Acta Agriculturae Zhejiangensis

Effects of different cultivation patterns on grain yield and nitrogen use efficiency of rice in South China

PAN Junfeng, ZHONG Xuhua, HUANG Nongrong, LIU Yanzhuo, TIAN Ka, LIANG Kaiming, PENG Bilin, FU Youqiang, HU Xiangyu

2019, 31(6): 857-868. DOI: 10.3969/j.issn.1004-1524.2019.06.01

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The objective of this study was to investigate if an integrated cultivation technique could coordinately increase both grain yield and nutrient use efficiency of rice in South China. The indica hybrid rice cultivar Yueza 889 was used and six cultivation patterns were conducted in the late seasons of 2011 and 2012. i.e., zero nitrogen application, farmer’s practice (FP) and 4 integrated crop managements (M1-M4) varying in nitrogen fertilizer management and planting density. Compared with that of FP, the grain yields of M1, M2, M3 and M4 were increased by 16.7%, 20.5%, 18.3% and 24.1% in 2011, and by 6.3%, 16.0%, 22.9% and 12.8% in 2012. The M2, M3 and M4 yielded more grains by 1.3%-15.6% than M1. Compared with those of FP, the nitrogen absorption and utilization efficiency, agronomic utilization efficiency and partial fertilizer productivity of M1, M2, M3 and M4 were significantly increased by 65.2%-82.4%, 55.6%-88.1% and 7.9%-33.9% in two years. The enhanced yield was mainly attributable to the increase in both spikelets per unit area and filled grain percentage. The yield enhancement was highly correlated with dry weight at maturity, or amount of dry matter accumulated from heading to maturity. It was also significantly correlated with nitrogen accumulation at panicle initiation or maturity, and nitrogen agronomic utilization efficiency. The newly-developed cultural practices could be used in rice production for additional enhancement in grain yield and nitrogen use efficiency.

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Study on metabolic differences of white quinoa from two areas based on GC-MS

SHI Yujie, LI Xinglong, TANG Yuan, YU Haiping, WU Xiaoyong

2019, 31(6): 869-877. DOI: 10.3969/j.issn.1004-1524.2019.06.02

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In order to investigate the metabolic difference of white quinoa from Yanyuan County, Sichuan Province and Doulan County, Qinghai Province, the non-targeted metabolomics analysis was carried out. The white quinoa from two different areas were compared by GC-MS technique and multivariate statistical analysis. It was shown that there were differences in the metabolites of quinoa from two areas, and a total of 29 significant differential metabolites were detected, including 15 amino acids, 6 organic acids and some alditol, amines, polyphenols and alkaloids. There were 22 up-regulated metabolites, 7 down-regulated in all metabolites, and there were 12 amino acids (glycine, L-valine, glutathione, GABA, etc) and 5 organic acids (orotic acid, trans-cinnamic acid, 2-oxo-glutaric acid, etc.) in the up-regulated metabolites. Through the pathway analysis of MetaboAnalyst, 24 metabolic pathways associated with the up-regulated metabolites were detected, of which 7 pathways had significantly different effects on glutathione metabolism, nitrogen metabolism, alanine, aspartate and glutamate metabolism, aminoacyl-tRNA biosynthesis, phenylalanine metabolism, sulfur metabolism, glycine, serine and threonine metabolism. The effect of glutathione metabolism pathway was the most significant, and this pathway was closely related to the resistance of plants, the main metabolites glycine and glutathione of quinoa from Yanyuan, Sichuan Province were detected with a higher level of expression, which indicated the white quinoa from Yanyuan, Sichuan Province, had a stronger antioxidant capacity than that from Doulan, Qinghai Province, so that the plants had a good resistance to survive in adversity, which provided a theoretical basis for guiding the cultivation of white quinoa in both areas and the study on the mechanism of resistance.

