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Effect of Nitrogen Solution on the Germination of Shattercane

1980; Kansas Academy of Science; Volume: 83; Issue: 2 Linguagem: Inglês

10.2307/3627719

1938-5420

J. Y. Yayock, R. L. Vanderlip, O. G. Russ,

Seed Germination and Physiology

Shattercane is a serious weed problem for many Kansas farmers. After reports that liquid nitrogen solution (urea ammonium nitrate) applied during late fall reduced infestations, two experiments were conducted to determine the potential of that practice for controlling shattercane. Nitrogen rates of 0, 110, 220, and 440 kg N/ha were applied to samples of seeds that were then allowed to remain under natural conditions up to 150 days. Shattercane emergence was not affected by nitrogen rates through 220 kg N/ha, so rates in a second trial were 0, 220, 440, and 660 kg N/ha and the seed samples then were stored at -10 C, 3 C, or 29 C. Seed germination was reduced but only the 660 kg N/ha rate gave valuable reduction, so nitrogen solution applied at normal rates (220 kg N/ha or less) would not be expected to effectively reduce stands. Shattercane (Sorghum bicolor (L.) Moench), also known as wild cane and black amber, is a serious weed in many corn, soybean, and sorghum fields. It probably is the result of natural crossing of diverse sorghum types within cultivated sorghum. The name shattercane comes from the characteristic early shattering of the seed before the cultivated crop is harvested. Crop yield losses of 40% under natural conditions (Burnside, 1973) and up to 95% under controlled conditions (Vesecky et al., 1973) have been reported. Shattercane seed has been reported to remain viable under field conditions for three to ten years (Burnside, 1965; Nilson, 1970; and Jacques et al., 1974). Casual observations indicated that when infested fields were fertilized with urea-ammonium nitrate (UAN) solutions during late fall infestation the following spring was reduced. This could be due either to direct reduction in germination because of the nitrogen or because of reduced dormancy of the seed resulting in fall germination and winter killing of the seedlings. Nitrogen placed directly with sorghum seed has 1 Contribution No. 80-134-J. This content downloaded from 157.55.39.246 on Tue, 27 Sep 2016 04:20:09 UTC All use subject to http://about.jstor.org/terms VOLUME 83, NUMBER 2 87 been shown to decrease stands by 36 and 78 percent under good and limited surface soil moisture conditions, respectively (Thompson, 1974). Germination of seed was 53, 84, and 90 percent at 3 days, 5 and 12 months after seed harvest, respectively, indicating the presence of dormancy immediately after harvest (Burnside, 1973). Nitrate solutions have been used to promote germination of dormant seeds (Toole et al., 1956). Treatment with potassium nitrate was shown to double the percent germination of Johnson grass (Sorghum halepenses) (Taylorson and McWhorter, 1968). Field applications of nitrogenous fertilizers have also been shown to hasten emergence of wild oats, thereby increasing the possibility of control through early cultivation (Watkins, 1966; Sexsmith and Pittman, 1963). The objective of this study was to determine if applications of liquid nitrogen (UAN) could be used to assist in controlling shattercane. MATERIALS AND METHODS Experiment 1. One hundred seeds were placed on the soil surface in plastic cups on 3 November 1972. On 10 November a urea-ammonium nitrate (UAN) solution was sprayed on the surface of the soil at rates of 0, 110, 220, and 440 kg N/ha and immediately worked into the soil in half of the cups to simulate a tillage operation. Cups containing the seed were allowed to remain in the field and 3 replicates of each treatment taken in for determination of emergence under favorable growing conditions 0, 7, 30, and 150 days after nitrogen application. Experiment 2. Nitrogen (UAN) rates of 0, 220, 440, and 660 kg N/ha were applied to seed and the seed then stored at three temperatures, -10 C, 3 C, and 29 C. Triplicate 100-seed samples were germinated according to standard germination procedures at 0, 7, 21, 35, 49, and 63 days after nitrogen application. RESULTS AND DISCUSSION Shattercane emergence was not affected by UAN nitrogen rates up through 220 kg N/ha (Table 1). The 440 kg N/ha rate resulted in significant Table 1. Effect of nitrogen rate on emergence. N rate, kg/ha % Emergence 0 32.4 110 33.9 220 30.0 440 25.9 LSD (.05) 7.4 This content downloaded from 157.55.39.246 on Tue, 27 Sep 2016 04:20:09 UTC All use subject to http://about.jstor.org/terms 88 TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCES Table 2. Effects of tillage and time after nitrogen application on emergence. % Emergence Days after application Tilled Not tilled 0 45.9 41.1 7 37.6 43.2 30 26.8 38.4 150 4.7 6.7 LSD (.05) 7.9 reduction in percent emergence as compared to the 110 kg N/ha rate (Table 2). Effect of tillage on emergence depended upon the time after application of the nitrogen solution. Where the soil was tilled, each succeeding sampling date showed a significant reduction in percent emergence. Where the soil was not tilled there was no change in percent emergence through the first 30 days following application. The extremely low emergence figures for 150 days following application are a combination of loss of seed viability and physical loss of seeds because of extremely heavy rains. The nitrogen rate by tillage interaction was not significant indicating that the effects of nitrogen on emergence could not be changed by a tillage practice. These results indicate that nitrogen solution applied at normal rates would not be effective in reducing stands. Shattercane seed germination was significantly reduced by application of nitrogen solutions at all three temperatures and at each time sampled after