiller emerging time was not significantly different than that of G 1 and G 2 treatments as well as had faster flowering time.The G 1 treatment showed better results in increasing of crown dry weight, root dry weight, maximum tiller numbers and productive tiller numbers (Figure 1 to Figure 3).Results of treatment combination of variety and PEG showed that the highest values of crop height, crown dry weight and root dry weight were found on V 10 G 3 treatment combination.The fastest tiller emerging time was found on V 9 G 1 treatment combination.The highest values of maximum tiller numbers and productive tiller numbers were found on V 6 G 3 treatment combination than that of other treatment combinations (Table 3).

Yield Parameter
Faster flowering time was found on V 6 treatment.Treatment of V 1 had unhulled rice weight/clump that was not significantly different than that of V 2 , V 3 , V 4 , V 5 , V 7 , V 8 and V 9 .Fully unhulled rice weight for V 7 treatment was not significantly different than that of V 1 , V 3 , V 5 and V 8 .The 1000 grains weight of unhulled rice for V 1 treatment was not significantly different than that of V 3 , V 7 and V 10 (Table 2).The G 1 treatment had produced the highest value of 1000 grains weight of unhulled rice.The weight of unhulled rice/clump and fully unhulled rice/clump for G 2 treatment were higher than that of other PEG treatments (Figure 4 and Figure 5).Treatment combination of V 6 G 2 had produced faster flowering stage.Treatment combination of V 7 G 3 had higher values of unhulled rice weight/clump and fully unhulled rice weight/clump than that of other treatment combinations.The highest value of 1000 grains weight of unhulled rice was found on V 7 G 2 treatment combination (Table 4).

Discussion
The results of F-test showed that all varieties used in this study had significant effect on all parameters except for tiller emerging time parameter.This showed that all varieties used in this study had different responses.These different responses were estimated due to higher than that of control treatment.The weight of unhulled rice/clump for V 7 G 0 was 33.37 g and for V 7 G 3 was 47.50 g, respectively.The weight of fully unhulled rice/clump for V 7 G 0 was 34.77 g and for V 7 G 3 was 49.30 g, respectively.Agai variety also had higher average values in term of weight of unhulled rice/clump (V 9 G 3 :46.88g) and weight of fully unhulled rice/clump (V 9 G 3 : 37.8 g) than that of control treatments (V 9 G 0 : 31.53 g and V 9 G 0 : 28.8 g, respectively).Duku and Agai varieties in combination with PEG 30% had higher yield than that of other treatment combinations.These varieties were more tolerance to drought stress than that of other varieties.Duku variety was capable to cope with critical period during seedling phase which was shown by higher value of crown dry weight found in combination treatment of Duku variety and PEG than that of combination treatment of Agai variety and PEG.However, average value of crown dry weight found in these two treatment combinations was not significantly different than that of control treatment.This showed the capability in coping with critical phase so that crop can absorb water and nutrients which were important for the on-going of photosynthesis process.Results of the study by Akram et al. (2013) showed that drought stress could decrease the crown dry weight of crop.

Conclusion
The results showed that varieties of Henik, Serenik, Semester, Selanggar, Duku and Tinta were capable to produce high yield at drought treatment condition.Treatment of 20% PEG and 25% PEG had significant effect on growth and yield of rice crop.Treatment combination which had high yield was Duku +25 % PEG and Duku + 30% PEG, respectively.This research was self funding research and we want to deliver our acknowledment to the Dean of Agricultural Faculty, Baturaja University, Head of Laboratory as well as Head of Farm Exprimentation Site of Agrotechnology Study Program that had already gave facilities for this research.

Table 1 .
Variance analysis (F test) of variety treatments (V) and PEG (G)on all variables.

Table 2 .
Average results of variety (G) as the main plot for all variables

Table 3 .
Average growth and yield of several local varieties of rainfed rice (V) at PEG treatment (G).

Table 4 .
Average growth and yield of several local varieties of rainfed rice (V) at PEG treatment (G).