Maize is widely cultivated in Papua New Guinea (PNG) and provides farmers with nutrition and income. However, the fall armyworm (FAW) (Spodoptera frugiperda) (J.E. Smith) (Lepidoptera: Noctuidae) invasion is a threat ...Maize is widely cultivated in Papua New Guinea (PNG) and provides farmers with nutrition and income. However, the fall armyworm (FAW) (Spodoptera frugiperda) (J.E. Smith) (Lepidoptera: Noctuidae) invasion is a threat to its production and supply. Hence, this field experiment was conducted to assess the bio-efficacy of plant-derived pesticides (PDPs) against FAW and their interactive effects on maize agronomic performance under field conditions. The treatments studied were turmeric rhizome extract (TRE), neem leaf ash solution (NLAS), neem bark extract (NBE), and untreated plots (control) and were replicated 5 times using the randomized complete block design. The data were subjected to analysis of variance and means were separated by Fisher’s protected least significant difference test. The result showed that the application of PDPs significantly reduced FAW infestation during the period of peak infestation. At 33 DAS, NBE significantly had the lowest number of FAW larvae (0.6) [F (4, 15) = 5.11, p = 0.02] and FAW attack intensity (29.8%) [F (4, 15) = 8.69, p F (4, 15) = 3.58, p = 0.04] and had the highest number of harvested ears (5.0) [F (4, 15) = 3.72, p = 0.04] and fresh ear weights (447 g) [F (4, 15) = 4.65, p = 0.02] compared to NLAS. The TRE and NLAS had performed poorly relative to the control. Hence, NBE can be used to control FAW infestation at a period of high attack intensity (33 DAS). Moreover, this study will provide basic information for future studies on biopesticidal plant extracts as a control of FAW infestation under field conditions in PNG.展开更多
Ear morphological traits such as volume and shape are important features of maize and the quantitative associations among them can help understand kernel yield determination. 150 mature ears each of 4 maize cultivars ...Ear morphological traits such as volume and shape are important features of maize and the quantitative associations among them can help understand kernel yield determination. 150 mature ears each of 4 maize cultivars were collected from field experiments, and ear length(L), diameter(D), area(S) and volume(V) were recorded for individual ears, kernel weight per ear also recorded for a portion of the examined ears. Following principles of dimensional analysis, 8 theoretical equations of 3 sets,which relate ear higher dimensions to its length and diameter, were developed and parameterized and validated with the field observations. The 3 optimized equations showed that the shape of ears in maize can be featured with 3 dimensionless form factors, namely diameter-to-length ratio(c=D/L), areal form factor(b=S/L/D), and volumetric form factor(a=V/L/D/D). Statistically,all of them were significantly different among cultivars, and a's values varied from 0.582 to 0.612, and b's 0.839-0.868, and c's 0.242-0.308. Volumetric form factor and areal form factor could estimate precisely ear volume and area respectively, but diameter-to-length ratio was not suitable to estimate ear diameter by its length. Ear volume explained almost all variation of ear kernel weight and product L*D*D did the same substantially. Dimensional analysis proved to be promising in understanding relationship among morphological traits of ears in maize. Its application in crop researches should improve our knowledge of the physical properties of crop plants.展开更多
文摘Maize is widely cultivated in Papua New Guinea (PNG) and provides farmers with nutrition and income. However, the fall armyworm (FAW) (Spodoptera frugiperda) (J.E. Smith) (Lepidoptera: Noctuidae) invasion is a threat to its production and supply. Hence, this field experiment was conducted to assess the bio-efficacy of plant-derived pesticides (PDPs) against FAW and their interactive effects on maize agronomic performance under field conditions. The treatments studied were turmeric rhizome extract (TRE), neem leaf ash solution (NLAS), neem bark extract (NBE), and untreated plots (control) and were replicated 5 times using the randomized complete block design. The data were subjected to analysis of variance and means were separated by Fisher’s protected least significant difference test. The result showed that the application of PDPs significantly reduced FAW infestation during the period of peak infestation. At 33 DAS, NBE significantly had the lowest number of FAW larvae (0.6) [F (4, 15) = 5.11, p = 0.02] and FAW attack intensity (29.8%) [F (4, 15) = 8.69, p F (4, 15) = 3.58, p = 0.04] and had the highest number of harvested ears (5.0) [F (4, 15) = 3.72, p = 0.04] and fresh ear weights (447 g) [F (4, 15) = 4.65, p = 0.02] compared to NLAS. The TRE and NLAS had performed poorly relative to the control. Hence, NBE can be used to control FAW infestation at a period of high attack intensity (33 DAS). Moreover, this study will provide basic information for future studies on biopesticidal plant extracts as a control of FAW infestation under field conditions in PNG.
基金Supported by the National Natural Science Foundation of China(31271658)National Key Research and Development Program of China(2016YFD0300306)
文摘Ear morphological traits such as volume and shape are important features of maize and the quantitative associations among them can help understand kernel yield determination. 150 mature ears each of 4 maize cultivars were collected from field experiments, and ear length(L), diameter(D), area(S) and volume(V) were recorded for individual ears, kernel weight per ear also recorded for a portion of the examined ears. Following principles of dimensional analysis, 8 theoretical equations of 3 sets,which relate ear higher dimensions to its length and diameter, were developed and parameterized and validated with the field observations. The 3 optimized equations showed that the shape of ears in maize can be featured with 3 dimensionless form factors, namely diameter-to-length ratio(c=D/L), areal form factor(b=S/L/D), and volumetric form factor(a=V/L/D/D). Statistically,all of them were significantly different among cultivars, and a's values varied from 0.582 to 0.612, and b's 0.839-0.868, and c's 0.242-0.308. Volumetric form factor and areal form factor could estimate precisely ear volume and area respectively, but diameter-to-length ratio was not suitable to estimate ear diameter by its length. Ear volume explained almost all variation of ear kernel weight and product L*D*D did the same substantially. Dimensional analysis proved to be promising in understanding relationship among morphological traits of ears in maize. Its application in crop researches should improve our knowledge of the physical properties of crop plants.
