Effect Of N Split Ratio On Cotton Growth,Dry Matter And Nitrogen Accumulation

Cotton plays an important role in our national economy but it is not realistic to improve the yield through the expansion of the planting area. There is an effective way relying on the cultivation of technical improvement to promote the cotton industry. The nitrogen fertilizer plays an important role in the yield and quality of cotton, so we often increase the nitrogen fertilizer application to improve the cotton production. But if the nitirogen is excessive, it not only causes the environmental pollution, wastes the resources and reduces the fertizlizer utilization, yet the effect of increasing the yield is not significant. It shows that the nitrogen fertilizer is not the minimum factor of increasing the cotton yield. The test is trying to adjust the nitrogen (300kg/hm2) points of the proportion of the single application, to explore the effect of cotton production.By using Huazamian H318as the materials, field and pot trials the same period in the way of seedling transplanting, study the same amount of nitrogen(300kg/hm2) fixed proportion of30%in first bloom application under the premise of different proportion of nitrogen application(Pre-plant application:First bloom application:Peak bloom application;N07,0:3:7;N16,1:3:6;N25,2:3:5;N34,3:3:4;N43,4:3:3;N52,5:3:2). The results showed that:1. Effects on cotton growth process. Pot and field trials show that, the cotton growth period variation is same of different treatments. With the ratio of N fertilizer is increase in third time, the seedling, squaring will be shorten, and the boll setting will be extended.2. Effects on yield and its component factors of cotton. As the ratio of N fertilizer is increase in third time, first the bolls number, boll weight, lint percentage and cotton yield will be improved, then there will be decline. All of the bolls number, boll weight, lint percentage and the seed cotton yield, N34is the highest, and N52is the lowest.The boll number, boll weight, lint percentage and seed cotton yield of potted cotton, N34and N52has significant, N34increased by68.1%,18.7%,18.3%and100%. N07. N16、N25、N34、N43have no significant.In2011, except N25, N34has significant with other treatments of pot cotton. N34compraing with N07, N16, N43, N52, bolls numbers is increased by33%,36%,27%,51%; lint percentage is increased by17%,12%,14%,22%; seed cotton yield is increased by42%,37%,28%,58%. The field cotton in2011, there has no significant among other treatments. The boll number of N34, N43have significant with the N07and the boll number is increased by12%and10%, the rest has no significant. The lint percentage of N34has significant with the N25and N34is increased by6%, and the rest has no significant. Seed cotton yield of N34, N43has significant with N07, there are increased by23%and19%, and the rest has no significant.3. Effects on physiological characteristics of cotton. The change trend is basically the same of all treatments. Chlorophyll content of functional leaf in the whole growth period showed "down-rise-down", when the nitrogen fertilizer is higher, chlorophyll content is also higher. The nitrogen is less before, more middle and late more, the chlorophyll can maintain the high levels.Soluble protein content and soluble sugar content can reach the peak in the64days after emergence, then drop. In the79days after emergence before,"larger percentage of the late N" treatments are higher than "larger percentage of the early N" treatments.79days after emergence later,"larger percentage of the late N" treatments soluble protein content and the content of soluble sugar decrease more quichly than "larger percentage of the early N" treatments. So "larger percentage of the early N" treatments are higher than "larger percentage of the late N" treatments.4. Effects on dry matter accumulation of cotton. The growth and development of the same treatment, that the whole growth process showed "slow-fast-slow", it can be fitted with the Logistic equation. Different treatments of dry matter accumulation, vegetative organ is always more than reproductive organ. In the fast accumulation period: start time vegetative organ is earlier than reproductive organ; Termination time reproductive organ is earlier than vegetative organ; length of time the vegetative organ is longer than reproductive organ; The biggest rate and average rate, except the N07and N16reproductive organ> vegetative organ.As the ratio of N fertilizer is increase in third time, first K is increased, then decreased. In the fast accumulation period:"larger percentage of the late N" treatments start earlier and lasts for longer, but the average rate and maximum rate are smaller;"larger percentage of the early N" treatments start later and last for shorter, but average rate and the maximum rate are faster. The characteristic value, N34is always the biggest, and N52is always the smallest. 5. Effects on nitrogen accumulation of cotton. Nitrogen accumulation also can be fitted with the Logistic equation. It is different from the dry matter, reproductive organ is always more than vegetative organ. The ratio of the content is about1.23-1.37. In the fast N accumulation period:start time, termination time reproductive organ is earlier than vegetative organ, and length of time the vegetative organ is longer than reproductive organ.All the treatments, in the fast accumulation period:"larger percentage of the late N" treatments start earlier and last for longer, but the average rate and maximum rate are smaller;"larger percentage of the early N" treatments start later and last for shorter, but average rate and the maximum rate are faster.6. Effects on nitrogen utilization efficiency. N fertilization ratio on partial productivity and N biomass efficiency index influence is bigger, reasonable proportion of nitrogenous fertilizer (3:3:4) can increased by100%and62%. Respectively, and the N yield efficiency index the impact is not big.