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Effects of retinol on in vitro biological characteristics of sertoli cells from prepubertal porcine testis

DENG Jiaqiang, ZHONG Lijun, LIU Huanhuan, CAO Suizhong, SHEN Liuhong, YU Shumin

2019, 31(6): 878-885. DOI: 10.3969/j.issn.1004-1524.2019.06.03

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Sertoli cells are principal components of testicular seminiferous tubule epithelium. Retinol and its derivatives also play a critical role in the regulation of testicular development and spermatogenesis through sertoli cell mediation. To explore the effect of retinol on the in vitro biological characteristics of testicular sertoli cells, sertoli cells from 3 to 5 week-old porcine testis were selected as materials. Cellular viability, the expression of proliferation-related and apoptosis-related genes and secretion of cytokines were assessed. The results showed that compared with the control group, when the concentration of retinol was 5.000 and 0.125 μmol·L^-1, significant effects were seen on sertoli cell viability after 24 h and 72 h (P<0.05). Adding 1.250 μmol·L^-1 retinol group compared with the control group, the proliferation-related genes PCNA, BCL-2 and C-MYC were significantly down-regulated (P<0.05), apoptosis-related genes BAX was significantly up-regulated (P<0.05),and support intracellular GDNF, CSF-1 and EGF were significantly reduced in gene expression and protein levels (P<0.05). In summary, the addition of retinol can inhibit the activity of supporting cells and promote apoptosis in vitro culture conditions.

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Effects of single and combined exposure of deoxynivalenol and aflatoxin B₁ on pathological changes, antioxidant capacity and tight junction protein expression of brain tissue in mice

WANG Xichun, CAO Li, LIU Qin, DONG Yanli, WANG Zhongzheng, LIU Jinfang, ZHU Lei, FENG Shibin, LI Yu, WU Jinjie

2019, 31(6): 886-892. DOI: 10.3969/j.issn.1004-1524.2019.06.04

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The present experiment was conducted to evaluate the effects of single and combined exposure of deoxynivalenol (DON) and aflatoxin B₁ (AFB₁) on pathological changes, antioxidant capacity and tight junction protein expression of brain tissues in mice. Ninety-six 18-day-old Kunming(male)mice were randomly divided into control group, DON group, AFB₁ group and AD group (DON+AFB₁ group). Each group was fed with physiological saline, 500 μg·kg^-1 DON, 200 μg·kg^-1 AFB₁ and 200 μg·kg^-1 AFB₁+500 μg·kg^-1 DON by gavage respectively. The trial was conducted for 45 d. On the days 0, 15, 30 and 45 of the experiment, six mice in each group were randomly selected and killed after anesthesia,the brain tissues were collected for observing pathological change and measuring the oxidative and antioxidant indexes and the mRNA expression of tight junction protein ZO-1 and Occludin of brain tissue in mice. The results showed that compared with the control group, the activities of superoxide dismutase (SOD) and catalase (CAT) in brain tissues of DON group were decreased significantly (P<0.05), while the content of NO was increased significantly (P<0.05). The activity of CAT in brain tissue of AFB₁ group decreased significantly (P<0.05). The activities of T-AOC, CAT and SOD of brain tissues in the AD group were decreased significantly (P<0.05). The contents of MDA and NO of brain tissues were increased significantly (P<0.05).The mRNA expression of ZO-1 and Occludin were decreased significantly in treatment group (P<0.05). In conclusion, single and combined exposure of DON and AFB₁ can lead to different degrees of pathological changes, as well as reduce antioxidant capacity in mouse brain tissue, produce oxidative damage, while decrease the mRNA expression of ZO-1 and Occludin. DON and AFB₁ exhibit a significant interaction with synergistic effects.

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Comparison of characteristics of strawberry varieties with different ploidy

WANG Shuzhen, ZHANG Yahui, QIU Jieren, ZHOU Liping, CHEN Sisi, CHAI Weiguo, MAO Bizeng

