재식밀도가 '초롱' 단수수의 생육 및 수량구성요소에 미치는 영향

Effect of Planting Density on Growth and Yield Components of the Sweet Sorghum Cultivar, 'Chorong'

Abstract

본 연구는 단수수 '초롱'(Sorghum bicolor (L.) Moench)의 재식밀도(16.7, 11.1, 8.3, 6.7, 5.6주${\cdot}m^{-2}$)에 따른 생육, 착즙액의 수량 및 품질을 비교하고 적정 재식밀도와 다변량 분석을 통해 수량에 관계된 요인을 분석하고자 수행하였다. 재식밀도에 따라 파종 후 일수별 주경장은 처리간 차이가 없었으나 재식밀도가 높아짐에 따라 경태는 얇아지고 분지의 퇴화가 빨라지는 경향을 보였다. 수확기 추정한 착즙액과 당수량은 재식밀도가 높은 16.7 (각각 42.9, $4.16Mg{\cdot}ha^{-1}$), 11.1 (37.1, $3.73Mg{\cdot}ha^{-1}$)주${\cdot}m^{-2}$ 처리구가 8.3(30.5, $2.96Mg{\cdot}ha^{-1}$), 6.7 (26.6, $2.41Mg{\cdot}ha^{-1}$), 5.6 (24.7, $2.22Mg{\cdot}ha^{-1}$)주${\cdot}m^{-2}$ 처리구보다 많았다. 가용성 고형물 및 유리당 함량은 통계적인 차이는 없었으나 11.1, 8.3주${\cdot}m^{-2}$ 처리구에서 높은 편이었다. 반면 재식밀도가 5.6~11.1주${\cdot}m^{-2}$까지 증가했을 때 도복지수(9에 가까울수록 도복피해가 커짐)가 2.00~6.33까지 급격히 증가하여 최종 재식밀도의 결정시 태풍의 도래 횟수나 지형적인 특성 등을 고려해야 할 것이다. 추가적으로 조사항목간 상관분석과 주성분 분석에서 재식밀도는 생경수량($r=0.62^{**}$), 건물수량($r=0.58^{**}$), 착즙액($r=0.63^{**}$) 및 당수량($r=0.66^{**}$)과는 정의관계를, 주경의 굵기($r=-0.65^{**}$)와는 부의관계를 나타내었다. 또한 수량 관련 요인들은 초장, 경태, 마디수와 통계적 관계가 없었다.

This study was conducted to investigate the effect of planting density on plant growth, yield, and quality in the sweet sorghum cultivar 'Chorong' (Sorghum bicolor (L.) Moench). Plants were cultivated at densities of 16.7, 11.1, 8.3, 6.7, and $5.6plants{\cdot}m^{-2}$. Factors related to yield and yield components were analyzed using correlation and multivariate analyses. There was no significant difference among plant densities in stem length from 20 to 110 days after sowing. But the stem diameter was thin, and a decrease in number of tillers occurred more rapidly as planting density increased. At harvest, juice and sugar yield were higher at densities of 16.7 (42.9, $4.16Mg{\cdot}ha^{-1}$, respectively) and 11.1 (37.1, $3.73Mg{\cdot}ha^{-1}$) $plants{\cdot}m^{-2}$ than at 8.3 (30.5, $2.96Mg{\cdot}ha^{-1}$), 6.7 (26.6, $2.41Mg{\cdot}ha^{-1}$), and 5.6 (24.7, $2.22Mg{\cdot}ha^{-1}$) $plants{\cdot}m^{-2}$. The soluble solids and total sugar contents were not different among treatments, but relatively high values were observed at the density of 11.1 and $8.3plants{\cdot}m^{-2}$. As plant density was increased from 5.6 to $11.1plants{\cdot}m^{-2}$, the lodging index (1 = no, 9 = lodging) increased rapidly from 2.00 to 6.33. To determine the optimal planting density, the number of typhoons and topographical characteristics should be considered. Correlation and principal components analyses revealed that plant density exhibited a positive relationship with fresh stem yield ($r=0.62^{**}$), dry stem yield ($r=0.58^{**}$), juice ($r=0.63^{**}$), and sugar yield ($r=0.66^{**}$), but a negative with stem diameter ($r=-0.65^{**}$). The yield factors were not statistically related to stem height, diameter, and number of nodes.

Fig. 1. Influence of planting density on the seasonal patterns of stem length (A), diameter (B), and number of additional tillers (C) of the sweet sorghum cultivar ‘Chorong’ in 2018. Vertical bars represent standard error of the means (n = 15). Legend in the graph indicates planting density (PD) and the unit is number of plants per square meter. The dotted line represents heading date (71 days after sowing).

Fig. 2. Correlation between plant density and lodging index at 30 days after heading date of the sweet sorghum cultivar ‘Chorong’. Lodging index is the indexed value of percentage.

Fig. 3. Scatter plot matrix and Pearson’s coefficient between growth and yield characteristics surveyed at harvest period of the sweet sorghum cultivar ‘Chorong’. Plant density (PD), stem length (SL), stem diameter (SD), number of nodes (Node), soluble solids content (SSC), moisture contents of stem (MCS), dry matter (DM), fresh stem yield (FSY), dry stem yield (DSY), conservative sugar yield (CSY), juice yield (JY), sugar yield (SY). **P ≤ 0.01, *P ≤ 0.05 represent significant values (n=75).

Fig. 4. Scatter plot of growth and yield characteristics from principal components analysis at harvest period of the sweet sorghum cultivar ‘Chorong’. Plant density (PD), stem length (SL), stem diameter (SD), number of nodes (Node), soluble solids content (SSC), moisture contents of stem (MCS), dry matter (DM), fresh stem yield (FSY), dry stem yield (DSY), conservative sugar yield (CSY), juice yield (JY), sugar yield (SY).

Table 1. Effect of planting density on yield components at harvest (50 days after heading) of the sweet sorghum cultivar ‘Chorong’.

Table 2. Effect of planting density on sugar contents in juice at harvest (50 days after heading) of the sweet sorghum cultivar ‘Chorong’.

Table 3. Principal component (PC) analysis results of growth and yield characteristics of the sweet sorghum cultivar ‘Chorong’.