Screening and evaluation methods of drought resistance index of sweet sorghum at maturity
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DOI:10.7606/j.issn.1000-7601.2020.01.36
Key Words: sweet sorghum  mature period  drought resistance  drought resistance index
Author NameAffiliation
YUAN Chuang College of Agronomy, Ningxia University, Yinchuan, Ningxia 750021, China 
Xu Xing College of Agronomy, Ningxia University, Yinchuan, Ningxia 750021, China
Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest, Ministry of Education China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China 
MAO Guilian College of Life Sciences, Ningxia University, Ningxia, Yinchuan 750021, China 
ZHU Lin Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest, Ministry of Education China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China
State Key Laboratory Breeding Base of Land Degradation and Ecological Restoration of Northwest China, Ningxia University, Yinchuan, Ningxia 750021, China 
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Abstract:
      In order to screen out the drought\|tolerant sweet sorghum cultivars (lines) and identification indicators, an experiment was conducted using 22 sweet sorghum cultivars (lines), normal irrigation (T1), severe drought (T2),plant height, spike weight, spike weight per plant, 1000-grain weight, and yield (yield per unit area) were measured. By using correlation analysis, principal component analysis, drought resistance coefficient(DRC), comprehensive drought resistance coefficient (CDRC value), weighted drought resistance coefficient (WDC value), membership function value (D value), cluster analysis, and other analytical methods, we did identification and index screening of drought resistance of different sweet sorghum varieties at maturity. The results showed that drought effected indicators remarkably (P>0.05). The frequency analysis of drought resistance coefficient showed that the drought resistance of each index was in the order of the grain number per spike>number of branches>plant height>culm diameter>1000-grain weight>spike culm diameter>spike weight>spike length>spike weight>yield. Correlation analysis showed that plant height was significantly negatively correlated with ear weight (P<0.05); yield was extremely significantly positively correlated with ear grain number, ear weight, kernel weight per plant, and thousand kernel weight (P<0.01) ; Ear weight and grain weight per plant were extremely significantly positively correlated (P<0.01); ear weight was extremely significantly positively correlated with grain number per ear (P<0.01); grain weight per plant was extremely significantly positively correlated with thousand\|grain weight (P<0.01). By using principal component analysis, those indicators were transformed into 5 new independent comprehensive indicators, which could replace 88.087% information of all the original indicators. The grey correlation analysis showed that the correlation level of indicators’ DRC and D values ranked as spike weight per plant>1000-grain weight>grain number per spike>yield>spike culm diameter>branch of number>spike weight>spike length>plant height>culm diameter. According to D value clustering analysis, tested sorghum materials were divided into 5 drought resistance grades, 3 belonged to grade I, 7 belonged to grade II, 6 belonged to grade III, 4 belonged to grade IV, and 2 belonged to grade V. The result of cluster analysis showed that except for the plant height, culm diameter, spike length, the 1000-grain weight, spike weight per plant, spike weight, grain number per spike, D value, number of branches, spike culm diameter, CDRC value, and WDC value went up following the index of drought tolerance. Stepwise linear regression indicated that the 1000-grain weight, spike weight per plant, grain number per spike, spike culm diameter and D value were strongly linked. Drought stress had significant effects on various indicators of sweet sorghum maturity. The 1000-grain weight, spike weight per plant, grain number per spike, and spike culm diameter were regarded as visual, precise, and simple evaluation indexes of drought\|tolerance. F417, F438 and F6137 were the most resistant sweet sorghum cultivar (lines).