Effects Of Temperature And Fertilization On Rice Quality And Studies On The Enzyme Dynamic Status And The Microstructures Of Rice Endosperms

Using difference varieites with varied quality as materials, effects of fertilization and temperature in ripening period on rice quality and the enzyme dynamic status were studied. The microstructures of endosperms before and after gelatinization and that of the four fractions which have been isolated by chemical methods were observed with scanning electron microscopy. The results were as follows.1 Variations of varieties or quality traits under varied temperature are different. Chalkiness and head rice rate possess the largest C.V., are named sensitive trait for temperature. Grain length, kernel shape, brown rice rate and milled rice rate possess the minor C. V., are named slow-witted trait for temperature. Other traits are named middle trait. Superior variety possess desirable C. V. because of little chalkiness while the inferior variety possess minor C. V. because of big chalkiness. All of the temperature factors during ripening period taken great roles for rice quality. The first part includes daily average temperature, daily average highest temperature, daily average lowest temperature and daily average temperature variation, are called average temperature factor. The second part include accumulate daily average temperature, accumulate daily highest temperature, accumulate daily lowest temperature and accumulate daily average temperature variation, are called accumulate temperature factor. The influence of average and accumulate temperature factor have a little change in view of different varieties. All of the items in each factor have the same influence direction. Higher daily average temperature index cause the better rice quality. The quality of appearance, milling, nutrition and cooking take great roles in rice quality by principal component analysis and correlation analysis. Their contribution ratios are 45.54%, 19.06%, 12.17% and 9.16%. The affection of different varieties and seasons for quality are general for each trait. The better rice possess high head rice rate, little chalkiness, good cooking quality and middle protein content. Correlation analysis show that brown rice rate have notable or very notable directly proportion with milled rice rate, kernel length and amylose content, but it has notable inversely proportion with length/width of grain. Head rice rate have notable directly proportion with gel consistency and protein content. Chalky rice rate has notable directly proportion with chalkiness, have notable inversely proportion with length/width of grain and protein content. Kernel length has notable directly proportion with rate of length/width, have notable inversely proportion withprotein content. Gelatinization temperature has notable directly proportion with protein content, have notable inversely proportion with amylose content. Amylose content has notable directly proportion with protein content. The multiple correlation coefficients of eleven items are all significant at 1% level.2 The grinding quality is polished, amylose content is improved and gel consistency is extended by spraying fertilizer solution during ripening period while the chalkiness is increased. The optimal nitrogen quantity for the best quality planted in early season is more than of the late season. For using the forte of improving grinding, cooking and nutrition quality, avoiding the weakness of increasing chalkiness, little chalkiness variety should be selected when adding the nitrogen quantity. Heavy basis fertilizer is best for the rice quality planted in early season because it coincide with its characters while heavy spike fertilizer is best for the rice planted in late season because of coinciding with its characters. Adjusting the rice quality by applying time and quantity of nitrogen is correlation with whether it could be coincided with the characters of different varieties or seasons. Little chalkiness variety is the key element of adjusting rice quality by nitrogen because it always increasing with the polishing of grinding, cooking and nutrition quality. Variations of grinding quality a...