Studies On The Physiological Characteristics Of Resource, Sink And Flow And The Microstructure Or Ultrastructure Changes Of Kernels During The Process Of Kernel Development In Wheat (Triticum Aestivum L.) Cultivars (Lines)

Some physiological characteristics of photosynthetic resource, nutrient transport and kernel sink formation of 11 wheat cultivars (Triticum aestivum L.)(lines) with different plant heights, spike types and kernel weights were entirely studied, the microstructure and ultrastructure changes of 3 type cultivars (lines) in the development processes of abdominal vascular bundle and kernel sink were systematically observed, and the relationship between the structure and function of vascular bundle and kernel sink was thoroughly probed with the aid of plant physiological and biochemical techniques, biological electron microtechniques, isotope tracer techniques and multivariate statistic analysis. The main results were as follows:There was a significant correlation between the flag leaf assimilation rates (FLAR) at full-bloom stage and yields, and there was an extremely significant negative correlation between the flag leaf net photosynthetic rate (Pn) and the flag leaf area. The cultivars (lines) with small grain, medium or large spike and medium plant height had an obvious advantage in Pn, but the cultivars (lines) with large grain, medium or small spike and medium or high plant height had an advantage in FLAR though their Pn values was low, and assimilated morenutrient substances by the flag leaves per plant than those of other cultivars. The dry matter output ratio of vegetative organs in the cultivars with medium grain, large spike and dwarf plant height was low, and the dry matter stored in spike at maturity stage mostly was contributed by the photosynthetic product that was assimilated after pre-milky stage. The nutrient requiring intensity of spike in dwarf cultivars was stronger than that in other cultivars.The agronomic traits and physiological indexes affecting wheat grain weights could be synthesized to 4 principal components by using Principal Component Analysis. The differences of grain weights among the different cultivars were caused by the principal component values and their co-ordination ways. To increase grain weight, the cultivars (lines) with long grain filling duration, high grain filling rate, and high grain filling rate at the second filling stage must be selected and applied at local production condition. The grain active growth duration of the cultivar (Een No.l) with large and plump grains was long, and the tendency of grain filling and increasing grain weight was vigorous. In contrary, the grain active growth duration of the cultivar (95A-10) with large grain volume but wrinkled grains was short, the supply of photosynthetic product for grain filling was not enough, and the flow of nutrient substances was inhibited. The agronomic traits and physiological indexes affecting wheat yields could be divided into 2 independent factors by using Factor Analysis. The differences of yield levels among the different cultivars were caused by the two factor values and their co-ordination ways. The cultivars (lines) with large grain, medium or small spike and medium or high plant height had large photosynthetic leaf area, strong photosynthetic ability, and enough grain sink capacity at later growth stages. To gain high and steady yields, the relation of carbohydrate and nitrogen nutrient metabolism, and the relation of Sink and Resource must be co-ordinated at wheat cultivation. The cultivars (lines) with small grain, medium or large spike and medium plant height had low light utilization ratio, and weak nitrogen nutrient metabolic capacity, but the yields could be enhanced by increasing spikes per hectare and leaf assimilation area. The cultivars (lines) with medium grain, large spike and dwarf plant height had advantages in nitrogen nutrient metabolic ability and grain sink capacity. To achieve high yields, the early senescence of leaf at later growth stage must be prevented.The observation on the microstructure or ultrastructure of abdominal vascular bundle in caryopsis showed that there was no certainly correlation between diameters or number of sieve elements and grain weight or grain f...