MATERIALS AND METHODS

The experiment was conducted in split-split plot in RCBD with 4 replications. Main plot was planting location (Pang-Da Research Station ((18°51’21.73" N, 98°45’31.63" E), PD) and Prabathuaytom Royal Project Development Center Plant ((17°43’45.69" N, 98°56’33.96" E), PB). Sub-plot was nitrogen fertilizer rate (0, 93.75, 187.5 and 312.5 kg N ha^–1) and sub-sub plot was quinoa cultivar (Moradas and Verdes). The experimental areas were located at average elevation of 720 for PD location and 500 for PB location meters above sea level, respectively. The climate characteristics and soil properties of both the research station was showed in Table 1-3, respectively. The experiment was done during November-March, 2015. Quinoa seed were hand sown on 5th and 6th December, 2014 in PD location and PB location, respectively. Quinoa was grown by row board casting method in 50 cm apart row with 2-3 cm depth. Plants were thinned to 10 cm intra spacing at 2 weeks after planted. The plant were irrigated by sprinkler method by 1 week interval. The water supply was stopped at 2-3 weeks before harvesting.

Table 1:	Climate characteristics of both research stations
PD: Pang-Da, PB: Phabaghuaytom

Table 2:	Climate characteristics of both research stations
PD: Pang-Da, PB: Phabaghuaytom, nd: No detected

Table 3:	Result of soil properties tested before growing at both research stations
L: Loamy soil, SL: Sandy loam soil

Phosphorus and potassium fertilizers were applied for 187.5 kg ha^–1, while nitrogen fertilizer was applied at 20, 40 and 60 days after planting. The weed was controlled by manpower method for twice time. Harvesting time was usually begins when the seed can barely be dented with a fingernail and plants had turned a pale yellow or red color and leaves have dropped. After harvesting quinoa panicle was tied into bundle and sundried for a week and then seed separated from panicle was done by manpower method and rice miller. After that quinoa seed will be cleaning was done by air blower (Seedburo equipment company). Finally, quinoa seed was kept in plastic sealed bag which was stored in the refrigerator to control the temperature for 12±2°C.

Crop physiological characteristics: Crop physiological characteristics were recorded according to Hunt⁹ as following, Leaf Area Index (LAI) were calculated by Eq. 1:

(1)

Leaf Area Ratio (LAR) were calculated by Eq. 2:

(2)

Net Assimilation Rate (NAR) were calculated by Eq. 3:

(3)

Crop Growth Rate (CGR) were calculated by Eq. 4:

(4)

Relative Growth Rate (RGR) were calculated by Eq. 5:

(5)

Seed yield: The quinoa seed of all the crops of each plot were bulked, after threshing by manpower methods and rice millers and quinoa seed will be cleaning by air blower, weighed and the seed yield per plant was then converted to kilogram per hectare.

Seed quality analysis: The seed quality was done as followed, ISTA¹⁰ were 1,000 seed weight: A sample of 100 seeds from the bulked seed of each plot was weighed with 8 replication and then converted to 1000 seeds.

Standard germination test: Seed germination test was done using between of paper method, 100 seeds were randomly selected in four replication each 25 seeds. Then the germination paper with see was pushed in germinator set at 20°C and the germination data was collected in 4 and 7 days after the start of the experiment. Germination index and mean germination time followed by Munir et al.¹¹.

Germination Index (GI) were calculated by Eq. 6:

(6)

Mean Germination Time (MGT) were calculated by Eq. 7:

(7)

Statistical analysis: The analysis of variance (ANOVA) was carried out using the Statistix software package version 8.0. Then, the mean comparison was done by Fisher’s LSD methods at p<0.05.

RESULTS AND DISCUSSION

Crop physiological characteristics: The experimented found that PD location showed higher of LAI and LAR (1.47 and 31.97 cm² g^–1, respectively) than PB location, while NAR, CGR and RGR were not significantly different (Table 4). It might be the effect of differences of soil fertility between those two locations. The PD soil contained higher of nitrogen, phosphorus, potassium, calcium and magnesium over than PB soil, which revealed higher of organic matter for 2.29% over than PB soil (Table 3). On the other hand, nitrogen fertilizer rate at 93.75, 187.5 and 312.5 kg N ha^–1 showed highest of LAI (1.04, 1.21 and 1.14, respectively), CGR (1.87, 1.85 and 1.48 mg cm^–2 day^–1, respectively) and nitrogen fertilizer rate at 93.75, 187.5 kg N ha^–1 showed highest of RGR (35.54 and 32.59 mg g^–1 day^–1, respectively). The values obtained correspond to those reported by Ainika et al.⁷ and Basra et al.⁵ that nitrogen fertilizer had promoting vegetative growth and Kineber¹² reported that nitrogen application enhance vegetative growth as well as the metabolism process in the plant and increase in dry matter accumulation. The LAR and NAR were not significantly different (Table 4). Moreover, Verdes cultivar provided higher of CGR (1.87 mg cm^–2 day^–1) and RGR (31.80 mg g^–1 day^–1) than Moradas cultivar. The LAI, LAR and NAR were not significantly different among cultivars (Table 4).

