Abstract
This study was aimed at evaluating the effect of different planting dates on the panicle growth trend (length, weight, and branches of panicle) and the performance of rice varieties in the north of Khuzestan province with east latitude of 48 o: 28 ◌َ and north longitude of 31 o: 50◌ executed as spilt plots in the form of randomized complete blocks with three repetitions. Main factor was the date of planting at three levels (June 5th, June 20th, and July 5th) and the secondary factor includes the varieties of red Anbori (tall and short grains), and Champa. Results indicated that the maximum performance of the seed, floret in panicle, and weight belonged to the date of July 5th and the maximum length of panicle and branches, without significant difference, be longed to the second date of planting. evaluating the growth trend, maximum increase (rate of growth) of the dry weight and number of floret was due to the more-appropriate heat and the reduction of sterility as well as a more demand for non-structural carbohydrates (unlike the planting date of June 5th) in the planting date of July 5th, but the length of panicle had its most growth rate in the first two planting dates, while the number of branches was not affected by the date of planting. Among the varieties, Champa , with an average of 3795/4 kg/ha , had the maximum efficiency . Based on the results of this study, by focusing on the modifying objectives to increase the dry weight of the panicle, because of its positive and high correlation (0/759**), increase of the rice seed`s efficiency can be hopefully predicted.Keywords: dates of planting, rice, growth trend, panicle
Highlights
Rate of the yield growth at the developing stage affect the rice seed performance, its amount, two weeks before heading, has critical effects on the final rice seed performance, so maximizing its amount during this period is one of the important managerial and modifying objectives to achieve the maximum seed (Horie et al, 2003)
This study was aimed at evaluating the effect of different planting dates on the panicles trend of changes and performance of rice varieties at Khuzestan conditions in order to identify the physiologic reaction of the tolerant or heat-sensitive mechanisms in addition to provide functional properties to modify the planted rice varieties and the role of the studied properties in increasing the performance
This is due to the varietiesgenotypic differences as, depending on the rice different genotypes, panicles with shorter length, but more compact, can reduce breathing and increase the efficiency of water use because it is the distal part with maximum presence in different heat conditions
Summary
Rate of the yield growth at the developing stage affect the rice seed performance, its amount, two weeks before heading, has critical effects on the final rice seed performance, so maximizing its amount during this period is one of the important managerial and modifying objectives to achieve the maximum seed (Horie et al, 2003). Erfani and Nasiri (2000), studying some of the morphologic and physiologic properties affecting the seed of rice varieties, stated that the leaf surface index in the modified varieties was more than the native varieties during the growth stage especially at flowering. Gilani (2010), evaluating the trend of panicle filling, resulted that the increase of the panicles dry weight at delayed planting date (2/25), because of the appropriateness of the growth conditions, was more than the previous plantings. This study was aimed at evaluating the effect of different planting dates on the panicles trend of changes and performance of rice varieties at Khuzestan conditions in order to identify the physiologic reaction of the tolerant or heat-sensitive mechanisms in addition to provide functional properties to modify the planted rice varieties and the role of the studied properties in increasing the performance
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