2019, 31(6): 893-899. DOI: 10.3969/j.issn.1004-1524.2019.06.05

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In order to effectively utilize the strawberry germplasm resources and improve the success rate of interspecific hybridization, comparative studies on the characteristics of different ploidy strawberry varieties were carried out. The agronomic traits of diploid RG, octoploid Benihoppe, decaploid Tokun were observed in the field; Nutritional qualities of vitamin C (V_C), titratable acid, soluble solid, soluble total sugar, polyphenols, flavonoids, etc. were determined; Antioxidant capacity of DPPH and FRAP was determined; Anther activity was determined by TTC staining; Stigma receptivity was determined by benzidine-hydrogen peroxide method. The results showed significant differences in plant height, fruit color and flavor, average single fruit weight, hardness and other agronomic traits. RG fully displayed the characteristics of rich nutrients including nutrient quality and antioxidant properties in wild resources. RG had higher content of V_C, titratable acid, soluble solids, polyphenols, flavonoids and antioxidant capacity of DPPH and FRAP than Benihoppe and Tokun. The results of TTC staining showed that Tokun had the strongest anther vigor and longest duration, followed by Benihoppe. The anther vigor peaks of’ Tokun and Benihoppe occurred in the big bud stage and 1^st day after flowering, while RG had only a few viable anthers in the bud stage, but no anther activity was detected in the other stages. The results of benzidine-hydrogen peroxide assay showed that stigma receptivity of Benihoppe and Tokun was the strongest at big bud stage and 1^st day after flowering. RG produced a small amount of bubbles in the stigmas of big bud stage, 1^st day, 2^nd day and 3^rd day after flowering, but its receptivity was weak. Stigmas at other flowering stages were not receptive. When RG was used as the male parent, the anther collection should be controlled at the bud stage. When RG was used as the female parent, enough pollen was needed and the pollination time should be from the bud stage to the 3^rd day of flowering. Benihoppe was an important parent material for variety improvement due to its outstanding quality and excellent comprehensive performance. Tokun could be used as an important resource for the improvement of characteristic varieties and interspecific hybridization because of its excellent appearance and peach-like aroma.

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Effects of rain-sheltered cultivation on sugar accumulation and nutritional growth of early-maturing sand pear fruit in Xuhuai area

LI Gangbo, ZHANG Mei, FAN Jide, ZHAO Lin, ZHANG Ting, LIN Jing, CHANG Youhong, YANG Feng

2019, 31(6): 900-907. DOI: 10.3969/j.issn.1004-1524.2019.06.06

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In order to study the effect of rain-sheltered cultivation on sugar accumulation and vegetative growth of early-maturing pear fruits, the changes of sugar content, shoot length, shoot diameter and leaf fresh weight , leaf dry weight and leaf water content of early-maturing pear Sucui 1 and Cuiguan fruits in rain-sheltered cultivation and open-field cultivation were analyzed by high performance liquid chromatography. The results showed that: (1) The light intensity of rain-sheltered cultivation environment was lower than that of open-field cultivation, and the diurnal average variation trends of light intensity of two cultivation modes were basically the same. The cultivation environment constructed by rain-sheltered facilities had an effect on the formation of fruit quality. Fructose and glucose contents were higher during the fruit growth and development period, and sucrose accumulation increased in the later period. The accumulations of fructose and sucrose were the highest in the late stage. The accumulation of soluble sugar in fruit was 21.73% and 17.97% higher in sheltered cultivation than in open field cultivation. (2) The contents of organic acid in the fruits of two early-maturing pear cultivars under rain-sheltered cultivation were lower than those of open-field cultivation, and the contents of malic acid, citric acid and quininic acid were mainly affected. The contents of malic acid in Sucui 1 and Cuiguan fruits were 35.08% and 21.05% lower than those of open-field cultivation, respectively, but the content of shikimic acid was not affected obviously. (3) Rain-sheltered cultivation had no significant (P>0.05) effect on shoot length, diameter and leaf dry weight of early-maturing pear, but had great effect on leaf fresh weight and leaf water content. Leaf fresh weight of Sucui 1 and Cuiguan under rain-sheltered cultivation were 8.22% and 10.15% lower than those of open field cultivation, respectively. Leaf water content of Sucui 1 and Cuiguan with rain shelter cultivation were both significantly (P<0.05) lower than those of open field cultivation.