The study of interaction between planting locations, nitrogen fertilizer rates and cultivars found that LAR, NAR and CGR were significantly different, while LAI and RGR were not significantly different (Table 4). Verdes cultivar grown at PD location applied with nitrogen fertilizer 93.75 kg N ha^–1 showed higher of LAR (44.38 cm² g^–1) than other treatments but no significant different when compare with Moradas cultivar was grown at PD location applied with nitrogen fertilizer for 0 and 187.5 kg N ha^–1 and no significant different when compare with Verdes cultivar was grown at PD location applied with nitrogen fertilizer for 0 kg N ha^–1. Moradas cultivar grown at PD location applied with nitrogen fertilizer 187.5 kg N ha^–1 showed higher of NAR (3.88 mg cm^–2 day^–1) than other treatments but no significant different when compare with Moradas cultivar was grown at PD location applied with nitrogen fertilizer for 93.75 kg N ha^–1 and no significant different when compare with Verdes cultivar was grown at PB location applied with nitrogen fertilizer for 93.75 and 187.5 kg N ha^–1. Verdes cultivar grown at PD location applied with nitrogen fertilizer for 312.5 kg N ha^–1 showed higher of CGR (3.29 mg cm^–2 day^–1) than other treatments but no significant different when compare with Moradas cultivar was grown at PD location applied with nitrogen fertilizer for 93.75 kg N ha^–1 and no significant different when compare with Verdes cultivar was grown at PD location applied with nitrogen fertilizer for 187.5 kg N ha^–1 (Table 5).

Table 4:	Effect of planting locations, nitrogen rates and cultivars on Leaf Area Index (LAI), Leaf Area Ratio (LAR), Net Assimilation Rate (NAR), Crop Growth Rate (CGR), and Relative Growth rate (RGR) of quinoa
a,bMean within a column followed by the same letter do not significantly different to LSD at p<0.05, ns: Not significantly different, *Significantly at p<0.05

Fig. 1(a-c):	Effect of (a) Planting locations, (b) Nitrogen rates and (c) Cultivars on seed yield

Table 5:	Effect interaction of planting location, nitrogen rates and cultivars on Leaf Area Ratio (LAR), Net Assimilation Rate (NAR) and Crop Growth Rate (CGR)
SE: Standard error of a mean, a,bMean within a column followed by the same letter do not significantly different to LSD at p<0.05

Seed yield and seed quality analysis: The PD location showed higher of seed yield and 1,000 seed weight (2144.20 kg ha^–1 (Fig. 1a) and 3.00 g, respectively) than PB location because at PD location had higher of LAI and LAR than PB location. Therefore, it had increased ability for photosynthesis and transport photosynthate to grain. On the other hand, at PB location showed higher seed germination (97%), germination index (7.8568) and the low of mean germination time (3.12 days) when compared with PD location because the weather at PD location where high humidity were found. Those weather may induce the decrease of seed deterioration rate, which affected to seed viability, germination potential and germination percentage¹³. On the other hand, nitrogen fertilizer rate of 93.75,187.5 and 312.5 kg N ha^–1 results on higher of seed yield than those control (1336.80, 1872.00 and 1726.70 kg ha^–1, respectively) (Fig. 1b). Nitrogen fertilizer rate of 187.5 kg ha^–1 revealed higher of 1,000 seed weight than 93.75 kg N ha^–1 and control by 3.02 g.

Table 6:	Effect of planting locations, nitrogen rates and cultivars on seed yield, 1,000 seed weight, germination percentage, Germination Index (GI) and Mean Germination Time (MGT) of quinoa
a,bMean within a column followed by the same letter do not significantly different to LSD at p<0.05, ns: Not significantly different, *Significantly at p<0.05

The values obtained correspond to those reported by Erley et al.⁶ that nitrogen fertilizer rates at 80 and 120 kg N ha^–1 had the highest of quinoa grain yield at 3,083 and 3,495 kg ha^–1, respectively. And related to Oelke et al.⁴, Basra et al.⁵, Carlsson et al.¹⁴, Thanapornpoonpong¹⁵, Shams¹⁶, Gomaa¹⁷ and Geren¹⁸ reported that nitrogen fertilizer rates affected grain yield of quinoa because nitrogen fertilizer had promoting vegetative growth. Therefore had increased ability for photosynthesis and photosynthate translocation to promote grain and these results agreed with Thanapornpoonpong¹⁵ who noticed that seed yield per plant increased with increasing nitrogen fertilizer rates, while germination percentage, GI and MGT were not significantly different. The values obtained correspond to those reported by Kansomjet et al.¹⁹ and there are several factors that effect to the emergence percentage such as photoperiod and temperature²⁰. Moreover, Verdes cultivar provided higher of seed yield (1892.80 kg ha^–1) and 1,000 seed weight (2.97 g) than Moradas (Fig. 1c), while germination percentage, GI and MGT were not significantly different (Table 6).

