Study on Development Characteristics and Fruit Growth Model of Pear Cultivated between Plastic Tunnel and Open Field
|School||Nanjing Agricultural College|
|Keywords||pear cultivated in plastic tunnel phonological phases development fruit quality growth model|
The 4 years old pear cultivars Cuiguan and Huang guan cultivated in plastic tunnel and open field were used to study the differences of air temperature, relative humidity and phonological phases of pear and the development features of shoots, leaves and fruit of pears cultivated in plastic tunnel and open field. In addition, the fruit growth model were established between plastic tunnel and open field. The main results of this paper showed that:The air temperature and soil temperature were gradually rising, but the air temperature, air relative humidity, soil temperature and day-and-night temperature difference in the plastic tunnel were higher than those in the open field before June. Then the temperature in the plastic tunnel hasn’t been significantly different from that in the open field. The beginning of flowering stage of Cuiguan and Huangguan pear cultivated in plastic tunnel was 18d earlier than those cultivated in open field, and the flowering stage was 2 days longer. Compared with cultivated in open field, the harvesting day of Cuiguan pear cultivated in plastic tunnel was 13 days earlier and it’s fruit ripening stage was 5d longer, while the harvesting day of Huangguan pear cultivated in plastic tunnel was 14 days earlier and it’s fruit ripening stage was 4 days longer. Cuiguan pear and Huangguan pear cultivated in plastic tunnel sprouted earlier and defoliated later, and the whole vegetative growth stage of Cuiguan pear was 242 days and was 27 days longer, while Cuiguan pear was 231 days and was 37 days longer.Compared with pear cultivated in open field, the beginning of shoot of Cuiguan and ’Huang Guan’ pear was about 15d earlier; the shoots were shorter and finer, but the relative length was larger; and plastic tunnel could increase internode length of Cuiguan pear by 6.74% and internode length of Huangguan pear by 10.80%. The changes of length, diameter, relative length, internode length of shoots and the number of leaves in the shoots and fruit development days were perfectly fit to the cubic curve; and there was a high correlation coefficient, so it could simulate and predict the growth and development periods of branches of pear cultivated in plastic house and open field well. Compared with cultivated in open field, both the Cuiguan pear and Huangguan pear had fewer short branches, while more long branches.Leaf fresh weight, leaf area, stomatal longitudinal diameter of Cuiguan and Huangguan pear in plastic tunnel were greater than those in open field, but the stomatal density was less than those in open field. The proportion of pear in plastic tunnel were lower than those in open field, while the proportion of pear in plastic tunnel were higher than those in open field. Correspondingly, the ratio of palisade and spongy tissue of pear leaf in plastic tunnel was lower than those in open field. Cuiguan and Huangguan pear in plastic tunnel has higher contents of chlorophyll content and lower transpiration rate than pear planted in open field. Moreover, they had higher net photosynthetic rate than pear planted in open field after the films thrown off. At the same fertilization level,the contents of N, P, and K of pear leaves in plastic tunnel were lower than those in open field at different stages. Pear cultivated in plastic tunnel exposed to lower malonaldehyde content while higher proline content than those planted in open field.Fruit development period of Cuiguan and Huangguan planted in plastic tunnel were 5 and 13 days longer than they planted in open field. The contents of soluble solids and soluble sugar of fruit in plastic tunnel were higher than they in open field, too. The same as fruit mass, diameter and fruit cell size. The contents of total soluble sugar, fructose, glucose and sucrose of Cuiguan and Huangguan planted in plastic tunnel were also higher than they planted in open field. But the total phenol content and antioxidant activity of Cuiguan and Huangguan planted in plastic tunnel were lower than they planted in open field. Fruit firmness of Cuiguan and Huangguan planted in plastic tunnel was lower than they in open field. Thus fruit titratable acid content of Cuiguan planted in plastic tunnel was lower than they planted in open field, and the content of VC of Huangguan planted in plastic tunnel was little than they planted in open field.The relationship among the fruit diameter, fresh weight, dry weight, fruit volume and fruit area:fruit fresh weight was linearly correlated with volume, other indices showed power regressions, correlation coefficients are all above 0.9. And the correlations between fruit transverse diameter with volume, area and fresh weight were all above 0.99, higher than those of longitudinal diameter. The variation of fruit volume and the days of fruit development accord with the cubic curve, the correlation coefficient are all above 0.9. The fruit development showed lacking of uniformity, presenting growing fast at night, while growing poorly or negatively in the daytime. The fruit growth rates of Cuiguan and Huangguan is 2.16cm3·d-1 and 1.10 cm3·d-1 during Young fruit stage daily. The growth rates of fruit formation stage significantly increased compared with young fruit stage, the daily growth rates of Cuiguan in plastic house, Huangguan in plastic house,Huangguan growing naturally and Cuiguan growing naturally are 2.1 times,5.0 times,4.1 times and 4.8 times than that of young fruit stage. The fruit daily growth variation negatively correlated with the daily temperature variation, while positively correlated with the relative humidity of the atmosphere variation.