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Effects of rootstocks on growth and fruit quality of Xinyu grape

CAO Yuehua, WEI Lingzhu, SHEN Biwei, CHENG Jianhui, XIANG Jiang, WU Jiang

2019, 31(6): 908-914. DOI: 10.3969/j.issn.1004-1524.2019.06.07

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In order to evaluate the effects of rootstock grafting on the growth and fruit quality of Xinyu grape in the humid and hot regions of South China, the experimental materials were Xinyu grapes grafted with four different rootstocks Gloire, Summer Black, Kangzhen No.1, Kangzhen No.6. The related indexes of different rootstock-scion combinations were investigated, including phenological period, growth and fruiting habits, fruit economic characteristics, nutrient composition, etc. The differences of rootstock-scion combinations were analyzed, and the fruit quality of grape rootstock-scion combinations was evaluated comprehensively by principal component analysis. The results showed that four rootstock-scion combinations could increase the germination rate and fruiting branch rate of Xinyu, and the total phenol and sugar content of Gloire and self-rooted seedlings were significantly higher than those of Summer Black, Kangzhen No.1, Kangzhen No.6. The average grain weight of Gloire and Kangzhen No.1 were significantly higher than that of Summer Black and self-rooted seedlings. Principal component analysis showed that among the four rootstocks, Gloire was the best one for Xinyu grape.

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Effect of soil simulated acidification on photosynthetic characteristics and ultrastructure of Sedum aizoon L. leaves

WANG Yiming, LONG Shengju, CHEN Yan, HE Zhongqun, ZHAO Yingpeng, YANG Luxi, YAN Wenyi

2019, 31(6): 915-921. DOI: 10.3969/j.issn.1004-1524.2019.06.08

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In this study, the effect of soil acid stress on photosynthetic characteristics and ultrastructure of Sedum aizoon L. leaves were studied by simulating soil acidification under different soil pH values (3.4, 4.6, 5.5). The results showed that with the intensification of soil acidification, the dissolution of aluminum ions in soil increased rapidly, while the total chlorophyll content in leaves decreased gradually and the relative cell conductivity and malondialdehyde content increased gradually. Under mild (pH 5.5) and moderate (pH 4.6) acidification, plant photosynthetic and fluorescence parameters were not significantly different from CK (pH 6.6), and chloroplast ultrastructure was intact. Under severe (pH 3.4) acidification, photosynthesis and fluorescence parameters showed obvious threshold response, P_n, C_i, T_r, G_s, F_o, F_m, Φ_PSⅡ, qP, F_v/F_m fell rapidly, NPQ and L_s were significantly higher, and the chloroplast was no longer uniformly distributed along the cell membrane, and the cluster aggregated in the cytoplasm, the granum lamella appeared obvious gap, parts of the internal capsule membrane blurred. Thus, the reason of soil acidification leading to membranous peroxidation of plant leaves might be that it promoted the increase of aluminum ions in soil. Mild and moderate soil acidification did not cause changes in leaf photosynthesis and ultrastructure, while severe soil acidification would lead to destruction of chloroplast structure and function and decrease of photosynthetic capacity. At the same time, the plant can defend against the harm of soil acidification by inducing the increase of osmotic substances and the enhancement of antioxidant enzyme activity.

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Distribution and resistance evaluation of 5 rice blast-resistant genes in cultivated rice varieties in Zhejiang

HE Haiyan, CHAI Rongyao, QIU Haiping, MAO Xueqin, WANG Yanli, SUN Guocang

2019, 31(6): 922-929. DOI: 10.3969/j.issn.1004-1524.2019.06.09

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In order to clarify the distribution of blast resistance genes in some rice cultivars and blast-resistant cultivars in Zhejiang Province, five functional molecular markers based on blast resistance allele sequences were used to detect Pit, Pib, Pii/Pi3/Pi5, Pia and Pi1 resistance genes in 40 main rice varieties in Zhejiang Province and 6 Chinese rice blast identification varieties. The results showed that the distribution frequencies of the five resistance genes were different, Pib gene was most widely distributed, accounting for 63.04%, followed by Pia, accounting for 58.70%, Pii/Pi3/Pi5 and Pit resistance genes were less, accounting for 21.74% and 10.87% respectively. At the same time, the resistance level of 46 rice varieties to Magnaporthe grisea was detected by 141 strains collected in the field from 2015 to 2017. The results showed that the resistance frequency of 15 varieties was more than 70%. Most of the varieties carried one or two resistance genes. The resistance level of varieties with multiple resistance genes was relatively higher.

