Relationship Between Basal Internode And Lodging Of High-yield Wheat During Its Later Growth Period

The main target of wheat breeding is to increase yield per unit on the basis of high yield. This is also the only way of wheat yield development. As the wheat yield increases constantly and the production conditions improve,the conflict between high yield and lodging stands out increasingly. It restricts seriously high yield and super-high yield of wheat. Therefore, we must resolve the lodging problem first in order to realize the span from high yield to super-high yield. The lodging resistance is the precondition of super-high yield. So it is very important to study further wheat lodging and to discuss the relationships between lodging and internode length, stem intension and so on. Then the study has the immensely guiding role for confirming breeding goal of super high yield and breeding efficiency. The high-yield wheats 0482, 0436, 9540, 9651 were regarded as materials. We analysed their tissue structures, fracture resistances, indexes of plant height. The results were as follows:(1)During the later period, we detected respectively 1000-grain weight, grain number, spike length, length of the second internode of basal stem and fracture resistance. The result indicated that 0482>0436>9651>9540 in 1000-grain weight; 0482> 9540 > 0436>9651 in grain number; 9540> 0482> 0436> 9651 in spike length; 9540>0436>9651>0482 in length of the second internode of basal stem. The correlation coefficients of fracture resistance and spike length, 1000-grain weight, grain number and length of the second internode of basal stem increased in turn. The lodging resistance force of 0436, 9540, 9651, 0482 expanded in turn.(2)There were the consistent performances as for plant height and internode length. Namely, the total lengths of internodes of the lodging plants were longer than that of un-lodging plants. And the proportion between length of peduncles and total internodes was greater than that of the un-lodging plants. The proportion between the spike and peduncle length and the plant height were greater than that of the un-lodging plants too. Comparatively, the longer peduncles were propitious to improve lodging tolerance. Gravity center height of the lodging plants was higher than that of un-lodging plants. So the higher gravity centers were not propitious to lodging resistance. The gravity center rises too as the plant grows. Then the arm of force can augment and the moment of outside force may augment too. The lodging phenomenon can occur when the moment of outside force beyond the moment of lodging resistance force.(3)The indexes of plant height of un-lodging plants (I) were greater than that of lodging plants in the same wheat. Namely, the lengths of the peduncles (L1) and penultimate internodes (L2) were greater. At the same time, the indexes of other internodes length (I1, I2, I3, and I4) in the un-lodging plants were greater than that of lodging plants. And their differences were significant or very significant. Lodging tolerances were stronger when the indexes of plant height were higher. For example, the index of plant height of the wheat 0482 was greater, and then lodging tolerance was also stronger. Therefore, we ought to research further whether lodging tolerance largens more strongly when the index of plant height largens.(4)According to the second internode of basal stem, we carried on freehand section. The results were as follows:the total number of vascular bundle of 0436, 9540, 0482, 9651 increased in turn; the area and perimeter of the single vascular bundle were shown as 0482>9540>9651>0436. They were related differently with lodging tolerance. The results were as follows: more vascular bundles, much bigger areas and perimeters of the single vascular bundle, then much stronger fracture resistance in the wheat 0482; less vascular bundles, much smaller areas and perimeters of the single vascular bundle, then much smaller fracture resistance in the wheat 0436. (5)As to mechanical tissue of basal stem, the correlation coefficient of lodging tolerance with thickness of mechanical tissue of basal stem was greater than that of lodging tolerance with number of cell layer. The former was 0.9599 and latter was 0.8180. In total there was significant positive correlation each other. The results showed much thicker mechanical tissue, much greater number of cell layer, and then much stronger fracture resistance in the wheat 0482; much thinner mechanical tissue, much smaller number of cell layer, then much smaller fracture resistance in the wheat 0436.(6) As to physiological aspects, the activity of peroxide enzyme and root activity were greater correspondingly and the contents of proline, soluble sugar and soluble protein in the un-lodging wheats were greater than that of lodging wheats.