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The development of new peanut cultivars (Arachis hypgaea L.) over the past forty years has more than doubled yield potential in the U.S.A. In Australia, few studies have been carried out to understand the physiological differences among peanut cultivars. Even with high agricultural technology, the yield of major food legumes, including peanut, is not very high.
An experiment was conducted in S.E. Queensland to determine growth, dry matter distribution, and solar energy conversion efficiency in nine peanut cultivars.
Red Spanish, TMV 2, McCubbin, Q-18801, Improved Virginia Bunch, Early Bunch, 8718-Virginia, 55-437 and CBR-R5. The growth rates of all cultivars was similar, and therefore the results of only four entries. Red Spanish, Improved Virginia Bunch, Early Bunch and 8718-Virginia, are presented.
Although leaf growth rates were similar among cultivars, the numbers of green leaves and branches per plant differed significantly. Stem growth differed among entries after 71 days after planting (DAP). Early Bunch produced the highest pod yield (830 g m-2) among all entries. Average crop growth rate for 36 to 84 DAP was also similar (22.4 g m- 2 d -1).
The yield differences among entries were due to the differences in dry matter distribution to stem and pod, and hence to different harvest indices. Dry matter distribution to vegetative organs was 63% in Red Spanish and 37% in Early Bunch at the end of the growing season. Root mass per plant was also similar.
The ground was almost completely covered by plants after 71 DAP. There was a positive relationship between leaf area index (LAI) and photosynthetically active radiation (PAR) interception of four peanut entries. Therefore, if the plant intercepted more PAR, more total dry matter would be produced. There were similar efficiencies (3.0-3.6%) in solar energy conversion in these entries as the result of similar LAI, light interception and total dry matter accumulation.
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