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Volatility, adsorption and degradation characteristics of isoxaflutole in water, soil and water-sediment system

ZHANG Chunrong, SHAN Lingyan, GUO Qian, XU Zhenlan, HE Hongmei, WU Min, ZHAO Xueping

2019, 31(6): 930-937. DOI: 10.3969/j.issn.1004-1524.2019.06.10

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In order to evaluate the risk of isoxaflutole in the environment, the volatility, absorption and degradation characteristics of isoxaflutol was examined by a laboratory test. The results demonstrated that absorption of isoxaflutole in four soil types (fluvo-aquic soil, paddy soil, black soil and red soil) accorded with Freundlich equation. The calculated adsorption coefficient of isoxaflutole in fluvo-aquic soil, paddy soil, black soil and red soil was 0.640 6, 1.376 2, 0.816 9 and 1.289 5, respectively. The results indicated that isoxaflutole was hardly absorbed in these four soil types. The degradation of isoxaflutole in lake (West Lake) and river (Grand Channel) water-sediment system accorded with first-order kinetic equation. The aerobic degradation half-life period was 73.7 h and 75.3 h, respectively, and the anaerobic degradation half-life period was 42.3 h and 43.0 h, respectively. The results indicated that isoxaflutole was an easily degradable pesticide in water-sediment system .The volatility rate of isoxaflutole in air, water and on soil surface was less than 1% under the conditions of 20-25 ℃ and 500 mL·min^-1 gas flow rate, indicating that isoxaflutole belonged to a difficult volatility pesticide. In general, isoxaflutole possessed the characteristics of difficult volatility, difficult absorption and fast degradation in water-sediment system, and had a relatively low risk to environment.

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Effects of atmospheric dust-fall pollution on growth and heavy metal contents of typical crops

SUO Chen, LUO Xiaosan, ZHAO Zhen, SUN Xue, ZHANG Dan, CHEN Yan

2019, 31(6): 938-945. DOI: 10.3969/j.issn.1004-1524.2019.06.11

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In order to investigate the influence of atmospheric dust-fall on the crop growth and product quality, the dust-fall collected from different sources was used to simulate the dust-fall deposition experiments with two typical crops under different concentrations. The photosynthetic and respiratory rates, chlorophyll content, biomass and heavy metal contents of aboveground parts of pakchoi (Brassica chinensis) and rice (Oryza sativa) seedling were analyzed. The results showed that atmospheric dust-fall significantly inhibited the photosynthetic rates of these crops, reduced the leaf chlorophyll contents, and enhanced the respiration rates, resulting in a decrease of dry weight of aboveground pakchoi and rice seedling by 11.8%-51.3 % and 12.7%-35.5%, respectively. Atmospheric dust-fall significantly increased the contents of some heavy metals accumulated in pakchoi and rise seedling, and eventually worsened the crop quality.

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Effect of fertilization on soil fauna community structure in farmland

LUO Manli, LAN Qin, WANG Ge, WEI Hong, XIAO Jiujin, ZHANG Jian

2019, 31(6): 946-954. DOI: 10.3969/j.issn.1004-1524.2019.06.12

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In order to explore the impact of fertilization on soil fauna community structure, urea was selected as test fertilizer, and an experiment with different fertilizing amounts, i.e. 225 kg·hm^-2 (T1), 450 kg·hm^-2 (T2), 900 kg·hm^-2 (T3), 1 800 kg·hm^-2 (T4), 3 600 kg·hm^-2 (T5), and plot without fertilizer as control (CK) was carried out. The hand-picked concentrations and wet and dry separation funnel were recorded to reflect the characteristics of soil fauna communities in the survey. It was shown that all the collected soil fauna samples went to 3 phyla, 13 classes, 19 orders, 40 families. The order of the average density of soil fauna of different treatments was as CK>T2>T1>T3>T5>T4. The order of species quantity of different treatments was as T1>CK>T2>T4>T5>T3. With the increasing application amount of fertilizer, the average density of both macro-fauna and nematodes and meso-fauna in soil showed a decreasing trend. Among all the treatments with fertilization, T2 exhibited the lowest Shannon-Wiener index and Simpson index, and the highest Pielou index. In general, over application of fertilizer would reduce the quantity of soil animals, the diversity of soil fauna community, and impact soil fauna community structure.

