【作者】 龚双军；

【导师】 李国英；

【作者基本信息】 石河子大学 ， 植物病理学， 2005， 硕士

【摘要】 新疆是我国最主要的棉花生产基地。但是由于其特殊的地理位置,春季气候多变,常有明显的倒春寒,每年都有因烂种、烂芽、死苗,导致大面积毁种、重播的现象。对其有各种各样的解释,如棉苗病害造成、除草剂药害所致、品种因素有关,种衣剂使用不当造成等等,众说不一。因此,有必要对这些问题进行一次比较系统地研究,以便更好地为生产服务。 通过室内和田间试验证明,不同品种对立枯丝核菌的抗性和对低温的抵抗性均存在明显差异。且品种苗期抗寒性和对立枯丝核菌的抗性存在明显一致性。即苗期抗寒性强的品种对立枯丝核菌的抗性也较强。如供试品种中新陆早10号、150-1、夏9的抗寒性最差,对立枯丝核菌的抗性也较差;而新陆早13号、中棉36号、系9等的抗寒性较强,其对立枯丝核菌的抗性也较强。这与农业生产中前三个品种或材料早播最易造成烂籽、烂芽和大面积毁种重播的情况相符。故农业生产中应将抗性强的品种适当早播,抗性较差的晚播,切忌露白期遇低温,以免引起大量缺苗断垄,从而造成不必要的经济损失。 查明禾耐斯除草效果和对棉苗生长的不良影响与混土深度、除草剂用量、土壤质地、土壤温度、土壤湿度密切相关。由于该药以位差选择为主,一般表面喷施不仅可取得良好的除草效果,还不易产生药害,若棉种处于药土层中或接近药土层则易造成药害发生,故一般情况下应整地后喷药播种或喷药后轻耙播种。近年来在新疆棉花生产中改革力度较大,如滴水出苗、膜上点播等,这些措施都与土壤表层的湿度密切相关。大量试验说明,农业措施的改变,常对除草剂的除草效果和对作物的不良反应产生重大影响,对此必须给予高度重视,为避免发生不良反应,建议对于滴水出苗的棉田,地下水位较低棉田沙质土壤等使用除草剂的下限用量。切忌因施不当引起大量烂种、烂芽和死苗。 目前福多甲和卫福种衣剂是北疆棉区应用较多的种衣剂,经对包衣种籽进行发芽试验、小区接菌试验和大田防治试验,查明福多甲单剂和卫福单剂包衣对棉籽的发芽率和出苗率都没有不良影响,一般情况下可提高出苗率10%左右。与3911混用后,其出苗率不如单剂,但好于敌克松拌种。从对棉苗病害的防治效果来看,福多甲明显好于卫福,这与以往调查卫福能较好防治烂种,但对防治出苗后的烂根病效果较差是一致的。因此福多甲种衣剂仍是目前北疆棉区棉种处理的首选种衣剂。另外还查明,2004年春季播种的种子硬籽率较高,与种衣剂无关,主要与2003年秋季遇低温,种子成熟度较差有关。更多还原

【Abstract】 Xinjiang is the main cotton production base of china. In spring, the climate is complex and multivariable, strong cold air usually occurs repeatedly and causes cotton seedling dead in large area, sometimes even over-sowing. There exist various explain for these phenomena, such as cotton seedling disease, drug injury of herbicide, varieties discrepancy, the improper usage of seed coating and so on, so it is necessary to study the reasons of cotton seedling death and make foundation for cotton production.Based on the experimental results in pot and field, it was found that the cotton variety to Rhizoctonia solani and chilling was significantly different, and there was a distinct coherent in resistance of the cotton varieties to Rhizoctonia solani and chilling. Xinluzao No.10, Xia 9 and 150-1 to Rhizoctonia solani and chilling were most susceptible, if these varieties were sowed early, they would be attacked by continuous low temperature and often resulted in sprouts or seed rot, even seedling dead. But the cotton varieties of "CCRI36", Xinluzao No.13, and Xi9 had high-level resistance to Rhizoctonia solani and chilling. So, the cotton varieties of higher resistance could be sowed a little earlier, while the lower resistance could be sowed later.In addition to Rhizoctonia solani and low temperature could cause cotton seed rot and seedling death, it was found herbicide could also cause cotton seed rot and seedling death, and the effect was most related to the herbicide-Acetochlor dosage, the depth, soil humidity, soil temperature, and soil character. The depth of herbicide in soil was critical for weed control. Spraying Acetochlor on the soil surface had good controlling effect and cause less drug injury. But when the soil layer including Acetochlor was near cotton seed, the drug injury occurred usually. So in field we should sow or harrow after spraying herbicide in soil surface. Recent years in Xinjiang, the cultivation methods were changed greatly such as sowing on the mulching film, seedling with dewing. These reforms had close relations to soil humidity. So, in order to avoid herbicide injury, a lower dosage should be applied for drop irrigation field, the fields with lower water level or the sandy soil.Recently, the seed coating of Fu Duojia and WeiFu were wide applied in the north of Xinjiang. Based on seed germination test, inoculation test and control test in the field, it was showed FuDuojia and WeiFu had not bad effect on the seedling and budding germination percent, but even could increase seedling germination to 10% usually. Mixed Fu Duojia and WeiFu with 3911 reduced the seedling germination compared with that of using Fu Duojia and WeiFu singly, but increased compared with that of using DiKesong. Fu Duojia is superior to the WeiFu on the control of the seedling disease. WeiFu had a good effect on the control of seeds rot, but the effect to cotton seedling damping-off was less than Fu Duojia. At present, in north of Xinjiang, we firstly suggested to use FuDuojia for seed coating. Furthmore, we found out there were more seed sprouted-later in spring of 2004 than ever, after investigation it was found that the phenomena had no relation to seed coating. The main reasons were related with cotton seed maturity and low-temperature in fall of 2003.更多还原