Physiological Basis For Yield Differences In Peanuts Arachis Hypogaea L

Author : Robert Luther McGraw
Publisher :
ISBN 13 :
Total Pages : 298 pages
Book Rating : 4.:/5 (627 download)

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Download or read book Yield Physiology of Peanuts (Arachis Hypogaea L.) written by Robert Luther McGraw and published by . This book was released on 1979 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific breeding of peanuts was initiated in 1928 at the University of Florida. Since that time the potential yield has more than doubled due to the release of four improved cultivars. These cultivars were Dixie Runner released in 1943, Early Runner released in 1952, Florunner released in 1969, and Early Bunch released in 1977. No previous attempt had been made to discover the physiological differences among the four cultivars that accounted for the large increase in potential yield. A growth analysis was conducted during the 1976 growing season at the University of Florida using the four Florida cultivars, a Spanish type peanut, and one soybean cultivar (Glycine max L. Merr.) There were two major physiological differences among the four Florida cultivars which were responsible for the majority of the potential yield increase. The new higher yielding cultivars reached a stable pod number earlier. Dixie Runner reached a stable pod number about day 105, Early Runner about day 96, Florunner about day 84, and Early Bunch about day 75. By early initiation of a full pod load the newer cultivars had a longer period in which to fill the last pods established. The major difference among the cultivars which resulted in the increased yield potential was a higher partitioning of assimilates to the reproductive portion of the plant in the higher yielding cultivars. Dixie Runner partitioned about 31% of its photosynthate to the pods, Early Runner 61%, Florunner 74%, and Early Bunch 85%. As the amount of photosynthate partitioned to the reproductive portion of the plant increased, the plants demonstrated an increased deterioration of the vegetative portion late in the filling period. The highest yielding peanuts more closely resembled the n self destructive" characteristics of the determinate soybean. In 1977 22 of the highest yielding genotypes from 11 different countries were analyzed to determine if they had similar characteristics to the high yielding Florida cultivars. The environment markedly affected the development of some of the genotypes which were bred for different climates. The harvest date and partitioning factor were found to be positively and significantly correlated to yield. The study indicated that in some of the cultivars yield may be increased by increasing the filling period and/or partitioning factor. In 1978 a high yielding Florida cultivar, Florunner, and a lower yielding Florida cultivar, Dixie Runner, were analyzed to determine if the canopy deterioration demonstrated by the high yielding cultivars late in the season was the result of increased remobilization of nutrients and assimilates from the canopy to the pods. Florunner was found to increase the remobilization of nitrogen and starch during the filling period. The increased remobilization of materials from the vegetative portion may be responsible for the increased canopy deterioration. No effect of the filling period on the remobilization of nitrogen and starch was found in Dixie Runner. A shading study conducted on Florunner provided evidence that the pods may have priority over the vegetative portion for assimilates and nutrients. Shading increased the remobilization of materials from the leaves and hastened the deterioration of the canopy.