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Influence of matrix effect on determination accuracy of potassium content in soil and plant samples by flame photometer

REN Jiaxin, YANG Wenna, LI Zhongyi, HU Yanyan

2019, 31(6): 955-962. DOI: 10.3969/j.issn.1004-1524.2019.06.13

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In order to study the interference of matrix effect on the measurement of soil and plant potassium content by flame photometer, the electrical signals of the K⁺ test solutions and K⁺ standard solutions with same matrix were measured. The K⁺ test solutions consisted of water soluble potassium, rapidly available potassium, slowly available potassium, total potassium of soil and total potassium of plant. The interference of different types of matrixes and different dilution factors of matrixes were studied. It was shown that the K⁺ content of standard samples had a high recovery rate when the matrixes of test solutions and standard solutions were the same. It caused a negative error, especially for total potassium of soil and total potassium of plant, when the matrix of K⁺ standard solutions was deionized water. The effect of matrix could be reduced by dilution of matrix. However, within the commonly adopted dilute times of soil or plant sample, the measured electrical signals of K⁺ standard solutions with different matrixes still varied. In order to eliminate the interference caused by the differences of matrixes, the matrixes between K⁺ test solution and K⁺ standard solution should be kept consistently when the potassium contents of soil and plant samples were measured by flame photometer.

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Differences in spectral characteristics of typical vegetation in Caofeidian wetland

WANG Meiling, JIAO Linlin, WANG Xiaohong, WU Bing, XIAO Xingxing

2019, 31(6): 963-969. DOI: 10.3969/j.issn.1004-1524.2019.06.14

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Analysis into the unique spectral features of the ground objects can effectively identify the ground objects by using hyperspectral remote sensing technology. In the present study, the Caofeidian wetland in Tangshan City, Hebei Province was selected as the research object. The spectral characteristics of two typical wetland vegetations, Suaeda salsa (L.) Pall. and Phragmites australis(Cav.)Trin.ex Steud., were identified by SR2500 portable ground spectrometer. The original reflectance spectral curves of the two wetland vegetations and the reflectance spectral curves transformed by the envelope removal method were studied. It was shown that, due to the limitation of the envelope removal method, it was easier to distinguish the growth curve of the original vegetation of Phragmites australis in the range of 340-380 nm and 716-1 020 nm. In the range of 340-595 nm and 710-920 nm, the analysis of the original spectral curve of Suaeda salsa was more favorable to distinguish the growth periods. The reflectivity of the two vegetations in the vigorous growth period was higher than that in the terminal growth period. The envelope removal method at 508, 550 , 678 nm could better distinguish the growth periods of Phragmites australis, and the method of envelope removal at 638, 678 nm could better distinguish the growth periods of Suaeda salsa. For the two vegetations, the Phragmites australis had a distinct reflection peak at 550 nm in the green light band, while the Suaeda salsa had an obvious reflection peaks at 638 nm in the red light band, which made the two vegetations easier to distinguish after the treatment of envelope removal. In the range of 753-1 020 nm, the analysis of the original spectral curve was more suitable to distinguish the two vegetations, and the reflectivity of Phragmites australi was higher than that of Suaeda salsa.

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Optimization of solid fermentation for enzymes produced by Aspergillar sulphureus SQ-3

MA Yanwen, GAO Huali, LI Qianwen, YU Junjie, LYU Zhiwei

2019, 31(6): 970-976. DOI: 10.3969/j.issn.1004-1524.2019.06.15

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In this research, effects of different carbon and nitrogen sources, initial pH value, culture temperature and culture time on the activities of cellulase, amylase and xylanase produced by Aspergillar sulphureus SQ-3 were studied. By investigating the influence of different baking temperature on survivability of this fungus and the activities of these enzymes, the results showed that the optimum culture medium for producing enzymes was as follows: 25.7% of corn stalk powder, 5.8% of soybean meal, 8.5% of wheat bran, 28 ℃ as fermentation temperature and initial pH value of 7.0. Under these conditions, higher activities of cellulase, amylase and xylanase were obtained, and they were 453.3 U·g^-1, 3.9×10³ U·g^-1 and 1.48×10⁵ U·g^-1, respectively. The number of viable spores under the baking temperature of 40 ℃ was over 1.1×10⁸ CFU·g^-1 and the activities of xylanase, cellulase and amylase were well preserved. The results indicated that the fermentation conditions listed above were suited to lower-cost and efficient culture for enzymes produced by Aspergillar sulphureus SQ-3.