The study of interaction between planting locations and nitrogen fertilizer rates found that seed yield and 1,000 seed weight were significantly different, while germination percentage, GI and MGT were not significantly different. Furthermore, the study of interaction between planting locations and cultivars found that seed yield and 1,000 seed weight were significantly different, while germination percentage, GI and MGT were not significantly different. On the other hand, the study of interaction between nitrogen fertilizer rates, cultivars and interaction between planting locations, nitrogen fertilizer rates and cultivars found that seed yield, 1,000 seed weight, germination percentage, GI and MGT were not significantly different (Table 6).

Table 7:	Influence of planting locations and nitrogen rates on seed yield and 1,000 seed weight
SE: Standard error of a mean, a,bMean within a column followed by the same letter do not significantly different to LSD at p<0.05

Quinoa grown at PD location applied with nitrogen fertilizer for 93.75 kg N ha^–1 showed highest of seed yield (2641.70 kg ha^–1), while at quinoa grown at PD location applied with nitrogen fertilizer for 93.75 kg N ha^–1 showed higher of 1,000 seed weight (3.0637 g) than other treatments but no significant different when compare with quinoa was grown at PD location applied with nitrogen fertilizer for 187.5 kg N ha^–1 and no significant different when compare with quinoa was grown at PB location applied with nitrogen fertilizer for 187.5 kg N ha^–1 (Table 7).

Furthermore, Verdes cultivar grown at PD location showed highest of seed yield and 1,000 seed weight (2479.80 kg ha^–1 and 3.0880 g, respectively) (Table 8).

Correlation between physiological characteristics: The study of correlation between physiological characteristics showed that the LAI had positively high correlation with the distribution of LAR (Fig. 2a).

Fig. 2(a-d):	Correlation analysis of LAI on (a) LAR, (b) CGR, (c) NAR and (d) Seed yield

Table 8:	Influence of planting locations and cultivars on seed yield and 1,000 seed weight
SE: Standard error of a mean, a,bMean within a column followed by the same letter do not significantly different to LSD at p<0.05

The LAI correlated with a number of leaves when LAI was high the number of leaves was increased. The high number of leaves can increased the distribution of leaves on plant which high correlated with high number of LAR. Figure 2b showed LAI had positively high correlated with CGR because when the plant had high of leaf area which could increased ability for photosynthesis and photosynthate translocation, which was important substance for crop growth, development and especially dry matter accumulation as well. However, value of high leaf area may not increased seed yield (Fig. 2d). The shading effect resulted the decrease of total photosynthesis or NAR. Figure 2c showed the negatively correlation between LAI and NAR which may indicated the leaves shaded cloud not provided the optimum of light interception. The total photosynthesis may decrease, then photosynthate did not translocated to only the primary sink (quinoa seed) but its also translocated to support the parasitic sink (shaded leaves), finally quinoa seed yield may decreased. The result were correlated to Basra et al.⁵ and Kansomjet et al.²¹.

CONCLUSION

Quinoa have high potential to produce in Thailand and Pang-Da research station location was highly responded to that nitrogen rate and cultivars for increased crop physiological growth and improved seed yield. Quinoa was grown with nitrogen fertilizer for 93.75 kg ha^–1 was suitable for quinoa seed production which provide high LAI, CGR, RGR and seed yield.

SIGNIFICANCE STATEMENT

Quinoa (Chenopodium quinoa Willd.) was contained high nutritional value especially essential amino acids and protein content twice more than common cereal grains. Those protein was highly quality and quantity close to the Food and Agriculture Organization (FAO) standard of human nutrition requirement quinoa is new crop in Thailand. Although there are many crop like rice, corn, soybean and mung bean but it’s quality nutritive value in quinoa is much higher compare with other crops. Also It grown in the area where the other crops cannot perform well.

ACKNOWLEDGMENT

This experiment was financially supported by a Kasetsart University 72 Year Anniversary Graduate Scholarship, from the Graduate School, The National Genetic Resource, Republic of Chile is particularly favorable seed samples for the research. Special thanks to Princess Sirindhorn International Center for Research, Development and Technology Transfer and Greatfully thanks to the Royal Project Foundation for crop management and maintenance and thanks to YVP fertilizer company to help the fertilizers for used in experiment. The Faculty of Agriculture, Kasetsart University to a generous place and equipment for research, for research achievements.