No abstract

Abiotic stress, particularly heat stress, affects various parts of the cotton plant and ultimately impacts the seed cotton yield. Different portions of a single cotton plant of a cultivar exhibit variable responses to stress during reproductive and vegetative phases. To test this hypothesis, physiological and morphological traits related to heat stress were observed for two flowering positions in 13 genotypes of upland cotton. These genotypes were sown in field conditions in triplicate following a randomized complete block design. Data were collected for pollen germination, pollen viability, cell membrane thermostability, chlorophyll content, boll weight, and boll retention for both the top and bottom branches of each genotype. The collected data were analyzed for the identification of variability within and between genotypes for these two flowering positions. Tukey’s test was applied to estimate the significance of differences between genotypes and positions within each genotype. Results showed that the two positions within the same plant statistically varied from each other. The bottom branches of the genotypes performed significantly better for all traits measured except boll weight. The genotype AA-933 performed best for pollen germination and boll retention, while CYTO-608 exhibited maximum pollen viability in both the bottom and top flower positions compared with other genotypes. Overall, MNH-1016 and CIM-602 showed better cell membrane thermostability and chlorophyll content, respectively. This intra-plant variability can be further exploited in breeding programs to enhance the stress tolerance capabilities of the resulting varieties.

Weeds are the undesirable and unwanted plants in the wrong place in a situation that can significantly decrease the yield of desirable plant such as sugarcane. One solution to tackle this problem is the development of herbicide resistant crops like sugar cane that are highly resistant to several herbicides or broad-spectrum herbicides which is done in most cases by genetic transformation, site-directed mutagenesis, and plant breeding. Sugarcane (Saccharum officinarum) is the 2nd vital cash crop of Pakistan, placed at 6th position in world cane acreage and 15th in sugar production. Hence, sugarcane occupies a crucial position in the economy of Pakistan and acts like a backbone in economic development of country. There are several reasons for the lower sugarcane yield in Pakistan but the most important is the large number of weeds that covered most of the area of sugarcane cultivated fields which results in major loss of sugarcane yield in terms of quality and quantity. Broad spectrum herbicide resistant plants are produced to tackle this issue by the insertion of CP4 EPSPS (Glyphosate tolerant gene; 5-enolpyruvulshikimate-3-phosphate synthase from Agrobacterium tumefaciens strain CP4) into sugarcane which provides them the ability to survive after the spray of glyphosate but weeds do not survive in this condition. The most common herbicide resistant technology is Glyphosate resistant technology which gives broad-spectrum weed control feasibility along with the flexibility in the application time of herbicide. There are numerous methods of transformation which are available now-a-days for insertion of foreign DNA into plant cells like Agrobacterium-mediated transformation, micro-projectile bombardment (gene gun) and protoplast transformation. Glyphosate tolerant gene expression is showed by three sugarcane cultivars (CPF-213, SPF-234 and HSF-240). Transgenic sugarcane plants showed these expressions are most stable against herbicide to control weeds. Several farmers in many countries have rapidly and extensively utilized herbicide-tolerant crops due to low production and labour costs, huge profit, increased weed control and many environmental benefits.