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Method and experiment for estimating emergence rate of water and fertilizer integrated maize based on drone technology

LIU Zhi, HE Zheng, MIAO Fangfang, JIA Biao

2019, 31(6): 977-985. DOI: 10.3969/j.issn.1004-1524.2019.06.16

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The seedling emergence rate is the prerequisite and guarantee for high yield of spring-sown maize in Northwest China. In view of the phenomenon of heavy workload, time-consuming, labor-consuming and error leakage by manual statistics in the process of large-scale cultivation of maize in Ningxia, different nitrogen treatment experiments were designed, which used a drone equipped with a digital camera to obtain HD images of maize seedlings. The ORB algorithm in MATLAB software and distance-weighted fusion algorithm were used to synthesize unmanned aerial vehicle images. The image outlines of maize seedlings were obtained through depth optimization techniques such as binarization and corrosion expansion, and then automatically planned routes and calculated using MATLAB eight-bit connected domain and ARCMAP 10.3 calculation method. The number of maize emergence was routed and calculated. Based on the field artificial survey data, a linear regression analysis method was introduced to establish a linear relationship model between manual counting and the number of maize seedlings obtained by drones. The results showed that the determination coefficient of the linear regression relationship model, root mean square error and normalized root mean square error were 0.895, 4.359 and 2.436%, respectively. Therefore, based on the low-altitude drone platform, the rapid acquisition of the number of emergence of maize in the field was a time-saving, efficient and accurate method for obtaining seedling rate. It could provide technical support for the accurate assessment of the subsequent high yield of maize, and was of great significance for optimizing the precise planting technology of water and fertilizer integration of maize in Ningxia.

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Effect of droplet volume on leaf contact angle of rice

ZHANG Jiantao, ZENG Jiajun, YIN Xuanchun, LAN Yubin, WEN Sheng, LIN Gengchun

2019, 31(6): 986-995. DOI: 10.3969/j.issn.1004-1524.2019.06.17

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Contact angle is the main indicator to measure the effect of droplets on the spreading and retention of rice leaves. In order to accurately measure the contact angle θ of droplets on rice leaf surface, influence of droplet volume on leaf contact angle of rice was studied. The leaf contact angle (θ), droplet height (h) and droplet contact surface diameter (d) of different droplet volumes were measured by experiment, and the variation of contact angle with droplet volume was analyzed. The results showed that droplet volume had a significant effect on leaf contact angle of the four tested rice. At the initial stage of the rise in droplet volume (about 1.0 to 7.5 μL), the ratio of rate at which the droplet height changes with droplet volume (h'_v) to the rate at which the droplet contact surface diameter changes with droplet volume (d'_v)>h/d, leaf contact angle of rice increased. In the later stage of the droplet volume continued to rise (7.5-20.0 μL), when h'_v/d'_v≈h/d, leaf contact angle of rice was basically unchanged. When h'_v/d'_v<h/d, leaf contact angle of rice decreases. Finally, the contact angle tended to be stable. It was concluded that the droplet volume had a significant effect on leaf contact angle of the rice, and the change trend of contact angle was closely related to the droplet height, contact surface diameter and growth rate of both. Finally, it was also proposed that the droplet volume used in the rice leaf contact angle experiment should be larger than the volume corresponding to the maximum contact angle of the rice leaf surface, and it was best controlled within the range of 7.5-20.0 μL. It was also concluded that the maximum contact angle of the rice leaf surface was within 7.5-10.0 μL of droplet volume, and it was approximated when h'_v/d'_v≈h/d for the first time.

