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Title: EFFECT OF PLANTING DATE AND CULTIVAR ON GROWTH, STALK YIELD, AND BAST AND CORE FIBER LENGTH OF SUNN HEMP

Author
item Cook, Charles
item SCOTT, ANDREW - RIO FARMS, INC.
item CHOW, POO - UNIV. OF ILLINOIS

Submitted to: Journal Of Industrial Crops And Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sunn hemp (Crotalaria juncea L.) has potential to be grown as an annually renewable, nonwood fiber source for industrial use. A two-year study was conducted in the Lower Rio Grande Valley of Texas to determine the effects of four planting dates (2-wk intervals) and two cultivars (Tropic Sun and PI248491) on stalk height, basal stalk diameter, and total stalk yield. Delayed planting generally reduced yield, especially if planting was delayed by four weeks or longer. Tropic Sun, a Hawaiian cultivar, produced significantly greater yields across the two-year study than the Brazilian plant introduction, PI248491. Plant height consistently showed a strong, positive correlation with stalk yield; whereas, the association between basal diameter and stalk yield was weak and erratic. Results indicated that selecting for plant height could be an easy, less time consuming selection for improving stalk yield. Single year results from the fiber analyses conducted in 1995 indicated that bast and core fiber lengths were not significantly affected by planting date; however, bast fiber length was shortest in the last planting date. Sunn hemp cultivars are generally short-day for flowering response; therefore, delayed plantings, which shorten the growing season, could result in lower stalk yields.

Technical Abstract: Due to the accelerated harvesting of forest resources, there is an international need to identify alternative fiber sources to meet the increasing consumer demands. Sunn hemp (Crotalaria juncea L.) has potential as an annually renewable, nonwood fiber source for industrial use. A two-year study was conducted in the Lower Rio Grande Valley of Texas to evaluate the effects of four planting dates (2-wk intervals) and two cultivars (Tropic Sun and PI248491) on stalk height, basal diameter, and dry matter yield. Results indicated that delayed planting generally reduced yield, especially when planting was delayed by four weeks or longer. The Hawaiian cultivar, Tropic Sun, produced the greatest yield across the two-year study averaging 2.2 Mg ha-1 more stalk yield than the Brazilian plant introduction, PI248491. Plant height consistently showed a strong, positive correlation with stalk yield; whereas, the association between basal diameter and stalk yield was generally weaker and often erratic. Single year results from the fiber analyses conducted in 1995 indicated that bast and core fiber lengths were not significantly affected by planting date; however, bast fiber length was shortest in the last planting date. Since most sunn hemp culivars have short-day flowering response, planting delays will shorten the growing season and could result in lower stalk yields.