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Rice leaf geometric parameter measurement system based on B-spline curve

LU Yan, YANG Hongyun, ZHOU Qiong, SUN Yuting, YIN Hua

2019, 31(6): 996-1004. DOI: 10.3969/j.issn.1004-1524.2019.06.18

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In order to obtain accurate geometric parameters of rice leaves non-destructively and to provide accurate data for agronomic research, the rice leaf geometric parameter measurement system based on B-spline curve was developed. The basic principle of B-spline curve fitting was elaborated, and the maximum leaf width of rice was obtained by using first order B-spline curve and the leaf length was obtained with gesture trajectory curve drawn to approximate the leaf vein based on cubic B-spline curve. Moreover, the number and position of control points could be manually intervened, therefore to realize real-time adjustment of the trajectory curve. In the results analysis, coefficient of variation (CV) and root mean square error (RMSE) were applied to evaluate the precision and accuracy of results. The leaf length CV was 2.4%, the leaf width CV was 5.4%, both were less than 15%, which meant that the results were of high precision; Meanwhile, linear regression fitting model of system prediction and measured values was established, found that the RMSE of leaf length was 1.534 0 cm and the RMSE of leaf width was 0.101 9 cm, which demonstrated that the system had excellent prediction ability. The results showed that the B-spline curve based measurement system could truly realize accurate acquisition of rice leaf length and leaf width conveniently and non-destructively and without much restriction in photo shooting, which provided a new measurement method for the determination of rice leaf geometric parameters and could satisfy the basic needs of agricultural scientific research.

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Research on recognition algorithm of field mulch film based on unmanned aerial vehicle

LIANG Changjiang, WU Xuemei, WANG Fang, SONG Zhujun, ZHANG Fugui

2019, 31(6): 1005-1011. DOI: 10.3969/j.issn.1004-1524.2019.06.19

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In order to meet the requirements of intelligent recognition of field mulch film based on machine vision, the images were taken vertically by unmanned aerial vehicle (UAV) to the tobacco seedlings with mulch film in the field. The component color information histograms based on RGB and HSV color model of mulch film, tobacco seedlings and soil were analyzed. The color information of B component and V component was able to identify mulch film from background with the threshold segmentation method. The manual threshold segmentation, iterative threshold segmentation, large-law segmentation and maximum entropy method based on genetic algorithm were compared. Results showed that the iterative threshold segmentation algorithm had the highest target recognition rate of 71%, and the processing time was the shortest. The mulch film recognition rates under different flight heights was analyzed and figured out. It was found that the film recognition rate at 50 m flight height was the highest as 80.06%, the film recognition area was 246.83 m², and the film coverage rate was 30.12%. This research provided a method and reference for intelligent identification of mulch film and residual membrane with crop based on UAV.

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Evaluation of China’s agricultural modernization and evolution of its spatial pattern

WEI Suhao, LIU Yingran, GAO Yanlei, ZONG Gang

2019, 31(6): 1012-1020. DOI: 10.3969/j.issn.1004-1524.2019.06.20

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The evaluation index system of agricultural modernization was constructed from three dimensions of input, output and production services. Based on the provincial panel data from 2000 to 2016, the temporal and spatial evolution law and spatial spillover effect of agricultural modernization in China were empirically analyzed by using the method of entropy weight. It was shown that from 2000 to 2016, China’s overall level of agricultural modernization development showed an upward trend, and exhibited the characteristics of spatial differentiation of high in east, low in west, high in north and low in south. It was divided into high-value areas with the Huang-Huai-Hai Plain as the core and low-value areas with the southwest mountainous areas as the core. There were significant spatial agglomeration trends and positive spatial spillover effects in agricultural modernization. The local spatial agglomeration mode was dominated by high-high and low-low. The government should formulate strategies to improve the development level of agricultural modernization in different areas, focus on promoting the level of agricultural modernization in mountainous areas, and give full play to the spatial spillover and radiation-driven effect.

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Progress in proteomics analysis of plant response to salt stress

WANG Zhe, CHAI Li’ang, FAN Huaifu, DU Changxia

2019, 31(6): 1021-1028. DOI: 10.3969/j.issn.1004-1524.2019.06.21

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Salt stress seriously affects the growth and development of crops, which is one of the main adverse factors leading to the decline of crop yield and quality. Protein is not only the performer of plant physiological function, but also the direct manifester of life activities. It is important to clarify the types and properties of differentially expressed proteins under salt stress for improving plant salt tolerance. Proteomics technology is a powerful tool for studying differentially expressed proteins. In this paper, the research advances in the application of proteomics in plant response to salt stress were reviewed. The different protein species of glycophytes and halophytes responding to salt stress were compared, and the application of proteomics in plant response to salt stress was prospected.

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